Unless you suffer from chronic knee problems and have a limited range of pain-free motion at your knee joint, having bad knees shouldn't stop you from being able to exercise. Many exercises can be modified to safely work the muscles surrounding the knee and ultimately help to strengthen it. A person who suffers from knee pain may benefit from wearing a quality knee brace, because it is designed to protect an injured knee and ensure the knee moves in a controlled manner without constriction. These basic tips allow you to exercise while having bad knees.
Keep your knees behind your toes when performing a squat. Both your heels and toes should remain in contact with the floor as you flex at your hips and drive them backward as if to sit in a chair. Keep your knees over your ankles with your shins perpendicular to the floor throughout the exercise. Avoid this exercise if you can't perform it with proper form.
Avoid high-impact exercises. If you can't avoid them, always land softly on the balls of your feet with slightly bent knees to cushion your landing and lessen the impact.
Wear a knee brace designed for functionality or patella stability when performing various explosive or lateral movements. Sudden changes in direction or twisting your knee may result in a torn anterior cruciate ligament or a torn meniscus.
Hold back from lowering your thighs past parallel when performing a squat. It is highly likely that if you have bad knees, you have avoided these exercises because of the pain, and consequently you may have weak quadriceps and glutes. If your quadriceps and glutes lack the strength to get you back to your starting position, you could fall or be forced to lose form in an attempt to stand, increasing your chances of further injuring your knees.
Train on stable surfaces. If your training or sport focuses on stability, a knee brace designed for joint stability will help. Also, limit your range of motion at your knee joint to what you can do with good form and without pain.
Swim or use a rowing machine for cardiovascular workouts. A moderate-level water aerobics class would also be beneficial, as the buoyancy of the water lessens the impact on the knees.
Use lighter weights when performing machine exercises such as the leg extension and leg curl. While these exercises are great for strengthening the major muscles of the leg, proper form requires full flexion and extension of your legs. If you can't fully bend or straighten your legs, simply use a lighter weight. This will slowly build strength in your thighs, which will help alleviate knee pain.
Use a prop or hold onto a wall for added balance and stability. For example, hold onto a counter as you lower your body into a bodyweight squat.