Putting on muscle with only light weights


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- Alex Hutchinson (@sweatscience)


This is a topic that should stir up some controversy: a study suggesting that you don’t need to lift heavy weights to put on muscle. I blogged about this when the study first came out a few months back; I’ve since had the chance to chat with Stuart Phillips, so I wrote a Globe column with more details:

For once, scientific studies, decades of practical experience in the gym, and logic all point to the same conclusion: you need to lift reasonably heavy weights to gain strength and muscle. The American College of Sports Medicine recommends 60 to 70 per cent of your “repetition maximum” or RM (the most you can lift for a given exercise) for novices, and 80 to 100 per cent for experts.

So recently published results from McMaster University, which suggest that you can build muscle just as well – or perhaps even better – with weights as light as 30 per cent RM, have been greeted with surprise, to put it mildly.

“There are plenty of people who just don’t believe it,” admits kinesiology professor Stuart Phillips, the senior author of the paper, which appeared in the journal PLoS ONE.

The results would be welcome news for older people and weight-room neophytes, but there is a catch. The key to stimulating muscle growth, Dr. Phillips believes, isn’t linked to any particular weight or number of repetitions – it’s reaching the point of failure, where you can’t lift anymore.

Phillips has since completed a training study that actually attempts to put these finding into practice. It’ll be exciting to see what the results of that study reveal when they’re analyzed and released.

17 Replies to “Putting on muscle with only light weights”

  1. I wondering how many days of rest are needed between training sessions that go to failure using lighter weights?

  2. Yes, a very interesting discussion — thanks for the link, Wazzup. A couple of follow-up points from my discussion with Stu Phillips. First, he has already completed the follow-up training study, but the results haven’t yet been released. That will address the comments about the difference between a protein synthesis study and an actual training study showing muscle accretion. Second, I don’t think he’d claim that high reps/low weight is BETTER than heavy weights for hypertrophy (despite the fact that some of the protein markers were higher in the light weight group) — his primary point is that low weights can just as effective (as long as you lift to near failure), which might be useful to people who aren’t comfortable with heavy weights.

  3. “I wondering how many days of rest are needed between training sessions that go to failure using lighter weights?”

    That is a very insightful question. Have you ever performed a low-weight exercise to failure? I once did this to near-failure (stopped at 400 reps, a round, psychologically appealing number), and the aftermath was extremely painful, lasting several days. I would much prefer the heavy weight.

  4. To be fair, I think that’s getting a little outside the regime Phillips was testing. His “low-weight” group reached failure at, on average, 24 reps. When I asked him about what regime of low weights his results would apply to, he said something along the lines of “It doesn’t really matter if you’re talking about 20 reps or 40 reps, but if you’re able to do 90 reps, that’s a different ballgame.”

    Another point Phillips emphasized to me is that he’s not trying to convince people who already use heavy weights to switch to light weights. There’s no doubt that heavy weights work, and they are more time efficient than light weights. The targets of this research are people who don’t (they’re intimidated) or can’t (they’re frail) use heavy weights, but might be willing to try lighter weights. He’s saying, hey, contrary to what the ACSM guidelines say, you don’t HAVE to be lifting >60% 1RM to build muscle. You can do it with lighter weight too — as long as you do enough reps to approach failure.

  5. When you think of it, it’s not all that surprising. Traditional ab crunches seem to be an example of a low weight, high repetition exercise that builds muscle.

  6. They way I’ve been working out for awhile is simply choosing an amount of reistance that feels challenging. I have at times got carried away with too much weight/resistance. For lack of a better way to put it after a certain point the weight starts to feel like I could injur myself. I don’t really count reps. I go until I reach concentric failure or when the discomfort gets too much for me. I’ve been debating if I’m going to keep track of the amount of weight/resistance for each exercise or if I’m simply going to just use the amount of weight that “feels” right each workout.

  7. I think it is a good idea to keep track of the amount of weight/resistance. I don’t know how else I would go about progressing if the goal is strength/hypertrophy.

  8. Yes, that would be my instinct too. Choosing your weight/resistance based on what “feels right” (and then lifting to failure) sounds like a great plan, but it also makes sense to keep track of how much weight that is each time, to figure out whether you’re making progress.

  9. Hi Alex, I think what I end up doing sometimes is trying to add more weight too quickly. As far as counting reps or time under load I don’t write these things down. I don’t know about you but when I’m performing a set I find it distracting counting the reps or it messes with my breathing and cadence. If I was guessing i’d say my time under loads vary from maybe 15 seconds to maybe 45 seconds. I’m not sure. Again I don’t know how relevant time under load is. It seems to me that the important things are to challenge the muscles and do it safely.

  10. In addition to what I have written here already I have this to say: If one is trying to track progress as accurately as possible I would say you would need to keep your form as close as possible for each exercise for each workout. If your form changes you could be using other muscles or using momentum. I would say keep track of your reps or keep track of your time under load for the set. I know i’m contradicting what have I have written here previously but if I take an honest look at strength training I don’t know how else one would accurately tell if you’re truly getting stronger.

  11. In a contrasting idea. What if someone did different exercises from workout to workout. But when doing those exercises they used a level of resistance that was challenging and/or took them to failure. Would they get similar or just as good results as someone that keeps meticulous records of each workout? Just somethings I’ve thought about.

  12. Interesting question, and I don’t think there’s one simple answer. For one thing, it depends on what exactly your goals are — e.g. if you’re trying to make your biceps as big as possible, or simply trying to build your strength for performance and health. I don’t think it’s necessary to keep meticulous records and plan the exact details of every workout. On the other hand, if you just show up at the gym and make up a workout as you go along, it takes a fair amount of discipline to ensure that you’re really getting a useful workout. In the end, I think it comes down to personality: some people thrive on structure and routine, others prefer spontaneity.

  13. I’ve wondered if it’s a good idea to do a wide variety of different exercises or ranges of motion. For example at on workout you might do flat bench presses, incline at the next, and maybe cable crossovers the next after that. You working similar muscle complexes but the stress wouldn’t be in the same exact areas of muscle or for the bones, joints, and connective tissue. When I workout I try to cover the whole body, not necessarily trying to isolate every muscle during every workout. I just feel like I should be trying to strengthen every part of my body. I kinda go back and forth on the importance record keeping. The thing that seems most important to me is keeping track of the amount of weight that I can handle safely in good form.

  14. I think the personality thing is very important as well like you talked about. I kno w some including myself have talked about strength training being “work” and not necessarily for enjoyment. But common, if we’re talking about something that one might do for the rest of their life wouldn’t you want to enjoy it!? Personally I’m not concerned about “how much I can bench” or “how much I can squat”. I want to keep my body strong and more injury resistant. Any muscle mass I can gain would be very nice as well.

  15. When I go workout. I will typically do some warm up sets on each exercise. To me this seems to have both a positive psychological and physical effect. For example at my last workout I did some leg presses early in the workout. On each exercise I keep adding more weight until I get to a level of reistance that “feels” right. I’m not having to break form to lift it but at the same time it is challenging and I eventually reach a point where I can no longer continue concentrically. For awhile I was keeping track of this “maximum for me” weight. I think I will continue to do so. As for me currently this seems to be the one thing I can easily keep track of. And try to either maintain using the current amount of resistance or add a bit more whenever I can safely.

  16. I’ve done alot of rambling here. Hopefully somebody will get some good out of it. I need to quit being lazy and unfocused and keep track of my reps or time under load or both.

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