How to Calculate Force on the Knee

The knees provide critical support for the body, especially during athletic activity such as running. During this activity, the knees endure a great deal of force, which can sometimes lead to injury. The amount of impact felt by the knees can be calculated using a training run and the weight of the runner.

Things You'll Need

• Bathroom scale
• Pedometer
• Scientific calculator

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Instructions

• 1

  Measure your body weight by standing on the bathroom scale.

• 2

  Run 1 mile at regular training pace while wearing the pedometer to count the number of steps you take during that mile.

• 3

  Multiply your body weight by 2 and also by 3. A runner's knees endure a force equal to two to three times the runner's body weight with each footstrike during a run. Your results should produce a range of weight the knees endure with each footstrike. For a 150-lb. runner, the range would be 300 to 450 lbs. of force per footstrike.

• 4

  Multiply each end of the range calculated in Step 3 by the number of steps measured on the pedometer in Step 2. The result is how much force the knees endure during a typical mile run at training pace. The average runner takes 400 steps on each leg per mile, meaning each knee endures a force of about 12,000 to 18,000 lbs. over the course of a 1-mile run.