Effects of low-load, higher-repetition versus high-load, lower-repetition resistance training not performed to failure on muscle strength, mass, and echo intensity in healthy young men: a time-course study.

In healthy young men, doing resistance training three times a week for eight weeks leads to measurable increases in muscle size and improvements in muscle tissue quality, with muscle size increasing by week four and tissue quality changes becoming significant only by week eight.

In healthy young men, lifting weights without pushing to complete exhaustion can still lead to significant gains in strength and muscle size over eight weeks.

In healthy young men, lifting lighter weights for more repetitions generates about 70% more total work than lifting heavier weights for fewer reps, but both approaches result in similar gains in muscle size and strength, suggesting that the total amount of work performed may be more important than how heavy the weights are.

In healthy young men, eight weeks of resistance training reduces a specific ultrasound measure of fatty or fibrous tissue inside muscles, regardless of how heavy the weights are or how many reps are done. This suggests the training improves muscle composition without necessarily increasing muscle size.

For beginners lifting weights, gaining strength is about the same whether they use heavier weights with fewer reps or lighter weights with more reps, as long as the total amount of work done is equal.

In healthy young men, two different resistance training methods—one using lighter weights with more repetitions and another using heavier weights with fewer repetitions—produced similar improvements in muscle strength, muscle size, and muscle quality after 8 weeks, as long as neither protocol was performed to muscle failure.