Strengthening connective tissues, to reduce the risk of injury.
The knee is vulnerable to overuse injuries such as tendonitis. The following will strengthen the connective tissue around the knee. Do one set of 20 reps with light weight 5 or 6 days a week. Tightening the muscle and holding (the isometric contraction) is what's important.
Single-leg short-arc quad extension: Seated with leg flexed 20 to 30 degrees and a weighted belt around your ankle. Straighten leg and lock knee, hold for 5 - 6 seconds, then lower 20 to 30 degrees. Do not do full range of motion leg extensions, which place tremendous compressive forces on the knee.
Single leg abductor: Lying on your left side with a weighted band around your right ankle. Tighten your quads to lock your knee, and raise and lower your right foot.
Single leg adductor: Lying on your left side with a weighted band around your left ankle. Tighten your quads to lock your knee, and raise and lower your left foot.