Resting as long as you like between sets gave similar leg muscle growth, strength and muscular endurance to a fixed rest of about 2 min over 8 weeks of lower-body training, but sessions took 78.5 instead of 56.0 min, in an RCT of 40 resistance-trained adults (21 vs 19); domain effects were trivial (hypertrophy −0.1 SD, 95% CrI −0.2 to 0.0; performance 0.0 SD, −0.3 to 0.3)

Mohan and colleagues asked whether letting trained lifters choose their own rest between sets changes muscle growth and strength compared with a fixed rest of about 2 min, and what it costs in time.

Forty resistance-trained participants were randomised to self-selected rest (21) or fixed rest of about 2 min (19) and did 8 weeks of supervised lower-body training: four sets of 8-12 reps of squat, leg extension, standing calf raise and seated calf raise.

Both groups improved muscle thickness measured by ultrasound, dynamic and isometric strength and muscular endurance similarly. In a domain-level analysis the treatment effects were trivial for hypertrophy (−0.1 SD, 95% credible interval −0.2 to 0.0) and performance (0.0 SD, −0.3 to 0.3).

The fixed-rest group finished sessions about 29% faster (56.0 ± 4.5 vs 78.5 ± 15.4 min) with similar session RPE (8.2 ± 1.0 vs 8.1 ± 0.7). The authors conclude that self-selected rest gives comparable adaptations but takes much more time, and that prescribing about 2 min appears efficient without compromising adaptation.