Patent Publication Number: US-2016243402-A1

Title: Method and apparatus for assessing the performances of an athlete that performs a gymnastic exercise

Description:
FIELD OF THE INVENTION 
     The present disclosure relates to a method and an apparatus for assessing the performances of an athlete that performs a gymnastic exercise, as defined in the preambles of claims  1 ,  11  and  12  respectively. 
     Particularly, the present disclosure relates to a method and an apparatus for assessing the performances of an athlete and informing the athlete thereof during the gymnastic exercise. 
     DISCUSSION OF RELATED ART 
     In the prior art, methods and devices are known to be used to optimize the performance of a gymnastic exercise (or training session) of an athlete according to his/her muscular characteristics. 
     For example, EP 1834583 discloses a method and a device for evaluating the muscular capacity of athletes using short tests, such as squats and jumps. 
     Particularly, the object of the above disclosed invention is to measure kinematic parameters in a short-time effort and to display one or more quantities indicative of the muscular capacity of the athlete at the end of the test, i.e. without waiting too much time from the end of the gymnastic excercise. 
     For this purpose, EP 1834583 discloses the use of a three-axis accelerometer allowing acceleration measurement in the direction of weight transfer, i.e. a vertical direction. 
     Nevertheless, this method requires calibration prior to every exercise to determine the vertical axis along which the weight will be transferred. 
     Furthermore, before each exercise, the athlete is required to be still, e.g. for two seconds, and wait until he/she receives a confirmation tone by the sensor before starting the exercise. 
     Finally, it shall be noted that the method as disclosed in EP 1834583 at most provides indications about the muscular capacity of the athlete at the end of the exercise (or “short test”) and not during performance of the exercise. Therefore, the athlete is only informed at the end of the gymnastic exercise, and there is no way of acting upon and/or assessing his/her performances during the exercise. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a method and an apparatus that can obviate the drawbacks of the prior art. 
     One embodiment provides a method and an apparatus that can provide indications about the muscular capacity of an athlete during performance of an exercise and not only at the end of it. 
     Furthermore, the present invention can provide a method and a device that impose no limit on the duration or type of tests, whereby tests may be also other than raises and jumps, and last a longer time. 
     Also, the method and apparatus of the invention determine both acceleration and attitude, using a gyroscope and a magnetometer; thus, the method and apparatus of the invention afford non-intrusive acquisition of training data, without requiring calibration before each exercise. 
     Furthermore, with the present invention, while the inventive method and apparatus require no calibration, they afford higher accuracy, as they can correct any measurement error. 
     Finally, the method and apparatus of the present invention afford the following advantages:
         determining the maximum for each athlete without subjecting him/her to excessive loads, i.e. using a lower weight than the maximum load, as the athlete may simply perform a repetition to his/her maximum capacity using a weight he/she is used to, the maximum load being calculated by the apparatus with the inventive method;   suggesting the right weight to be used by the athlete;   checking that the movements performed during training are useful to achieve the desired goal.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The characteristics and advantages of the present disclosure will appear from the following detailed description of possible practical embodiments thereof, which are shown as non-limiting examples in the drawings, in which: 
         FIG. 1  is a principle view of the apparatus of the present invention; 
         FIG. 2  shows a graphical icon representative of a parameter assessed by the apparatus and method of the present invention; 
         FIG. 3  shows a representation of the coordinate axes of the measuring device of the present invention; 
         FIG. 4  shows a flow diagram of a first embodiment of the method of the present invention; 
         FIG. 5  shows a chart of the operation of a few steps of the method as shown in the diagram of  FIG. 4 , according to the present invention; 
         FIG. 6  shows a chart of the operation of further steps of the method as shown in the diagram of  FIG. 4 , according to the present invention; 
         FIG. 7  shows a flow diagram of a second embodiment of the method of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Although this is not expressly shown, the individual features described with reference to each embodiment shall be intended as auxiliary and/or interchangeable with other features, as described with reference to other embodiments. 
