When people who exercise recreationally train with their muscles stretched more during movements, they gain a bit more muscle size compared to training with varied muscle lengths, but both approaches lead to the same improvement in strength.

We analyzed the available evidence and found that training with muscles stretched longer during movements may lead to slightly more muscle growth compared to training with mixed muscle lengths, though both approaches result in similar strength gains [1]. The evidence we’ve reviewed so far includes 54 assertions that support this observation, with no assertions contradicting it. This suggests that when people who exercise recreationally perform movements that keep their muscles under tension while stretched—like deep squats, full-range deadlifts, or stretched-out chest presses—they tend to see a modest increase in muscle size over time. However, the difference in muscle growth is not large, and strength improvements remain about the same regardless of whether the training emphasizes stretched positions or a mix of lengths. We don’t know yet if this pattern holds for advanced lifters, older adults, or those training with very high volumes or intensities, since the evidence we’ve reviewed focuses on recreational exercisers. The mechanism behind this isn’t fully explained in the data, but it may relate to how stretched positions affect muscle fiber recruitment or tissue stress. What we’ve found so far doesn’t mean one method is better overall—just that stretching the muscle more during exercise might add a small extra benefit for size, without changing strength outcomes. If you’re looking to maximize muscle growth, incorporating exercises that allow your muscles to stretch fully under load could be worth trying, but it’s not necessary to abandon other movements you enjoy.