Mixed
When total volume load is equated, high-intensity resistance training (3 sets of 3RM with 3-minute rest) produces significantly greater maximal strength gains than moderate-intensity training (3 sets of 10RM with 90-second rest), while both protocols yield equivalent increases in muscle thickness.
If your goal is maximum strength, use heavy weights (around 3 reps per set) with longer rest periods (3 minutes), even if you are experienced. If your goal is just muscle size, you can use lighter weights (10 reps) with shorter rest (90 seconds) and get the same muscle growth, but you will likely gain less strength. Make sure you are doing the same total amount of work (sets x reps x weight) in both cases to make a fair comparison.
In conclusion, this study showed that both bodybuilding- and powerlifting-type training promote similar increases in muscular size, but powerlifting-type training is superior for enhancing maximal strength.
Why this rating
Randomized controlled trial with well-trained subjects, though sample size is small (n=17) and duration is short (8 weeks).
Source
Effects of Different Volume-Equated Resistance Training Loading Strategies on Muscular Adaptations in Well-Trained Men
Brad J. Schöenfeld et al. · The Journal of Strength and Conditioning Research · 2014
This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →