Written by Laurie Tis, Ph.D., FACSM
Prevention of knee injuries, whether acute (knee ligament sprains) or chronic (knee tendonitis, bursitis, or the management of arthritis) is a frequent question to any fitness and health practitioner.
Regardless of the exercise program or the age or gender of the participant, there are key points that should be addressed. First, a flexibility program incorporated into an exercise program is usually a good start. Second, a strength program (regardless of your current muscle strength) will typically work to prevent injury. Third, it is important, based on your level of fitness, any other surrounding health issues, or other previous injuries or current injuries or health issues that the correct exercises are chosen, and when they are, that overtraining is avoided. Lastly, as all of these are considered, make sure to consider proper equipment and technique. When in doubt, consult health and fitness experts or a sports medicine physician.
The following recommendations are designed for knee injury prevention, not performance enhancement.
Flexibility of the Hip and Thigh Musculature
In any injury prevention program, flexibility or a stretching program of the surrounding muscles is crucial. The muscles most important for prevention of knee injuries are the hip and thigh muscles: the gluteals, hip adductors or groin muscles, and the knee flexors and extensors. There are countless stretching programs, but the basic guidelines of warming up prior to exercise still ring true: warm up until you “break a sweat,” stretch each muscle group two to three times, and stretch after activity for your cool down. Stretching does not improve performance but will work to prevent injury and, as a general rule, is an absolute must if you have sustained an injury. Flexibility declines with age, so it is best to incorporate and maintain early on, since flexibility can be difficulty to regain.
Strengthening of the Hip, Thigh
As with any injury prevention program, strengthening of the muscles surrounding the knee is important. The muscles that should be the focus of a knee injury prevention program are the hip muscles: gluteus maximus or hip extensors; rectus femoris and iliopsoas or hip flexors; and the hip adductors. Also important are the knee joint, knee extensors (quadriceps group) and the knee flexors (hamstring group). Although these are the key muscles to focus on, many sources also recommend strength exercises for the lower-leg muscles such as the ankle plantarflexors and dorsiflexors.
To strengthen these areas, utilize weight machines or some other form of resistance exercise, such as sport cords or resistance tubing. Each exercise should focus on individual muscle groups and be performed in eight to 10 repetitions. Complete at least one set, increasing up to three sets, with at least 20 to 40 seconds of rest between each set. Focus on performing each exercise properly, not on doing a lot of exercise or lifting a great amount of weight.
Another second strength-training option is to use body-weight exercises such as squats, wall squats or lunges. These exercises can be done anywhere, require little space or equipment, and utilize multiple muscle groups. However, often maintaining proper form can be challenging, so use caution.
Avoid Overtraining, Regardless of Activity Choice
Overtraining is a concern with any activity, be it walking, running, swimming, or the plethora of other choices available to exercisers. The first step in avoiding knee overtraining is to choose your activity wisely to ensure it’s a good fit. For example, if you have many lower-leg problems, knee pain, or a history of back pain, a non-weight-bearing activity such as swimming may be a better choice than running. Then start slowly, with a day of rest between each exercise bout, and progress either by increasing the time of each exercise session or by adding a day of activity per week. For people who like variety, choosing different activities, often called crosstraining, is a good option. Choose a weight-bearing and a non-weight-bearing activity and alternate workouts. Regardless of the activity, be sure to use proper technique, particularly in technique-intense sports such as speed walking or swimming, and always get instruction if needed.
Many activities have equipment guidelines and recommendations, and these recommendations can change frequently. For example, running shoes should be replaced approximately every 300 miles. The shoes’ shock absorption will typically not be adequate in the average runner after that mileage. Conversely, the use of walking or hiking poles has been shown to reduce impact and may be beneficial to walking or hiking, regardless of the terrain.
When in doubt, always check with a physician, fitness expert, or professional such as a physical therapist or certified athletic trainer to prevent an injury and ensure you are ready to begin your exercise program and prevent knee injury.
View the full spring 2010 issue of the ACSM Fit Society® Page online.