The main findings were that overall (males and females combined), less repetitions were completed with the bench press when adjusted for the weight exerted during push-ups, and secondly, male participants completed a higher number of repetitions in both bench press and push-ups compared to females. A strong correlation was observed between the number of bench press and push-up repetitions. Triceps and biceps brachii demonstrated a lower extent of muscular activity during the concentric phase of the push-up compared to the concentric phase of the bench press. The anterior deltoid also showed a lower amount of muscular activity during the eccentric phase of the bench press compared to the eccentric phase of the push-up. Generally, males had a lower amount of muscular activity compared to females in both exercises. The amount of muscle activity also increased with the number of repetitions. The greater repetitions with push-ups than bench press are in accord with prior research (Amasay et al., 2016). From a biomechanical standpoint, this finding can be justified. The vertical distance of the center of mass traveled when performing a bench press is higher compared to push-ups. The center of mass for a human body is located at 41.2% of their height, which would be roughly close to the mid-section of the human body (Clauser et al., 1969). Although the movement in the shoulder joint between push-up and bench press may be similar (van den Tillaar and Saeterbakken, 2014), the center of mass load displacement is quite different. In a sagittal view, the push-up is considered to be a second-class lever whereas, the bench press when ascending the bar, would progress towards a third-class lever as the bar moves towards the bench relative to the shoulder joint (Duffey and Challis, 2007; Elliott et al., 1989; Madsen and McLaughlin, 1984). Eckel et al. (2017) found similar results showing that more repetitions were performed with push-ups compared to bench press. They argued that higher core activation during push-ups is correlated with the higher repetitions performed during push-ups. Body position was another factor discussed by Eckel et al. (2017). The changes in the centre of mass position during push-up from the up position to down position may be a primary reason higher repetitions are performed during push-ups. It is suggested that push-ups are more similar to a decline bench press leading to a shorter moment arm and limited range of motion (Eckel et al., 2017). Due to the changes in moment arm flexion during a push-up, the amount of mass that has to be supported would change from 69% in the up position to 75% in the down position (Contreras et al., 2012). These changes were also similar to the results of this study where the participants supported 66% of their body mass in the top position compared to 72% in the down position. The stability of the exercise mode has been proposed as another factor contributing to differences in push-ups vs. bench press repetitions. During the push-up, force is exerted upon a stable surface, whereas in a bench press the barbell is freely moving and thus unstable (Chou et al., 2012) increasing the demand to stabilize and reduce the movement of the barbell (Amasay et al., 2016). Stability challenges are greater with the Olympic bar as any perturbation movements lead to greater disruptive torques due to the length of the barbell, which must be stabilized by the associated musculature. Closed chain exercises like push-ups are characterized by inducing an axial compressive load on the glenohumeral joint and functionally stabilizing it. This stabilization is achieved through the rotator interval structure, which mainly consists of ligaments as well as the biceps brachii tendon encapsulating the glenohumeral joint and the shoulder joint capsule (Yamamoto et al., 2006), thus reducing the energy expenditure. However, when performing an open chain exercise such as bench press, the stabilization of the shoulder is mainly achieved through activation of the surrounding muscles of both scapular and glenohumeral joint (Lephart and Henry, 1996). The deltoids and serratus anterior along with the upper trapezius function to stabilize the scapular and shoulder joint. These muscles have illustrated a higher activation in bench press compared to push-ups (Calatayud et al., 2014), which would increase the energy expenditure resulting in premature fatigue. For example, the increased middle deltoid EMG activity in the fourth quartile would be ascribed to increased motor unit recruitment and rate coding to compensate for fatiguing motor units (Behm, 2004). Increased muscle activation would also contribute to greater stabilization (Ostrowski et al., 2017) of a fatigue-induced unstable joint (Behm and Anderson, 2006). Our results also showed that males generally demonstrated a higher number of repetitions in both push-ups and bench press compared to females, which is in accord with previous research (Amasay et al., 2016). In contrast, Clemons et al. (2019) reported similar push-up repetitions between men and women. However, the women in that study performed modified push-ups with their knees as the pivot point. The justification for this discrepancy has been suggested to be correlated to the