From our basketball playing tips gym section.

Stretch properly before training. If anything hurts, stop. Never over-do it. If you have an injury, consult a doctor or physical therapist before training.

CALF RAISE: Stand normally, with your feet shoulder width apart (or slightly closer together). Slowly raise your heals, steadily, until you're standing on your tip-toes, balance for a few seconds, then slowly lower yourself back down. Do not use your hands at all, except if you have trouble maintaining your balance, in which case touch a wall or chair. Repeat.

DEEP KNEE BEND: Be standing. Slowly bend at the knees while keeping your back straight. Slowly crouch down as low as possible (it shouldn't hurt) and slowly rise back up. Do this 15 times. Over time increase to 20, 30, etc.

JUMPING DEEP KNEE BEND: Be standing. Crouch down as described above but fairly quickly, almost touching your bottom to the ground, then explode upwards as high as you can. The moment you land, immediately crouch and launch back up again. Do this 15 times, and when you can, increase to 20, 30, etc.

These are the best leg training exercises you can do without the aid of weights.