Exercise Effect With the Wheelchair Aerobic Fitness Trainer on Conditioning and Metabolic Function in Disabled Persons: A Pilot Study.

Exercise Effect With the Wheelchair Aerobic Fitness Trainer on Conditioning and Metabolic Function in Disabled Persons: A Pilot Study Midha M, Schmitt JK, Sclater M (Spinal Cord Injury Service and General Internal Medicine Sections, Hunter Holmes McGuire Veterans Administration Medical Center, Richmond, Va), Arch Phys Med Rehabil. 1999;80:258-261.

Following spinal cord injury and other physical disabilities, individuals often reduce physical activity and experience deconditioning. As a result of inactivity, problems with cardiorespiratory fitness and increases in serum cholesterol and triglyceride levels may occur, increasing the risk of coronary disease. Abnormalities in thyroid function have also been reported in people with disabilities. This study was designed to determine the effects of an upper-extremity exercise training device on anthropometric characteristics, cardiovascular conditioning, and endocrine/metabolic parameters in people with lowerextremity disability.

Twelve subjects (11 men, 1 woman) participated in this pilot study; 3 subjects had quadriplegia, 7 had paraplegia, 1 had a cerebrovascular accident, and 1 had a bilateral above-knee amputation. Subjects ranged in age from 25 to 58 years. They used the wheelchair aerobic fitness trainer (WAFT), which offers resistance to arm pedaling through computer-controlled electronic particle brakes. The subjects receive feedback from the computer, including target versus actual wheel speed, resistance setting, total distance, and expended kilocalories.

Each subject completed a maximal graded exercise test on the WAFT with increases in exercise intensity every 2 minutes that progressed from 55% to 90% of maximal heart rate. The maximal heart rate was based on age using the formula 220 - age. Mean exercise intensity was 177 watts (range= 47-384 W) with a duration of 20 to 30 minutes. Testing was followed by a 10-minute cool-down. Training consisted of 2 to 3 exercise sessions per week for 10 weeks, and, at each session, the subjects were encouraged to increase the duration of exercise up to a maximum of 30 minutes. Methods for advancing the subjects through training were not discussed. Information regarding consistency of attendance, intensity of training, and use of feedback during training was not provided.

Baseline and posttraining measurements included weight; blood pressure; heart rate; skinfold caliper measures (triceps, quadriceps); mid-arm circumference; abdominal circumference; and levels of fasting serum glucose, cholesterol, triglycerides, and lipoprotein fractions. Serum thyroxine and radioactive triiodthyronine uptake were also tested prior to and following training. In 8 subjects, peak oxygen utilization ([VO.sub.2]max) was measured by the open circuit method. Following the study, the subjects were asked to judge the effect of training on their feelings of well-being.

All subjects reported improved feelings of well-being as a result of the training. Training produced a significant decrease in resting heart rate and an increase in [VO.sub.2]max. Blood pressure did not change substantially. Mid-arm circumference increased significantly, and upper arm fat area (calculated from the circumference and skin-fold measures) decreased. Abdominal circumference and quadriceps skin-fold thickness did not change significantly nor did mean arm power.

Fasting serum cholesterol levels decreased significantly with training, but there was no change in the levels of fasting serum glucose, triglycerides, or high-density lipoprotein (HDL) cholesterol. The serum free thyroxine index increased significantly, but there was no change in serum thyroid-stimulating hormone.

The authors suggested that the increase in the free thyroxine index after training may be caused by increased sympathetic activity associated with exercise, and the decrease in serum cholesterol may be linked with increases in free thyroxine. They further speculated that improved thyroid function might improve myocardial contractility and neuromuscular function, which might improve [VO.sub.2]max. The authors suggested that the lack of improvement in HDL cholesterol levels with training might be attributed to the short duration of training and the fact that HDL levels were measured 48 to 72 hours after the exercise sessions (that is, HDL levels had returned to baseline levels before they were measured). Nevertheless, they argued that the WAFT appears to be a useful tool for cardiovascular conditioning for patients with lower-extremity disabilities.

Karen McCulloch, PT, NCS
University of North Carolina at Chapel Hill
Chapel Hill, NC