Patent Publication Number: US-2023148907-A1

Title: Muscle activity output system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2021-184939 filed on Nov. 12, 2021, incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to muscle activity output systems, muscle activity output methods, and non-transitory storage media. 
     2. Description of Related Art 
     Japanese Unexamined Patent Application Publication No. 10-94577 (JP 10-94577 A) discloses a pedal exercise device that is used in a sitting position. 
     SUMMARY 
     Surface electromyography sensors that measure a myopotential that is an action potential generated during contractile activity of muscle fibers are known in the art. By attaching a surface electromyography sensor to the skin closest to a muscle site to be monitored, the muscle activity of this muscle site can be monitored. 
     However, monitoring of the muscle activity using a surface electromyography sensor has the following problems. A surface electromyography sensor can monitor only the muscle site of the part to which it is attached. Therefore, when it is desired to monitor the muscle activities of a large number of muscle sites simultaneously, a large number of surface electromyography sensors need to be attached to desired parts each time. This is very troublesome. 
     A surface electromyography sensor can also only monitor the muscle activity of a surface muscle. A needle electrode is required to monitor the muscle activity of a deep muscle. However, needle electrodes cannot be used during exercise. 
     The present disclosure provides a technique of being aware of a current muscle activity of each muscle site including deep muscles. 
     A muscle activity output system according to a first aspect of the present disclosure includes: a muscle activity database configured to hold movable part attitude information and muscle activity information in such a manner that the movable part attitude information and the muscle activity information are linked to each other; and a processor. The movable part attitude information indicates an attitude of a movable part of training equipment when an exerciser moves a body of the exerciser along a trajectory defined by the training equipment. The muscle activity information indicates a muscle activity of each of muscle sites of the exerciser. The training equipment being equipment that applies a load to muscles of the exerciser. The processor is configured to acquire the movable part attitude information while the exerciser is moving the body along the trajectory. The processor is configured to acquire current muscle activity information for each of the muscle sites based on current movable part attitude information of the training equipment and the muscle activity database. The processor is configured to output the current muscle activity information for each of the muscle sites. 
     With the above configuration, it is possible to be aware of the current muscle activity of each of the muscle sites including deep muscles. It is therefore possible to check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, it is possible to check whether an exercise the exerciser is performing is an exercise that suits his or her purpose. As a result, an effective exercise is achieved. Moreover, presenting muscles being activated on an exercising human body model to the exerciser allows the exerciser to exercise while paying attention to those muscles. Therefore, the exercise effect can be expected to be enhanced. 
     In the muscle activity output system according to the first aspect of the present disclosure, the training equipment may be a pedal exercise device with which the exerciser performs a pedaling exercise while being in a sitting position. The movable part attitude information of the training equipment may be crank angle information indicating a crank angle of the pedal exercise device. 
     In the muscle activity output system according to the first aspect of the present disclosure, the muscle activity database may be configured to hold the movable part attitude information and the muscle activity information in such a manner that the movable part attitude information and the muscle activity information are linked to exercise condition information indicating an exercise condition of the exerciser. The processor may be configured to acquire the exercise condition information. The processor may be configured to acquire the current muscle activity information for each of the muscle sites based on the current movable part attitude information of the training equipment, the exercise condition information, and the muscle activity database. With the above configuration, it is possible to be accurately aware of the current muscle activity of each of the muscle sites including deep muscles. 
     In the muscle activity output system according to the first aspect of the present disclosure, the muscle activity database may be configured to hold the movable part attitude information and the muscle activity information in such a manner that the movable part attitude information and the muscle activity information are linked to body-specific information of the exerciser. The processor may be configured to acquire the body-specific information. The processor may be configured to acquire the current muscle activity information for each of the muscle sites based on the current movable part attitude information of the training equipment, the body-specific information, and the muscle activity database. With the above configuration, it is possible to be accurately aware of the current muscle activity of each of the muscle sites including deep muscles. 
     In the muscle activity output system according to the first aspect of the present disclosure, the muscle activity information may indicate muscle activities of deep muscles of the exerciser. 
     A muscle activity output method according to a second aspect of the present disclosure includes: acquiring movable part attitude information while an exerciser is moving a body of the exerciser along a trajectory defined by training equipment that applies a load to muscles of the exerciser; acquiring current muscle activity information for each of muscle sites based on current movable part attitude information of the training equipment and a muscle activity database; and outputting the current muscle activity information for each of the muscle sites. The movable part attitude information indicates an attitude of a movable part of the training equipment when the exerciser moves the body along the trajectory. The muscle activity database is configured to hold the movable part attitude information and the muscle activity information in such a manner that the movable part attitude information and the muscle activity information are linked to each other. The muscle activity information indicates a muscle activity of each of the muscle sites of the exerciser. 
     With the above method, since it is possible to be aware of the current muscle activity of each of the muscle sites including deep muscles, it is possible to check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, it is possible to check whether an exercise the exerciser is performing is an exercise that suits his or her purpose. As a result, an effective exercise is achieved. 
     A non-transitory storage medium according to a third aspect of the present disclosure stores instructions that are executable by one or more processors and that cause the one or more processors to perform functions. The functions include: acquiring movable part attitude information while an exerciser is moving a body of the exerciser along a trajectory defined by training equipment that applies a load to muscles of the exerciser; acquiring current muscle activity information for each of muscle sites based on current movable part attitude information of the training equipment and a muscle activity database; and outputting the current muscle activity information for each of the muscle sites. The movable part attitude information indicates an attitude of a movable part of the training equipment when the exerciser moves the body along the trajectory. The muscle activity database is configured to hold the movable part attitude information and the muscle activity information in such a manner that the movable part attitude information and the muscle activity information are linked to each other. The muscle activity information indicates a muscle activity of each of the muscle sites of the exerciser. 
     With the above non-transitory storage medium, since it is possible to be aware of the current muscle activity of each of the muscle sites including deep muscles, it is possible to check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, it is possible to check whether an exercise the exerciser is performing is an exercise that suits his or her purpose. As a result, an effective exercise is achieved. 
     A muscle activity output system according to a fourth aspect of the present disclosure includes: a muscle activity database configured to hold movable part attitude information and muscle activity information in such a manner that the movable part attitude information and the muscle activity information are linked to each other; and a processor. The movable part attitude information indicates an attitude of a movable part of training equipment when an exerciser moves a body of the exerciser along a trajectory defined by the training equipment. The muscle activity information indicates a muscle activity of each of muscle sites of the exerciser. The training equipment is equipment that applies a load to muscles of the exerciser. The processor is configured to acquire body posture information of the exerciser while the exerciser is moving the body along the trajectory. The processor is configured to convert the body posture information to the movable part attitude information. The processor is configured to acquire current muscle activity information for each of the muscle sites based on current movable part attitude information of the training equipment and the muscle activity database. The processor is configured to output the current muscle activity information for each of the muscle sites. 
     With the above configuration, since it is possible to be aware of the current muscle activity of each of the muscle sites including deep muscles, it is possible to check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, it is possible to check whether an exercise the exerciser is performing is an exercise that suits his or her purpose. As a result, an effective exercise is achieved. 
     A muscle activity output method according to a fifth aspect of the present disclosure includes: acquiring body posture information of an exerciser while the exerciser is moving a body of the exerciser along a trajectory defined by training equipment that applies a load to muscles of the exerciser; converting the body posture information to movable part attitude information; acquiring current muscle activity information for each of muscle sites based on current movable part attitude information of the training equipment and a muscle activity database; and outputting the current muscle activity information for each of the muscle sites. The movable part attitude information indicates an attitude of a movable part of the training equipment when the exerciser moves the body along the trajectory. The muscle activity database is configured to hold the movable part attitude information and the muscle activity information in such a manner that the movable part attitude information and the muscle activity information are linked to each other. The muscle activity information indicates a muscle activity of each of the muscle sites of the exerciser. 
