The push-up (PU) is a popular exercise that is performed with the purpose of increasing strength and hypertrophy of upper extremity musculature (Dillman et al., 1994; Rogol et al., 1998; Ubinger et al., 1999; Uhl et al., 2003). It is also considered the standard measurement of upper-body muscular endurance (ACSM, 2008). Though the PU serves as meantime an exercise to primarily target the pectoralis major (PM); it also activates the anterior deltoid (AD) and triceps brachii (TB) (Uhl et al., 2003; Youdas et al., 2010). This exercise is traditionally performed on a flat, stable surface with hand placement at slightly wider than shoulder width. However, common variations exist involving changes in hand position from standard (e.g., wide or narrow) and modifying body posture by elevating the feet.

A change in surface stability has recently been shown to also add variation and increased intensity of the PU. Most research in this area that has suggested that performing PU with instability devices such as Swiss balls, inflated discs, BOSUs and wobble boards may increase the activity of shoulder girdle and upper arm muscular compared to the traditional approach (Cogley et al., 2005; Contreras et al., 2012; Gouvali and Boudolos, 2005; Lehman et al., 2008; Youdas et al., 2010). Suspension training (ST) is one of the newest forms of stability training that utilizes hanging ropes and straps that are anchored to a fixed point from above (e.g., ceiling or pull-up bar) allowing the user to work against their own body weight from a suspended position.

Hypothetically, the greater disruption in stabilization from ST elicits increased motor unit recruitment, essentially causing the muscle to ��work harder�� to perform a particular movement (Beach et al., 2008; Marshall and Murphy, 2006). Unfortunately, limited scientific data exist regarding the effectiveness of this newer form of exercise. Two recent studies demonstrated that the PU performed on a suspension device elicited a greater activation of the rectus abdominis (Snarr et al., 2013) and latissimus dorsi (Beach et al., 2008) compared to a traditional stable PU. However, neither study examined the activity of the prime movers of the glenohumeral (e.g., PM and AD) and humeroulnar (e.g., TB) joints. Therefore, the purpose of this investigation was to determine the extent of electromyographic (EMG) activity of the PM, AD, and TB while performing push-ups with (SPUs) and without (PUs) a suspension device.

As mentioned above, previous research has shown a greater EMG output of the selected muscles when performing the PU on common instability devices such as the Swiss ball (Cogley et al., 2005; Contreras et al., 2012; Gouvali and Boudolos, 2005; Lehman et al., 2008; Marshall and Murphy, 2006; Youdas et al., 2010). Therefore, it was hypothesized in the current study that SPUs Batimastat would elicit a greater activation of the studied musculature compared to PUs.