Here’s a question for you.
Take a group of guys who have been lifting weights for at least a year.
Split them into two groups.
Get both groups to follow the same training program – bench press, military press, wide grip lat pulldown, seated cable row, squat, leg press and leg extension – three times per week for eight weeks.
But with one key difference.
The first group does 3 sets of 8-12 reps to failure with a heavy(ish) weight.
The second group uses a lighter weight and does 3 sets of 25-35 reps to failure.
All other variables – rep tempo and rest between sets – are kept the same.
Which group do you think will build the most muscle?
A new study, published in the Journal of Strength and Conditioning Research, set out to answer that very question .
The “stock answer” is that the group lifting the heavier weights would gain the most size and strength, while those in the light group would gain some size and strength, but to a much smaller degree.
In fact, the results show no difference in the rate of muscle growth between the two groups.
Training with higher reps and lighter weights led to gains in muscle size that were on par with heavier training.
It was a different story where strength and endurance were concerned – guys lifting the heavy weights saw the greatest gains in strength, while those in the high rep group improved their muscular endurance.
One potential explanation for the muscle growth seen in the low load group is an increase in the size of the type I muscle fibers, although this wasn’t actally measured in the study.
Given that type I muscle fibers are highly resistant to fatigue, the increase in time under tension associated with low-load training may have stimulated growth in fibers that were relatively underdeveloped compared to their type II counterparts.
To quote the researchers:
“None of the subjects in our study reported training with more than 15 repetitions per set as part of their normal resistance-training programs. Thus, it is possible that the type I fibers of subjects were underdeveloped in comparison to the type II fibers as a result of training methodologies. The type I fibers therefore may have had a greater potential for growth compared to the type II fibers, and the extended duration of the low-load sets conceivably provided a novel stimulus to promote greater growth in the endurance-oriented type I fibers.”
As with any study, there are a few limitations to consider.
Firstly, muscle growth was measured only in three locations (biceps, triceps and quadriceps femoris). The results may have been different had other muscle groups been included in the analysis.
Second, the study lasted only eight weeks. This was long enough to produce significant gains in muscular strength and size. But we don’t know how things would have panned out had the study lasted longer.
What’s more, the fact that it’s possible to build muscle using higher reps and lighter weights doesn’t necessarily mean that it’s a good idea to do so.
Remember, 3 sets of 25-35 reps was no better than 3 sets of 8-12 reps for building muscle. But each set took around three times longer to complete.
Training to failure in a higher rep range is also highly unpleasant and extremely painful – a lot harder than lower reps and heavier weights.
Doing longer, more painful workouts simply to generate the same results doesn’t sound like a great idea to me.
While this study shouldn’t be interpreted to mean that training with high reps and low loads is now the official “best way” to build muscle, it does suggest that the range of repetitions you can use to add mass is a lot wider than previously thought.
SEE ALSO: THE MUSCLE BUILDING CHEAT SHEET
If you're fed up spending hours in the gym with nothing to show for it, then check out The Muscle Building Cheat Sheet.
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ABOUT THE AUTHORChristian Finn is a former "trainer to the trainers" and fitness writer based in Northamptonshire, England. He holds a masters degree in exercise science, and has been featured in or contributed to major media on two continents, including the BBC and Sunday Times in the U.K. and Men’s Health and Men’s Fitness in the U.S.
1. Schoenfeld BJ, Peterson MD, Ogborn D, Contreras B, Sonmez GT. (2015). Effects of low- versus high-load resistance training on muscle strength and hypertrophy in well-trained men. Journal of Strength and Conditioning Research
2. Burd NA, West DW, Staples AW, Atherton PJ, Baker JM, Moore DR, Holwerda AM, Parise G, Rennie MJ, Baker SK, Phillips SM. (2010). Low-load high volume resistance exercise stimulates muscle protein synthesis more than high-load low volume resistance exercise in young men. PLoS One, 5, e12033