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- Alex Hutchinson (@sweatscience)

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The traditional view is that it takes at least 6-8 weeks of hard resistance training before your muscles start getting bigger. You’ll see strengths gains long before that, the theory goes, but they come from neural factors (basically the “contract” signal from your brain gets the message to your muscle fibres more effectively). In the last few years, though, that orthodoxy has been challenged by a few studies that claimed to see muscle increases after just a few weeks of training. A new study from the University of Oklahoma, published in the European Journal of Applied Physiology, should help settle the debate. They set out to do a study with three key characteristics:

Hard training: the subjects trained three times a week for eight weeks. The program was leg press, leg extension and bench press. Each exercise was three sets to failure with two minutes rest, with the weight chosen so that failure occurred after 8 to 12 reps in each set. Frequent testing: instead of just doing before-and-after measurements, the testers measured strength and muscle cross-sectional area every week for eight weeks. Sensitive measurement: a tape measure won’t cut it. They used a CT scanner to measure the muscle cross-sectional area at the midpoint of the thigh.

Here’s what they found:

The top line is muscle size, bottom is strength. The first two data points are the pre-training baseline measurements. It’s possible that the initial jump in muscle size after the first week (i.e. after just two training sessions) is predominantly due to swelling associated with muscle soreness. But the soreness had totally dissipated by week 3, so by then we’re unquestionably dealing with actual hypertrophy. By the end of the eight weeks, the total increase in muscle size (CSA) was 9.6%. Two comments. First, I was curious as to why they included bench press when all the measurements are on the legs. In discussing why an earlier study failed to see gains quite this early, the researchers note that

subjects only performed one exercise (leg extensions), so the training stimulus was not as great as that in the present study.

Does this mean that upper-body training can contribute to lower-body hypertrophy, perhaps by tweaking anabolic hormone levels and ramping up whole-body protein synthesis? I’m not sure — if anyone can clarify, please do so in the comments section. Second, this training program is hard. Three times a week, three sets of three exercises may not sound that tough — but every set is to failure (much like the controversial low-weight approach advocated by Stu Phillips, actually). If you really want to put on muscle quickly, you have to work hard.