Science now says lighter weight and more reps builds just as much muscle strength and size, so are we risking health and safety by lifting heavy just for ego?
Says researcher Rob Morton of McMaster University, “…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 six to 12. If you want to increase your endurance, you've got to be greater than 12…I do know that the governing bodies, the ones that give those trainers their certifications — we challenge those bodies for sure.”
Mr. Morton and Stuart Phillips of McMaster published their peer-reviewed findings of a 2016 study in the Journal of Applied Physiology. (1) Similar studies have resulted in the same conclusions.
Mr. Morton and Philips’ study included experienced weightlifters. The study used light weights that represented a percentage of what the subjects could lift. The heavier weights were set to 90% of a person’s best lift and the light weights at a mere 30% of what people could lift. “It’s a very light weight,” says Phillips, noting that the 90-80% range is usually something people can lift from 5-10 times before fatigue sets in. At 30%, subjects could lift that weight at least 24 times before they felt fatigue.
Th 12-week study assessed both muscle mass and muscle fiber size. Gains were virtually identical.
Lifting to muscle failure is what mattered. “Fatigue is the great equalizer here,” said senior study author Stuart Phillips. “lift to exhaustion and it does not matter whether the weights are heavy or light.”
So why does anybody lift heavy anymore, other than for ego? Consider this:
Lifting weights at or near your max undoubtedly risks greater injury than lifting lighter. Even experienced lifters ,with trainers standing by, can make mistakes with serious consequences, especially near their max rep, when they are close to failure Why would you even risk it, if simply lifting lighter weights for more reps results in the same strength and mass gains with reduced risk of injury?
Muscles, especially the larger muscles like glutes, can often, technically, support or lift greater weights than our joints (and backs) are capable of safely handling. In the never-ending goal of bigger and stronger, lifting heavy will invariably put backs and joints at risk, and do so unnecessarily. Why not reduce the weight and increase the reps, resulting in the same gains without putting the back, knees, etc. at risk?
If the science says lifting light weights for 24 reps is just as effective for building muscle size and strength, as lifting heavy weights for 6-12 reps, why risk it, if not for just for ego? And why is it still recommended by the governing bodies mentioned by Mr. Morton? Can you (safely) claim that lifting 6-12 reps of weight is optimal for strength development, and claim that your recommendation is backed by science, if science now says that the lighter reps can more safely deliver the same results? Has the “science” of lifting heavy now become merely a rationalization for the pursuit of ego over safety?
It seems that science has determined that fatiguing the muscles is what matters, and if you can do that with less resistance more safely, why wouldn’t you? Perhaps the focus of the governing bodies should be shifting to how effectively, efficiently and safely to fatigue the muscles for the benefit of trainers, athletes and everyday fitness consumers everywhere.