     With the above method, since it is possible to be aware of the current muscle activity of each of the muscle sites including deep muscles, it is possible to check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, it is possible to check whether an exercise the exerciser is performing is an exercise that suits his or her purpose. As a result, an effective exercise is achieved. 
     A non-transitory storage medium according to a sixth aspect of the present disclosure stores instructions that are executable by one or more processors and that cause the one or more processors to perform functions. The functions include: acquiring body posture information of an exerciser while the exerciser is moving a body of the exerciser along a trajectory defined by training equipment that applies a load to muscles of the exerciser; converting the body posture information to movable part attitude information; acquiring current muscle activity information for each of muscle sites based on current movable part attitude information of the training equipment and a muscle activity database; and outputting the current muscle activity information for each of the muscle sites. The movable part attitude information indicates an attitude of a movable part of the training equipment when the exerciser moves the body along the trajectory. The muscle activity database is configured to hold the movable part attitude information and the muscle activity information in such a manner that the movable part attitude information and the muscle activity information are linked to each other. The muscle activity information indicates a muscle activity of each of the muscle sites of the exerciser. 
     With the above non-transitory storage medium, since it is possible to be aware of the current muscle activity of each of the muscle sites including deep muscles, it is possible to check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, it is possible to check whether an exercise the exerciser is performing is an exercise that suits his or her purpose. As a result, an effective exercise is achieved. 
     A muscle activity output system according to a seventh aspect of the present disclosure includes: a muscle activity database configured to hold body posture information and muscle activity information in such a manner that the body posture information and the muscle activity information are linked to each other; and a processor. The body posture information indicates a body posture of an exerciser when the exerciser moves a body of the exerciser along a predetermined trajectory. The muscle activity information indicates a muscle activity of each of muscle sites of the exerciser. The processor is configured to acquire the body posture information while the exerciser is moving the body along the trajectory. The processor is configured to acquire current muscle activity information for each of the muscle sites based on current body posture information of the exerciser and the muscle activity database. The processor is configured to output the current muscle activity information for each of the muscle sites. 
     In the muscle activity output system according to the seventh aspect of the present disclosure, the body posture of the exerciser may include a joint angle of a joint of the body of the exerciser. 
     In the muscle activity output system according to the seventh aspect of the present disclosure, the muscle activity information may indicate muscle activities of deep muscles of the exerciser. 
     A muscle activity output method according to an eighth aspect of the present disclosure includes: acquiring body posture information while an exerciser is moving a body of the exerciser along a predetermined trajectory; acquiring current muscle activity information for each of muscle sites based on current body posture information of the exerciser and a muscle activity database; and outputting the current muscle activity information for each of the muscle sites. The body posture information indicates a body posture of the exerciser when the exerciser moves the body along the predetermined trajectory. The muscle activity database is configured to hold the body posture information and muscle activity information in such a manner that the body posture information and the muscle activity information are linked to each other. The muscle activity information indicates a muscle activity of each of the muscle sites of the exerciser. 
     With the above method, since it is possible to be aware of the current muscle activity of each of the muscle sites including deep muscles, it is possible to check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, the exerciser can check whether an exercise the exerciser is performing is an exercise that suits his or her purpose. As a result, an effective exercise is achieved. 
     A non-transitory storage medium according to a ninth aspect of the present disclosure stores instructions that are executable by one or more processors and that cause the one or more processors to perform functions. The functions include: acquiring body posture information while an exerciser is moving a body of the exerciser along a predetermined trajectory; acquiring current muscle activity information for each of muscle sites based on current body posture information of the exerciser and a muscle activity database; and outputting the current muscle activity information for each of the muscle sites. The body posture information indicates a body posture of the exerciser when the exerciser moves the body along the predetermined trajectory. The muscle activity database is configured to hold the body posture information and muscle activity information in such a manner that the body posture information and the muscle activity information are linked to each other. The muscle activity information indicates a muscle activity of each of the muscle sites of the exerciser. 
     According to the above non-transitory storage medium, since it is possible to be aware of the current muscle activity of each of the muscle sites including deep muscles, it is possible to check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, it is possible to check whether an exercise the exerciser is performing is an exercise that suits his or her purpose. As a result, an effective exercise is achieved. 
     According to the above configuration, it is possible to be aware of the current muscle activity of each of the muscle sites including deep muscles. It is therefore possible to check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, it is possible to check whether an exercise the exerciser is performing is an exercise that suits his or her purpose. As a result, an effective exercise is achieved. Moreover, presenting muscles being activated on an exercising human body model to the exerciser allows the exerciser to exercise while paying attention to those muscles. Therefore, the exercise effect can be expected to be enhanced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the present disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein: 
         FIG.  1    is a side view of a pedal exercise device (first embodiment); 
         FIG.  2    is a side view of the pedal exercise device (first embodiment); 
         FIG.  3    is a functional block diagram of a muscle activity output system (first embodiment); 
         FIG.  4    illustrates the relationship between the crank angle and the muscle activity (first embodiment); 
         FIG.  5    illustrates the relationship between the crank angle and the muscle activity (first embodiment); 
         FIG.  6    shows the structure of a muscle activity database (first embodiment); 
         FIG.  7    shows a display example of a touch panel display (first embodiment); 
         FIG.  8    is a flowchart of the operation of the muscle activity output system (first embodiment); 
         FIG.  9    is a functional block diagram of a muscle activity output system (second embodiment); 
         FIG.  10    is a flowchart of the operation of the muscle activity output system (second embodiment); 
         FIG.  11    is a functional block diagram of a muscle activity output system (third embodiment); and 
         FIG.  12    is a flowchart of the operation of the muscle activity output system (third embodiment). 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, the present disclosure will be described based on first to third embodiments. The disclosure in the claims is not limited to the following embodiments. Not all of the configurations described in the embodiments are essential as means for solving the problems. For the sake of clarity, omission and simplification are made in the following description and drawings as appropriate. The same elements are denoted by the same reference signs throughout the drawings, and duplicate descriptions will be omitted as necessary. 
     First Embodiment 
     A first embodiment of the present disclosure will be described with reference to  FIGS.  1  to  8   . In the first embodiment, a pedal exercise device will be described as an example of training equipment. The training equipment is a pedal exercise device (hereinafter sometimes simply referred to as the “exercise device”) for an exerciser to perform a pedaling exercise. A muscle activity output system and muscle activity output method according to the present embodiment perform a process of outputting current muscle activity information of each muscle site including deep muscles during training with the pedal exercise device. The muscle activity output system and the muscle activity output method output, for example, current muscle activity information of each muscle site to an exerciser who performs a pedaling exercise or an assistant who assists the exerciser in the pedaling exercise via a display. The exerciser or the assistant can thus be aware of the current muscle activity of each muscle site including deep muscles. The exerciser or the assistant can therefore check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, the exerciser or the assistant can check whether the exercise the exerciser is performing is an exercise that suits the exerciser&#39;s purpose. As a result, an effective exercise is achieved. Moreover, presenting muscles being activated on an exercising human body model to the exerciser allows the exerciser to exercise while paying attention to those muscles. Therefore, the exercise effect can be expected to be enhanced. 
