Effects of a proposed challenge on effort sense and cardiorespiratory responses during exercise

Purpose: Highly trained endurance athletes train and race at relatively hig h intensities and are often confronted with challenges throughout a running event. The purpose of this study was to examine the effects of the anticip ation of a proposed challenge on effort sense, heart rate (HR), ventilation ([dotV(E)), and ventilatory equivalent (V) over dot(E)/(V) over dotO(2)), a measure of ventilatory efficiency. Methods: Highly trained endurance athl etes ((V) over dotO(2max) = 68.46 +/- 1.47 mL.kg(-1).min(-1)) ran two sessi ons at approximately 75% of (V) over dotO(2max) for 35 min in a control con dition and a proposed challenge condition. During the control condition, th e subjects ran on a treadmill while simultaneously viewing a video depictin g a runner exercising at 75%, of (V) over dotO(2max) and were told the run would continue at a speed that elicited 75% of (V) over dotO(2max). During the proposed challenge condition, subjects completed the same exercise prot ocol but viewed a video of a struggling runner and were told that the tread mill speed would be increased to "an extremely difficult" 95% of (V) over d otO(2max) matching the intensity of the runner on the video. However, after data assessment at 17 min, subjects were told that the treadmill was malfu nctioning and the treadmill speed could not be altered. The same intensity was maintained in both conditions. RPE, HR, (V) over dot(E), and (V) over d ot(E)/(V) over dotO(2) were assessed during the treadmill runs at 10, 17, 2 5, and 35 min. Results: The effects of the manipulation were represented by a significant increase in state anxiety immediately following the video pr oposing the 95% challenge. RPE, HR, and (V) over dot(E) increased similarly under both conditions, while (V) over dot(E)/(V) over dotO(2) did not chan ge. Conclusion: These findings suggest that for highly trained endurance at hletes, anticipation of proposed challenge during running does not influenc e cardiorespiratory responses; thus these athletes demonstrate a "physiolog ically toughened" response.