By Dave Beatty @CBC
A new study at McMaster University suggests lifting lighter weights is as effective as lifting heavier weights, as long as you do it enough to tire you out. This contradicts conventional wisdom around strength training where lifting heavier weights is seen as the fast track to getting jacked. Rob Morton, a co-author of the study along with Professor Stuart Phillips and Sara Oikawa, talked to the CBC about the study.
Q: This study is saying lighter weights can be just as effective as heavier weights when you're lifting to gain muscle and build strength. Can you tell us about the study?
A: We took resistance-trained guys - so, guys who had been lifting weights pretty seriously for about two years - and we divided them into two groups.
There was a heavy lifting group, and a light lifting group. We supervised all the guys. Each time they came in and we'd make sure, and this is the key point, that they'd exercise until volitional failure, or until they couldn't do another repetition. They came in four times a week for 12 weeks.
The big takeaway is that they both got big and strong; that is, they got just as big and just as strong. Our take-home message is that it's not so much about the load that you lift with or any certain exercise variable. Instead, it's about: are you exercising and lifting weights with a high degree of effort? Are you exercising until failure, or until you can't lift anymore?
Q: Should these results be encouraging to people who are just starting out with weight training?
A: Yeah, there was a study before ours, and that was in untrained participants. So, guys who weren't necessarily big weightlifters. And, same thing: you can lift with heavy and light; the caveat is that when you exercise - if you're going to use light weights - you need to do it just as if you're using heavy weights. You really need to push yourself. You need to fail or to reach that point of exhaustion.
Q: Your study only focused on men. How do these results apply to women?
A: I don't think it would be any different for women. There's plenty of research to suggest that women respond relatively the same as men - relative to their muscle mass and bone structure as is. So, no difference I would presume.
Q: To what extent are trainers already giving this advice - or to what extent would they have to, or should they, start changing their advice that they're giving to people in this area?
A: I think that most trainers would understand this principle and would be ok with it. But I think the real implication is that, if in a certain week or a certain phase of your training period that you want to decrease the load - or in a certain population, like aging people - you don't want them to be under really, really heavy loads all the time. I think this is just a proof of principle to say, that's okay, you can lift light weights with the exact same results. There's no worry if you have to take weights off the bar, or get different dumbbells, or whatever it is.
Q: Some people are saying they've heard this before from various trainers. Is it possible these findings aren't challenging conventional thinking as much as you would have thought?
A: I definitely think there are trainers that do this. But the governing bodies that put out recommendations for these trainers, and I won't mention them, but they do say: if you're going to increase your strength, you want to lift eight repetitions. If you want to increase your muscle mass, you've got to be between 6 to 12. If you want to increase your endurance, you've got to be greater than 12. So, I don't doubt that some trainers know this or already practice this way, but I do know that the governing bodies, the ones that give those trainers their certifications - we challenge those bodies for sure.
Q: In terms of getting peer reviewed and replicating these results, what would it take for this conclusion to become scientifically accepted as the new normal?
A: I think we're there. The study itself is published, so it's gone through the peer review. But we've also had two other studies released before this. We've had one paper go out that measured acute muscle growth, and ... muscle protein synthesis. So that was kind of our first hit.
Then we came out again in the untrained group of guys, and that was a "within subjects" study - the right leg versus left leg. And then this we think was the nail in the coffin so to speak: that we took 50 guys, they all had training experience, and one group did one thing and another group did another thing, and we showed it again.
So I think our hope is that now we've gained the attention that this principle - this, "no substitute for hard work," this "effort is king" approach is going to start taking flight, even in the scientific community.
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