Patent Publication Number: US-2009227427-A1

Title: Exercising Air Footboard and Buffer for Air Footboard

Description:
TECHNICAL FIELD 
     The present invention relates, in general to an exercise step and an air-cushioning leg for the exercise step and, more particularly, to an exercise step which is designed to have an excellent air cushioning effect, thus protecting a user&#39;s knees from injury and allowing the user to exercise in comfort and safety, and which is designed to minimize noise generated during a cushioning operation. 
     BACKGROUND ART 
       FIG. 1  is a perspective view of a conventional exercise step. As shown in the drawing, the conventional exercise step  100  includes a rectangular panel  110 , and four legs,  130 . The legs  130  are provided at four corners of the panel  110  under the panel  110 , and are made of elastic materials. A foot contact plate  120  is provided at a top surface of the panel  110 . Actually, a user&#39;s feet are in contact with the foot contact plate  120  of the panel  110 . 
     When one desires to exercise using the exercise step  100 , the exercise step  100  having such a construction is placed on a flat surface, that is, a floor. Thereafter, a user repeatedly steps onto and off of the foot contact plate  120  of the panel  110 . Or, the user jumps on the foot contact plate  120 . At this time, a load of the user is transmitted from the foot contact plate  120  and the panel  110  through the legs  130  to the support surface. 
     In this case, the legs  130  are elastically deformed to absorb a load applied to the panel  110 , thus preventing a shock from being transmitted to the user&#39;s knees. That is, such an exercise step  100  prevents a user&#39;s knees from being injured, when the user repeatedly steps onto and off of the foot contact plate  120  or jumps on the foot contact plate  120  of the exercise step  100 . 
     However, the conventional exercise step  100  has a problem that only the legs  130  are made of a cushioning material, such as polyurethane, so a cushioning capacity of the exercise step  100  is insufficient to prevent a shock from being transmitted to a user&#39;s knees. Thus, the conventional exercise step  100  does not sufficiently prevent a shock from being transmitted to a user&#39;s knees and allow the user to exercise safely and comfortably. 
     Further, the conventional exercise step  100  has another problem that only the legs  130  have a cushioning capacity, so the foot contact plate  120  and the panel  110  may be undesirably deformed when the exercise step  100  is used for a lengthy period of time. The conventional exercise step  100  has a further problem that the cushioning capacity of the legs  130  is not controlled, so a different exercise step must be purchased according to a user&#39;s weight. 
     DISCLOSURE OF THE INVENTION 
     Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an exercise step with air-cushioning legs, which has an excellent air cushioning effect, thus protecting a user&#39;s knees from injury and allowing the user to exercise in comfort and safety. 
     Another object of the present invention is to provide an exercise step with air-cushioning legs, which is designed to minimize noise generated during a cushioning operation and have an excellent cushioning effect. 
     A further object of the present invention is to provide an exercise step with air-cushioning legs, which is designed to prevent a panel from being undesirably deformed due to a user&#39;s load. 
     Still another object of the present invention is to provide an exercise step with air-cushioning legs, which is designed to allow a user to check the number of steps and an exercise time while exercising. 
     In order to accomplish the above object, the present invention provides an exercise step, including a plate-shaped panel, and an air-cushioning leg provided under the panel to support the panel and absorbing a load applied to the panel by an air cushioning effect. 
     Further, in order to accomplish the above object, the present invention provides an air-cushioning leg for an exercise step, which is provided under a support unit to absorb a load applied to the support unit, and which includes a main body having a double- or more-layered structure and an air control unit functioning to discharge a part of cushioning air from the main body to the outside, when a load is applied to the support unit. 
