Knee Pain and Injury in Weight Training

Knee injury in the gym

Lower back, shoulder, and knee are the big three "injury"' joints for active people. Even the inactive will inevitably have a mild or serious injury to one or more of these joints over a lifetime. Knee injuries, especially to the knee ligaments, are exceedingly common in sporting communities. Knee injuries can result in pain, swelling, and immobility from minor to severe effect.

For weight trainers and physically active men and women, the knee joints endure a wide range of stresses and strains. For the most part, in younger years, the knee joints serve us well. However, in sports with twisting movements—such as football, basketball, hockey, and many others—ligaments that bind the complex bones of the knee joint together can be damaged, often severely. In addition, as we age, normal wear and tear can result in osteoarthritis of the knee joints. In this condition, the cartilage that provides cushioning between bones deteriorates and causes bones to rub together resulting in pain and stiffness.

Weight Training and Knee Injuries

While it may seem like weight training could contribute to knee injuries, this is not the case. Lifts like deadlifts and squats do place high forces on the knee joints, but these forces are applied mostly vertically and not horizontally or rotationally (twisting). The knees cope with vertical forces much better than high-impact horizontal and twisting forces. Even so, knee injuries do occur in weight training and in the very high forces of Olympic weightlifting, and if you have an existing knee injury from another activity, inappropriate weight training exercises could make it worse.

In general, weight training is safe for the knees as long as proper form is practiced. The body is designed to manage vertical forces on the joints. However, sudden twisting movements, poor alignment, and pre-existing injuries may put you at risk for an injury.

In each of the knee ligament injuries below, the damage can range from a sprain to a slight tear or a complete tear in the most serious cases. Here's what you need to know.

Common Injuries

  • Anterior Cruciate Ligament (ACL). This ligament ties the femur bone of the thigh to the tibia or shin bone of the lower leg and controls excessive rotation or extension of the knee joint. Anterior means at the front. A rear (posterior) ligament is also present. ACL injuries are seen mostly in athletes. Severe damage to the ACL usually means surgical reconstruction and up to 12 months rehabilitation. In the gym, be careful not to allow twisting knee movements under excessive load, intentionally or accidentally.
  • Posterior Cruciate Ligament (PCL). The PCL connects the femur and tibia at different points to the ACL and controls any rearward motion of the tibia at the joint. The PCL is mostly injured with high-impact forces as a result of accidents and sometimes in sports activities where a sharp blow to the knee occurs.
  • Medial Collateral Ligament (MCL). This ligament keeps the knee from bending too far to the inside (medially). Damaged MCLs mostly occur from an impact to the outside of the knee, or even from an accidental bodyweight force when the leg reaches an unusual angle.
  • Lateral Collateral Ligament (LCL). This is the opposite ligament to the MCL. It's on the outside of the knee and controls excessive movement outward. This ligament connects the fibula (the smaller bone of the lower leg) to the femur. Similarly the LCL is injured when a force pushes the knee outward.
  • Cartilage Injury. Cartilage prevents bones from rubbing together and cushions impacts. The two knee menisci (meniscus single) are cartilages that cushion the inside and outside of the knee joint. Other types of cartilage protect the ends of the thigh and shin bones. When cartilage is torn or damaged, surgery with an arthroscope may be necessary. (An arthroscope is an implement that allows a surgeon to see and fix cartilage injuries with a small incision.)
  • Tendonitis. Aggravated and overused tendons of the knee can cause disabling knee injuries. A related injury called "iliotibial band syndrome" (ITB) causes pain to the outside of the knee, often in runners, but it can occur in any overuse situation. Rest, stretching, and a short, two-week course of anti-inflammatory medication is often recommended. Longer duration of medication usage can result in more side effects than benefits. For pain lasting longer than two weeks, consult a physical therapist. Anti-inflammatory medication is often recommended for these types of injuries.

Weight Training Exercises to Avoid

If you have an existing knee injury, take the advice of your doctor or physical therapist in the first instance. Gym exercises that may be best avoided are the isolation exercises like the leg extension machine, and the leg curl exercises, either standing or on a bench. Heavy loads or deep squats should mostly be avoided. On the other hand, if your knee was perfectly healthy, with accurate technique under expert supervision and gradually progressive training load, current research shows the deep squat is a great exercise to protect against lower leg injury.

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