Durabilidade no Mountain Bike Cross-Country Olímpico: implicações para o desempenho

Abstract

Durability is an important factor in the assessment of endurance athletes. Although the body of evidence on the durability of professional road cyclists is growing, there is limited information about its relevance for Olympic cross-country mountain bike (XCO-MTB) athletes. Therefore, this thesis was structured into three studies: The study 1 aimed to: determine the test-retest repeatability of intermittent tests, the power profile, and the power-duration relationship performed in the field in mountain bikers. The results demonstrated that the intraclass correlation coefficient (ICC) was excellent for intermittent tests, efforts >1 min, and total work in the power profile test. For efforts ≤1 min in the power profile test, the ICC ranged from good to excellent, while for critical power (CP) and W’, it ranged from moderate to excellent. The typical error of measurement (TEM%) was between 1.6% and 5.7%, except for W’ (≈18%). The lowest variability was observed in the 30/15 intermittent test and for efforts >1 min and total work in the power profile test. The study 2 aimed to: (i) verify the effect of the fatigue protocol on the power profile and (ii) examine the interaction between fatigue and performance level on the power profile of mountain bikers. The results revealed that, across all effort durations (5 s to 10 min) and total work, power output values were significantly lower in the fatigued condition compared to the “fresh” condition. Both groups (high performance, HP, and low performance, LP) showed percentage reductions in power output, but the LP group showed a significantly greater decline (≈14% to ≈20%) compared to the HP group (≈4% to ≈8%). The study 3 aimed to: (i) verify whether intermittent tests performed under fatigue are better predictors of XCO-MTB performance compared to the “fresh” condition, (ii) examine whether prior prolonged exercise reduces power output during intermittent tests, and (iii) investigate whether the ability to maintain high power output during intermittent tests under fatigue differentiates the competitive level of mountain bikers. The results showed that tests performed under fatigued condition demonstrated a higher predictive capacity for XCO-MTB time trial performance. Specifically, the 10/20 intermittent test (W∙kg-1) in the fatigued condition explained 89% of the performance variability. In all tests, power output was significantly lower in the fatigued condition compared to the “fresh” condition. Furthermore, the LP group showed a significantly greater power output reduction in the 30/15, 10/20, and 3/2 tests after the fatigue protocol (≈15% to 20%) compared to the HP group (≈6% to 10%). In conclusion, this thesis provides evidence that the evaluated tests demonstrated high repeatability, making them useful tools for identifying real changes in performance. The ability to sustain power output under fatigue is a relevant indicator of performance in this sport. Intermittent tests performed under fatigued condition have greater predictive capacity for XCO-MTB performance. Collectively, the studies of this thesis provide insights to optimize training strategies, identify talents, and support athlete monitoring in XCO-MTB