The most effective muscular contractions occur when a muscle is pre-stretched to 120% of resting length. The pre-stretch is a necessity to optimize the alignment of the attachment sites between the muscle’s actin and myosin filaments. Certain exercises will need adjusting to achieve 120% of resting length. Caution should be used to make sure the exercise remains SAFE while you are increasing effectiveness.
When your goal is to optimize the development of the quadriceps or parts of the quadriceps, you can use this “Pre-Stretch Method” to increase the effectiveness to selected heads of the Four muscles of the quadriceps.
Variations to increase effectiveness of the Vastus Medialis (Lowest Inner Head):
Sumo Squats: Perform the Squats in the “Sumo Position”.
To perform correctly: Stand in a wide stance, feet as wide apart as your flexibility will comfortably allow.
Make sure to keep your knees directly over your toes throughout the Squat and follow all IFPA Knee Safety Guidelines.
This position will create a greater stretch to the medial head: Vastus Medialis.
Sumo Deadlifts: Perform Deadlifts in the “Sumo Position”.
Always follow all IFPA Knee Safety Guidelines.
The Sumo Position (in Squats/Deadlifts/Leg Press) also moves emphasis from quads to glutes.
Leg Extension with Leg Rotated Laterally (Out): Rotating the entire leg outward starting at the hip joint will increase the stretch to the Vastus Medialis.
Leg Extensions are an “OPEN CHAIN” Exercise, and this class of exercise places the greatest amount of stress on the joint.
The “CHAIN” refers to the “chain” of body parts (joints): foot-ankle-knee-hip-spine-shoulder-neck-elbow-wrist (think of the old song: “…the ankle bone is connected to the shin bone…”).
The Squat, Leg Press, and Deadlift listed above are “Closed Chain” because your feet remain stationary while your quadriceps are contracting, resulting in your knee joint finishing the contraction with your bones in straight alignment through the joint. In the Leg Extension, the distal end of your body, in this case: your feet are not free or fixed to an object. Since the torque on the knee will be the greatest in the fully extended position, many physical therapists and other health-care providers think the stress caused by the torque of OPEN CHAIN exercises can be excessive and lead to injury.
Other physical therapist and health-care providers think that OPEN CHAIN exercises are far better at isolating a muscle. Isolation can be useful when rehabilitating a specific muscle or when training for sports requiring open chain activities (which is most of them).
Others consider CLOSED CHAIN exercises more functional since they approximate activities of daily living, i.e.: Squatting to pick-up furniture or bending over to pick-up a child, etc.
Leg Presses with feet wide apart and/or further forward or upward/higher than normal. Moving the feet forward/upward/higher on the foot-plate moves the stress forward, from the gluteals to the quadriceps.
Moving the feet wider apart moves the stress from the Rectus Femoris and Vastus Intermedius (Central muscles of the quadriceps), medially (inward) to the Vastus Medialis.
Leg presses with feet in Narrow Stance Position: Narrow stance in exercises moves the emphasis laterally to Vastus Lateralis.
Single Leg-Leg Press moves the emphasis to the Vastus Lateralis. It is considered a great rehab exercise and very functional. Caution must be used however. The leg must remain in straight alignment from hip to foot. Moving the leg-foot placement farther than straight alignment can place unsafe levels of stress on the hip joint.
Single Leg Squats also move the stress to the Vastus Lateralis. It is highly functional and can increase agility, balance, and coordination. Caution must be used to prevent falls from this advanced balance exercise.
Deep Squats: Taking Squats down into a Deep Squat- “the Bucket” which requires you to continue the Squat past the Knee-Hip-Line to the point where your Glutes are touching your heels is an excellent exercise; not only for the Vastus Medialis, but the Vastus Medialis Obliques (VMO’s). Those are the primary stabilizers for the patella (knee cap).
Caution: as you already know, the IFPA Knee Safety Guidelines requires you to remain at or above the Knee-Toe-Line. To perform the Deep Squat or Bucket Squats safely, you need to start the exercise “Unloaded”. Children and many other cultures spend a lot of time in the “Bucket” and have perfectly healthy knees.
You can limit the risk to your knees by starting UN-LOADED, and slowly increasing the LOAD, while following all other IFPA Safety Guidelines.
NOTE 1: “The Bucket” refers to the sensation a Powerlifter feels when they “Fail” during their Deep Squat at the bottom of the Squat. Failing at the bottom feels like you just squatted down into a bucket and can’t get out.
NOTE 2: In general, when you spread your legs laterally the Vastus Medialis receives additional stretch and increasing emphasis in a leg exercise. If you position your legs close together, the Vastus Lateralis will receive additional stretch and increasing emphasis in a leg exercise.
Future FitBits will provide additional information on the Rear Thigh (Hamstrings) and Lower Leg (Calf).
Best of Luck in all Your Training!
Dr. Jim Bell