Recently, there has been increasing interest in using backward running (BR) as an exercise and rehabilitation tool. To date, no study has been performed that combined electromyography (EMG) and joint kinetics to study BR. The purpose of this study was to compare selected EMG and kinetic parameters in the stance phase of forward running (FR) and backward running (BR). The sagittal plane of the right knee was analyzed during three trials of FR and BR in six male subjects. Four 60-Hz video cameras collected motion data, and a link segment model of the right lower extremity was established. Force plate and EMG data were collected at 1000 Hz and synchronized with the video data. The knee muscle peak (+) and peak (-) mechanical power and total (+) and total (-) mechanical work were calculated. Electromyography signals were captured from the right lower extremity on the rectus femoris, vastus lateralis, vastus medialis, biceps femoris, gastrocnemius, and tibialis anterior muscles. Statistical analysis indicated that significantly less (p < 0.05) peak (+) and (-) power and total (+) work occurred at the knee during BR than during FR. Significant differences (p < .05) in muscle firing patterns between conditions were observed. Muscle action of the vastus lateralis (VL) and vastus medialis oblique (VMO) was largely eccentric and concentric during FR and isometric and concentric during BR. Backward running appears to be a good method for achieving isometric and concentric muscle action of the VMO and VL and may be useful in clinical conditions that require an increase in knee extensor strength.

J Orthop Sports Phys Ther 1993;17(2):108-112.

Key Words: backward running, muscle action, biomechanics

The use of backward running is becoming more common in the rehabilitation setting. In particular, backward running has been suggested as a treatment modality in patients experiencing patellofemoral pain syndrome. To date, no study has examined the loads at the patellofemoral joint during backward running. The purpose of this study was to compare patellofemoral joint compressive forces during forward and backward running. Ground reaction force and kinematic data were collected on 5 male joggers during free speed forward and backward running. A floor reaction force vector model was used to calculate the stance phase knee extension moments. The distance used for the extensor muscle lever arm was 4.9 cm. Patellar mechanism angle was calculated based on knee joint angle. There was a reduction in the peak patellofemoral joint compressive forces in backward compared with forward running (2277 ± 192N vs. 4253 ± 1292N; p < 0.05) at self-selected speeds. Peak patellofemoral joint compressive force occurred significantly later (p < 0.05) in the stance phase of backward running (52 ± 4%) than in forward running (35 ± 3%). The peak patellofemoral joint compressive force normalized to subject body weight was 5.6 ± 1.3 body weight in forward running and 3.0 ± 0.6 body weight in backward running. The results suggest that backward running at a self-selected speed may reduce patellofemoral joint compressive forces and, coupled with the quadriceps strengthening that has previously been reported, may be beneficial in the rehabilitation of patellofemoral pain syndrome in runners. However, constant speed comparisons or other models may yield different results.

J Orthop Sports Phys Ther. 1995;21(5):277-282.

Key words: patellofemoral pain, backward running, rehabilitation