To examine the acute response to 2 resistance-exercise protocols performed to repetition failure, but different in load configuration, and determine whether the acute response was related to strength increases after 8 weeks of training.
Eighteen resistance-trained men completed a single session of 2 resistance-exercise protocols. The constant-load protocol (CL) required subjects to complete 3 sets of single-arm preacher curls (elbow flexion) to failure using a load of ~77% 1RM. The reduced-load protocol (RL) was similar, but training load was reduced for the second and third sets. Maximal isometric force (MVIC) and blood lactate were assessed preprotocol and postprotocol to determine the acute response. For the 8-week training phase, subjects (N = 12) were divided into 2 programs, each corresponsing to 1 of the protocols. Strength was measured before and after training.
MVIC decreased from 106.2 ± 13.8 to 84.3 ± 12.1 N · m and from 109.1 ± 14.7 to 82.5 ± 13 N · m after the CL and RL protocols, respectively. The decrements in MVIC were significant (P < .001), with the decline after RL tending to be greater (P = .051). Postprotocol blood lactate concentrations after CL and RL were 3.4 ± 1.1 and 4.1 ± 1.3 mmol/L, respectively, with greater increases after RL (P = .036). Similar and significant 1RM strength increases were observed after both programs (from 20.7 ± 2.7 to 23.3 ± 3.5 kg after CL and from 22.4 ± 2.9 to 25.5 ± 3.2 kg after RL; P < .001).
The similar increases in strength suggest that either the greater acute response to RL was not related to the increases in strength or a minimal (threshold) response was achieved during both programs.
Brandenburg is with the Dept of Kinesiology and Physical Education, Northern Illinois University, De Kalb, IL 60115. Docherty is with the School of Physical Education, University of Victoria, Victoria, BC, Canada.