A few years ago, a grainy image of a PowerPoint slide circulated online, suggesting a study demonstrating that stretching between sets boosts muscle hypertrophy. Although the study was never published, the abstract hinted at significant calf growth in subjects who stretched for 30 seconds between sets of calf raises. A 1993 study showed impressive muscle growth in quail from weighted stretching, but this has never been replicated in humans.
A 2009 study from Brazil investigated the effects of inter-set stretching on muscle growth in humans. Twenty-nine subjects participated in a full-body training program, with one group incorporating 30-second stretches between sets. The stretching group experienced approximately 50% more overall muscle growth after eight weeks. However, the statistically significant increase was primarily observed in the vastus lateralis (outer quad) muscle.
While the biceps, triceps, and rectus femoris also showed growth favoring the stretching group, the differences weren’t statistically significant. This suggests that inter-set stretching might be more effective for certain muscle groups, or that longer study durations and larger sample sizes are needed to confirm broader benefits.
If you’re already resting for one to three minutes between sets, incorporating 30 seconds of stretching could be beneficial. However, it’s essential to avoid over-stretching, as stretching to the point of pain can hinder hypertrophy. Keep stretches below 30 seconds and at a mild discomfort level to avoid impacting force and power output.
The exact mechanism behind the potential benefits of inter-set stretching remains unclear. It might be related to increased blood flow and nutrient delivery, similar to blood flow restriction training, or simply due to increased cumulative muscle tension. Further research is needed to fully understand these effects.
When implementing inter-set stretching, start by stretching the agonist muscle for the first few heavy sets of an exercise. For instance, stretch your pecs between bench press sets on a push day, but not during subsequent isolation exercises. Similarly, stretch your lats between pull-up sets, but not during rowing exercises. This approach can help you gauge the effectiveness and avoid potential diminishing returns from excessive stretching volume. Finding the optimal balance between stretching and training is key to maximizing muscle growth.
