People often stress how important exercise is, but something else that is important to consider when performing exercises is to make sure that your legs are lined up the right way. So you might think that you are doing your exercises the right way, but then you have pain in your foot, or your knee, or even your hip and it gets worse as you try to push through the pain, and it doesn’t go away until you take a break from the activity that you’re doing. It can start when you’re doing squats, jumping to take jump shots while playing basketball, or even going for a short run. Many times when people work out they experience pain or get injured because they position their body in a way that puts extra strain on their muscles, ligaments (which connect bone to bone), tendons (which connect bone to muscle), and the bone itself. By simply changing the position of your legs while working out, you can prevent many of the injuries that people get while working out. In order to do this, you must first know what the right position for your legs is while working out.
The normal human body is set up so that the legs are slightly curved inward at the knees. When exercising, this curve can change if certain muscles in the hip are weak. The curve may increase to the point where the knees are almost touching, causing the person to resume a kissing knee or knock-kneed position. This can also cause the arches of the feet to drop, causing the person to be more flatfooted. Therapists will sometimes refer to this as a valgus position.
How do you measure the amount of inward curve or kissing knees a person has?
So there is a scientific way to measure for this that has a huge name, but isn’t important to know- it’s commonly abbreviated FPPA. Basically, three lines are drawn and connected and the angle between two of the lines is measured. The angle that you find can be compared to normal values to see if the inward curve at your knees is too much during exercise. If the angle you find is between 5-10° the amount of inward bend at your knees is normal. If the angle is bigger than 10°, it means that you have an increased inward curve at your knees and you may be at risk for some of the problems listed below. Now, unless you have a picture of yourself in the squatting position, this method probably won’t be the most effective way of determining if you are moving into this kissing knee position while exercising. An easier way to do this is simply by positioning yourself in front of a mirror and doing a squat. If your knees move towards each other to the point where they are close to touching or even touching then you are moving into the kissing knee position.
What causes your knees to move toward each other during exercise?
When your knees move inward while you are exercising or just performing activities in your daily life it usually means that the muscles that are meant to hold your thigh outward are weak. Moving into a position that causes your knees to come towards each other more can cause strains on tissues throughout the leg. The following problems can happen from your hips to your knees if you move into a kissing knee position while you exercise or perform daily activities:
Hip Piriformis Syndrome: The piriformis is a muscle that is located in the butt. It helps other bigger muscles with moving the hip outward. If the bigger muscles that are in charge of moving the hip outward are weak then the piriformis is forced to take over their job and it is not designed to take on what the bigger muscles do. Because of this it gets irritated (Tonely et al., 2010). Irritation can lead to this syndrome, that literally causes a pain in the butt that can travel down into the hip and the back of the thigh.
IT Band Syndrome: The Iliotibial band, or IT band, is the tendon of a small muscle on the outside top of the pelvis called the tensor fascia lata. The IT band extends from this muscle down to its attachment on the outside of the shin bone. It has been shown that runners who allow their knees to move inward due to weak hip muscles that are supposed to keep the thigh out, tend to develop IT band syndrome. This is because moving into this kissing knee position increases the stretch put on the IT band (Fredericson, 2002). This stretch can cause pain on the outside of the knee just above the knee joint line (where the two bones meet) that goes away when you rest.
Knee ACL Injury: The Anterior Cruciate Ligament, or ACL, is the ligament in the knee that restricts the tibia, or shin bone, from going too far forward in relation to the femur, or thigh bone. You are at an increased risk for injuring your ACL if you tend to land with your knee directed too far inward in that kissing position when jumping (Hewett et al., 2005).
MCL Injury: The Medial Collateral Ligament, or MCL, is the ligament on the outside of the knee that keeps the knee from sliding too far right or left. Allowing the knee to move too far inward increases the stretch put on the MCL which makes it more susceptible to possible tears and ruptures.
PFPS: Patellofemoral Pain Syndrome or PFPS occurs when the patella, or knee cap, and the femur, or thigh bone are not in as much contact as they should be. This decrease in contact area leads to an increase in the forces being put through the joint which can cause pain around the knee. Research has shown that if you allow your knee to curve too far inward, there is a decrease in the amount that the knee cap and the thigh bone are in contact which can lead to PFPS (Salsich & Perman, 2007).
Lower leg Tibial stress fractures: The tibia is your shin bone. Tibial stress fractures can happen when you do something such as running over and over again without letting the bone have enough time to repair itself. If you let your knees move inward or have kissing knees during an exercise that is repetitive, more pull (tensile) forces are put on the inside part of the tibia, or shin bone, while more push (compressive) forces are put through the outside part of it. Bone is weaker under pull forces than it is push forces. If you have increased inward curve at the knees, you are at an increased risk for stress fractures on the inside portion of the shin bone (Pohl et al., 2008).
Foot Bunions: Bunions, or what therapists like to call hallux valgus, occurs when the big toe starts to point away from the midline of your body. This can be caused by abnormal pressures placed on the foot. If you have kissing knees, you tend to be flatfooted which puts different pressures on the foot and increases the risk of developing bunions, which can come with a lot of pain. The effects of kissing knees during exercise and daily activities are not limited to just the ones listed above.
How do you keep your knees from coming together?
So with all of the problems that kissing knees can cause, once you recognize you have it, you’ll probably want to know how to reduce it. It’s quite simple. The major problem with increasing inward curving at the knees is that the thigh is brought in towards the midline due to weak hip muscles. The simple solution is that you need to strengthen these muscles. An example of an exercise that can be done is the clamshell. All you have to do is lie on your side and stack your legs on top of each other with your knees slightly bent. You then bring your top leg up until it is parallel with vertical and bring it down while keeping your feet in contact, touching the whole time. You can do this for 3 sets of 10 repetitions. To increase the intensity you can add a theraband right above your knees.
If you notice symptoms of any of the conditions above, and have tried strengthening your hip muscles without a huge decrease in pain or the pain has even increased in the past two weeks it may be necessary to see a physical therapist. Weak hip muscles are not the only thing that can cause the knees to move inward to where they are almost touching and the physical therapist will be able to determine what is most appropriate to decrease the pain that you are experiencing.