     An exercise device  100  will be described with reference to  FIGS.  1  and  2   .  FIGS.  1  and  2    show the exercise device  100  as viewed from the side. For the sake of clarity, the following description will be given using a three-dimensional XYZ Cartesian coordinate system. Specifically, the +X direction is an anterior (forward) direction, the −X direction is a posterior (backward) direction, the +Y direction is a superior (upward) direction, the −Y direction is an inferior (downward) direction, the +Z direction is a left direction, and the −Z direction is a right direction. The anteroposterior (front-back) direction, the lateral (left-right) direction, and the vertical (up-down) direction are the directions based on the normal direction of gaze of an exerciser U during exercise. 
     The exercise device  100  can adjust the range of motion of the ankle joint. In the following description, the rotational direction of the ankle joint about the Z axis is referred to as the “plantar/dorsal flexion direction,” and the angle of this rotation is referred to as the “plantar/dorsal flexion angle.” More specifically, the direction in which the toes of a foot FT are moved downward is referred to as the “plantarflexion direction,” and the direction in which the toes of the foot FT are moved upward is referred to as the “dorsiflexion direction.” 
     As shown in  FIG.  1   , the exercise device  100  includes a main body  20 , a link  30 , a crank (movable part)  40 , and a tilted base  50 . A chair  10  is placed behind the exercise device  100 . The exerciser U performs a pedaling exercise while sitting on the chair  10 . The exerciser U performs a pedaling exercise while being in a sitting position. The chair  10  therefore serves as a seating portion on which the exerciser U sits. The chair  10  may be integral with the exercise device  100 , or may be a separate member from the exercise device  100 . For example, the chair  10  may be a chair in a facility or home where the exerciser U is located. That is, the exerciser U or the assistant may place the chair  10  behind the exercise device  100 . 
     The chair  10  includes a seat portion  11  that serves as a seating portion and a backrest portion  12 . The backrest portion  12  supports the back of the exerciser U sitting on the seat portion  11 . That is, the exerciser U can perform a pedaling exercise while leaning against the backrest portion  12 . The chair  10  can be replaced or adjusted for the individual exerciser U. For example, an exerciser U who does heavier load training can use a chair  10  with no backrest portion  12 . Alternatively, the backrest portion  12  may have a reclining mechanism. The angle of the backrest portion  12  may be adjusted by the reclining mechanism. 
     In the exercise device  100 , components attached to the main body  20  are symmetrically. In  FIG.  2   , in order to distinguish between the right and left components, reference signs for the components on the right side of the main body  20  have the letter “R” at the end, and reference signs for the components on the left side of the main body  20  have the letter “L” at the end. For example, in  FIG.  2   , the left tilted base  50  is shown as a tilted base  50 L, and the right tilted base  50  is shown as a tilted base  50 R. Similarly, the left link  30  is shown as a link  30 L, the left pedal  31  is shown as a pedal  31 L, the right link  30  is shown as a link  30 R, and the right pedal  31  is shown as a pedal  31 R. Similarly, the left foot FT is shown as a left foot FTL, and the right foot FT is shown as a right foot FTR. In the following description, the letters “R” and “L” will be omitted when the right and left components are not distinguished from each other. 
     The main body  20  rotatably holds the crank  40 . For example, the main body  20  is provided with a rotating shaft  21 . The crank  40  is connected to the rotating shaft  21 . The crank  40  extends in a direction perpendicular to the longitudinal direction of the rotating shaft  21 . The crank  40  rotates about the rotating shaft  21 . The main body  20  may have a load resistor that applies a load to the rotational motion of the crank  40 . The main body  20  may have a gear etc. that can change the load. 
     The main body  20  is placed on an installation base  15 . The installation base  15  is placed on the floor surface. For example, the front (anterior) part of the main body  20  is located on the installation base  15 , and the back (posterior) part of the main body  20  is located on the floor surface. The installation angle of the main body  20  can be changed by changing the height, position, etc. of the installation base  15 . For example, the main body  20  is placed horizontally by removing the installation base  15 . The installation angle of the main body  20  is made steep by raising the installation base  15 . The posture of the exerciser U during training is thus changed by changing the height of the installation base  15  or removing the installation base  15 . The exerciser U&#39;s joint range of motion by training can thus be adjusted. With or without the installation base  15  is an example of exercise conditions of the exerciser U using the exercise device  100 . 
     The distance between the main body  20  and the chair  10  in the anteroposterior direction may be changed according to the individual exerciser U. For example, the exerciser U can place the chair  10  near the main body  20 . In this case, the exerciser U performs a pedaling exercise with his or her knee joints etc. relatively flexed. Alternatively, the exerciser U can place the chair  10  far from the main body  20 . In this case, the exerciser U trains with his or her knee joints etc. relatively extended. The posture of the exerciser U during training is thus changed by changing the distance between the main body  20  and the chair  10  in the X direction. The exerciser U&#39;s joint range of motion by training can thus be adjusted. The distance between the main body  20  and the exercise device  100  in the anteroposterior direction is an example of the exercise conditions of the exerciser U using the exercise device  100 . 
     The link  30  includes a pedal  31  and a sliding wheel  35 . The crank  40  is connected to the front (anterior) end of the link  30 , and the sliding wheel  35  is connected to the back (posterior) end of the link  30 . The crank  40  and the link  30  are rotatably connected to each other. For example, the link  30  is attached to the crank  40  via a bearing etc. The pedal  31  is attached to an intermediate position on the link  30 . The pedal  31  is a step (footrest) on which the exerciser U places his or her foot FT. The seated exerciser U places his or her foot FT on the pedal  31 . 
     The sliding wheel  35  is attached to the link  30  via a rotating shaft (axle). That is, the link  30  rotatably holds the sliding wheel  35 . The sliding wheel  35  is a sliding member that slides on a tilted surface of the tilted base  50 . 
     The exerciser U performs a pedaling exercise with his or her foot FT on the pedal  31 . That is, the exerciser U moves his or her knee joint, hip joint, and ankle joint so as to step on the pedal  31 . As a result, the crank  40  rotates about the rotating shaft  21 . The angle between the link  30  and the crank  40  changes according to the rotation of the crank  40 . That is, the relative angle of the link  30  with respect to the crank  40  changes according to the rotation angle of the crank  40  (also referred to as the “crank angle”). The crank angle typically means the angle formed between a reference line extending forward (anteriorly) from the rotating shaft  21  and the crank  40 . The sliding wheel  35  moves in the anteroposterior direction while in contact with the tilted surface. The crank  40  and the link  30  therefore rotate with the pedaling motion so that the pedal  31  follows an elliptical trajectory. That is, the exerciser U mainly applies a load to a plurality of muscles constituting the lower leg of the exerciser U by moving the foot FT placed on the pedal  31  along an elliptical trajectory defined by the exercise device  100 . 
     The pedal  31 , the sliding wheel  35 , the link  30 , the crank  40 , and the tilted base  50  are provided for each of the right and left feet FT of the exerciser U. That is, the pedal  31 , the sliding wheel  35 , the link  30 , the crank  40 , and the tilted base  50  are provided on the right and left sides of the main body  20 . The pedal  31 R, the sliding wheel  35 R, the link  30 R, the tilted base  50 R, etc. that are provided on the right side of the main body  20  are for the right foot FTR of the exerciser U. The pedal  31 L, the link  30 L, the tilted base  50 L, etc. provided on the left side of the main body  20  are for the left foot FTL of the exerciser U. 
     The crank  40  is attached to the rotating shaft  21  of the main body  20  so as to be in antiphase between the right and left feet FT. That is, the rotation angle of the crank  40  for the left foot and the rotation angle of the crank  40  for the right foot are shifted by 180°. The exerciser U performs a pedaling exercise by alternately bending and extending his or her right and left legs. 
