Accuracy of W ′ Recovery Kinetics in High Performance Cyclists- Modeling Intermittent Work Capacity

Purpose: With knowledge of an individual's critical power and W', the SKIBA 2 model provides a framework with which to track W' balance during intermittent high-intensity work bouts. There are fears that the time constant controlling the recovery rate of W' (tau(W')) may require refinement to enable effective use in an elite population. Methods: Four elite endurance cyclists completed an array of intermittent exercise protocols to volitional exhaustion. Each protocol lasted approximately 3.5-6 min and featured a range of recovery intensities, set in relation to the athlete's critical power (D-CP). Using the framework of the SKIBA 2 model, the tau(W') values were modified for each protocol to achieve an accurate W' at volitional exhaustion. Modified tau(W') values were compared with equivalent SKIBA 2 tau(W') values to assess the difference in recovery rates for this population. Plotting modified tau(W') values against DCP showed the adjusted relationship between work rate and recovery rate. Results: Comparing modified tau(W') values against the SKIBA 2 tau(W') values showed a negative bias of 112 (46) s (mean +/- 95% confidence limits), suggesting that athletes recovered W' faster than predicted by SKIBA 2 (P =.0001). The modified tau(W')-D-CP relationship was best described by a power function: tau(W') = 2287.2 x D-CP -(0.688) (R-2 =.433). Conclusions: The current SKIBA 2model is not appropriate for use in elite cyclists, as it underpredicts the recovery rate of W 0. The modified tau(W') equation presented will require validation but appears more appropriate for high-performance athletes. Individual tau(W') relationships may be necessary to maximize the model's validity.