The knee joint is the largest and probably the most stressed joint in the body. It is a hinge joint that allows flexion (bending) and extension (straightening) and a slight amount of rotation side to side. The bones of the knee joint are the femur (the upper bone), the tibia (the lower bone), and the patella (the kneecap). The smaller lower leg bone, (the fibula) is not part of the knee joint. Ligaments connect the femur and tibia and hold them in place. Two menisci cover the top of the tibia and serve as shock absorbers. Knee pain can be caused by a torn ligament, fractures, a torn meniscus, knee bursitis, patellar tendonitis, a loose body in the knee, a dislocated kneecap, osteoarthritis and other causes. For more information on knee pain symptoms and causes see the article on knees from the Mayo Clinic. The most common cause of chronic knee pain is arthritis (osteoarthritis, rheumatoid arthritis or posttraumatic arthritis), A Healthline Report in 2020 says that approximately 600,000 knee replacement surgeries are performed every year in the United States.
It is not always possible to prevent knee pain, but you can reduce your risk by maintaining a healthy weight, and keeping the muscles that support the knees strong and healthy, since weak muscles are a leading cause of injury. The muscles that support the knees are the 4 muscles of the quadriceps on the front of the thighs and the 3 muscles of the hamstrings on the back of the thighs. The pool is a great place to do exercises for the quadriceps and hamstrings because the buoyancy of the water lifts and supports the body, reducing the stress on the knees. Some good exercises that can be done in the pool for the knees include quad kicks (kicks from the knee), hamstring curls, squats, and lunges. We squat every time we sit down in a chair. Squats can stress the knee if done too deeply, but that is very unlikely in the pool! Vary the squat by having the feet wide apart, hip distance apart or together. You can also have one foot forward more than the other foot. In the pool you can do one-legged squats. To activate the deep core muscles before squatting, use the Heavy Concept. Imagine that you are trying to squat but are not able to. You will feel both your abdominals and the hamstrings contract isometrically. Use the same concept to return to standing. If you imagine that you are not able to stand up, you will feel both your abdominals and quadriceps contract isometrically. For an additional challenge, do your squats standing on a noodle. Lunges can be performed forward, to the side, to the back, or diagonally.
In addition to strengthening the quadriceps and hamstrings, there are some cautions to help you avoid an injury in your water fitness class. Rebounding is good for the knees, but landing with the knees turning inwards causes abnormal forces through the knees. The middle of the knee should align with the second and third toes when landing from a jump. Ballistic hip abduction (cheerleader jumps) puts a lot of pressure on the outside of the knees, and knees are not designed for this stress. Don’t include this exercise in your routine. Avoid forcefully throwing the knee during a kick. Cue to press your kicks rather than power popping your kicks. Eggbeater kicks have a circular motion that puts a lot of torque on the knees. They are not recommended for a group exercise class.
It is a good idea to stretch the quadriceps and hamstrings at the end of class. Cue the quad stretch properly: the thighs are close together and the knee points down to the floor, then lift the abdominals, press the hip forward and take the knee slightly back until a stretch is felt in the muscle. Do not cue to bring your heel to your buttocks, as this forceful end range of motion can cause a meniscus tear. A hamstring stretch can be done by lifting the knee, then extending the leg, which is easy to do with the help of the buoyancy of the water. Do not round out the back to increase the stretch. A hamstring stretch can also be done by placing the foot on the pool wall. Exercising your legs to keep your quadriceps and hamstrings strong will reduce your risk of knee problems later on.
Resources: Ruth Sova, MS – Feet Ankle Knees Mini Session 10-06-22
Pauline Ivens, MS and Catherine Holder, PT, Do No Harm, 2011
See you in the pool!