In this article

Should you train with light or heavy weights to maximize muscle growth? Scientific Insights

Understanding Training Intensity

How many reps per set? This is akin to determining the optimal training intensity. In exercise science, training intensity refers to the percentage of your one repetition maximum (%1RM) utilized. A more suitable term might be relative load, as “intensity” can be ambiguous. Training intensity and rep count are closely linked. For instance, most individuals can complete 8 reps at 80% 1RM and 3 reps at 90%. At 100% 1RM, only one rep is feasible.

The Myth of the Hypertrophy Zone

A prevalent myth in fitness circles is the notion of an optimal hypertrophy zone of 6–12 reps. However, this is based on subjective feelings rather than empirical evidence. Sets with weights light enough for over 12 reps lack sufficient intensity, while heavy weights for fewer than 6 reps lack the desired sensation. The ideal range appears to be 6-12 reps per set. (Reference: Schoenfeld, B. J., et al. “Resistance training volume enhances muscle hypertrophy but not strength in trained men.” Medicine and Science in Sports and Exercise 51.1 (2019): 94-103.)

Mechanical Tension and Muscle Growth

The belief that heavy weights are inferior to lighter ones contradicts established muscle growth principles. Mechanical tension primarily drives muscle growth. Heavier weights induce more tension, suggesting they’re more conducive to muscle growth. (Reference: Wernbom, Mathias, Jesper Augustsson, and Roland Thomeé. “The influence of frequency, intensity, volume and mode of strength training on whole muscle cross-sectional area in humans.” Sports Medicine 37.3 (2007): 225-264.)

Evidence-Based Repetition Ranges

Research consistently demonstrates that low rep work yields similar muscle growth as higher rep work. Even very high rep sets, performed close to failure, prove effective for muscle growth. Training close to failure is pivotal for high rep sets to be maximally effective. (Reference: Schoenfeld, B. J., et al. “Dose-response relationship between weekly resistance training volume and increases in muscle mass: A systematic review and meta-analysis.” Journal of Sports Sciences 35.11 (2017): 1073-1082.)

Optimizing Neuromuscular Recruitment

To achieve full motor unit recruitment and stimulate all muscle fibers maximally, training with a heavy weight or close to failure is imperative. Sets to failure recruit all motor units and induce similar anaerobic work, irrespective of rep range. Sets with 30% and 80% of 1RM produce comparable glycogen depletion and muscle anabolic signaling. Reference: Mitchell, C. J., et al. (20212).

I'm Bas Gosewisch

I’m into marketing, growth and fitness and I’ve been helping clients such as &C, Longines Global Champions and many more companies with direct response digital marketing in one way or another.

Gelukt 🏆