     In order to accomplish the above object, the present invention provides an air-cushioning leg for an exercise step, which is provided under a support unit to absorb a load applied to the support unit, and which includes a main body having a plurality of tubular bulged parts having different capacities, the bulged parts arranged to form a layered structure, a closed base part coming into contact with a support surface, and an upper end partially opened to define an air passage, an air control unit seated in the open part of the upper end to control an amount of air which flows in and out the main body, and a cover member covering the upper end of the main body in which the air control unit is seated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a conventional exercise step; 
         FIG. 2  is a perspective view of an exercise step according to a primary embodiment of the present invention; 
         FIG. 3  is an exploded perspective view of an air-cushioning leg shown in  FIG. 2 ; 
         FIGS. 4   a  to  4   c  are a plan view, a side sectional view, and a bottom view of the air-cushioning leg shown in  FIG. 3 , respectively; 
         FIG. 5   a  is a perspective view of an air control unit included in the air-cushioning leg of the primary embodiment of the present invention; 
         FIG. 5   b  is a perspective view of an air control unit according to a modification of the primary embodiment of the present invention; 
         FIG. 6  is a perspective view of an exercise step according to a second embodiment of the present invention; 
         FIG. 7  is a side sectional view showing a part of the exercise step shown in  FIG. 6 , in which air-cushioning legs are removed from a panel; 
         FIGS. 8   a  and  8   b  are perspective views of one of the air-cushioning legs included in the exercise step shown in  FIG. 6 , respectively; 
         FIG. 9  is a side sectional view of an air-cushioning leg according to a third embodiment of the present invention; 
         FIG. 10  is a side sectional view of an air-cushioning leg according to a fourth embodiment of the present invention; 
         FIGS. 11   a  and  11   b  are plan views of air-cushioning legs according to fifth and sixth embodiments of the present invention, respectively; 
         FIG. 11   c  is a bottom view of an air-cushioning leg according to a seventh embodiment of the present invention; 
         FIG. 12  is a perspective view of an exercise step according to an eighth embodiment of the present invention; 
         FIG. 13  is an exploded perspective view of one of air-cushioning legs included in the exercise step shown in  FIG. 12 ; and 
         FIG. 14  is a perspective view of a sub-support leg included in the exercise step shown in  FIG. 12 . 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Reference should now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. 
       FIG. 2  is a perspective view of an exercise step according to a primary embodiment of the present invention. As shown in the drawing, an exercise step  1  according to the primary embodiment of the present invention includes a plate-shaped panel  10  and four air-cushioning legs  30 . The air-cushioning legs  30  are mounted to four corners of the panel  10  under the panel  10 . 
     A plurality of embossments  20  are formed on a top surface of the panel  10 . The embossments  20  prevent a user from slipping and falling on the panel  10  during an exercise, in addition to functioning to massaging the sole of the user&#39;s foot. The embossments  20  may be separately manufactured and mounted to the top surface of the panel  10 . Preferably, the embossments  20  are integrated with the panel  10  to form a single structure. 
     The panel  10  is a kind of laminated compressed wood, and is fabricated by processing multi-layered sheets to which a synthetic resin is added, under high temperature and high pressure. When the panel  10  is manufactured in this way, the panel  10  is somewhat hard, and has excellent elasticity and elastic strain, so the panel  10  is not easily damaged or deformed. 
     A plurality of air-cushioning legs  30  are provided at four corners of the panel  10  under the panel  10  to absorb the load applied to the panel  10 . The air-cushioning legs  30  may be glued to the panel  10  under the panel  10 . Alternatively, the air-cushioning legs  30  may be screwed to the panel  10  under the panel  10 . 
     As shown in  FIGS. 3 and 4   a  to  4   c , each of the air-cushioning legs  30  includes a main body  31 , an air control unit  35 , and a cover member  34 . The main body  31  has a plurality of tubular bulged parts  31   b  and  31   c  which have different capacities and are arranged to form a layered structure. The main body  31  also has a base part  31  and an upper end  31   d . The base part  31  is closed and comes into contact with a support surface. The upper end  31   d  is partially opened to define an air passage. The air control unit  35  is seated in an open part  33  of the upper end  31   d  to control an amount of air which flows in and out the main body  31 . The cover member  34  covers the upper end  31   d  of the main body  31  in which the air control unit  35  is seated. 
     As shown in  FIG. 4   a , the open part  33  of the upper end  31   d  of the main body  31  includes a central opening  33   a , and a plurality of radial slits  33   b . The central opening  33   a  is formed at the center of the upper end  31   d  of the main body  31 . The radial slits  33   b  are provided along the circumference of the upper end  31   d  of the main body  31  at predetermined intervals in such a way as to communicate with the central opening  33   a . A single radial slit may be formed, but it is preferable that a plurality of radial slits are formed, like the primary embodiment of the present invention. 
     That is, when a user steps onto or jumps on the panel  10 , air is discharged from the main body  31  through the central opening  33   a  and the radial slits  33   b  to the outside. Subsequently, the bulged parts  31   b  and  31   c  are compressed to absorb the load applied to the panel  10 . 
