The modern “hack squat” machine is a unique piece of weight training equipment that puts you in a fixed position in order to carry out the squat exercise. Your feet are fixed by virtue of the fact that your body bears weight while your feet are positioned on a footplate. (The footplate may vary in angulation depending upon the equipment manufacturer.) Your shoulders are fixed not just by the weight carriage that rests on your shoulders but also by a backrest that is attached to a sliding track. (The track also varies in angulation among different equipment manufacturers.) Therefore, the backrest follows a fixed path regardless of who uses the machine or how his/her body is constructed, and it is this that can create problems, like knee pain, for certain people.
Knee pain from squats commonly originates between the kneecap (patella) and the thigh bone (femur),in an area that is called the patellofemoral joint. Health-care providers refer to persistent knee pain in this area as “patellofemoral pain syndrome” (PFPS).
PFPS has several causes. The back side of the patella is lined with articular cartilage that allows it to slide smoothly against the surface of the femur, and the femur has a groove through which the patella slides. The groove is also lined with articular cartilage. Sometimes wear and tear, which is called degenerative joint disease or osteoarthritis, roughens the cartilage surfaces, and, when two roughened surfaces glide across each other, friction is created and pain ultimately results.
Some of our patients have what is known as a patellar tracking problem. In this case, the kneecap doesn’t move up and down in the groove as normally as it should. That causes wear and tear and uneven compression of the joint that also can cause pain.
Besides the various anatomical and pathological factors, differences in lifting techniques and movement patterns can influence the development of knee pain. And in this regard, there are certain mechanical factors that are difficult for some people to avoid with hack squats. For instance, when your knees move forward over your toes during the descent, the mechanical forces are greatly increased in your patellofemoral joints, and that causes increased compression. If any wear and tear is present, there will be more friction on the joint surfaces, which can lead to inflammation…and, ultimately, pain.
Unfortunately, the hack squat backrest does not allow the trainee to lie farther back, which would reduce the knee angles, compression/friction, and pain. Nor do most hack squat machines allow adjustment of the footplate angle. Certainly, in regard to knee stress, hack squat machines are not created equally so it is helpful to take note of the different exercise brands. Over many years of experience, this author has noted that the BodyMasters and Cybex brands seem to impart more knee stress than the hack squat machines manufactured by Flex/StarTrac or Icarian. However, because of individual differences in height/body type, this is not a universal truism.
One way to reduce knee pain on this exercise is to change your foot placement. If your feet are placed more directly underneath you, your knees will move farther forward, which INCREASES the force on the knees and causes MORE pain and MORE wear and tear. BUT, if you place your feet farther forward on the platform, your knees won’t move so far forward, and that, of course, will DECREASE the stress on your knees.
Of course, some of the more hardcore bodybuilders may respond to these suggestions by saying: “But if I move my feet farther forward on the footplate, I won’t feel it as much in my lower quads.” Well, that may be true for some, but sometimes you have to modify an exercise or your exercise technique in order to keep it in your exercise routine
Another strategy to reduce knee pain with hack squats is to attach powerlifting bands to both sides of the machine. Attach one end of a band to a fixed member at the base of the machine and attach the other end to the weight holding bar. This creates a more “knee-friendly” variable resistance, controls repetition speed, and provides a missing element of eccentric contraction which assists strength and muscle development.
If you have a patellar tracking problem, another modification is to keep your feet pointed relatively straight ahead, rather than turning them inward or outward significantly. Some people may find that this “evens out” the compression on the patella and affords a reduced level of pain when performing this exercise.
Again, a modified performance is better than not doing an exercise at all..especially if you are “gung-ho” to keep it in your routine. And there are certainly circumstances that make it wise to completely discontinue an exercise and replace it with another one. Fortunately, there are other exercises that effectively work your quads with less strain on the knees. Stay tuned because they will be featured on this site in the future.
But, for now, remember that training smart will keep you training hard longer—and bring you the greatest gains possible.