Even Light Resistance Builds Muscle—If Lifted to Failure

[BendtheBar]

Even Light Resistance Builds Muscle—If Lifted to Failure

Exercise:* More support for effort-based training

Many find it hard to believe that the same training effect can result from a 20-rep maximum effort and a 5-rep all-out effort. The idea that effort—not reps or poundage--is the critical factor just doesn’t square with their notion of strength training. They read about the Carpinelli and Jungblut review studies, but can’t bring themselves to accept the conclusions. See our earlier articles: Muscle Fibers and Weight training and Weight Training With Effort - Many Ways

Dr. Richard Winett reported in Master Trainer (Master Trainer: Bodybuilding, Weightlifting and Lifetime Fitness) on a new study from McMaster University in Canada that strengthens the case for effort-based training. The study, by Nicholas A. Burd and his colleagues, is abstracted in the journal Medicine & Science in Sports & Exercise (May 2009). Unlike the obscure “size principle,” it’s straightforward and easy to understand.

The study looked at how muscle formation (muscle protein synthesis) is influenced by training load. Resistance training breaks down or damages muscle tissue, which the body repairs and rebuilds with protein and other nutrients. If the resistance is sufficient, the restored muscle tissue is bigger and stronger than before.

Study participants did leg extensions three different ways, resting for several days between exercise modes. They did 4 sets with 90% or 30% of one-repetition maximum. (1RM is the maximum resistance that can be lifted one time.) For both loads (90% & 30%), sets were continued to failure. For 90% load, failure came at 5 reps; and for 30%, failure was about 23 reps. In the third mode, the 30% load was lifted only 14 times, well short of failure.

If effort is the key factor determining muscle formation, one would expect the same result for 90% and 30% carried to failure, but not for the 30% sets stopped well short of failure. And that’s what the researchers found. A light weight (30% of maximum) lifted lightly did not stimulate muscle formation, while the same weight lifted to failure did.

Muscle protein synthesis (MPS) for 90% and 30% carried to failure was 241% greater than for 30% stopped 9 reps short of failure. Training with 30% of 1RM—but not to failure—produced negligible increase in MPS.

“These findings support the notion that heavy and light training loads may elicit similar training-induced increases in hypertrophy provided exercise is performed to maximum failure,” the researchers concluded. They believe the greater increase after exercise at 90% and 30% to failure “is likely related to recruitment of more type II [fast twitch] muscle fibers not activated” with 30% lifted well short of failure. (Emphasis mine)

The size principle would, of course, predict that sub-maximal effort would not activate the larger fibers, which come into play after activation of the smaller slow-twitch fibers—and only for the most difficult tasks. The body protects itself by using only the fibers required, keeping the larger fibers in reserve for fight-or-flight situations. Makes perfect sense for a time when survival was often in the balance.

In modern times when survival is rarely at issue, it means we have to exert our muscles in exercise to maintain and build strength. Sub-max effort means sub-max strength. That’s what “use it or lose it” is about.

Maximum effort can be achieved with both light and heavy resistance. This study shows that light resistance will build muscle if lifting is continued until effort is required. You can use 30 pounds or 100 pounds, as long as there is a good effort at the end of the set. Put another way, resistance doesn’t even have to be moderate—light will suffice for muscle building. The choice of resistance is yours—but you still have to work at the end to build muscle.

(As usual, I have simplified these findings for clarity. It should also be noted that this is a small study peer reviewed only for presentation at a conference. The citation above is for the abstract alone.)

Winett Commentary

Dick Winett commented in Master Trainer that the powers that be are behind the curve on proper implementation of the size principle. The guidelines and recommendations of the American College of Sports Medicine and the National Strength and Conditioning still suggest that heavier is better.

The McMaster study also raises other questions, according to Winett. “For example,” he asks, “are 4 sets as used in this study needed to increase MPS?"

"What are the effects of just one set per muscle group to failure?” Good questions. My guess is that one set to failure is enough. Being a scientist, Winett doesn’t guess, at least in public. I would bet that he agrees with me.

Finally, Winett observed that there is “no evidence that performing many exercises to create a large hormonal response additionally contributes to enhance MPS for a given group such as the biceps targeted by an exercise such as curls.” That suggests that the now popular hyper-metabolic, muscle-confusion routines burn calories, and perhaps develop fitness, but very likely do not build much muscle.

Remember: Light, moderate, and heavy resistance all build muscle—if the last few reps are hard.

[strkout35]

cool. why are these studies always performed on gay machines like leg extensions? why not use something like bench press?

[gaspers04]

Originally Posted by strkout35

cool. why are these studies always performed on gay machines like leg extensions? why not use something like bench press?

I feel like a chump....lol

[strkout35]

Originally Posted by gaspers04

I feel like a chump....lol

ha i'm not saying they shouldn't be used in training, alot of people use them i'm just saying i think more accurate conclusions could be made from the bench IMO

[BendtheBar]

I think the key nugget in this study is the following:

“These findings support the notion that heavy and light training loads may elicit similar training-induced increases in hypertrophy provided exercise is performed to maximum failure,” the researchers concluded. They believe the greater increase after exercise at 90% and 30% to failure “is likely related to recruitment of more type II [fast twitch] muscle fibers not activated” with 30% lifted well short of failure. (Emphasis mine)

All loads caused hypertrophy, as long as the last few reps were difficult.

The only group not growing muscle were loads done well short of "close to failure."

This isn't the first study pointing in this direction. Carpinelli is one of the brightest names in the iron game, and has been pointing this way for a while. Basically, he has been saying...rep range isn't important for strength or hypertrophy...progression is key for strength and pushing close to failure is key for hypertrophy.

I would caveat this, of course, for advanced trainees. I think the game is much more complicated at that level.

Master Trainer: Bodybuilding, Weightlifting and Lifetime Fitness