Validity and reliability of critical power field testing

Purpose: To test the validity and reliability of field critical power (CP). Method: Laboratory CP tests comprised of three exhaustive trials at intensities of 80%, 100% and 105% maximal aerobic power and CP results were compared with those determined from the field. Experiment 1: cyclists performed three CP field tests which comprised maximal efforts of 12 min, 7 min and 3 min with a 30 min recovery between efforts. Experiment 2: cyclists performed 3 x 3 min, 3 x 7 min and 3 x 12 min individual maximal efforts in a randomised order in the field. Experiment 3: the highest 3 min, 7 min and 12 min power outputs were extracted from field training and racing data. Results: Standard error of the estimate of CP was 4.5%, 5.8% and 5.2% for experiments 1–3 respectively. Limits of Agreement for CP were -26 – 29 W, 26 – 53 W and – 34 – 44 W for experiments 1–3 respectively. Mean coefficient of variation in field CP was 2.4%, 6.5% and 3.5 % for experiments 1–3 respectively. Intraclass correlation coefficients of the three repeated trials for CP were 0.99, 0.96 and 0.99 for experiments 1–3 respectively. Conclusions: Results suggest field-testing using the different protocols from this research study, produce both valid and reliable CP values.