     The sliding wheel  35  is attached to the lower end of the link  30 . The sliding wheel  35  has a wheel that slides on the tilted surface of the tilted base  50 . The tilted base  50  has a tilted surface that is tilted upward toward the back (posterior). The sliding wheel  35  reciprocates in the X direction (anteroposterior direction) with the rotational motion of the link  30 . As shown in  FIG.  2   , when the exerciser U is pedaling in such a direction that his or her right leg is extended and his or her left leg is bent, the right sliding wheel  35  moves forward (anteriorly) and the left sliding wheel  35  moves forward backward (posteriorly). As shown in  FIG.  1   , when the exerciser U is pedaling in such a direction that his or her left leg is extended and his or her right leg is bent, the left sliding wheel  35  moves forward (anteriorly) and the right sliding wheel  35  moves backward (posteriorly). 
     The height of the sliding wheel  35  changes along the tilted surface of the tilted base  50 . The tilted surface of the tilted base  50  becomes higher toward the back (posterior). That is, the tilted base  50  is an uphill for the sliding wheel  35  moving backward (posteriorly). Therefore, the height of the sliding wheel  35  gradually increases as the sliding wheel  35  moves backward (posteriorly). The height of the sliding wheel  35  gradually decreases as the sliding wheel  35  moves forward (anteriorly). The angle of the link  30  is determined according to the height of the sliding wheel  35 . 
     The angle of the pedal  31  located on the link  30  is limited according to the height of the sliding wheel  35 . That is, the pedal  31  rotates in the plantarflexion direction as the height of the sliding wheel  35  increases. The pedal  31  rotates in the dorsiflexion direction as the height of the sliding wheel  35  decreases. Therefore, the range of motion for plantarflexion and dorsiflexion of the ankle joint can be adjusted according to the tilt angle of the tilted base  50 . The range of motion for plantarflexion and dorsiflexion of the ankle joint can be adjusted according to the rotation angle of the crank  40 . With or without the tilted base  50  and the tilt angle of the tilted base  50  are examples of the exercise conditions of the exerciser U using the exercise device  100 . 
     The exerciser U performs a pedaling exercise with the exercise device  100  for training. That is, the pedaling exercise can place a load on the muscles of the lower limbs and trunk of the exerciser U. The muscles that can be built with the exercise device  100  include rectus abdominis, gluteus maximus, obturator externus, erector spinae, vastus  medialis , vastus  intermedius , rectus femoris, gastrocnemius, adductor  brevis , biceps femoris, gluteus medius, plantaris, soleus, gluteus minimus, popliteus, tibialis anterior, iliacus, psoas major, and quadratus femoris. Of these muscle sites, gluteus medius, plantaris, soleus, gluteus minimus, popliteus, iliacus, psoas major, and quadratus femoris are deep muscles whose muscle activities cannot be measured with an electromyography sensor. 
     Exercise Conditions 
     The exercise conditions of the exerciser U using the exercise device  100  can be adjusted. That is, training can be effectively performed by adjusting various exercise conditions as appropriate. The muscle site that can be built by the pedaling exercise and the load amount to be placed on the muscle site can be adjusted by adjusting the various exercise conditions as appropriate. This allows effective training. The exercise conditions of the exerciser U using the exercise device  100  need not necessarily be set and changed by the exerciser U who trains, but may be set and changed by the assistant who assists the exerciser U in training. The assistant may be, for example, a physical therapist or an occupational therapist. 
     The exercise conditions of the exerciser U using the exercise device  100  can be divided into those related to the exercise device  100  and those related to the exerciser U. 
     The exercise conditions related to the exercise device  100  include, for example, the rotational speed of the crank  40 , the load amount of the crank  40 , and the rotational direction of the crank  40 . For example, a heavy load can be placed on muscles by increasing the rotational speed of the crank  40  or increasing the load amount of the crank  40 . The muscle site on which a load is placed can be changed by changing the rotational direction of the crank  40 . 
     The exercise conditions related to the exercise device  100  include physical quantities that define the geometrical arrangement of the exercise device  100 . Such exercise conditions include the distance between the chair  10  and the main body  20  in the anteroposterior direction, the installation angle (tilt angle) of the main body  20 , the tilt angle of the pedal  31 , the tilt angle of the tilted base  50 , and the position of the tilted base  50  in the anteroposterior direction. The range of motion angle of the ankle joint can be changed according to the position of the tilted base  50  in the anteroposterior direction and the tilt angle of the tilted base  50 . The range of motion angles of the knee joint and the hip joint are also changed by changing the distance between the main body  20  and the chair  10  in the anteroposterior direction, the tilt angle of the main body  20 , etc. That is, the posture etc. during training can be changed by changing these exercise conditions. The muscle site to be built and the load amount to be placed on the muscle site can be adjusted by changing such exercise conditions. 
     The exercise conditions related to the exercise device  100  include with or without the backrest portion  12 . For example, a chair  10  with a detachable backrest portion  12  is prepared, and the backrest portion  12  is removed when the exerciser U does heavy load training. Alternatively, a chair  10  with a backrest portion  12  and a chair  10  with no backrest portion  12  may be prepared, and the chair  10  may be replaced depending on the training. 
     The exercise conditions related to the exerciser U are typically conditions related to the postures and motions of the exerciser U. Specific examples of such exercise conditions include with or without crossed arms and with or without arm swinging motion. For example, the exerciser U can change the exercise conditions by selecting either with or without arm swinging motion while performing a pedaling exercise. Alternatively, the exerciser U can change the exercise conditions by selecting either with or without cross arms. The muscle site to be build can thus be changed according to the posture or motion of the exerciser U. 
     Next, a muscle activity output system  1  will be described with reference to  FIG.  3   .  FIG.  3    is a functional block diagram of the muscle activity output system  1 . As shown in  FIG.  3   , the muscle activity output system  1  includes a muscle activity output device  2  and the exercise device  100 . The muscle activity output device  2  may be implemented by a single device, or may be implemented by distributed processing using a plurality of devices. 
     The muscle activity output device  2  includes a central processing unit (CPU)  2   a  as a central arithmetic processor (processor), a random access memory (RAM)  2   b  that is readable and writable, and a read-only memory (ROM)  2   c  that is only readable, a muscle activity database (DB)  201 , and a touch panel display  202 . The CPU  2   a  reads and executes a control program stored in the ROM  2   c . The control program thus causes hardware such as the CPU to function as a plurality of functional units. 
     The functional units include a body-specific information acquisition unit  203 , an exercise condition information acquisition unit  204 , a crank angle information acquisition unit  205 , a muscle activity information acquisition unit  206 , and an output unit  207 . 
     The muscle activity DB  201  is a database that holds crank angle information (movable part attitude information) and muscle activity information in such a manner that the crank angle information and the muscle activity information are linked to each other. The muscle activity information indicates the muscle activity of each muscle site of the exerciser U. Next, description will be given with reference to  FIG.  4   .  FIG.  4    shows in a graph form the correspondence between the crank angle information and the muscle activity information when the height of the exerciser U is 175 cm, the rotational speed of the crank is 70 rpm, the load amount of the crank is 7 Nm, and the installation base  15  is not installed. The abscissa represents the crank angle, and the ordinate represents the muscle activity. As an example, the data on soleus is shown with markers (circles). As shown in  FIG.  4   , the muscle activity of each muscle site of the exerciser U changes with a change in crank angle. Specifically, the muscle activity DB  201  holds the muscle activity of each muscle site when the crank angle is 120 degrees, the muscle activity of each muscle site when the crank angle is 118 degrees, the muscle activity of each muscle site when the crank angle is 116 degrees, . . . , the muscle activity of each muscle site when the crank angle is 30 degrees, and the muscle activity of each muscle site when the crank angle is 10 degrees. 
