Whether you want to squat 500 lbs, run a marathon without knee pain, or simply get off the toilet gracefully when you are 80, you need a healthy Adductor Magnus.

Because the muscle attaches so close to the knee (at the adductor tubercle), strain here can mimic MCL (medial collateral ligament) sprains. If you have pain on the inside of your knee, just above the joint line, don't just assume it’s your knee. It might be a tight, angry Adductor Magnus pulling on its tendon. Forget the seated adductor machine at the gym where you squeeze your knees together. While that works the adductor brevis and longus , it barely touches the massive magnus .

Because the hamstring part of the AM attaches to the adductor tubercle on the femur (near the knee), it maintains a consistent moment arm (leverage) throughout the squat. When your hamstrings "turn off" in the hole of a squat, the Adductor Magnus is working overtime to extend your hip.

Here are the three best exercises for the Adductor Magnus: The sumo stance is the king of AM training. By taking a wide stance with your toes turned out, the adductor magnus is placed under a massive stretch at the bottom of the lift. Driving the floor apart and extending the hips recruits the AM like no other exercise.

Why? Look at a deep squat. As you descend past parallel, your hamstrings actually slacken because they attach above the knee and below the hip. When the knee bends, the hamstring tension drops. However, the Adductor Magnus doesn't have this problem.

If you have weak adductor magnus muscles, your squat depth will suffer, or you will compensate by leaning too far forward (a "good morning" squat). The Three Critical Functions Beyond the anatomy book, what does this muscle actually do for your movement?