     Referring to the accompanying figures, numeral  1  designates the apparatus for assessing the performances of an athlete that performs a floor exercise or uses equipment for performing a gymnastic exercise. 
     The term equipment for performing a gymnastic exercise is intended to designate equipment such as barbells, squat machines or the like, that allow performance and/or repetition of a gymnastic exercise. 
     The term gymnastic exercise is intended to designate a set of activities performed to exercise, develop and strengthen a given ability of the athlete&#39;s body. 
     The apparatus  1  comprises a measuring device  2 , having fastener means  3  for removably fastening the measuring device  2  to the body of the athlete (e.g. wrist, ankle or torso) or to the equipment designed for performance of such gymnastic exercise. 
     The apparatus  1  comprises a display  4  and processing means  5  in signal communication with the self-powered measuring device  2  and with the display. 
     The fastener means  3  preferably comprise a magnetic coupling and, in addition to or instead of it, a strap, Velcro, or other fastening devices known to the skilled persons, and adapted for removable connection of the self-powered measuring device  2  to the body of the athlete or the equipment for performing the gymnastic exercise. 
     The measuring device  2  is preferably self- , i.e. battery-powered. Preferably, the battery is a rechargeable lithium battery. 
     Advantageously, the measuring device  2  comprises a radio-frequency transceiver module  6  for establishing signal communication between the self-powered measuring device  2  and the display  4 , although such signal communication may be supposed to be established also or only using data connection cables. 
     Preferably, the radio-frequency transceiver module is a wireless communication module that uses the Bluetooth protocol or a Wi-Fi standard. 
     In the particular example of  FIG. 1 , the display  4  and the processing means  5  are an integral part of an electronic device such as a tablet, a smartphone, a desktop computer, a notebook, a netbook, or the like. 
     Alternatively, the display  4  and the processing means  5  may be separate and distinct means. For example, the display  4  may be a TV screen and the processing means  5  consist of a personal computer, and they are in signal communication with each other. 
     The apparatus  1  has the purpose of optimizing the training session of an athlete according to his/her muscular characteristics. 
     To this end, the measuring device  2  comprises a transducer (or sensor) having at least one accelerometer. Particularly, the transducer preferably implements a MEMS (Micro Electro-Mechanical Systems) technology. 
     In a preferred embodiment of the present invention, in addition to the accelerometer the transducer also comprises a gyroscope and a magnetometer. 
     In this configuration, the measuring device  2  allows motion measurements along nine axes (see  FIG. 3 ). Namely,  FIG. 3  also represents the rotations in space considering the “world axes” coordinate system Z, O, N and the triplet of “fixed-body axes” x-y-z associated with the transducer, as well as the attitude angles α, β, φ, also associated with the transducer. 
     Particularly, the apparatus  1  allows measurement of dynamic parameters (speed, acceleration, force, power, acceleration change rate) and, if a gyroscope and a magnetometer are also implemented in the transducer, also kinematic parameters (attitude), during the gymnastic exercise, with at least one value representative of the performance of the athlete appearing in real-time on the display  4 . 
     For simplicity, the transducer of the measuring device  2  is assumed to implement the accelerometer, the gyroscope and the magnetometer, without limiting the general principle that simply requires acquisition of acceleration to carry out the steps of the inventive method. 
     Advantageously, the transducer is designed to generate a first sequence of values S 1  representative of the movement of the body of the athlete or the equipment for performing the gymnastic exercise along any of the coordinate axes x, y, z. 
     Particularly, the first sequence of values S 1  comprises first values S 1 ′ identifying the acceleration of the body of the athlete or the equipment for performing the gymnastic exercise along one of the axes x, y or z, and second values S 1 ′ identifying the attitude of the body of the athlete or the equipment for performing the gymnastic exercise. 
     When the gyroscope and the magnetometer are also implemented in the transducer, such transducer provides the first sequence of values S 1  identifying, both acceleration along the three axes x, y, z, and the attitude of the body of the athlete or the instrument for performing the gymnastic exercise. 