     In the case where only the open part  33  is formed at the upper end  31   d  of the main body  31 , air excessively easily flows in and out the main body  31 , so the load applied to the panel  10  is not effectively absorbed. Thus, according to the present invention, the air control unit  35 , which is made of a porous material, such as a sponge, is seated in the open part  33 . 
     As shown in  FIG. 5   a , the air control unit  35  includes a control body  35   a , and a plurality of flanges  35   b . The control body  35   a  is seated in the central opening  33   a . The flanges  35   b  outwardly extend from the control body  35   a  in a radial direction to be seated in the radial slits  33   b.    
     When a user steps onto or jumps on the panel  10  after the air control unit  35  is seated in the open part  33  of the upper end  31   d  of the main body  31 , air is discharged from the main body  31  through the control body  35   a  seated in the central opening  33   a  and the flanges  35   b  seated in the radial slits  33   b  to the outside. Simultaneously, the bulged parts  31   b  and  31   c  are compressed to absorb the load applied to the panel  10 . According to the present invention, since the air control unit  35  is made of a porous material, noise is not generated even when air flows in and out the main body  31 , thus allowing a user to exercise in comfort and safety. 
     Meanwhile, as shown in  FIG. 5   b , an air control unit  35 ′ may have a shape different from the air control unit  35  of  FIG. 5   a . That is, a plurality of through holes  35   c  are provided in the control body  35   a  to additionally control the amount of air which flows in and out the main body  31 . In this case, the shape and number of the through holes  35   c  may be changed. 
     The air control unit  35 ′ having a plurality of the through holes  35   c  in the control body  35   a  as shown in  FIG. 5   b , has a higher cushioning effect in comparison with the air control unit  35  of  FIG. 5   a . Thus, the air-cushioning leg  30  equipped with the air control unit  35  of  FIG. 5   a  is suitable for heavy adults, whereas the air-cushioning leg  30  equipped with the air control unit  35 ′ of  FIG. 5   b  is suitable for light adults and children. 
     As shown in  FIG. 4   b , the bulged parts  31   b  and  31   c  comprise a first bulged part  31   b  and a second bulged part  31   c . The first bulged part  31   b  is provided adjacent to the base part  31   a  of the main body  31 . The second bulged part  31   c  is placed on the first bulged part  31   b  to form a layered structure. 
     As shown in  FIG. 4   b , it is preferable that the radius R 1  of the first bulged part  31   b  is larger than the radius R 2  of the second bulged part  31   c  to maintain a high cushioning effect and stability. Further, it is preferable that junctions between the base part  31   a , the first and second bulged parts  31   c  and  31   d , and the upper end  31   b  are constricted and inwardly rounded (see, “A”), thus allowing the main body  31  to be smoothly compressed. Of course, the radius R 1  of the first bulged part  31   b , the radius R 2  of the second bulged part  31   c , and the capacities of the first and second bulged parts  31   b  and  31   c  must be properly determined according to the size of the panel  10  and the magnitude of the load, but such variations are not described herein in detail. 
     As shown in  FIG. 4   c , a plurality of foot parts  32  are projected from a bottom surface of the base part  31   a  of the main body  31 , thus preventing the base part  31   a  of the main body  31  from being compressed due to the load. According to the primary embodiment of the present invention, the foot parts  32  each have a rectangular block shape. However, the foot parts  32  may have a different shape without being limited to the rectangular block shape. 
     The use of the exercise step  1  constructed in this way will be described in the following. 
     First, the exercise step  1  is placed on a flat surface, that is, a floor. Next, when a user repeatedly steps onto and off of the panel  10  or jumps on the panel  10 , the load applied to the panel  10  is transmitted to the support surface through the panel  10  and the air-cushioning legs  30 . 
     At this time, the load applied to the panel  10  is absorbed by the panel  10  to some extent, but the load is mostly absorbed by the air-cushioning legs  30 . That is, when the user compresses the panel  10 , air is discharged from the main body  31  through the control body  35   a  seated in the central opening  33   a  and the flanges  35   b  seated in the radial slits  33   b  to the outside. Simultaneously, the second bulged part  31   c  is downwardly compressed toward the first bulged part  31   b , thus absorbing the load applied to the panel  10 . 
     In this case, each of the air-cushioning legs  30  is provided with the air control unit  35  which is made of a porous material, thus preventing noise from being generated even when air is discharged from the main body  31  to the outside, therefore allowing a user to enjoy exercising in comfort and safety. 
