Comparison of inter-trial recovery times for the determination of critical power and W’ in cycling

Karsten B., Hopker J., Jobson S., Baker J., Petrigna L., Klose A., Beedie C.

Abstract

Critical Power (CP) and W’ are often determined using multi-day testing protocols. To investigate this cumbersome testing method, the purpose of this study was to compare the differences between the conventional use of a 24-h inter-trial recovery time with those of 3 h and 30 min for the determination of CP and W’. Methods: 9 moderately trained cyclists performed an incremental test to exhaustion to establish the power output associated with the maximum oxygen uptake (p V O2max), and 3 protocols requiring time-to-exhaustion trials at a constant work-rate performed at 80%, 100% and 105% of p VO2max. Design: Protocol A utilised 24-h inter-trial recovery (CP24/W’24), protocol B utilised 3-h inter-trial recovery (CP3/W’3), and protocol C used 30-min inter-trial recovery period (CP0.5/W’0.5). CP and W’ were calculated using the inverse time (1/t) versus power (P) relation (P = W’(1/t) + CP). Results: 95% Limits of Agreement between protocol A and B were −9 to 15 W; −7.4 to 7.8 kJ (CP/W’) and between protocol A and protocol C they were −27 to 22 W; −7.2 to 15.1 kJ (CP/W’). Compared to criterion protocol A, the average prediction error of protocol B was 2.5% (CP) and 25.6% (W’), whilst for protocol C it was 3.7% (CP) and 32.9% (W’). Conclusion: 3-h and 30-min inter-trial recovery time protocols provide valid methods of determining CP but not W’ in cycling.