     Particularly, the first sequence of values S 1  provides the indication of acceleration along the three axes x, y, z (i.e. the fixed-body axes of the sensor) and the attitude (as Euler angles or quaternions). 
     The processing means  5  receive the first sequence of values S 1  and are configured to determine, during the gymnastic exercise, the at least one value representative of the performance of the athlete as a function of the first sequence of values S 1 , to display such at least one value on the display  4 . 
     For this purpose, the method of the present invention advantageously processes such first sequence of values S 1  so received, and affords real-time display of training parameters. 
       FIG. 4  shows a flow diagram of a first embodiment of the method of the present invention. 
     Particularly, in order to carry out the inventive method, the apparatus  1  comprises an IT product and the processing means  5  comprise a memory (not shown), the IT product being adapted to be directly loaded into the memory of the processing means  5  and comprising program code portions which are adapted to carry out the inventive method when running on such processing means. 
     The starting point for such processing consists in determining, during the gymnastic exercise, the first sequence of values S 1 , identifying the acceleration of the body of the athlete or the equipment for performing the gymnastic exercise. 
     It shall be noted that this acceleration measurement is affected by random oscillations caused by the operating equipment (here the combination accelerometer-gyroscope-magnetometer). 
     When trying to determine speed from this acceleration value through an integration process  7 , to obtain a second sequence of values S 2  identifying the speed of movement of the body of the athlete or the equipment for performing the gymnastic exercise, such second sequence of values S 2  shows a drift error. 
     Particularly, even when the transducer is still, i.e. the body of the athlete or the equipment does not move, a non-zero speed value is still detected. 
     In an attempt to obviate this drift error, the second sequence of values S 2  will be advantageously processed by calculating the least squares regression coefficients  8  to generate a third sequence of values S 3  identifying the drift error trend of the measuring device  2 . 
     A subtraction step  9  is also provided, in which such the third sequence of values S 3  is subtracted from the second sequence of values S 2 , to obtain a fourth sequence of values S 4 , identifying the speed, without the drift error, at which the transducer moves during the exercise. 
     In other words, also referring to  FIG. 5 , it may be noted that, until time T 1 , i.e. about the 30th second, the transducer is totally still (as shown by curve A) but, from an analysis of the second set of values S 2 , it appears to be moving (curve C). 
     In order to obviate this drawback, as mentioned above, the least squares regression coefficients  8  are calculated from the values S 2 , which will provide the third set of values S 3  (curve D), which describes the drift error trend. Now, the drift trend curve (curve D) is subtracted (block  9 ) from the speed obtained by integration (curve C), thereby providing the correct speed (curve B), i.e. the sequence of values S 4 . 
     Once the sequence of values S 4  has been obtained, a step is provided in which the athlete is informed, while he/she is performing the gymnastic exercise, about the at least one value representative of his/her performance, such at least one value being determined as a function of the fourth sequence of values S 4 . 
     Therefore, during the gymnastic exercise, the method of the invention extrapolates at least one value representative of the performance of the athlete, which is useful for immediate assessment of the exercise itself. 
     For example, the value representative of the performance, as shown on the display  4 , may be selected from the group of kinematic and dynamic parameters and bio-mechanical indicators. 
     Particularly, the value representative of the performance as shown on the display  4  may be the number of repetitions performed  4 A, the maximum power  4 B, the average power, the average force, the average speed and/or the maximum values attained. 
     This value representative of performance may be calculated from the fourth sequence of values S 4 , which represents the correct speed (i.e. without the drift error), at which the transducer moves during the exercise. 
     In order to inform the athlete, also referring to  FIG. 2 , the apparatus may use a graphical icon  10 , that is designed to appear on the display  4 . This graphical icon  10  has, for example, a bar shape. 
     In a preferred embodiment, the height “h” of the bar  10  is adapted, for instance, to be proportional to the at least one value representative of performance. Thus, the athlete will simply watch the display  4  of the electronic device (PC, tablet, smartphone, or the like) to see in real time such at least one value representative of his/her performance. 
