Cardiovascular, Thermoregulatory, Metabolic and Performance Responses to Repeated Ultraendurance Cycling

The purpose of this study was to describe physiological and performance responses in six highly trained cyclists during four days of repeated ultraendurance cycling. Each subject raced in four consecutive 100 mile per day time trials using their own bicycles mounted to a computerized ergometer. The race course profile consisted of rolling terrain with simulated gradients of minus five to ten percent. Body weight was measured prior to each time trial. Total performance time and fluid intake for each time trial were recorded. All other data were measured at ten mile intervals during each 100 mile time trial. Means for days one through four were obtained by averaging respective time trial means for all subjects combined. Data were analyzed for differences among days one through four using repeated measures ANOVA. Heart rate and rate pressure product were significantly higher on day one than days two through four. These changes may have been related to competitive effort and unfamiliarity with the race course on day one. Alternatively, significant differences may have been related to a type one error. When alpha levels were adjusted using the Bonferroni technique, heart rate and rate pressure product were no longer significantly different. Blood pressure, mean arterial pressure, peak aortic velocity, peak aortic acceleration, stroke distance, rectal temperature, fluid intake, oxygen uptake, body weight, power output and performance time were not significantly different among days one through four. Highly trained cyclists are able to maintain cardiovascular, thermoregulatory and metabolic function from day to day during four days of repeated ultraendurance cycling without detrimental changes in physiological function or performance.