Journal of Physical Education and Sport

Abstract

IntroductionThe push-up exercise is widely used for the training of the torso (Freeman et al. 2006), the muscles of the upper extremities (Donkers et al. 1993), the serratus anterior muscle and the stabilizing muscles of the scapula (McCann et al. 1993, Decker et al. 1999). It is also used in the rehabilitation and recovery protocols mostly after injuries or surgical procedures on the glenohumeral joint (Kibler, 1998; Decker et al. 1999; Ekstrom et al. 2003; Molonge et al. 2007), during military training (Bell et al. 2000; Knapik et al. 2001; White et al. 2007) and in various protocols which study the general physical ability (Gregg et al. 2002, Lin et al. 2006). Moreover, Kotani and Tokuhiro (2002) mention the great importance that push-ups have on Activities of Daily Living (ADL) for people with Spinal Cord Injury (SCI).Although this particular exercise is very popular and it is used as a kind of movement even in daily activities, there are very few kinesiological studies (Anderson et al. 1984). Donkers et al. (1993) specifically mention that even if push-ups is the most popular exercise which is used to strengthen the muscles and the upper extremities, there is very little data on kinematics and kinetics regarding this activity due to the difficulties in measurements.The fact that the specific exercise is a widely spread exercise is due to the significance of the muscular group that exerts, just like the anterior cogged muscle and the muscles that standardize the scapula (Decker 1999).Freeman et al. (2006) mention that the standard push-up position is the one where the palms and the toes touch the ground. The anatomical curves of the spine are maintained and there is an upright body position from the glenohumeral joint to the knee joint. The hands are straight and the glenohumeral joint is right above the wrist joint. From this position the body lowers down towards the ground with a 90o flexion of the elbows, the hands are extended and it comes back to its initial position. The concentric phase of the movement is slow and the eccentric phase is explosive. To be more specific regarding the hand position, the middle finger must be under the acromio-clavicular joint (Lehman et al. 2007). Moreover, regarding the concentric phase, many researchers support that the chest should reach the ground as much as it can before the eccentric phase begins (Donkers et al. 1993). This position is the basis for all variations of the push-up exercise (Freeman et al. 2006), such as the one where the hands are placed either wider apart from the shoulders, usually at a distance 50% greater than the width between the shoulders or they are placed closer, reducing the distance from the shoulders' width at less than 50% (Donkers et al. 1993). Also, there could be a change in the height of the support base, so the upper extremities would be in a support base higher than the position of the lower extremities (positive inclination) or the lower extremities are placed higher (negative inclination), (Ludewig et al. 2004; Lehman et al. 2006; Lehman et al. 2007). There are also changes concerning the type of the support surface which can be a steady level, such as the ground or a bench or an unsteady level, such as a balance board, a Swiss ball or even a simple ball (Donkers et al. 1993; Ludewig et al. 2004; Freeman et al. 2006; Lehman et al. 2006; Lehman et al. 2007). Finally, there are other variations of this exercise some of which are easier regarding their performance and aggravation, such as the bended knees and hips position and the upright position with the upper extremities touching the wall (Hartmann & Tunnemann 1991; Lear & Gross 1998; Decker et al. 1999; Lehman et al. 2007). Decker et al. (1999) mention that performing the push-up exercise based on the knees instead of the toes is a friendlier position for the glenohumeral joint having almost the same electromyographic activity in most muscle groups. This variation is preferred mostly by people who cannot manage the standard push-up exercise due to limited strength (Hartmann & Tunnemann 1991). …