Accounting for Dynamic Changes in the Power-Duration Relationship Improves the Accuracy of W' Balance Modelling.

Abstract

Purpose This study aimed to: 1) examine the accuracy with which W′ reconstitution (W′REC) is estimated by the W′ balance (W′BAL) models following a 3-min all-out test (3MT); 2) determine the effects of a 3MT on the power-duration relationship, and; 3) assess whether accounting for changes in the power-duration relationship during exercise improved estimates of W′REC.

Methods The power-duration relationship and the actual and estimated W′REC was determined for 12 datasets extracted from our laboratory database where participants had completed two 3MT separated by 1-min recovery (i.e., control, C-3MT and fatigued, F-3MT).

Results Actual W′REC (6.3 ± 1.4 kJ) was significantly overestimated by the W′BAL·ODE (9.8 ± 1.3 kJ; P < 0.001) and the W′BAL·MORTON (16.9 ± 2.6 kJ; P < 0.001) models, but was not significantly different to the estimate provided by the W′BAL·INT (7.5 ± 1.5 kJ; P > 0.05) model. End power (EP) was 7% lower in the F-3MT (263 ± 40 W) compared to the C-3MT (282 ± 44 W; P < 0.001), and work done above EP (WEP) was 61% lower in the F-3MT (6.3 ± 1.4 kJ) compared to the C-3MT (16.9 ± 3.2 kJ). The size of the error in the estimated W′REC was correlated with the reduction in WEP for the W′BAL·INT and W′BAL·ODE models (both r > -0.74, P < 0.01) but not the W′BAL·MORTON model (r = -0.18, P > 0.05). Accounting for the changes in the power-duration relationship improved the accuracy of the W′BAL·ODE and W′BAL·MORTON, but they remained significantly different to actual W′REC.

Conclusions These findings demonstrate that the power-duration relationship is altered following a 3MT, and accounting for these changes improves the accuracy of the W′BAL·ODE and the W′BAL·MORTON, but not W′BAL·INT models. These results have important implications for the design and use of mathematical models describing the energetics of exercise performance.