Schoenfeld, BJ, Grgic, J, Ogborn, D, and Krieger, J, have reviewed the current body of literature and a meta-analysis to compare changes in strength and hypertrophy between low- vs. high-load resistance training protocols. A total of 21 studies were ultimately included for analysis that met the following criteria:
- an experimental trial involving both low-load training [≤60% 1 repetition maximum (1RM)] and high-load training (>60% 1RM);
- with all sets of the training protocols being performed to momentary muscular failure;
- at least one method of estimating changes in muscle mass or dynamic, isometric, or isokinetic strength was used;
- the training protocol lasted for a minimum of 6 weeks;
- the study involved participants with no known medical conditions or injuries impairing training capacity.
Gains in 1RM strength were significantly greater in favor of high-load vs. low-load training, whereas no significant differences were found for isometric strength between conditions.
Changes in measures of muscle hypertrophy were similar between conditions.
The findings indicate that maximal strength benefits are obtained from the use of heavy loads while muscle hypertrophy can be equally achieved across a spectrum of loading ranges.
You can find the full article (PDF) here.