Obesity and osteoarthritis of the knee: hypotheses concerning the relationship between ground reaction forces and quadriceps fatigue in long-duration walking.

The principal risk factors of osteoarthritis of the knee are: age, obesity and gender. It is hypothesized that long-duration walking (e. g. 20 min) in the elderly obese will lead to quadriceps fatigue. Changes in the gait pattern due to fatigue will lead to altered knee kinematics at heelstrike and consequently decreased shock absorption. This scenario will result in an increased rate of loading and possibly an increase in the overall magnitude of peak ground reaction forces, both of which could cause articular cartilage degeneration. Obese females are at an overall higher risk of developing osteoarthritis than males. This gender discrepancy may be explained by the fact that females have a higher percentage of body fat content (lower proportion of lean mass) that may increase the rate of quadriceps fatigue. These biomechanical hypotheses can be examined by studying continuous periods of walking in which ground reaction forces, knee kinematics and electromyography data are recorded.