Partial range of motion does not alter acute regional muscle responses in elbow fl exors in recreationally trained men

Abstract

This study examined the acute regional muscular responses to two uni-lateral isokinetic resistance-training (IRT) biceps curl protocols performed in partial ranges of motion (pROM) in recreationally trained men. Fifteen resis-tance-trained men (age 22.9 ± 2.8 years, total body mass 85.7 ± 13.0 kg, height 175.9 ± 7.4 cm) participated in this study. The participants performed 6 sets of 10 repetitions of concentric elbow fl exion at 60°/s, with a 3-min rest interval between sets, in one of two diff erent IRT protocols: (1) pROM between 0-60° (IRT 0-60 ) or (2) pROM between 60-120° (IRT 60-120 ). Muscle thickness (MT) and echo intensity (EI) were assessed pre-IRT, immediately post-IRT, and 15 min post-IRT at two elbow-fl exor sites (30% and 70% of arm length). Peak torque (PT) and angular work (W) were assessed during the fi rst and last sets, and session rating of perceived exertion (sRPE) was recorded 15 min after each protocol. PT decreased signifi cantly across sets for both IRT protocols (IRT 0-60 : 15.3% and IRT 60-120 : 9.6%), with no protocol × set interaction. W remained unchanged between IRT protocols. MT increased predominantly at the 30% site in both IRT protocols, whereas responses at the 70% site were more limited and time-dependent. EI also increased over time (13.4–14.9%) without signifi cant interactions. sRPE did not diff er between IRT protocols. These fi ndings indicate that pROM at short or long joint angles produces comparable acute reductions in PT, increases in MT and EI, and perceived eff ort when angular work (assessed in the fi rst and last sets) is similar.