The Claim
In amateur bodybuilders with at least two years of resistance training experience, using 90-second or 180-second rest intervals between sets during a 10-week hypertrophy program results in significantly greater increases in vastus lateralis and biceps brachii muscle thickness (8.0–8.9%) compared to 60-second rest intervals (3.9–4.2%), with the difference attributed to better preservation of training volume.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
Among amateur bodybuilders with at least two years of training experience, resting 90 or 180 seconds between sets during a 10-week muscle-building program leads to larger increases in muscle thickness of the thigh and biceps compared to resting 60 seconds between sets, due to higher total training volume maintained.
See the scientific wording
In amateur bodybuilders with at least two years of resistance training experience, using 90-second or 180-second rest intervals between sets during a 10-week hypertrophy program results in significantly greater increases in vastus lateralis and biceps brachii muscle thickness (8.0–8.9%) compared to 60-second rest intervals (3.9–4.2%), likely due to better preservation of training volume.
When rest periods between sets are longer, muscles recover more energy and clear out fatigue-causing chemicals faster, allowing a person to lift heavier weights or do more reps in each set. This increases the total force applied to muscle fibers over the workout, which repeatedly triggers signals inside muscle cells to build more contractile proteins. Over weeks, this leads to thicker muscle fibers.
What the research says
1 studyStudy: Effects of Rest Interval Length on Muscle Hypertrophy in Amateur Bodybuilders
For amateur bodybuilders, taking longer breaks between sets—like 90 or 180 seconds—lets them lift heavier or do more reps overall, which helps their muscles grow more than if they only rest 60 seconds.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.