An abundance of research has examined the EMG activity of selected selleck chem inhibitor musculature while performing different exercises on various instability devices (Beach et al., 2008; Freeman et al., 2006; Marshall and Murphy, 2005; Marshall and Murphy, 2006; Marshall and Murphy, 2006). For example, the Swiss Ball has been shown to be an effective device for eliciting an increased level of muscular activity when used with exercises designed to target the PM, AD, and TB (Lehman et al., 2006; Marshall and Murphy, 2006; Marshall and Murphy, 2006). Our findings are consistent with previous research about the global topic of instability exercise; i.e., increased muscular activation during body weight exercise when stability is challenged (Anderson et al., 2011; Freeman et al., 2006; Lehman et al.

, 2006; Marshall and Murphy, 2005; Marshall and Murphy, 2006; Snarr et al., 2013). However, the current study is one of the first to suggest ST may be a superior method for increasing EMG activity of PM, AD, and TB. Several theories are available to help explain our findings, which are detailed within the following two paragraphs. During a typical PU, each dynamically active joint has only one degree of freedom in which to function (i.e., a vertical, up-and-down movement). However, the ST decreases the base of support for the upper body, as it is suspended above the floor. This unstable kinetic chain results in additional degrees of freedom as the limbs work to prevent unnecessary horizontal and diagonal movements. This creates a ��multiple-role�� within the active musculature as they not only serve as PU agonists, but also as joint stabilizers (Lander et al.

, 1985; Marshall and Murphy, 2006; McCaw and Friday, 1994). The hands being placed in the handles of the suspension trainer provides additional degrees of freedom compared to the standard [fixed] floor placement. With additional ranges of freedom, a greater number of motor units is recruited to execute a particular exercise resulting in an increased EMG output (Beach et al., 2008; Behm, 1995; Marshall and Murphy, 2005; Marshall and Murphy, 2006; Vera-Garcia et al., 2000; Wahl and Behm, 2008). This characteristic is similar when performing dumbbell versus barbell chest presses, as the former has been shown to provide an increased level of instability (Behm, 1995; Saeterbakken et al., 2011). Furthermore, Saeterbakken et al.

(2011) showed that with a shift from a one degree to a multiple degree of freedom bench press exercise (i.e., comparing barbells to dumbbells), EMG activation levels remained consistent in the primary musculature. However, the average load of the barbell bench press was 17% greater compared to the dumbbell AV-951 bench press (Saeterbakken et al., 2011). In the current study, the participants performed both exercises while using the same load (i.e., their personal body weight) even though the degrees of freedom were greater with SPUs. Therefore, EMG output was higher.