     Next, description will be given with reference to  FIG.  5   .  FIG.  5    shows in a graph form the correspondence between the crank angle information and the muscle activity information when the height of the exerciser U is 175 cm, the rotational speed of the crank is 90 rpm, the load amount of the crank is 3 Nm, and the installation base  15  is installed. The abscissa represents the crank angle, and the ordinate represents the muscle activity of each muscle site of the exerciser U. As an example, the data on soleus is shown with markers (circles). As shown in  FIGS.  4  and  5   , when the exercise conditions of the exerciser U using the exercise device  100  change, the correspondence between the crank angle information and the muscle activity information indicating the muscle activity of each muscle site of the exerciser U also changes significantly. Similarly, when the height of the exerciser U changes, the correspondence between the crank angle information and the muscle activity information indicating the muscle activity of each muscle site of the exerciser U also changes significantly. 
     In the muscle activity DB  201 , the correspondence between the crank angle information and the muscle activity information indicating the muscle activity of each muscle site of the exerciser U is therefore held for each exerciser U&#39;s height and each set of exercise conditions of the exerciser U using the exercise device  100 . 
       FIG.  6    illustrates the structure of the muscle activity DB  201 . In  FIG.  6   , the height means the height of the exerciser U. The crank rotational speed, the crank load amount, the crank rotational direction, and exercise conditions  4  to  16  mean the exercise conditions of the exerciser U using the exercise device  100 . Correspondence information is information indicating such correspondence between the crank angle information and the muscle activity information indicating the muscle activity of each muscle site of the exerciser U that can be represented in a graph form as in  FIGS.  4  and  5   . In the example of  FIG.  6   , the muscle activity DB  201  includes data for the height of 145 cm, 150 cm, 155 cm, 160 cm, and 165 cm. However, the muscle activity DB  201  may actually include data for the height of 170 cm, 175 cm, 180 cm, and 185 cm. The muscle activity DB  201  includes data for the crank rotational speed of 30 rpm, 40 rpm, 50 rpm, and 60 rpm. However, the muscle activity DB  201  may actually include data for the crank rotational speed of 70 rpm, 80 rpm, 90 rpm, and 100 rpm. The muscle activity DB  201  includes data for the crank load amount of 0.1 Nm, 0.3 Nm, 0.5 Nm, 0.8 Nm, 1.0 Nm, 1.3 Nm, and 1.5 Nm. However, the muscle activity DB  201  may actually include data for the crank load amount of 3 Nm, 5 Nm, 7 Nm, 9 Nm, 11 Nm and 13 Nm. The muscle activity DB  201  includes data for forward rotation and reverse rotation as the crank rotational direction. The muscle activity DB  201  holds a huge amount of correspondence information for various combinations of height, crank rotational speed, crank load amount, crank rotational direction, and other exercise conditions. In the example of  FIG.  6   , the muscle activity DB  201  holds the correspondence information for two million combinations. 
     The correspondence information for the two million combinations held in the muscle activity DB  201  can be generated by, for example, a simulator using a human body computer model (e.g., a human body model such as a human body finite element model). That is, the simulator generates a human body model and an exercise device model based on body-specific information and exercise condition information, and calculates a change in muscle activity of each muscle site that occurs with a change in crank angle. 
     The touch panel display  202  is an integrated unit composed of a touch panel and a display. The exerciser U or the assistant can enter the height of the exerciser U and the exercise conditions of the exerciser U using the exercise device  100  to the muscle activity output device  2  via the touch panel display  202 .  FIG.  7    shows a display example of the touch panel display  202 . 
     The body-specific information acquisition unit  203  acquires body-specific information of the exerciser U. In the present embodiment, the body-specific information acquisition unit  203  outputs to the touch panel display  202 , a message  202   a  prompting to enter the height of the exerciser U. The exerciser U or the assistant enters the height of the exerciser U to the muscle activity output device  2  via the touch panel display  202 . The body-specific information acquisition unit  203  thus acquires the body-specific information indicating the height of the exerciser U. The height of the exerciser U is a specific example of the body-specific information of the exerciser U. The body-specific information of the exerciser U may be the inseam of the exerciser U instead of the height of the exerciser U. 
     The muscle activity output device  2  may include a database that holds the correspondence between the identification (ID) of the exerciser U and the body-specific information of the exerciser U. In this case, the body-specific information acquisition unit  203  may output to the touch panel display  202 , a message prompting to enter the identification (ID) of the exerciser U, acquire the identification (ID) of the exerciser U entered via the touch panel display  202  by the exerciser U or the assistant, and search the database for the acquired identification (ID) to acquire the body-specific information of the exerciser U. 
     The exercise condition information acquisition unit  204  acquires exercise condition information indicating the exercise conditions of the exerciser U using the exercise device  100 . In the present embodiment, the exercise condition information acquisition unit  204  outputs to the touch panel display  202 , a message  202   b  prompting to enter the exercise conditions for the exercise device  100 . The exerciser U or the assistant enters the exercise conditions of the exerciser U using the exercise device  100  to the muscle activity output device  2  via the touch panel display  202 . The exercise condition information acquisition unit  204  thus acquires the exercise condition information. 
     Returning back to  FIG.  3   , the crank angle information acquisition unit  205  acquires the crank angle information in real time by receiving the crank angle information from the exercise device  100  connected to the muscle activity output device  2 . 
     The muscle activity information acquisition unit  206  acquires the current muscle activity information for each muscle site based on the current crank angle information of the exercise device  100  and the muscle activity DB  201 . Specifically, the muscle activity information acquisition unit  206  identifies the correspondence information to be referred to in the muscle activity DB  201  based on the body-specific information and the exercise condition information, and refers to the identified correspondence information. The muscle activity information acquisition unit  206  thus acquires the current muscle activity information for each muscle site corresponding to the current crank angle of the exercise device  100 . A part of the body-specific information and exercise condition information is discrete. Therefore, when identifying the correspondence information to be referred to in the muscle activity DB  201  based on the body-specific information acquired by the body-specific information acquisition unit  203  and the exercise condition information acquired by the exercise condition information acquisition unit  204 , the muscle activity information acquisition unit  206  can search the muscle activity DB  201  for body-specific information closest to the body-specific information acquired by the body-specific information acquisition unit  203 , and search the muscle activity DB  201  for exercise condition information closest to the exercise condition information acquired by the exercise condition information acquisition unit  204 . 
     The output unit  207  outputs the current muscle activity information of each muscle site to the touch panel display  202 . In the present embodiment, as shown in  FIG.  7   , the output unit  207  displays a human body muscle anatomy model  202   c  on the touch panel display  202 , and colors each muscle site differently according to its muscle activity. For example, a muscle site whose muscle activity is 100% is colored in red, a muscle site whose muscle activity is 50% is colored in green, and a muscle site whose muscle activity is 0% is colored in blue. By checking the color of each muscle site of the human body muscle anatomy model  202   c , the exerciser U or the assistant can be aware of the current muscle activity of each muscle site. That is, the exerciser U or the assistant can check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, the exerciser U or the assistant can check whether the exercise the exerciser U is performing is an exercise that suits the exerciser U&#39;s purpose. As a result, an effective exercise is achieved. 
