Exercise Variability Did Not Affect Muscle Thickness and Peak Force for Elbow Flexors After a Resistance Training Session in Recreationally-Trained Subjects.

The purpose of this study is to measure the acute effects of exercise variability on muscle thickness and physical performance after two resistance training (RT) protocols using the same or different exercises in recreationally-trained subjects. Fifteen resistance-trained men (23.1 ± 2.6 years, 83.4 ± 16.6 kg, 173.5 ± 8.3cm) performed one of two RT protocols: SINGLE: six sets of 10RM/two-minutes rest of the unilateral biceps curl exercise using cables or MIX: six sets of 10RM/two-minutes rest for the unilateral biceps curl exercises (cable: three sets and dumbbells: three sets, randomly). Muscle thickness (MT) and peak force (PF) were measured ten-minutes before (control), pre-RT session, and post-RT (immediately after and 15-minutes after). All acute RT variables were measured during both RT protocols: the maximal number of repetitions (MNR), the total number of repetitions (TNR), time under tension (TUT), and rating of perceived exertion (RPE). Two-way ANOVA (2 x 4) was used to test differences between RT protocol (SINGLE and MIX) and time (control, pre-test, post0, and post15) for MT and PF. Two-way ANOVAs (2 x 6) were used to test differences between RT protocol (SINGLE and MIX) and sets for MNR, RPEset, and TUT. For PF and MT, there were significant differences in time for both RT protocols (p < 0.05), however, there were not statistical differences between RT protocols. For MNR, RPEset, and TUT, there were significant differences in time (p < 0.05), however, there were not statistical differences between RT protocols. In conclusion, both RT protocols induced a similar increase in MT for elbow flexors and a reduction in peak force.