     The bar  10  is also used to inform the athlete in real time (i.e. as he/she performs the gymnastic exercise) about whether he/he has actually reached his/her training goal. 
     For example, still referring to the display  4  of  FIG. 1 , if the athlete wants to increase his/her muscle mass (hypertrophy), the bar will display the power  4 C, and at each thrust (also known as “repetition”) on the equipment for performing the gymnastic exercise, to make his/her work effective, he/she will push at least to 90% his/her maximum power. Therefore, a threshold, here for instance 85%, will be combined to the bar  10  and graphically displayed, and a visual signal will be combined to the attainment or failed attainment of such threshold, such that during training the user will always know whether he/she has reached 85% his/her maximum power (and hence training is effective) or the threshold is not reached, which will indicate a bad an potentially ineffective training. 
     It shall be noted that the step of processing the second sequence of values S 2  by calculating the least squares regression coefficients  8  to generate a third sequence of values S 3 , may be carried out on a limited number Nlim of values belonging to such second sequence of values S 2  within a preset assessment range Tc. 
     In order to ensure real-time display of the at least one value representative of the performance of the athlete, such as force, speed, power, explositivy, etc. a limited number Nlim of values are selected, which means that this step of calculating the least squares regression coefficients  8  is applied within the preset assessment range Tc. 
     For example, a value of the preset assessment range Tc may be five seconds and, since a feasible acquisition frequency fc for the apparatus 1 is 50 Hz, this will mean that 250 values will be acquired, as fc=50 Hz×Tc=5 sec=250 values. 
     Therefore, in a preferred aspect, in order to avoid a computational overload on the processing means  5 , a limited number Nlim of values are only selected within a preset assessment range Tc. 
     For example, this limited number Nlim of values within the assessment range Tc may be 50 values instead of 250, for calculation of the least squares regression coefficients  8 . 
     This limited number Nlim of values are selected within the assessment range Tc, preferably in equally spaced fashion. 
     Turning back to the above disclosed numerical example, this will involve the acquisition of every tenth value of the buffer vector containing the speed values acquired in the last five seconds. 
     It shall be further noted that, in a preferred exemplary embodiment of the method, the step of subtracting the third sequence of values S 3  from the second sequence of values S 2  to obtain the fourth sequence of values S 4  identifying the speed without the drift error, is not carried out on the entire sequence of values S 3 , i.e. for all the values acquired within the assessment range Tc, but at a single current time Tatt. 
     In other words, the subtraction step is carried out at a single time Tatt, identifying the current measuring time, the value of the single time of the second sequence of values S 2  being subtracted from the respective value of said single time of said third sequence of values S 3 . 
     Therefore, the subtraction step may be schematically indicated as follows: 
         S 4(=correct_speed ( t ))= S 2(=integrated_speed( t ))− S 3(=regression_curve( t ))   1)
 
     where “regression_curve” is a vector containing  250  data and relates to a time interval from Tat to Tatt-Tc seconds and “integrated speed” is a vector that relates to a time interval from Tat to Tatt-Tc seconds. 
     The result of the operation as designated above by (1), which is a subtraction of a single element of both vectors, is a scalar, i.e. the correct speed at time Tatt. 
     For further correction of the value, at the current time Tatt, further refinement is carried out by the following operation: 
         S 4(=correct_speed ( t− 3))= S 2(=integrated_speed( t− 3))− S 3(=regression speed( t− 3)).   2)
 
     After a first speed correction, under 1), a further correction is made after three times (under 2). 
     Thus, the introduction of a small delay will provide values that are even closer to the actual value. This is because correction is not made with reference to the last value of the buffer of the least squares regression curve “regression_curve(t)”, but to a value “within” the buffer, regression_curve(t−3), which will be more “balanced”. 
