BACKWARD WALKING AT 3 LEVELS OF TREADMILL INCLINATION - AN ELECTROMYOGRAPHIC AND KINEMATIC ANALYSIS

Backward walking on a treadmill is a common tool for lower extremity r ehabilitation in the clinical setting. The purpose of this study was t o evaluate the adaptations in the gait cycle produced by walking backw ard on a treadmill at 0, 5, and 10% inclination. Sixteen healthy adult subjects (14 females, two males), mean age of 23.19 +/- 3.02, partici pated. Joint positions for hip, knee, and ankle were measured during a complete gait cycle. Values were time matched with average electromyo graphic (EMG) activity (surface electrode) of the rectus femoris, hams trings, gastrocnemius, and anterior tibialis during each subphase oi g ait (initial contact, midstance, heel-off, and midswing). Values of jo int position and average EMG were compared over the three treadmill co nditions. Subjects walked for approximately 1 minute at 4.0 km/h. A si mple repeated measures analysis of variance (p < .05) with a Duncan po st hoc test war used to analyze for changes. Significant changes occur red in the joint positions of the knee and ankle al initial contact (a nkle increased from 9.81 +/- 5.06 degrees to 13.08 +/- 3.68 degrees; k nee increased from 30.94 +/- 5.25 degrees to 42.42 +/- 4.08 degrees) a s the treadmill was raised from 0 to 10%. Significant changes occurred for average EMG activity for each muscle studied over the three tread mill conditions. The greatest changes occurred in the gastrocnemius at initial contact (increase from 189.76 +/- 44.29% to 293.09 +/- 79.16% ) between the O and 10% conditions. The results of this investigation confirm that backward walking up an incline may place additional muscu lar demands on an individual. These results may be used as a guide for adapting a rehabilitation program, especially al the knee and ankle.