Knee pain is a common problem for many, including those who exercise on a regular basis. According to a 2006 study by the Centers for Disease Control, 18 percent of individuals reported having knee pain during a 30-day time frame. Popular forms of exercise, especially running and walking, can aggravate knee pain. Although there are many causes, patellofemoral pain syndrome, osteoarthritis and illiotibial band syndrome are common sources of knee pain after exercise.
Anatomy
The knee joint consists of three bones: the tibia, femur and the patella -- commonly called the shin, thigh bone and kneecap, respectively. Cartilage at the ends of both the tibia and femur, as well as behind the kneecap, provides smooth movement. Between the tibia and femur are two small, semicircular shaped pads that help distribute loads through the knee; the pad is called a called meniscus. On the sides of the knee are collateral ligaments, and in the center are the two additional stabilizing ligaments of the knee, the anterior cruciate ligament and the posterior cruciate ligament.
The muscles surrounding this joint include the quadriceps, hamstrings and gastrocnemius. Training, wear and tear, muscle imbalances, and tightness can lead to problems in the knee.
Patellofemoral Pain Syndrome
Patellofemoral pain occurs when the patella, or kneecap, moves improperly or with excessive compression of the patella during activity. Characteristics of patellofemoral pain include a dull pain in the front and sides of the kneecap. Swelling and a grinding sensation around the kneecap also may occur. Typically, this pain increases with running, squats and stairs. If left untreated, cartilage behind the kneecap may become softened and worn.
Osteoarthritis
Osteoarthritis occurs when the knee's articular cartilage begins to thin or wear away. Bone spurs and other changes within the joint can make the pain even worse. Characteristics of osteoarthritis include a deep, dull pain in the center of the knee and along the joint line where the tibia and femur meet. Increased pain after exercise, swelling and morning stiffness may also occur. Being over age 50, having previous injuries and obesity can increase your chances of having osteoarthritis.
Illiotibial Band Syndrome
Illiotibial band syndrome is common in runners. The IT band is a fibrous strip of connective tissue that starts at the hip and runs down the side of the leg, connecting just below the knee. It can become inflamed by excessive stress on the band as it moves along the side of the knee joint during activity. Individuals with ITB syndrome may feel pain in the outside of the knee during and after exercising. If severe, the pain may radiate up the side of the leg toward the hip. Poor core and hip strength, excessive mileage, muscle tightness and improper footwear can contribute to this problem.
Prevention and Treatment
If you are having increased knee pain after exercise, consult your doctor. If starting a new exercise program, remember to always start slow. Seasoned athletes should decrease their exercise duration and intensity while symptoms resolve. ITB, quadriceps, calf and hamstrings stretching may be beneficial. Avoid deep squats or exercises that involve kicking motions in the air. Core, hip and quadriceps strengthening are also key in recovery and prevention. A medical professional should address knee pain that does not improve with basic rest, stretching and exercise modification or if the pain is accompanied by instability, popping or swelling.
References
- Centers for Disease Control and Prevention: Adults Reporting Joint Pain or Stiffness in the Past 30 Days, 2006
- American Academy of Orthopedic Surgeons: Frequently Asked Questions about Osteoarthritis of the Knee
- National Institute of Arthritis and Musculoskeletal and Skin Diseases: Questions and Answers About Knee Problems
- "Medicine and Science in Sports and Exercise"; Biomechanics of the knee during closed kinetic chain and open kinetic chain exercises; Rafael F. Escamilla, et al.; April 1998
