Reproducibility and validity of physiological parameters measured in cyclists riding on racing bikes placed on a stationary magnetic brake

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Abstract
The purpose of this study was: 1) To evaluate the reproducibility of physiological parameters measured during cycle exercise, and 2) To validate the predictive capacity of physiological parameters related to endurance performance. Therefore, physiological variables were measured twice during cycling exercise in a group of seven cyclists. Each cycle exercise session was separated by one week and included progressive submaximal cycling followed by a 5‐km time trial. Two and three weeks later, endurance performance was evaluated by calculating average work output during a 50‐km time trial (W50km). To simulate cycle performance, the cyclists’ private racing bikes were placed on a stationary magnetic brake. No differences were observed between paired physiological observations in the test‐retest (P>0.05). The coefficient of variation (CV) was calculated from the differences between test‐retest parameters. CV for the maximal oxygen uptake (VO2max), average work output during the 5‐km trial (W5km), the calculated work intensity which increased the blood lactate concentration to 2 and 4 mmol/1 (W2mM and W4mM) and W50km were 1.9, 2.7, 6.1, 5.9 and 6.3%, respectively, while the 95% confidence interval (CI) showing the expected range for variation in a retest was calculated to be 80 ml.min−1, 9, 16, 18 and 18 W, respectively. Simple linear regression showed significant correlations between VO2max, W5km, W2mM, W4mM and W50km (r‐values: range 0.83–0.98, P2max,W5km, W2mM, and W4mM as predictive parameters of endurance was demonstrated.