     Of course, as described above, the air-cushioning leg  30  equipped with the air control unit  35  of  FIG. 5   a  is suitable for heavy adults, whereas the air-cushioning leg  30  equipped with the air control unit  35 ′ of  FIG. 5   b  is suitable for light adults and children. 
     As such, the exercise step  1  equipped with the air-cushioning legs  30  minimize noise generated during a cushioning operation, and has an excellent cushioning effect, thus protecting a user&#39;s knees from injury and allowing the user to exercise in comfort and safety. 
     As shown in  FIG. 6 , an exercise step  1  according to a second embodiment of the present invention includes a rectangular plate-shaped panel  10  and a plurality of air-cushioning legs  30 . The air-cushioning legs  30  are mounted to four corners of the panel  10  under the panel  10 . A rectangular foot contact plate  20  is provided on a top surface of the panel  10 . The foot contact plate  20  is made of an elastic material, such as rubber, thus giving comfort to a user and having some cushioning effect. 
     The panel  10  is a kind of laminated compressed wood, and is fabricated by processing multi-layered sheets to which a synthetic resin is added, under high temperature and high pressure. Thus, the panel  10  is somewhat hard, and has excellent elasticity and elastic strain, so the panel  10  is not easily damaged or deformed. 
     A display unit  14  is provided at a predetermined portion of the panel  10 . The display unit  14  is connected to a control unit (not shown), and displays at least one of the number of steps and a time. Thus, a user may set the number of steps and a time as desired when exercising. 
     As shown in  FIG. 7 , a plurality of bolts  10   a  are provided at four corners of the panel  10  under the panel  10 . Each air-cushioning leg  30  is provided with a bolt receiving part  30   a  so that the bolt  10   a  is tightened into the bolt receiving part  30   a  (see,  FIG. 8   a ). That is, by tightening the bolts  10   a  of the panel  10  into the bolt receiving parts  30   a  of the air-cushioning legs  30 , the air-cushioning legs  30  are easily mounted to the panel  10 . 
     Although not shown in the drawings, the positions of the bolts  10   a  and the bolt receiving parts  30   a  may be changed. That is, the bolts  10   a  may be provided on the air-cushioning legs  30 , while the bolt receiving parts  30   a  may be provided on the bottom surface of the panel  10 . 
     The air-cushioning legs  30  are provided under the panel  10  to support it, and absorb the load applied to the panel  10 . Each of the air-cushioning legs  30  includes a main body  40  and an air control unit  50 . The main body  40  is made of a material, such as polyurethane. The air control unit  50  functions to discharge a part of cushioning air from the main body  40  to the outside, when the load is applied to the panel  10 . 
     The main body  40  may have a two-layered structure having two bulged parts or a multi-layered structure having four or more bulged parts. However, according to the second embodiment of the present invention, the main body  40  has three bulged parts  40   a ,  40   b , and  40   c , which are layered in a vertical direction. 
     As shown in  FIG. 8   b , the air control unit  50  according to the second embodiment of the present invention includes a cover part  51  and a control part  52 . The cover part  51  covers an open part of the main body  40 . Air flow holes  51   a  and  51   b  of different sizes are formed in the cover part  51 . The control part  52  is rotatably mounted to the cover part  51  to selectively open or close the air flow holes  51   a  and  51   b . Preferably, the control part  52  is provided with a handle  52   a.    
     When a heavy adult uses the exercise step  1  of the present invention, the control part  52  is rotated to open a smaller air flow hole  51   a . On the contrary, when a light child uses the exercise step  1  of the present invention, the control part  52  is rotated to open a larger air flow hole  51   b . Thus, the exercise step  1  of the present invention allows a cushioning effect to be controlled according to the user&#39;s load. 
     The use of the exercise step  1  according to the second embodiment of the present invention will be described in the following. 
     First, the exercise step  1  is placed on a flat surface, that is, a floor. Next, when a user repeatedly steps onto and off of the foot contact plate  20  of the panel  10  or jumps at a fixed position on the foot contact plate  20 , the load applied to the panel  10  is transmitted to the support surface through the panel  10  and the air-cushioning legs  30 . 
