The Ol' Hammy Whammy

THE RUN OF FOUR hamstring injuries that helped cost Marty Miller his job as the Yankees' director of performance enhancement—as well as the one that sidelined Cubs outfielder Alfonso Soriano (above) last month—are just a few in the line of recalcitrant hammies that slow athletes from beer leagues to the NBA. Hamstrings "are the weakest muscles in your legs," says Tom Shaw, a speed coach who has trained hundreds of NFL prospects (including 2007 No. 2 pick Calvin Johnson), as well as scores of baseball players.

The hamstring constitutes the back of the leg, from the glutes to the knee, and strains involve the tearing of any of three muscles—the semitendinosus, the semimembranosus or the biceps femoris. They'll tear from long-term overuse or from a single, violent overstride and are susceptible to cold weather, when tissue becomes less supple. Miller, who was three months into a three-year contract, had a somewhat nontraditional approach to conditioning. He removed popular leg curl and leg extension machines from the weight room (they were returned when players complained), and, Yankees players say, he de-emphasized distance running, a move that puzzled them.

For his part, Shaw has clients do daily combinations of sprinting and endurance running, believing them vital to strengthening, and thus protecting, the health of the hamstrings—especially for athletes who alternate quick bursts with time spent sitting on the sidelines. Shaw also has his favorite exercises that target the hamstrings, exercises he says are just right for his star clients and, most likely, for you too.

LIE ON your back with one leg straight up. Lower leg toward ground while a spotter, with hands under your ankles, lightly resists. When foot is two feet from the ground, return to starting position without resistance. A set of 10 reps for each leg.

KNEEL ON ground, arms crossed over chest, with a spotter holding your feet. Slowly lean forward six inches, then return to starting position. One set of 10 reps. Eventually you'll be able to go all the way to the ground and then back up.

LIE ON stomach and have spotter roll a medicine ball down both hamstrings to your heels. Once it gets there, kick up with heels and the ball will fly back to the spotter (who makes sure it doesn't land on your head). Three sets of 10 reps.