Tibiofemoral joint reaction force during the stance phase of backward- and forward-walking at variable speeds

Background: The knee is the joint that often suffers from sport injury. Adequate post-injury rehabilitation helps the patients come back to the game earlier, and prevents re-injury. As part of the program, backward-walking is sometimes used, but information available for the knee-joint reaction force is limited.

Objective: Determine tibiofemoral joint reaction force (TFJRF) during the stance phase of backward- and forward-walking at variable speeds.

Methods: Fifty-four healthy Thai males (age 20 to 39 year old, body mass index <30) performed forward- and backward-walking on a split-belt treadmill to record the ground reaction force (GRF) on the force platform under each belt. The subjects were controlled to walk from the slowest to fastest speeds (0.8, 1.0, 1.2, 1.4, and 1.6 m/second). Kinematic data were recorded using six cameras, and analyzed by the motion analysis software. Based on the obtained kinematic and GRF data, TFJRF was calculated using an inverse dynamic model. Heart rates (HR) were also recorded using wireless electrocardiography.

Results: Backward-walking produced higher peak TFJRF during the stance phase than that of forward-walking in every speed. The subjects had higher HR in every speed during backward-walking, but the average TFJRF was lower in all test speeds except 0.8 m/second.

Conclusion: Peak TFJRF and HR during backward-walking were higher than those during forward-walking in every speed, but backward-walking showed a trend to lower the averaged TFJRF compared with forward-walking. In clinical practice, lower speed of backward-walking may be appropriate to prescribe as an exercise for those with tibiofemoral joint problems.