Fat oxidation at different intensities in wheelchair racing

Study design: Determination of fat oxidation at three different intensities in trained wheelchair athletes on the treadmill. Objective: The aim of the study was to assess the level and highest rate of fat oxidation in endurance-trained wheelchair athletes for recommendation on endurance training. Setting: Institute of Sports Medicine, Swiss Paraplegic Centre, Nottwil, Switzerland. Methods: Nine (seven men and two women) endurance-trained wheelchair athletes (VO 40.2 ± 6.7 ml/kg/min) were studied over 20 min at 55, 65 and 75% VO on a treadmill in their own racing wheelchairs in order to find the exercise intensity with the highest absolute fat oxidation. Results: As presumed, total energy expenditure for wheelchair racing was highest at 75% VO, while absolute fat oxidation was statistically not significantly different at the three tested intensities. Percentage of energy expenditure from fat oxidation decreased with increasing intensity from 31.4% at 55% VO to 20.9% at 75% VO, while percentage from carbohydrate oxidation increased from 68.6% at 55% VO to 79.1% at 75% VO. Conclusion: For wheelchair athletes, we recommend training of fat metabolism for endurance exercise at an intensity of 55% VO, because absolute fat metabolism is not higher at higher intensities but less carbohydrates are used at lower intensity levels. At lower intensities, exercise can be performed over a longer time before the emptied glycogen stores will limit exercise duration. This may apply especially to paraplegic subjects whose active muscle mass is limited in contrast to able-bodied athletes.