Multiple-set resistance training: immediate changes in muscle thickness, echo-intensity, force production, and perception of effort

This investigation examined how performing multiple-set resistance training (RT) acutely influences maximal repetitions (MNR), muscle thickness (MT), echo intensity (EI), peak force (PF), and perceived exertion (RPE) in recreationally trained subjects. Twenty-one recreationally resistance-trained subjects (16 males and five females) performed a unilateral biceps curl with eight sets of 10RM, and 2-minute rest. During each set, MNR was recorded, and RPE set was assessed. PF at 90° elbow flexion and ultrasound measurements of the elbow flexors (MT and EI) were obtained before and immediately after each set of the RT session. Session RPE (sRPE) was reported 15 minutes after completion of the RT session. One-way ANOVAs were used to examine differences across sets for all dependent variables. Findings showed a progressive rise in RPE set , MT, and EI across sets, while both MNR and PF declined ( p < .05). In summary, performing multiple RT sets reduced MNR and PF but elevated RPE set , EI, and MT, with MT stabilizing after the fifth set. Coaches should prioritize not only the chronic effects of RT but also the effective prescription and control of each RT session by implementing multiple sets per exercise, monitoring physical performance and perceived exertion to regulate neuromuscular fatigue, emphasizing high-intensity loading, and ensuring adequate recovery to maximize muscle responses after each RT session.