Range of motion of resistance exercise affects the number of performed repetitions but not a time under tension

Abstract

The resistance training volume along with the exercise range of motion has a significant impact on the training outcomes. Therefore, this study aimed to examine differences in training volume assessed by a number of performed repetitions, time under tension, and load-displacement as well as peak barbell velocity between the cambered and standard barbell bench press training session. The participants performed 3 sets to muscular failure of bench press exercise with the cambered or standard barbell at 50% of one-repetition maximum (1RM). Eighteen healthy men volunteered for the study (age = 25 ± 2 years; body mass = 92.1 ± 9.9 kg; experience in resistance training 7.3 ± 2.1 years; standard and cambered barbell bench press 1RM > 120% body mass). The t-test indicated a significantly higher mean range of motion for the cambered barbell in comparison to the standard (p < 0.0001; ES = -2.24). Moreover, there was a significantly greater number of performed repetitions during the standard barbell bench press than cambered barbell (p < 0.0001) in a whole training session, while no difference was found in total time under tension (p = 0.22) and total load-displacement (p = 0.913). The two-way repeated-measures ANOVA indicated a significant barbell × set interaction effect for peak velocity (p = 0.01) and a number of repetitions (p = 0.015). The post-hoc analysis showed a significantly higher number of repetitions for standard than cambered barbell bench press in set 1 (p < 0.0001), set 3 (p < 0.0001) but not in set 2 (p = 0.066). Moreover, there was a significantly higher peak velocity during the cambered than standard barbell bench press in set 1 (p < 0.0001), and set 2 (p = 0.049), but not in set 3 (p = 0.063). No significant differences between corresponding sets of the standard and cambered barbell bench press in time under tension and load-displacement were found. However, concentric time under tension was significantly higher during cambered barbell bench press in all sets (p < 0.05) when compared to the standard barbell bench press, while eccentric time under tension was significantly lower during the cambered than standard barbell bench presses only in the set 3 (p = 0.001). In summary, this study briefly showed that measuring training volume by the number of performed repetitions is not reliable when different exercise range of motion is used.