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Textbook muscle: add size and strength faster—one arm at a time - Personal Trainer

Men's Fitness, March, 2004 by Craig Ballantyne

In the weight room, one plus one doesn't always equal two. It's a phenomenon called the bilateral deficit, which describes your natural ability to lift more weight with your arms or legs individually than you can together. For instance, research shows that untrained guys lift about 15% less when doing the leg press with both legs at the same time than the combined weight of performing the leg press with each leg separately.

But most guys wipe out this deficit by lifting almost exclusively with both arms and legs. And that's a mistake. The reason: You not only use more muscle fibers in single-arm and single-leg movements than you do when working both at the same time. But you also recruit more fast-twitch fibers--which have the greatest potential for size and strength gains.

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So keep your bilateral deficit by doing heavy dumbbell work. Here's how to test yourself: Try an exercise that uses both arms (like the barbell curl) and lift the heaviest amount you can for one rep. Rest one minute, then do a dumbbell curl with your right arm. Rest for another minute, then repeat with your left arm. The combined total of the two dumbbell curls should be around 15% greater than the weight you could do in the barbell curl.

Craig Ballantyne, C.S.C.S., is the owner of workout manuals.com.

Textbook muscle: add size and strength faster—one arm at a time - Personal Trainer

Men's Fitness, March, 2004 by Craig Ballantyne

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