     Next, the operation of the muscle activity output system  1  will be described with reference to  FIG.  8   .  FIG.  8    is a flowchart of the operation of the muscle activity output system  1 . 
     Step S 100   
     First, the body-specific information acquisition unit  203  acquires body-specific information indicating the height of the exerciser U. 
     Step S 110   
     Next, the exercise condition information acquisition unit  204  acquires exercise condition information indicating the exercise conditions of the exerciser U using the exercise device  100 . 
     Step S 120   
     The crank angle information acquisition unit  205  then acquires crank angle information indicating the crank angle of the crank  40  of the exercise device  100 . 
     Step S 130   
     Thereafter, the muscle activity information acquisition unit  206  refers to the muscle activity DB  201  and acquires current muscle activity information for each muscle site based on the body-specific information, the exercise condition information, and the crank angle information. 
     Step S 140   
     Subsequently, the output unit  207  outputs the current muscle activity information of each muscle site to the touch panel display  202 . 
     Step S 150   
     The muscle activity output device  2  then determines whether there is a change in crank angle. When there is no change in crank angle (step S 150 : NO), the muscle activity output device  2  ends the process. On the other hand, when there is a change in crank angle (step S 150 : YES), the routine returns to step S 120 . The muscle activity output device  2  performs the series of steps from step S 120  to step S 150 , for example, once per second. 
     The first embodiment is described above, and the first embodiment has the following features. 
     The muscle activity output system  1  includes the muscle activity DB  201  (muscle activity database). The muscle activity DB  201  holds the crank angle information (movable part attitude information) and the muscle activity information in such a manner that the crank angle information and the muscle activity information are linked to each other. The crank angle information indicates the crank angle (attitude) of the crank  40  (movable part) of the exercise device  100  (training equipment) when the exerciser U moves his or her body along a trajectory defined by the exercise device  100  that is a device that applies a load to muscles of the exerciser U. The muscle activity information indicates the muscle activity of each muscle site of the exerciser U. The muscle activity output system  1  includes the crank angle information acquisition unit  205  (movable part attitude information acquisition unit) that acquires the crank angle information in real time while the exerciser U is moving his or her body along the trajectory. The muscle activity output system  1  includes the muscle activity information acquisition unit  206  that acquires the current muscle activity information for each muscle site based on the current crank angle information of the exercise device  100  and the muscle activity DB  201 . The muscle activity output system  1  includes the output unit  207  that outputs the current muscle activity information of each muscle site. According to the above configuration, the exerciser U or the assistant can be aware of the current muscle activity of each muscle site including deep muscles. The exerciser U or the assistant can therefore check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, the exerciser U or the assistant can check whether the exercise the exerciser U is performing is an exercise that suits the exerciser U&#39;s purpose. As a result, an effective exercise is achieved. Moreover, presenting muscles being activated on an exercising human body model to the exerciser U allows the exerciser U to exercise while paying attention to those muscles. Therefore, the exercise effect can be expected to be enhanced. 
     That is, since the exerciser U exercises while paying attention to the muscles to be moved, the muscle contraction time increases. This is known to enhance the effect of strength training. Presenting the muscles to be moved to the exerciser U allows the exerciser U to exercise while paying attention to those muscles. Therefore, the exercise effect can be expected to be enhanced. It is also possible to present stresses applied between joints and stresses applied to bones during exercise. The database holds information on loads placed on joints and bones during exercise. Therefore, by presenting the levels of stress applied to bones and joints in addition to muscle activities, a person who is at a high risk of injury when loads are applied to bones and joints during exercise can be careful not to do an exercise too hard for him or her. 
     As an example, the training equipment is the pedal exercise device  100  with which the exerciser U performs a pedaling exercise while being in a sitting position. The movable part attitude information of the training equipment is the crank angle information indicating the crank angle of the pedal exercise device  100 . 
     The muscle activity DB  201  holds the crank angle information and the muscle activity information in such a manner that the crank angle information and the muscle activity information are linked to the exercise condition information indicating the exercise conditions of the exerciser U. The muscle activity output system  1  further includes the exercise condition information acquisition unit  204  that acquires the exercise condition information. The muscle activity information acquisition unit  206  acquires the current muscle activity information for each muscle site based on the current crank angle information of the exercise device  100 , the exercise condition information, and the muscle activity DB  201 . With the above configuration, the exerciser U or the assistant can be accurately aware of the current muscle activity of each muscle site including deep muscles. 
     The muscle activity DB  201  holds the crank angle information and the muscle activity information in such a manner that the crank angle information and the muscle activity information are linked to the body-specific information of the exerciser U. The muscle activity output system  1  further includes the body-specific information acquisition unit  203  that acquires the body-specific information. The muscle activity information acquisition unit  206  acquires the current muscle activity information for each muscle site based on the current crank angle information of the exercise device  100 , the body-specific information, and the muscle activity DB  201 . With the above configuration, the exerciser U or the assistant can be accurately aware of the current muscle activity of each muscle site including deep muscles. 
     The muscle activity DB  201  holds at least the crank angle information and the muscle activity information indicating the muscle activities of deep muscles of the exerciser U in such a manner that the crank angle information and the muscle activity information are linked to each other. With the above configuration, since the exerciser U or the assistant can be aware of the current muscle activities of deep muscles, the exerciser U or the assistant can check whether deep muscles to be activated have been activated and deep muscles not to be activated have not been activated. Accordingly, the exerciser U or the assistant can check whether the exercise the exerciser U is performing is an exercise that suits the exerciser U&#39;s purpose. As a result, an effective exercise is achieved. 
     The muscle activity output method uses the muscle activity DB  201  (muscle activity database) that holds the crank angle information (movable part attitude information) and the muscle activity information in such a manner that the crank angle information and the muscle activity information are linked to each other. The crank angle information indicates the crank angle (attitude) of the crank  40  (movable part) of the exercise device  100  (training equipment) when the exerciser U moves his or her body along a trajectory defined by the exercise device  100  that is a device that applies a load to muscles of the exerciser U. The muscle activity information indicates the muscle activity of each muscle site of the exerciser U. The muscle activity output method includes the movable part attitude information acquisition step (step S 120 ) of acquiring the crank angle information in real time while the exerciser U is moving his or her body. The muscle activity output method includes the muscle activity information acquisition step (step S 130 ) of acquiring the current muscle activity information for each muscle site based on the current crank angle information of the exercise device  100  and the muscle activity DB  201 . The muscle activity output method includes the output step (step S 140 ) of outputting the current muscle activity information for each muscle site. With the above method, since the exerciser U or the assistant can be aware of the current muscle activity of each muscle site including deep muscles, the exerciser U or the assistant can check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, the exerciser U or the assistant can check whether the exercise the exerciser U is performing is an exercise that suits the exerciser U&#39;s purpose. As a result, an effective exercise is achieved. 
     In the present embodiment, the output unit  207  outputs the current muscle activity information of each muscle site to the touch panel display  202 . However, the output unit  207  may alternatively output the current muscle activity information for each muscle site by voice via a speaker, not shown. The output unit  207  may output the current muscle activity information for each muscle site via a vibration motor, not shown, attached to the body of the exerciser U. In this case, whether the muscle site is a superficial muscle or a deep muscle and the muscle activity of the muscle site may be represented by changing the frequency, attitude, or duty cycle of the vibration motor. 
     Second Embodiment 
     Next, a second embodiment of the present disclosure will be described with reference to  FIGS.  9  and  10   . The differences of the present embodiment from the first embodiment will be mainly described, and duplicated description will be omitted. 