     At this time, the load applied to the panel  10  is absorbed by the panel  10  and the foot contact plate  20  to some extent, but the load is mostly absorbed by the air-cushioning legs  30 . That is, the load is primarily absorbed when the bulged parts  40   a ,  40   b , and  40   c  of the main body  40  are compressed. Secondarily, the load is absorbed when air is discharged from the main body  40  through at least one of the air flow holes  51   a  and  51   b  to the outside. 
     When a heavy adult uses the exercise step  1 , the control part  52  is rotated to open a smaller air flow hole  51   a . Meanwhile, when a light child uses the exercise step  1 , the control part  52  is rotated to open a larger air flow hole  51   b . Thus, the exercise step  1  of the present invention allows an air-cushioning effect to be controlled according to the user&#39;s load. 
     In the exercise step  1  according to the second embodiment of the present invention, a cushioning operation is effectively carried out by the air-cushioning legs  30 , thus reducing a shock transmitted to the user&#39;s knees, allowing the user to exercise in comfort and safety, and preventing the panel  10  from being deformed by the load. Further, the user may set and confirm a time and the number of steps during exercise. 
     Further, it is not necessary to provide the air control unit  50  shown in  FIG. 8   b.    
     According to a third embodiment shown in  FIG. 9 , a main body  40 ′ of each air-cushioning leg  30 ′ is designed such that two cover parts  42  and  43  are provided at an open lower part of the main body  40 ′. In this case, the two cover parts  42  and  43  partially overlap with each other to form an overlapping part. An adjusting bolt  44  is tightened into the overlapping part in such a way that the cover parts  42  and  43  are spaced apart from each other by a predetermined interval, thus controlling the amount of air which flows out of the main body  40 ′. 
     According to a fourth embodiment shown in  FIG. 10 , an air flow opening  45  is provided at a side of a main body  40 ″, and a sliding door  46  is mounted to the air flow opening  45  to control an opening ratio of the air flow opening  45 . The main bodies  40 ′ and  40 ″ according to the third and fourth embodiments also have foot parts  32  at the bottom surfaces of the main bodies  40 ′ and  40 ″. 
     Although not shown in the drawings, several through holes having a predetermined size may be provided in a side of the main body  40  to accomplish a higher cushioning effect. 
     Further, according to a fifth embodiment shown in  FIG. 11   a , a plurality of air flow holes  151   a  are bored through a cover part  151  which is provided at the upper portion of the main body  140 . When a control part  152  is rotated, one or more air flow holes  151   a  are opened. Alternatively, the main body of each air-cushioning leg may be designed to have a structure shown in  FIG. 11   b . In  FIG. 11   b , the reference numerals designate components corresponding to those shown in  FIG. 11   a . The components similar to those shown in  FIG. 11   a  are not described herein in detail. 
     According to the fifth and sixth embodiments of  FIGS. 11   a  and  11   b , the air flow holes  151   a  and  252   a  are provided at the upper portions of the main bodies  140  and  240 , respectively. However, air flow holes may be formed as shown in  FIG. 11   c , to accomplish the same effect as the air flow holes  151   a  and  252   a  of  FIGS. 11   a  and  11   b . That is, according to a seventh embodiment of  FIG. 11   e , a plurality of air flow holes  353   a  are provided in the bottom surface of a main body  340 , and a sliding door  346  is provided to selectively open or close the air flow holes  353   a , thus controlling an opening ratio of the air flow holes  353   a . Further, foot parts  342  according to the seventh embodiment of the present invention are radially arranged on the bottom surface of the main body  340 , differently from the above embodiments. 
       FIG. 12  shows an exercise step according to an eighth embodiment of the present invention. The exercise step  401  includes a panel  410 . A foot contact plate  420  is provided on a top surface of the panel  410 . A handle  470  is provided on the top surface of the panel  410  around the foot contact plate  420 . A plurality of air-cushioning legs  430  are provided on four corners of the panel  410  under the panel  410 . 
     As shown in  FIG. 13 , each of the air-cushioning legs  430  includes a body  431  and an air cushioning tube  433 . The body  431  is made of an elastic material, such as thermoplastic polyurethane. The air cushioning tube  433  is installed in the body  431 . A recess  431   b  is provided at a side of the body  431 . A plurality of air cushioning holes  431   a  are vertically formed in the body  431  to accomplish a higher air cushioning effect. 
