Are you one of those old school gym rats who believe heavy and low 6-10 rep resistance training the best stimulus for muscle growth? If so, you’re not alone. Many of us (yours truly included, so I’m not pointing any fingers) believe that the best stimulus for muscle growth is heavy lifting in the 6-10 rep range. However, recent scientific findings show that the classical heavy and low 6-10 rep training might not be the best way to induce muscle anabolism…

More reps might be better

The classic weight lifting recommendation for building muscle is to lift relatively heavy (over 70% of 1RM), or within the 6-10 rep range (1, 2). However, a recent study has shown that a training mode with lower weight and higher reps actually is more effective at inducing muscle anabolism and muscle growth (3).

This study had subjects perform 4 sets of leg extension at different loads and volumes (reps):

90% of 1RM to failure: corresponding to 180 lb for 5 reps (90 FAIL)

30% of 1RM to failure: corresponding to 62 lb/24 reps (30 FAIL)

30% of 1RM with a total work output similar to the 90% 1RM protocol: corresponding to 62lb for 14 reps

The scientists measured myofibrillar protein synthesis (the type of muscle protein synthesis that makes the muscles grow) and several anabolic signalling pathways in the trained muscles.

This is the first study to show that low-load high volume resistance exercise (30FAIL) is more effective at increasing muscle protein synthesis than high-load low volume resistance exercise (90FAIL). Specifically, the 30FAIL protocol induced similar increases in myofibrillar protein synthesis to that induced by the 90FAIL protocol at 4 h post-exercise but this response was sustained at 24 h only in 30FAIL protocol. The 30FAIL protocol also stimulated the anabolic signalling pathways to a greater degree than the other exercise modes.

What does this mean?

This finding counters previous recommendations that heavy loads (i.e., high intensity) are necessary to maximally stimulate muscle protein synthesis (1, 2, 4, 5). It is now apparent that the extent of muscle protein synthesis after resistance exercise is not entirely load dependent, but is also related to exercise volume (that is, number of reps in this case). Thus, the total volume of contractions (number of reps), independent of load (intensity) apparently results in full motor unit activation and muscle fibre recruitment

Now, probably you’re thinking “am I supposed to start lifting like a chick” to build muscle? I want to point out that this study only investigated the effect of one bout of resistance exercise, comprising four sets) on muscle (myofibrillar) protein synthesis. In order to get a definite answer, long-term training studies need to be conducted. According to a personal communication with the head researcher (6), one such training study has been done and is now awaiting publication. With the reply “we are very confident in the short-term data”, at least I will start to throw in some high rep sets here and there in my training program. But in order for this to work, you have to train until complete failure. No sissies!

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