     In the first embodiment, the muscle activity output device  2  receives crank angle information from the exercise device  100  and refers to the muscle activity DB  201  to acquire muscle activity information corresponding to the received crank angle information. 
     On the other hand, the muscle activity output device  2  of the present embodiment receives body posture information from a sensor attached to the exerciser U. The muscle activity output device  2  converts the received body posture information to crank angle information and refers to the muscle activity DB  201  to acquire muscle activity information corresponding to the obtained crank angle information. 
       FIG.  9    shows the muscle activity output system  1  of the present embodiment. The muscle activity output device  2  includes a body posture information acquisition unit  208  and a conversion unit  209 , instead of the crank angle information acquisition unit  205 . 
     A trunk posture angle sensor  300 , a thigh posture angle sensor  301 , a lower leg posture angle sensor  302 , and a foot posture angle sensor  303  are attached to the exerciser U. 
     Specifically, the trunk posture angle sensor  300  is attached to the trunk of the exerciser U. The trunk posture angle sensor  300  outputs trunk posture information indicating the posture of the trunk of the exerciser U to the muscle activity output device  2 . 
     The thigh posture angle sensor  301  is attached to a thigh of the exerciser U. The thigh posture angle sensor  301  outputs thigh posture information indicating the posture of the thigh of the exerciser U to the muscle activity output device  2 . 
     The lower leg posture angle sensor  302  is attached to a lower leg of the exerciser U. The lower leg posture angle sensor  302  outputs lower leg posture information indicating the posture of the lower leg of the exerciser U to the muscle activity output device  2 . 
     The foot posture angle sensor  303  is attached to a foot of the exerciser U. The foot posture angle sensor  303  outputs foot posture information indicating the posture of the foot of the exerciser U to the muscle activity output device  2 . 
     Each of the trunk posture angle sensor  300 , the thigh posture angle sensor  301 , the lower leg posture angle sensor  302 , and the foot posture angle sensor  303  is typically a posture sensor composed of a gyroscope and a three-axis acceleration sensor. 
     The body posture information acquisition unit  208  receives and acquires the trunk posture information, the thigh posture information, the lower leg posture information, and the foot posture information from the trunk posture angle sensor  300 , the thigh posture angle sensor  301 , the lower leg posture angle sensor  302 , and the foot posture angle sensor  303 , respectively. The body posture information acquisition unit  208  calculates hip joint angle information indicating the pitch angle of the hip joint from the trunk posture information and the thigh posture information. The body posture information acquisition unit  208  calculates knee joint angle information indicating the pitch angle of a knee joint from the thigh posture information and the lower leg posture information. The body posture information acquisition unit  208  calculates ankle joint angle information indicating the pitch angle of an ankle joint from the lower leg posture information and the foot posture information. 
     The trunk posture information, the hip joint angle information, the knee joint angle information, and the ankle joint angle information constitute body posture information. The body posture information includes at least one of the following pieces of information: the trunk posture information, the hip joint angle information, the knee joint angle information, and the ankle joint angle information. The body posture information preferably includes at least the hip joint angle information and the knee joint angle information. This is because the crank angle is roughly obtained from the hip joint angle information and the knee joint angle information. 
     The method for the body posture information acquisition unit  208  to acquire the body posture information is not limited to the above method. For example, the trunk posture information, the thigh posture information, the lower leg posture information, and the foot posture information can be obtained by placing motion capture markers on the trunk, thigh, lower leg, and foot of the exerciser U and identifying the positions of the markers with a three-dimensional measurement camera. 
     The conversion unit  209  converts the body posture information to crank angle information. Specifically, the conversion unit  209  geometrically calculates a current crank angle based on the current trunk posture information, hip joint angle information, knee joint angle information, and ankle joint angle information. The conversion unit  209  may calculate a current crank angle based on the current trunk posture information, hip joint angle information, knee joint angle information, and ankle joint angle information by considering the body-specific information indicating the height of the exerciser U and the exercise conditions of the exerciser U using the exercise device  100 . 
     Next, the operation of the muscle activity output system  1  will be described with reference to  FIG.  10   .  FIG.  10    is a flowchart of the operation of the muscle activity output system  1 . 
     In the control flow of the muscle activity output device  2  of the present embodiment shown in  FIG.  10   , step S 120  of the first embodiment shown in  FIG.  8    is replaced with step S 120 _ 1  and step S 120 _ 2 . 
     Step S 120 _ 1   
     After step S 110  is completed, the body posture information acquisition unit  208  acquires body posture information. 
     Step S 120 _ 2   
     The conversion unit  209  then converts the body posture information to crank angle information. 
     The second embodiment is described above, and the second embodiment has the following features. 
     The muscle activity output system  1  includes the muscle activity DB  201  (muscle activity database) that holds the crank angle information (movable part attitude information) and the muscle activity information in such a manner that the crank angle information and the muscle activity information are linked to each other. The crank angle information indicates the crank angle (attitude) of the crank  40  (movable part) of the exercise device  100  (training equipment) when the exerciser U moves his or her body along a trajectory defined by the exercise device  100  that is a device that applies a load to muscles of the exerciser U. The muscle activity information indicates the muscle activity of each muscle site of the exerciser U. The muscle activity output system  1  includes the body posture information acquisition unit  208  that acquires the body posture information of the exerciser U in real time while the exerciser U is moving his or her body along the trajectory. The muscle activity output system  1  includes the conversion unit  209  that converts the body posture information to crank angle information. The muscle activity output system  1  includes the muscle activity information acquisition unit  206  that acquires the current muscle activity information for each muscle site based on the current crank angle information of the exercise device  100  and the muscle activity DB  201 . The muscle activity output system  1  includes the output unit  207  that outputs the current muscle activity information of each muscle site. With the above configuration, since the exerciser U or the assistant can be aware of the current muscle activity of each muscle site including deep muscles, the exerciser U or the assistant can check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, the exerciser U or the assistant can check whether the exercise the exerciser U is performing is an exercise that suits the exerciser U&#39;s purpose. As a result, an effective exercise is achieved. 
     The muscle activity output method uses the muscle activity DB  201  (muscle activity database) that holds the crank angle information (movable part attitude information) and the muscle activity information in such a manner that the crank angle information and the muscle activity information are linked to each other. The crank angle information indicates the crank angle (attitude) of the crank  40  (movable part) of the exercise device  100  (training equipment) when the exerciser U moves his or her body along a trajectory defined by the exercise device  100  that is a device that applies a load to muscles of the exerciser U. The muscle activity information indicates the muscle activity of each muscle site of the exerciser U. The muscle activity output method includes the body posture information acquisition step (step S 120 _ 1 ) of acquiring the body posture information of the exerciser U in real time while the exerciser U is moving his or her body. The muscle activity output method includes the conversion step (step S 120 _ 2 ) of converting the body posture information to crank angle information. The muscle activity output method includes the muscle activity information acquisition step (step S 130 ) of acquiring the current muscle activity information for each muscle site based on the current crank angle information of the exercise device  100  and the muscle activity DB  201 . The muscle activity output method includes the output step (step S 140 ) of outputting the current muscle activity information for each muscle site. With the above method, since the exerciser U or the assistant can be aware of the current muscle activity of each muscle site including deep muscles, the exerciser U or the assistant can check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, the exerciser U or the assistant can check whether the exercise the exerciser U is performing is an exercise that suits the exerciser U&#39;s purpose. As a result, an effective exercise is achieved. 
     Third Embodiment 
     Next, a third embodiment will be described with reference to  FIGS.  11  and  12   . The differences of the present embodiment from the first embodiment will be mainly described, and duplicated description will be omitted. 
