| Context: Push-up (PU) and push-up plus (PUP) are common exercises for developing strength of the primary scapular movers: upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), and serratus anterior (SA). Objective: To determine the differences in muscle activation between PU and PUP in suspended and stable positions. Design: Single-cohort crossover design. Setting: Research laboratory. Patients or Other Participants: 19 individuals (age 21.5+/-1.6 years; height 183.3+/-8.8cm; weight 83.6+/-11.2kg; females=1, males=18; Quick DASH-9=3.5+/-7.2pts) who were able to perform a PU and PUP. Interventions: We measured muscle activation of UT, MT, LT, and SA using wireless, surface EMG. Participants completed maximum isometric voluntary contractions (MVIC) on the muscles of interest followed by 5 repetitions for each exercise: suspended PU, stable PU, suspended PUP and stable PUP. For suspended exercises, we utilized the TRXRTM suspension system. Kinematic data were recorded to identify the beginning and end of each repetition. Participants performed stable PU/PUPs with feet together, hands shoulder-width apart gripping dumbbells, while maintaining a neutral spine. Participants performed suspended PU/PUPs with feet together on a platform at a height consistent with the handles of the suspension system, hands shoulder-width apart gripping the suspension handles, while maintaining a neutral spine. Trials were approved by two raters if the participant reached a minimum 90 degrees of elbow flexion at the depth of the exercise (inter-rater reliability ICC=0.79, intra-rater reliability tester 1 ICC=0.90, tester 2 ICC=0.87). Main Outcome Measures: We calculated root mean square percent MVIC (%MVIC) of the four muscles of interest during each stable and suspended PU and PUP. We used eight separate paired t-tests to evaluate %MVIC. Significance was set at p<0.05 a-priori. Results: When we compared the PU to suspended PU, we did not identify significant different muscle activation in the MT (t27 = -1.766, p = 0.089). However, we did find significant differences in muscle activation of LT (t27 = 2.124, p = 0.043), SA (t27 = 4.906, p< 0.000) and UT (t27 = -5.992, p<0.001). When we compared the PUP to the suspended PUP, we did not identify significant difference muscle activation in the LT (t27 = 1.358, p = 0.0.186), or MT (t 27 = -1.668, p = 0.107). However, SA (t27 = 2.066, p = 0.049) and UT (t27 = -4.155, p<0.001) became significantly more activated in the suspended PUP condition. Conclusions: Over activation of the UT has been associated with scapular dyskinesis and concomitant shoulder pathologies. The results of the study suggest that the use of the suspended PU and PUP elicit increased activation of the UT, which, in a symptomatic population, could exacerbate the condition. When treating patients with scapular dyskinesis and related pathologies, consideration should be made for selecting exercises that focus on coordinated activation of the scapular stabilizers and those exercises that do not require over compensation of one muscle over the others. |
