Gabe Mirkin, M.D.
Lifting weights makes you a better athlete, provided that you know how you do it.
You become strong for a particular sport by exercising against resistance, using your muscles in the same way that you would use them in your sport. Muscles are made of millions of fibers. You become stronger by enlarging each fiber, and by contracting a greater percentage of fibers at the same time. You enlarge muscle fibers by contracting them against greater resistance.
You make more fibers contract together by strengthening them in the same way that you use them in your sport. High jumpers, basketball players, shotputters and football linemen need strong thigh muscles to raise their body up against gravity, so they should squat with heavy weights on their shoulders. Swimmers, baseball players and oarsmen should use pulleys with weights, that allow them to mimic their strokes against resistance.