Optimal exercise intensities for fat metabolism in handbike cycling and cycling

Energy expenditure (EE) and fat oxidation in handbike cycling compared to cycling in order to determine the intensity that elicits maximal fat oxidation in handbike cycling.

To establish the exercise intensity with the highest fat oxidation rate in handbike cycling compared with cycling (control group) in order to give training recommendations for spinal cord-injured (SCI) athletes performing handbike cycling.

Institute of Sports Medicine, Swiss Paraplegic Centre, Nottwil, Switzerland.

Eight endurance-trained handbike cyclists (VO2 peak(handbike cycling) 37.5+/-7.8 ml/kg/min) and eight endurance trained cyclists (VO2 peak(cycling) 62.5+/-4.5 ml/kg/min) performed three 20-min exercise blocks at 55, 65 and 75% VO2 peak in handbike cycling on a treadmill or in cycling on a cycling ergometer, respectively, in order to find the intensity with the absolutely highest fat oxidation.

The contribution of fat to total EE was highest (39.1+/-16.3% EE) at 55% VO2 peak in handbike cycling compared to cycling, where highest contribution of fat to EE (50.8+/-13.8%) was found at 75% VO2 peak. In handbike cycling, the highest absolute fat oxidation (0.28+/-0.10 g/min) was found at 55% VO2 peak compared to cycling, where highest fat oxidation (0.67+/-0.20 g/min) was found at 75% VO2 peak.

Well-trained handbike cyclists have their highest fat oxidation at 55% VO2 peak(handbike cycling) compared to well-trained cyclists at 75% VO2 peak(cycling). Handbike cyclists should perform endurance exercise training at 55% VO2 peak(handbike cycling), whereas well-trained cyclists should be able to exercise at 75% VO2 peak(cycling). For training recommendations, the heart rate at 55% VO2 peak(handbike cycling) lies at 135+/-6 bpm in handbike cycling in SCI compared to 147+/-14 bpm at 75% VO2 peak(cycling) in well-trained cyclists. We presume that the reduced muscle mass involved in exercise during handbike cycling is the most important factor for impaired fat oxidation compared to cycling. But also other factors as fitness level and haemodynamic differences should be considered. Our results are only applicable to well-trained handbike cyclists with SCI and not for the general SCI population.