upper-body relative strength difference between men and women (Bishop et al., 1987). The mean percentage difference for upper-body strength between men and women ranges from 75%-116% with males demonstrating higher amount of upper-body strength compared to women (Bishop et al., 1987), which may explain the difference in the amount of repetitions performed for men and women. Clemons et al. (2019) reported a strong association (r=0.71; p=0.0001) between push-up repetition number and relative strength (bench press 1RM as a percentage of body mass). Furthermore, males are generally more accustomed to push-up training with their toes or feet as the fulcrum point, whereas females are more familiar with doing the modified variation of push-up from the knees. Hence, male participants exhibited lower muscle activity and thus indicative of why push-ups are a less taxing activity for males compared to females. Calatayud et al. (2015) did not find any difference in muscle activity of the pectoralis major and anterior deltoid between bench press and push-up. However, the purpose of their study did not involve a fatigue protocol. Furthermore, the intensity was not equated to the participant’s push-up mass, rather they incorporated elastic bands to increase the load so the amount of repetitions both in bench press and push-ups would be similar. The results of this study show a lower anterior deltoid activity during the eccentric phase of bench press, which is similar to the previous report. It was found that the triceps brachii and biceps brachii demonstrated lower muscular activity during the concentric phase of the push-up compared to the concentric phase of the bench press. When a muscle experiences greater stress or is fatigued to a greater extent it must increase recruitment and rate coding to maintain or sustain the task. Since push-ups illustrated lower EMG activity, the demands on the muscle must have been less, allowing a lower extent of muscle activation to achieve the goal. Hence, less muscle activation could conserve energy and contribute to less fatigue and more repetitions. A non-significant similar finding can be seen in research by Gottschall et al. (2018) where they compared the EMG activity of different muscles in bench press vs. push-ups. However, the anterior deltoid in this study elicited a lower EMG activity during bench press whereas higher EMG activity was detected for the bench press compared to push-up in a previous study (Gottschall et al., 2018). During the bench press, the participants showed less neuromuscular activity in the anterior deltoids compared to the push-up. Similar, although non-significant, differences were observed in a previous study (Calatayud et al., 2015). This result was also comparable to another study, which did not find significant differences in anterior deltoid activity between bench press and push-up, although it displayed relatively higher activity during the push-up (van den Tillaar and Saeterbakken, 2014). This is in contrast to the findings presented by Dillman et al. (1994) who found higher anterior deltoid activity during the bench press. One important factor to consider is the speed of the movement, which influences the amount of muscle activation (Sakamoto and Sinclair, 2012). The previous studies did not report on the speed of the movement whereas the movement speed considered for this study was considered to be faster compared to prior studies (Hsu et al., 2011; Sakamoto and Sinclair, 2012). Sakamoto and Sinclair (2012) for example had participants perform their bench press at 0.5 rep/sec compared to 1 second concentric and eccentric durations respectively in the present study. Although most results demonstrated large effect sizes, as with many studies, a limitation of this study might be the moderate sample population of 10 men and 10 women. A greater number of data points could have provided more rigorous regression values. Furthermore, the results would only apply to resistance trained individuals as it was found that untrained women typically could not complete a single bench press repetition in this study and thus had to be excluded. Fat mass and fat free mass were not analyzed and could again have provided more precise interpretations. However, all participants were trained individuals with no male or female participant exhibiting excessive fat mass. Future studies could attempt to evaluate a wider scope of the population as well as analyze the kinematics in combination with the EMG. In conclusion, greater push-up repetitions were completed compared with a similar load bench press. Lower male EMG activity during the exercises representing lower stress or relative load on the muscle potentially contributed to their higher repetitions in both bench press and push-ups compared to women. A strong correlation between the number of bench press and push-up repetitions permitted a formulation of a regression equation to predict the number of bench press repetitions from push-up performance. Triceps and biceps brachii demonstrated a lower muscular activity during the concentric phase of the push-up compared to the bench press, while the anterior deltoid also exhibited less activity during the eccentric phase of the bench press compared to the push-up. |