     The air cushioning tube  433  is installed in the recess  431   b  to absorb a load applied to the panel  410 , in cooperation with the body  431 . The air cushioning tube  433  may be fabricated in the form of a sealed tube with which air is filled. Further, the air cushioning tube  433  may be made of transparent thermoplastic polyurethane, thus allowing people to see an advertising member  432  which will be later described herein. Two or more air cushioning tubes may be installed in the recess of the body, differently from the air-cushioning leg  430  shown in  FIG. 13 . 
     The advertising member  432  is provided between the inside wall of the recess  431   b  and the air cushioning tube  433 . The advertising member  432  comprises a notice for advertising an article. However, the air-cushioning leg  430  may not be provided with the advertising member  432 . 
     Sub-support legs  460  are provided between the air-cushioning legs  430  to elastically absorb the load applied to the panel  410 , in cooperation with the air-cushioning legs  430  (see,  FIG. 14 ). Each sub-support leg  460  is made of an elastic material, such as thermoplastic polyurethane. Air cushioning holes  460   a  are formed at each sub-support leg  460  to accomplish a higher air cushioning effect. 
     Each sub-support leg  460  is shorter in length than each of the air-cushioning legs  430 . Thus, when the exercise step  401  according to the eighth embodiment of the present invention is placed on a flat surface, the air-cushioning legs  430  are in contact with the support surface, but the sub-support legs  460  are spaced apart from the support surface. 
     When a strain of the panel  410  exceeds a reference level due to an excessive load, the sub-support legs  460  come into contact with the support surface, thus preventing the strain of the panel  410  from exceeding an elastic limit. Meanwhile, the air cushioning holes  460   a  formed in each sub-support leg  460  function to increase the elastic strain of the panel  10 . 
     The exercise step  401  according to the eighth embodiment of the present invention is provided with the body  431 , the air cushioning holes  431   a  formed on the body  431 , the air cushioning tube  433 , the sub-support legs  460 , and the air cushioning holes  460   a  formed on the sub-support legs  460 , thus enhancing an air cushioning effect, therefore preventing a shock from being transmitted to a user&#39;s knees, and allowing the user to exercise in comfort and safety, like the exercise steps according to the above-mentioned embodiments. 
     According to the above-mentioned embodiments of the present invention, each air-cushioning leg  30  includes the main body  40  and the air control unit  50 . In this case, since the main body  40  has a three-layered structure and is made of thermoplastic polyurethane having a relatively high elastic force, a sufficient cushioning effect is accomplished using only the main body  40  of each air-cushioning leg  30 . However, when each air-cushioning leg  30  includes the air control unit  50  as well as the main body  40 , the cushioning effect of the exercise step  1  is maximized. 
     According to the above-mentioned embodiments, the panel  10  is made of a laminated compressed wood. However, the panel  10  may be made of wood having elasticity or other elastic materials. Further, the panel  10  has a rectangular or circular shape, but the panel may have other shapes. 
     According to the above-mentioned embodiments, the foot contact plate  20  is provided on the top surface of the panel  10 . But, the panel  10  may not be provided with the foot contact plate  20 . 
     According to the above-mentioned embodiments, the air-cushioning legs  30  are provided under the panel  10  to support the panel  10 , and function to absorb a load applied to the panel  10  during an exercise. However, the air-cushioning legs  30  are not necessarily provided at the panel  10 . That is, the air-cushioning legs may be mounted to support legs (not shown) of a bed or a chair to achieve a cushioning effect. Since the air-cushioning legs mounted to the support legs have the same construction as the air-cushioning legs  30  of the above-mentioned embodiments, the air-cushioning legs are not described in the following. 
     Although not shown in the drawings, in place of the air control unit according to the above-mentioned embodiments, an air inlet port and an air outlet port may be provided at both sides of the main body and a damper may be provided at the air outlet port to control an opening ratio of the air outlet port, thus having the same effect as the air control unit of the above-mentioned embodiments. 
     INDUSTRIAL APPLICABILITY 
     As described above, the present invention provides an exercise step, which has an excellent cushioning effect, thus preventing a shock from being transmitted to a user&#39;s knees and allowing the user to exercise in comfort and safety. 
     Further, the present invention provides an exercise step, which is capable of minimizing noise generated during a cushioning operation, and has an excellent cushioning effect. The exercise step of the present invention has a more excellent cushioning effect, in comparison with a conventional exercise step, thus preventing a panel from being deformed and thereby having a long life-span. 
     The present invention provides an exercise step, which is provided with a display unit, thus allowing a user to confirm the number of steps and a time during an exercise. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.