More on low-load hypertrophy

If you’ve been following my site over the last year, you’ll notice that I’ve written a few articles on the concept of low-load hypertrophy training (here, here and here), and how our understanding of the relationship of training intensity and hypertrophy is a bit skewed. These arguments relied pretty heavily on the relatively recent data from Dr Stu Phillip’s at McMaster University; however, I rediscovered another article (1) while working on a review article this morning that is definitely of interest in this context. I believe it’s freely available online too, so don’t rely on my short summary, check out the full article while you can.

Low-load bench press training to fatigue results in muscle hypertrophy similar to high-load bench press training

The authors recruited nine untrained, young men to complete two different 6 week training programs, with a 12 month washout period in between. This is an interesting design as it avoids the cross-education argument, or potential systemic confounding variables that may influence hypertrophy that people cite when discussing the single leg exercise protocols used in previous studies (2,3), but also shows that these guys are patient researchers. I’d have a hard time waiting to get results over a 12 month wash-out period. The authors did not randomize treatment order, such that all participants completed the high-load condition, then followed with the low-load a year later which is a limitation; however, they do acknowledge this and present their rationale for this clearly in the paper.

Each subject performed free-weight bench press three days per week (M/W/F) over six weeks with three sets of 10 reps at 75%-1RM for the high-load condition (HL) and four sets at 30%-1RM lifted to volitional fatigue, with three minutes rest between sets regardless of grouping. Training loads were adjusted at the three week mark to account for increased strength over the course of training. Bodyweight increased (0.6kg) regardless of training condition, and 1RM and isometric knee extensor MVC increased in both groups, albeit with lower percent increases in the low-load training. This is in direct agreement with Mitchell et al (2), and further validates that heavy weights are essential for strength development. However as we’ve seen previously, the percent change in hypertrophy following either training protocol in both the triceps and pec major were similar, suggesting that as long as lower-load training is taken to volitional fatigue, equivalent hypertrophy will be produced as with high-intensity training.

Summary

This was a nice quick study that builds on the questions that were raised based on previous research (2,3) and validates the assertion that when work isn’t matched (low load training to fatigue), light weights can generate appreciable hypertrophy on par with that of high-intensity training. From a programming perspective, using multiple rep ranges as opposed to pigeon-holing yourself to a single rep range is still the best option, as it allows you to capitalize on the volume/intensity relationship to maximize hypertrophy while providing the optimal development of strength.