For much of her adult life, Glenda Twining wanted stronger, more toned, shapelier arms. She tried everything from weight lifting to rock climbing, but her arms remained relatively weak, thin, and undefined. Things finally changed about eight years ago, when she discovered yoga.
"My arms, shoulders, and back underwent a total transformation," says Twining, 52, who wrote Yoga Turns Back the Clock and Yoga Fights Flab (both published by Fair Winds) and teaches vinyasa-style yoga in Dallas. Her praise for yoga's ability to shape up and strengthen the arms is echoed by Leigh Crews, a yoga instructor in Rome, Georgia, and a program developer for Reebok University (the educational arm of the apparel and equipment designer). Crews says many of her students particularly like the look they have achieved through yoga: "It's not bulky. Rather, it's sculpted."
Vanity aside, strong arms do much more than allow you to wear tank tops or spaghetti straps with confidence. They make the rest of your life easier, Crews says, by enabling you to lift and carry things like groceries, babies, packages—you name it—without strain.
Anatomy of Arm Strength
Although yoga might not be the first fitness pursuit that comes to mind when you think of strong arms, yoginis such as Twining and Crews argue that it can tone and sculpt the arms as effectively as traditional weight training. Just about any yoga posture in which you place your palms on the floor and use them as a foundation to support your body weight strengthens your arms and shoulders. Standing postures in which the arms must work to resist the downward pull of gravity develop arm strength as well.
Yoga, however, takes a somewhat different approach than weightlifting does to building arm strength. When you curl a barbell or dumbbell, the biceps muscle contracts and shortens. That's what physiologists call a concentric (or isotonic) contraction. It builds the explosive strength needed to perform actions such as quickly scooping up a child who is toddling into a busy intersection. If you do "negative reps"—that is, you resist the pull of the weight strongly even as the arm lowers back down to its original position—you're doing an eccentric contraction, in which the muscle works even as it's lengthening. In yoga practice, you engage in both of these types of conditioning when you move from pose to pose, as in the push-up-like movement from Plank Pose to Chaturanga Dandasana (Four-Limbed Staff Pose) and back. But when you hold postures in yoga, you strengthen your muscles mostly through what's known as isometric work; that means the muscle is activated but its length remains the same. Isometric work builds the kind of muscle endurance that helps you hold a child in your arms as you wait for the traffic to cease.