Non-Specific Strength Changes Between High- and Low-Load Isotonic Resistance Training: A Systematic Review and Meta-Analysis

When people lift heavy weights versus light weights to muscle failure, heavy lifting leads to bigger increases in maximum strength, but both approaches produce the same amount of muscle growth.

Training with heavy weights (60% or more of maximum strength) and training with light weights (40% or less of maximum strength), both taken to muscle failure, produce similar amounts of overall strength gain based on current data.

The range of possible strength gains from different training methods includes both small losses and moderate to large gains, showing that current evidence cannot reliably predict which approach will work better.

Most studies in this review involved people who had not trained before and focused on leg exercises, so the results may not apply to trained individuals or exercises that target the upper body.

When people perform resistance training to muscle failure, lifting heavier weights (at least 60% of their maximum) results in larger increases in overall strength measured by isometric and isokinetic tests than lifting lighter weights (at most 40% of their maximum).

The studies used in this meta-analysis had methodological flaws, such as poor reporting of how participants were assigned to groups and no public registration before the study began, which reduces confidence in the results.