Myth: Your knees should never go past your toes
- The idea behind this myth is that by letting your knees drift too far forward, in front of your toes, during squats and lunges places dangerous shearing forces on the knee ligaments. This concept dates back to a study performed at Duke in the late 70s. They stated that the "shin bone" should stay as vertical as possible.
We have since learned that it is not as much about the lower limbs themselves as it is about the upper body leaning too far forward. Now let's bust this myth!
Let's start by just talking about the movement and the muscles involved.
The squat movement utilizes the quadriceps femoris, hip extensors, hip adductors, and hip abductors.(aka your butt, quads and hamstrings) Also, there is a great amount of tension in the abdominals, spinal erectors, and upper back to facilitate trunk stabilization. There are 3 categories of squats including: partial squats (40 degree knee angle), half squats (70-100) and deep squats (greater than 100). When performed properly, squat related injuries are uncommon. Normal range of motion at the ankle joint is 20 degrees of dorsiflexion and 50 degrees plantar flexion (pointing your toes). When ankle flexibility is limited, your heels tend to leave the floor, shifting the weight into the front of the foot. This changes the forces on the ankles, knees, hips, and spine which can increase risk of injuries. A study by Hemmerich et al. found that a dorsiflexion angle of about 38.5 was necessary to keep the heels down during a full squat. And a study by Schoenfeld found that the knee has from 0 to 160 degrees of flexion, which allows for deep squatting.
Above you can see three different squat bar placements (with good form). The first is the front squat, the second high bar back squat, and finally low bar back squat.
Proper lifting technique: Three important things to note, with regard to the above photo, is the knees in front of the toes, feet flat on the floor and the weight or load directly above mid-foot.
When trainers and strength coaches talk about squatting to parallel, we mean the top of the thigh being parallel to the floor. When we talk about squatting to 90 degrees, we're talking about the femur. Since you can't directly see your femur, it is best to go to the "top-of-the-thigh parallel" or deeper.
Here is an example of a split squat or a stationary lunge. In this movement you have a split stance, or lunge stance. Don't be afraid to take a big step out. From here the feet do not move, and you simply move down and up maintaining the weight over the center of your stance.
Please understand that I am saying that it is okay for the knee to pass the toe during lunges; HOWEVER most people cannot control the weight while moving forward. That lack of control typically lead to the front heel leaving the ground and the weight shifting too far forward and, as stated above, this increases the risk of injury.
Above is one stretch that I use, with clients and athletes alike, to increase ankle flexibility, or dorsiflexion. Stand with the working leg closest to the wall, the big toe about 2 inches away. Keeping the heel on the ground try to touch the wall with your knee. If you can easily reach the wall, move your foot back half an inch or so. Continue in this manner until it is difficult to reach the wall. Perform 2-3 sets of 10 repetitions each leg.
Good squat form reminder:
- Hands on the bar, close to the body to minimize excess movement of the weight
- For a regular squat, feet shoulder width or slightly wider
- Toes pointed slightly outward, don't over exaggerate
- Keep the chest up, back and abs tight
- Deep breath before decent, begin exhale about halfway through standing back up
- Squeeze glutes (butt cheeks) upon standing up to avoid knees collapsing in
- KEEP FEET FLAT ON THE FLOOR, WEIGHT OVER MID FOOT
Articles:
Hemmerich, A, Brown, H, Smith, S, Marthandam, SS, and Wyss, UP. Hip, knee, and ankle kinematics of high range of motion activities of daily living. J Orthop Res 24: 770–781, 2006.
Schoenfeld, BJ. Squatting kinematics and kinetics and their application to exercise performance. J Strength Cond Res 24(12):
3497–3506, 2010.