     In the first embodiment, it is assumed that the exerciser U exercises using the exercise device  100  as training equipment. On the other hand, in the present embodiment, it is assumed that the exerciser U does not exercise using training equipment but exercises by moving his or her body along a predetermined trajectory. 
     The predetermined trajectory is typically a trajectory determined for each bodyweight training. Examples of the bodyweight training include front bridge, plank leg raise, normal push-up, crunch, bicycle crunch, narrow push-up, reverse push-up, squat, pull-up, back extension, high reverse plank, and standing calf raise. Each bodyweight training defines which part of the body is moved back and forth along what trajectory. The predetermined trajectory may be a trajectory specified by an instructor in real time with his or her movement. 
       FIG.  11    shows a functional block diagram of the muscle activity output system  1  of the present embodiment. As shown in  FIG.  11   , the muscle activity output device  2  of the present embodiment includes the muscle activity DB  201 , the touch panel display  202 , the body posture information acquisition unit  208 , the muscle activity information acquisition unit  206 , and the output unit  207 . 
     In the first embodiment, the muscle activity DB  201  is a database that holds the crank angle information and the muscle activity information indicating the muscle activity of each muscle site of the exerciser U in such a manner that the crank angle information and the muscle activity information are linked to each other. On the other hand, the muscle activity DB  201  of the present embodiment is a database that holds the body posture information and the muscle activity information indicating the muscle activity of each muscle site of the exerciser U in such a manner that the body posture information and the muscle activity information are linked to each other. The body posture is, for example, the joint angle of a joint of the body of the exerciser U. In the present embodiment, examples of the body posture includes a neck joint angle, a shoulder joint angle, an elbow joint angle, trunk posture information, a hip joint angle, a knee joint angle, and an ankle joint angle. As an example, the muscle activity DB  201  holds the body posture information indicating the elbow joint angle and the muscle activity information indicating the muscle activity of each muscle site of the exerciser U in such a manner that the body posture information and the muscle activity information are linked to each other. The muscle activity DB  201  can be generated by a simulator using a human body computer model as in the above embodiment. 
     The body posture information acquisition unit  208  receives and acquires body posture information from a body posture sensor  304 . The body posture sensor  304  may be a sensor that measures in a contactless manner the positions of markers attached to various body parts of the exerciser U. Alternatively, posture sensors may be placed on various body parts of the exerciser U, and the body posture sensor  304  may receive and acquire body posture information from the posture sensors. 
     The muscle activity information acquisition unit  206  refers to the muscle activity DB  201  and acquires current muscle activity information for each muscle site based on the body posture information. 
     The output unit  207  outputs the current muscle activity information of each muscle site to the touch panel display  202 . 
     Next, the operation of the muscle activity output system  1  will be described with reference to  FIG.  12   .  FIG.  12    is a flowchart of the operation of the muscle activity output system  1 . 
     Step S 200   
     First, the body posture information acquisition unit  208  acquires the body posture information. 
     Step S 210   
     Next, the muscle activity information acquisition unit  206  refers to the muscle activity DB  201  and acquires current muscle activity information for each muscle site based on the body posture information. 
     Step S 220   
     The output unit  207  then outputs the current muscle activity information of each muscle site to the touch panel display  202 . 
     Step S 230   
     Subsequently, the muscle activity output device  2  determines whether a predetermined time has elapsed. When the predetermined time has elapsed (step S 230 : YES), the muscle activity output device  2  ends the process. On the other hand, when the predetermined time has not elapsed (step S 230 : NO), the routine returns to step S 200 . 
     The third embodiment is described above, and the third embodiment has the following features. 
     The muscle activity output system  1  includes the muscle activity DB  201  (muscle activity database) that holds the body posture information and the muscle activity information in such a manner that the body posture information and the muscle activity information are linked to each other, the body posture information indicating the body posture of the exerciser U when the exerciser U moves his or her body along a predetermined trajectory, and the muscle activity information indicating the muscle activity of each muscle site of the exerciser U. The muscle activity output system  1  includes the body posture information acquisition unit  208  that acquires the body posture information in real time while the exerciser U is moving his or her body along the trajectory. The muscle activity output system  1  includes the muscle activity information acquisition unit  206  that acquires the current muscle activity information for each muscle site based on the current body posture information of the exerciser U and the muscle activity DB  201 . The muscle activity output system  1  includes the output unit  207  that outputs the current muscle activity information of each muscle site. With the above configuration, since the exerciser U or the assistant can be aware of the current muscle activity of each muscle site including deep muscles, the exerciser U or the assistant can check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, the exerciser U or the assistant can check whether the exercise the exerciser U is performing is an exercise that suits the exerciser U&#39;s purpose. As a result, an effective exercise is achieved. 
     The body posture of the exerciser U includes the joint angle of a joint of the body of the exerciser U. 
     The muscle activity DB  201  holds at least the body posture information and the muscle activity information indicating the muscle activities of deep muscles of the exerciser U in such a manner that the body posture information and the muscle activity information are linked to each other. With the above configuration, since the exerciser U or the assistant can be aware of the current muscle activities of deep muscles, the exerciser U or the assistant can check whether deep muscles to be activated have been activated and deep muscles not to be activated have not been activated. Accordingly, the exerciser U or the assistant can check whether the exercise the exerciser U is performing is an exercise that suits the exerciser U&#39;s purpose. As a result, an effective exercise is achieved. 
     The muscle activity output method uses the muscle activity DB  201  (muscle activity database) that holds the body posture information and the muscle activity information in such a manner that the body posture information and the muscle activity information are linked to each other, the body posture information indicating the body posture of the exerciser U when the exerciser U moves his or her body along a predetermined trajectory, and the muscle activity information indicating the muscle activity of each muscle site of the exerciser U. The muscle activity output method includes the body posture information acquisition step (step S 200 ) of acquiring the body posture information in real time while the exerciser U is moving his or her body along the trajectory. The muscle activity output method includes the muscle activity information acquisition step (step S 210 ) of acquiring the current muscle activity information for each muscle site based on the current body posture information of the exerciser U and the muscle activity DB  201 . The muscle activity output method includes the output step (step S 220 ) of outputting the current muscle activity information of each muscle site. With the above method, since the exerciser U or the assistant can be aware of the current muscle activity of each muscle site including deep muscles, the exerciser U or the assistant can check whether muscle sites to be activated have been activated and muscle sites not to be activated have not been activated. Accordingly, the exerciser U or the assistant can check whether the exercise the exerciser U is performing is an exercise that suits the exerciser U&#39;s purpose. As a result, an effective exercise is achieved. 
     In the examples described above, the program can be stored using various types of non-transitory computer-readable media (non-transitory storage media) and supplied to a computer. The non-transitory computer-readable media include various types of tangible storage media. Examples of the non-transitory computer-readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, and hard disk drives), and magneto-optical recording media (e.g., magneto-optical disks). Other examples of the non-transitory computer-readable media include compact disc read-only memories (CD-ROMs), compact disc-recordable discs (CD-Rs), compact disc-rewritable discs (CD-R/Ws), and semiconductor memories (e.g., mask ROMs). Other examples of the non-transitory computer-readable media include programmable ROMs (PROMs), erasable PROMs (EPROMs), flash ROMs, and random access memories (RAMs). The program may be supplied to the computer by various types of transitory computer-readable media. Examples of the transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer-readable media can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path. 
     The present disclosure is not limited to the above embodiments, and can be modified as appropriate without departing from the spirit and scope of the present disclosure.