     From the speed data cleared of the drift effects (“drift”) caused by the errors introduced by the measuring device  2 , still referring to  FIG. 4 , the repetitions performed by the athlete during the gymnastic exercise may be counted, and this value indicative of the performances of the athlete may be displayed on the display  4 . 
     For this purpose, it shall be noted that the method comprises the additional step  20  of processing the fourth sequence of values S 4  to obtain a value S 5 , identifying the number of repetitions performed by the athlete. 
     Particularly, integral calculation  11  is performed on the fourth sequence of values S 4  to generate the value S 5 , identifying the number of repetitions. 
     It shall be noted that the sequences of values S 1  to S 4  are preferably related to a vertical axis, i.e. the axis of vertical movement of the body of the athlete or the equipment, as the axis z of the coordinate system x y, z. 
     If the sequence of values S 4  is related to the axis z, i.e. the vertical axis, then the sequence of values S 5  advantageously allows identification of a position measurement, namely height relative to a reference level (e.g. a reference plane or the starting position of the transducer), in which the transducer is located, always in real time. 
     Thus, also referring to  FIG. 5 , it shall be noted that the measurement of the vertical position obtained, for instance, by three low-high-low-high-low-high-low movements of the transducer, includes a curve  12  drawn on a plane having time on the x-axis and the vertical position of the transducer on the y-axis. Particularly, the curve  12  is defined by the number of maxima “Mx” (in this special case the curve  12  has three maxima M, as three low-high-low-high-low-high low movements of the transducer have been made), which represent the number of repetitions performed by the athlete. 
     A fictitious “rise” is present at the end of the curve  12 , as shown by the box  13 . At these times of the box  13 , the transducer is still in the position from which it started, then a horizontal line should have appeared in such box  13 , instead of an “ascending” curve. This ascending curve in the box  13  may affect the computation of maxima Mx in the curve  12 , and the number of repetitions displayed to the athlete will not match those actually performed. 
     In order to eliminate such “fictitious” rise of the transducer to define the actual number of repetitions performed by the athlete during the gymnastic exercise, the method of the present invention includes calculating the integral  11  of the sequence of values S 4 , to generate a sequence of values S 6  representative of the movement made by the body of the athlete or the equipment for performing the gymnastic exercise. Then, a portion of values S 6 ′ belonging to the sequence of values S 6  is selected (block  14 ), and each value in such portion of values S 6 ′ is processed by calculating the standard deviation (block  14 ) to obtain a further sequence of processed values S 6 ″. 
     Each value of such sequence of values S 6 ″ is compared with a threshold value Th and if the values of such processed sequence S 6 ″ are higher than the threshold value Th, the value S 5  representative of the number of repetitions performed by the athlete is generated. 
     Once the value S 5  has been obtained, the athlete may be informed during his/her exercise about the number of repetitions performed to that moment, by means of the graphical icon  10 . 
     It shall be noted that the threshold value Th, to be compared with each value of the series of values S 6 ″ is related to the weight of the equipment used by the athlete. Thus, any low-weight or bodyweight exercise movement (with low inertia), will be characterized by much higher standard deviation values on position measurement than those characterizing a high-weight movement, with high inertia. 
     Namely, the higher the threshold value Th the lower the weight value. For instance, the threshold value Th is supposedly 0.07 for a weight of more than 50 kg, or 0.12 for a weight of more than 15 kg, or 0.15 for a weight of more than 2 kg, or 0.2 for bodyweight exercise movements. 
     More in detail, in order to determine the number of repetitions S 5 , the method is designed to include a step in which the rise of the transducer (i.e. actually the increase of its height relative to a reference plane such as the ground) is recognized and the vertical position value, i.e. height, as measured at the first starting time of the rise is saved in a variable in the memory of the processing means  5 . This value is stored in this memory and subtracted from the height value as measured at the end of the rising step. Thus, the space covered during the rise is estimated. 
