Peak oxygen uptake in sportsmen with spinal cord injury: importance of body composition

BACKGROUND: Although peak oxygen uptake (VO2peak) is considered the most useful index of functional capacity; it's difficult to interpret the results of cardiopulmonary exercise testing (CPET) in individuals with spinal cord injury (SCI). In fact, VO2peak is usually normalized for total body weight, but body composition in persons with SCI largely varies depending on physical activity and time since injury, with a progressive loss of fat-free mass (FFM). This can lead to a misinterpretation of the cardiopulmonary fitness in this population.AIM: Our study proposes a methodology of evaluation, based on bioelectrical impedance analysis (BIA), which could provide more individualized and accurate data in sportsmen with SCI.DESIGN: Case-control study.POPULATION: Ambulatory patients at the Sports Medicine Unit of the IRCCS A. Gemelli University Polyclinic Foundation, Rome, Italy.METHODS: Comparison of data derived from BIA, echocardiography and CPET between 10 male sportsmen with complete, high SCI (group T) and 10 able-bodied controls (group C).RESULTS: Mean VO2peak, weight-normalized VO2peak, fat-free mass (FFM)-normalized VO2peak and body cellular mass (BCM)-normalized values were significantly lower in group T. At the same heart rate (on average the 55% of the maximal theoretical for age), mean of absolute VO2, weight-normalized VO2 and FFM-normalized VO2 were still significantly lower in group T. Considering the BCM-normalized VO2, the group T showed greater values than controls, 39.4 +/- 7.8 vs. 31.1 +/- 8.5 mL/kg/min.CONCLUSIONS: Body composition is a crucial factor for properly interpreting a CPET in individuals with SCI. In particular, normalization of VO2peak values for the BCM seems the most reliable tool to assess the real functional capacity in this population.CLINICAL REHABILITATION IMPACT: A more accurate definition of the aerobic power and functional capacity of people with SCI can improve the monitoring of rehabilitations protocols and physical exercise in this population.