Search Results

Purpose: To evaluate the predictive validity of critical power (CP) and the work above CP (W′) on cycling performance (mean power during a 20-min time trial; TT20). Methods: On 3 separate days, 10 male cyclists completed a TT20 and 3 CP and W′ prediction trials of 1, 4, and 10 min and 2, 7, and 12 min in field conditions. CP and W′ were modeled across combinations of these prediction trials with the hyperbolic, linear work/time, and linear power inverse-time (INV) models. The agreement and the uncertainty between the predicted and actual TT20 were assessed with 95% limits of agreement and a probabilistic approach, respectively. Results: Differences between the predicted and actual TT20 were “trivial” for most of the models if the 1-min trial was not included. Including the 1-min trial in the INV and linear work/time models “possibly” to “very likely” overestimated TT20. The INV model provided the smallest total error (ie, best individual fit; 6%) for all cyclists (305 [33] W; 19.6 [3.6] kJ). TT20 predicted from the best individual fit-derived CP, and W′ was strongly correlated with actual TT20 (317 [33] W; r = .975; P < .001). The bias and 95% limits of agreement were 4 (7) W (−11 to 19 W). Conclusions: Field-derived CP and W′ accurately predicted cycling performance in the field. The INV model was most accurate to predict TT20 (1.3% [2.4%]). Adding a 1-min-prediction trial resulted in large total errors, so it should not be included in the models.

Purpose: To determine aerobic and anaerobic demands of mountain bike cross-country racing. Methods: Twelve elite cyclists (7 males; $\dot{\mathrm{V}}{\mathrm{O}}_2\text{max}$ = 73.8 [2.6] mL·min^-1·kg⁻¹, maximal aerobic power [MAP] = 370 [26] W, 5.7 [0.4] W·kg⁻¹, and 5 females; $\dot{\mathrm{V}}{\mathrm{O}}_2\text{max}$ = 67.3 [2.9] mL·min⁻¹·kg⁻¹, MAP = 261 [17] W, 5.0 [0.1] W·kg⁻¹) participated over 4 seasons at several (119) international and national races and performed laboratory tests regularly to assess their aerobic and anaerobic performance. Power output, heart rate, and cadence were recorded throughout the races. Results: The mean race time was 79 (12) minutes performed at a mean power output of 3.8 (0.4) W·kg⁻¹; 70% (7%) MAP (3.9 [0.4] W·kg⁻¹ and 3.6 [0.4] W·kg⁻¹ for males and females, respectively) with a cadence of 64 (5) rev·min⁻¹ (including nonpedaling periods). Time spent in intensity zones 1 to 4 (below MAP) were 28% (4%), 18% (8%), 12% (2%), and 13% (3%), respectively; 30% (9%) was spent in zone 5 (above MAP). The number of efforts above MAP was 334 (84), which had a mean duration of 4.3 (1.1) seconds, separated by 10.9 (3) seconds with a mean power output of 7.3 (0.6) W·kg⁻¹ (135% [9%] MAP). Conclusions: These findings highlight the importance of the anaerobic energy system and the interaction between anaerobic and aerobic energy systems. Therefore, the ability to perform numerous efforts above MAP and a high aerobic capacity are essential to be competitive in mountain bike cross-country.

Purpose: To investigate single-day time-to-exhaustion (TTE) and time-trial (TT) -based laboratory tests values of critical power (CP), W prime (W′), and respective oxygen-uptake-kinetic responses. Methods: Twelve cyclists performed a maximal ramp test followed by 3 TTE and 3 TT efforts interspersed by 60 min recovery between efforts. Oxygen uptake ($\dot{\mathrm{V}}{\mathrm{O}}_2$) was measured during all trials. The mean response time was calculated as a description of the overall $\dot{\mathrm{V}}{\mathrm{O}}_2$-kinetic response from the onset to 2 min of exercise. Results: TTE-determined CP was 279 ± 52 W, and TT-determined CP was 276 ± 50 W (P = .237). Values of W′ were 14.3 ± 3.4 kJ (TTE W′) and 16.5 ± 4.2 kJ (TT W′) (P = .028). While a high level of agreement (−12 to 17 W) and a low prediction error of 2.7% were established for CP, for W′ limits of agreements were markedly lower (−8 to 3.7 kJ), with a prediction error of 18.8%. The mean standard error for TTE CP values was significantly higher than that for TT CP values (2.4% ± 1.9% vs 1.2% ± 0.7% W). The standard errors for TTE W′ and TT W′ were 11.2% ± 8.1% and 5.6% ± 3.6%, respectively. The $\dot{\mathrm{V}}{\mathrm{O}}_2$ response was significantly faster during TT (~22 s) than TTE (~28 s). Conclusions: The TT protocol with a 60-min recovery period offers a valid, time-saving, and less error-filled alternative to conventional and more recent testing methods. Results, however, cannot be transferred to W′.