Attention fans of heavy lifting: Grab your torches and pitchforks! Someone is questioning your long-held beliefs told by preachers of the hard-core gospel and published ad nauseam in magazines with the word "muscle" in the title.
Here goes: Lifting near your maximum weight is not necessary to build muscle mass and gain strength.
"Consistent practice combined with good nutrition and practicing good form and working to fatigue — no matter what the load — is what makes up the majority of results," says Stuart Phillips, a professor of kinesiology at McMaster University in Hamilton, Ontario.
It's that "no matter what the load" part that has people up in bulging, veiny arms. "Load" is how heavy the weight is, and "heavy = huge" has been preached since Schwarzenegger wore short pants.
"At the risk of inviting death threats," Phillips told me, "I think a lot of the variables in a resistance training program — rest, sets, loads and other variables — are largely redundant in their capacity to bring about strength and (bigger muscles)." More important to Phillips is that you, "Get to the weight room, consistently practice, work to fatigue — this is 80 percent of the job."
And Phillips has some science to back up his claims.
Phillips and his team studied 18 college-age men for 10 weeks. Published in April in the Journal of Applied Physiology, the research examined the results on three weight-lifting routines:
Three sets at 30 percent of maximum (with 100 percent being the maximum amount of weight they could lift for one repetition).
One set of 80 percent of maximum.
Three sets of 80 percent of maximum.
The study focused on leg-extension exercises, and participants were allocated to two of the three routines (a different routine for each leg). The findings fly in the face of current recommendations and state that the lighter-weight routine had the same muscle growth results as the three sets of heavy weights routine. It also showed that the number of sets is important, because lifting three sets to fatigue at the lighter load made muscles bigger than did a single set of much heavier weight.
How is this possible? Traditional thinking is that only heavy lifting works the larger, "fast-twitch" muscle fibers that are more responsive to gaining size, and that lighter weights only engage the smaller "slow-twitch" fibers that are for muscular endurance.
But Phillips says traditional thinking isn't on target. His main reason: fatigue. Even with lighter weights, when you do enough reps to tire the muscle — so that no further lifts can be made while maintaining good form — then both fast- and slow-twitch muscle fibers are recruited and muscles grow in size.
Size vs. strength
But though your muscle grows and you do get stronger with the lower-weight routine, your muscles won't be as strong as those of people doing the heavier-lifting routine, the study showed.
Ten weeks into these routines, when strength was measured by seeing how much a test subject could lift for one rep, those lifting light weights to fatigue were 20 percent stronger, but those lifting heavier weights were almost 40 percent stronger. Those doing the single-set routine were about 30 percent stronger.
No small potatoes.
Phillips suggests the difference lies in neural adaptations that enable these greater strength capabilities, perhaps coupled with extra confidence from having practiced with heavier weights.
And the proof was in subsequent isometric testing — where test subjects tested their strength against a fixed resistance, so without any movement. The results were just a few percentage points apart.