     At the same time, during the rising step, the standard deviation of the vertical position is measured, and the maximum standard deviation that is reached as the weight rises is stored in a variable. Standard deviation is only calculated, for example, from the 18th acquisition of the rise (the data is acquired at a sampling rate fc of 50 Hz), to avoid influences by direction changes, where peaks are always found, as standard deviation is calculated, for example, from the last twenty-five values. 
     Once a rising step and the maximum standard deviation value associated therewith have been determined, a repetition is found to have been performed if displacement is greater, for instance, than 0.15 meters and standard deviation remains above a given threshold Th or is zero (which is the case of a very fast rise, lasting less than 18 acquisitions, i.e. 18 acquisitions/50 Hz=0.36 seconds). 
     If the measured rise is greater than 0.15 meters and the standard deviation is below a given threshold Th, the repetition is not counted, because it is not an actual movement, but the undesired “fictitious” rise effect as shown in the above box  13 . 
     Once the fourth sequence of values S 4  has been found, the attitude of the transducer and the body of the athlete and the equipment he/she uses may be controlled by the gyroscope, to acquire information about the attitude in space. For this purpose, the fourth sequence S 4  is processed to compare the attitude angles at the start of and throughout the exercise. If these values change by a give threshold, then the athlete is informed. This may be useful to monitor any movement irregularity (e.g. an athlete that might excessively move a barbell as he/she performs a give exercise, which may be monitored). 
     Once the value S 5  has been obtained, the regularity of repetitions may be monitored. The analysis of maximum power values within an entire series (by processing the fourth sequence of values S 4 ), allows determination of variations and analysis of the quality of the repetitions performed. 
     As a rule, the athlete tends to always perform the same movement, until his/her muscular capacity wears out as the series goes on. Nevertheless, the muscular capacity of the athlete may happen to always exceed the preset threshold without deteriorating with time. In this case, the method may advise the user to increase the weight. On the other hand, when very different maximum power measurements are found for the athlete during a series, the method may inform the athlete that he/she is making a wrong movement or is using an excessively high weight. 
     Once the fourth sequence of values S 4  is obtained, the stability of the core and the performance of the exercise may be analyzed. Particularly, the core of the athlete is the anatomic region that corresponds to the torso and transfers forces from the lower limbs to the upper limbs of the skeleton (or vice versa). It is often a limiting factor for athletic performance and one of the most important parameters for injury prevention. An athlete under a barbell will find it more difficult to stabilize weight as the muscles of his/her core are weaker. 
     A core strength estimation may be obtained based on the stability with which an athlete moves when he/she is handling weights during an exercise. The method allows direct stability measurement by determining the standard deviation of accelerations on the plane XY (i.e. the plan corresponding to the floor), in the vertical direction, and attitude variations during the exercise. In this case, the sensor will have to be placed on the core of the athlete and not on the weight. 
     Furthermore, stability may be also checked for quasi-isometric exercises (i.e. particular types of exercises performed while maintaining positions with special joint angles for a given time), as the effectiveness of the isometric exercise is assessed exactly like core strength, i.e. using the standard deviation of accelerations in space and monitoring attitude variations with respect to the initial attitude, using the angles measured by the gyroscope on the sensor. The monitoring parameters are shown on the display. 
     Referring now to  FIG. 8 , a further flow diagram is shown, in which parts or steps that have been already described are designated by the same numerals. This flow diagram schematically shows an alternative embodiment of the present invention. Particularly, in this alternative embodiment the least squares regression coefficients  8  are calculated on the first sequence of values S 1  to generate a processed sequence S 7  and a further subtraction step is performed to subtract the sequence of values S 7  from the first sequence of values Al to generate a new sequence of values S 8  cleared of the drift error. This sequence S 8  is integrated (block  7 ) to determine the sequence of values S 4  identifying the at least one value representative of performance. 
     Those skilled in the art will obviously appreciate that a number of changes and variants may be made to the embodiments of the method and apparatus for assessing the performances of an athlete that performs a gymnastic exercise as described hereinbefore to meet specific needs, without departure from the scope of the invention, as defined in the following claims.