Many women worry about getting a man's physique by doing chest exercises, but working out the pectoral muscles can help firm sagging breasts. A strong chest helps perform all kinds of daily tasks, like manipulating the steering wheel, pushing a baby carriage and pushing a grocery cart. Even sitting at the computer all day can keep chest muscles activated, which sounds like a good thing, right? Not exactly. When the pecs are constantly engaged, it can shorten muscles, which leads to inflexibility. And when chest muscles are doing all the work, back muscles can get neglected and weaken.

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Improve your posture at your desk by squeezing shoulder blades together, as if you're trying to hold a pencil between them. Keep abs engaged as well to take some of the work out of the pecs. There's nothing wrong with doing weight-bearing chest exercises, but like working arms - biceps and triceps - it's more effective to alternate chest exercises with back exercises. It's even more efficient because you don't have to take a break to let the muscle rest before starting another repetition; simply move on to another muscle group and back. Engage not only pecs while doing push-ups, a classic chest move, but also use abs, delts, lats and upper arms.