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The Science of Weight Lifting: Why You Don't Need Big Muscles To Have Strong Muscles

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Bodybuilders, with their large, defined muscles, may look like the strongest people in the gym—but looks can be deceiving. In fact, fiber for fiber, bodybuilders' muscles may actually be weaker than those of power athletes and even those of people who don't exercise at all, according to a new study published in Experimental Physiology.

Surprised? We sure were. So we went straight to the source: Hans Degens, Ph.D., a professor of physiology at Manchester Metropolitan University in England and lead author of the paper.

Despite the overwhelming visual of bulging muscles, judging who is stronger isn't as easy as you'd think, Degens explains. Because strength is relative to a person's size, his team couldn't just put a bunch of people in a weight room and see who could sling the most iron. Instead, the researchers looked at the individual muscle fibers of 12 bodybuilders, six power athletes, and 14 people who didn't exercise. The bodybuilders' usual gym routine involved lifting heavy weights often. The power athletes—those who train for strength and speed like soccer players and track-and-field runners—lifted lighter weights for more reps a few days a week. These guys also hit cardio hard.

So who was stronger? On a molecular level, the power athletes' muscle fibers were, individually, 58 percent stronger. But if it came down to a squat-off, both the power athletes and the bodybuilders would be in the same league. Why? It's just that bodybuilders had literally bigger muscles, which can be caused by a ton of weak muscle fibers (brought about by heavy lifting). The power athletes, on the other hand, had fewer (but stronger) muscle fibers—and looked leaner because of it.

And how on earth can you be just as strong sitting on the couch as hitting the gym? Well, you can't. Both of the exercising groups achieved greater strength than people hanging around doing nothing.

What it comes down to, really, is how you want to look or what your goal is in the gym. Degens says that the key finding of the study is that appearance and performance of muscles are two different things. If you want a Kim Kardashian butt, then you should be training with heavier weights at fewer reps. But if you're looking for muscles to support a more powerful run, stick to lower weights at more reps.


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