We have a physical therapist that works out of our athletic club. When off duty, I saw him performing the 45 degree angle leg press with his feet low on the plate, (seat is stationary and plate moves). That is, his knees were extended over his toes. When I asked him about this, he said they use this form in knee rehab. He does not have knee issues but was using this form. I have many clients who have knee issues. I was always trained NOT to have the knees over the toes but rather over the ankles. I can see his point, I guess, that it helps strengthen the knee. Does it? The load is not maximum but significant.
Great question! It appears to be a universal truism that today’s fitness professionals believe that an exerciser should avoid, at all costs, any position in which the knee moves over or forward of the toes while in a fully flexed knee position. This misconception is routinely offered whenever we talk about the squat, the leg press, the lunge or any other exercise in which full knee flexion occurs.
To specifically address your question, if I may presume the observed individual’s feet remained flat throughout the leg press and all other details of proper technique were followed, there is no problem with the knees moving past the ankles or the toes while in a fully flexed knee position. Yes, this would tend to emphasize (strengthen) the muscles and connective tissue surrounding the knee compared to a “knee over ankle” posture. Finally, this is a much more natural position to assume than that advocated by so many fitness professionals.
A short historical review of how we got here.
Much of this cautionary advice can be traced to the questionable conclusions on squatting reached in the early 1960s by Karl Klein. It is interesting to note that Klein’s “study” probably could not survive present-day scientific scrutiny. Also, despite numerous attempts, no one has ever replicated Klein’s findings. However, his writings had a huge impact on the physical education field, namely, “Squatting is bad for your knees.”
In order to fully appreciate the significance of this landmark conclusion, PTontheNET.com readers should note some differences between the 1960s and now.
- Lifting weights was neither common nor popularly embraced.
- The squat was not the keystone of program success that it is today.
- Squat racks existed, but it wasn’t unusual to “clean” light barbells to the shoulders for squats.
- Very few resistance training machines existed (the leg press was much different than the model you describe).
- Squats were sometimes known as “deep knee bends,” which oftentimes meant the heels did not remain on the floor (the extreme example of “knee in front of foot”).
Personal trainers must realize that there are numerous individual factors that impact on a person’s ability to achieve proper squatting positions. Most notably are femur length, torso length and the flexibility of the hips and ankles. Not everyone is able to squat in the same posture. Awareness of individual differences and knowledge of proper exercise technique is where personal trainers can really have an impact.
Back to our history lesson. The now popular sport of powerlifting, barely in its infancy at the time of Klein’s writing, includes the squat as a competitive lift. In order to maximize the amount of weight lifted in the squat, powerlifters have, over time, significantly altered the traditional squat’s “knee forward” bottom position. Not all squats are created equal.
Powerlifters do not place the bar on top the trapezius muscles, as in a traditional squat. They hold the bar considerably lower, which results in “shortening the lever.” In this posture, the torso inclines forward and the hips are located behind the heels when in the bottom position. Powerlifters also avoid ankle dorsi-flexion and keep the shank (lower leg) portion of their leg almost perpendicular to the ground. This somewhat distorted posture keeps the barbell over the mid-foot and throws most of the muscular load to the gluteals. It also results in more weight being lifted.
This significant change in squatting posture, along with Klein sounding the alarm against squatting, has affected how the fitness world looks at knee flexion.
Old school, traditional squatting posture with the bar on the trapezius calls for a more upright position in the bottom. This is accomplished with a knee-over-toe bottom position that keeps the torso more nearly perpendicular to the floor. Much more of the muscular load is handled by the quadriceps and, as a result, the knees.
Nearly all competitive weightlifters utilize a “squat style” for the snatch lift and the clean portion of the clean-and-jerk lift. They also spend a considerable amount of time training the squat and the front squat. In order to receive heavy weights in a balanced “bottom” position, weightlifters seek a squat posture with their hips nearly on top of their heels, the calves fully flattened against the hamstrings, ankles sharply dorsi-flexed and the torso nearly perpendicular to the ground. The construction of their specialty shoes contributes to a dorsi-flexed ankle. The knee injury rate among weightlifters is not significant.
In presentations I make to medical professionals, most cringe when they see illustrations of this deep squatting position. Memories echo of Klein’s message or the teachings that continue to occur.
There are some promising signs of enlightenment and a realization that squatting, in and of itself, is not harmful for a healthy knee. Some athletic trainers (ATCs) and a few physical therapists (as you have observed) are beginning to “see the light.” Groups like Velocity Sports Performance training systems talk about “positive shin angle” (dorsi-flexed) and its impact on running efficiency.
What is old is new again.
The knee-over-foot or dorsi-flexed position is natural for those with adequate flexibility. In many cultures around the world, people conduct much of their daily business in a full squat position with their knees forward of their ankles. Young kids easily sit in a full squat position and appear to suffer no ill effects. In my opinion, much of the problem occurs when ankle flexibility is lost, which I think coincides with our move to sitting on furniture most of the day.
As with any other affected area, knee “issues” are a concern when designing training programs. For those with serious knee “issues” (and this should be a sports medicine professional’s call), squatting may be out completely, as might be the case in any knee-flexed exercise. Don’t fool yourself and think the leg press is any safer than the squat. In fact, distortion of good, basic technique in any exercise may lead to injury.
Also, keep in mind that although the squat is considered by most to be the keystone lift for improved performance, the squat is a very physically and psychologically challenging exercise that many people literally hate to perform. Excuses often result in the opportunity to sit on a machine, such as a leg press, and “work the legs.”
For a thorough review of the squat and its implications, check the National Strength and Conditioning Association’s position paper on this subject. Look beyond the nine key points or conclusions and check the literature review. There is also a great deal of information available on the Internet that supports squatting as a healthy activity. Just remember, not all squats are created equally. Know and appreciate the fine differences.