Metabolic and cardiorespiratory responses of tetraplegic subjects during treadmill walking using neuromuscular electrical stimulation and partial body weight support

Study design: Determination of differences in the cardiorespiratory responses of tetraplegic subjects with incomplete and complete lesions during treadmill gait and endurance exercise provided by neuromuscular electrical stimulation (NMES). Differences between rest and exercise phases were also examined. Objectives: To compare the cardiorespiratory responses in tetraplegic individuals during endurance exercise in the sitting position and treadmill gait with 30-50% body weight relief, both provided by NMES. Setting: Rehabilitation Ambulatory at University Hospital, Brazil. Methods: A total of 31 tetraplegic subjects were evaluated. Individuals were separated into two groups: gait group and endurance exercise group. In the gait group (n = 17), the exercise protocol consisted of three different phases: 8 min of rest, 10 min of treadmill walking using NMES and 10 min of recovery. In the endurance exercise group( n 14), the cardiorespiratory test consisted of 8 min of rest, 15 min of quadriceps endurance exercise in the sitting position by NMES and 10 min of recovery. Oxygen uptake (VO2), carbon dioxide production (VCO2), respiratory exchange ratio (RER), pulmonary ventilation (V-E) and heart rate (HR) were measured. Results: All parameters increased considerably in the gait group from rest to the walking phase, although individuals with incomplete lesions presented a more pronounced increase than those with complete lesion. In the gait group, for incomplete tetraplegics, the mean VO2 peak was 0.81 +/- 70.314 l/ min, corresponding to 11.41 +/- 3.11 ml/kg/min; the mean value for VCO2 was 0.660 +/- 0.24 l/min, mean HR was 124.54 +/- 28.72 bpm and mean V-E was 28.38 +/- 6.28 l/min. In the endurance exercise group, for incomplete tetraplegics, the mean VO2 peak was 0.246 +/- 0.07 l/min, corresponding to 3.84 +/- 0.92 ml/kg/ min; the mean value for VCO2 was 0.205 +/- 0.06 l/min, mean HR was 71.45 +/- 15.51 bpm and mean V-E was 11.83 +/- 2.72 l/min. In the endurance exercise group, smaller differences were observed in all variables from rest to the exercise phase, compared with the large increases observed in the gait group. Conclusions: These preliminary results have shown that gait training probably improves physical capacity in tetraplegic individuals more than the endurance exercise.