Reliability of the parameters of the power-duration relationship using maximal effort time-trials under laboratory conditions

Abstract

The purpose of this study was to assess the reliability of critical power (CP) and the total amount of work accomplished above CP (W´) across repeated tests using ecologically valid maximal effort time-trials (TT) under laboratory conditions. After an initial incremental exercise test, ten well-trained male triathletes (age: 28.5 ± 4.7 years; body mass: 73.3 ± 7.9 kg; height: 1.80 ± 0.07 m; maximal aerobic power [MAP]: 329 ± 41 W) performed three testing sessions (Familiarization, Test I and Test II) each comprising three TT (12, 7, and 3 min with a passive recovery of 60 min between trials). CP and W´ were determined using a linear regression of power vs. the inverse of time (1/t) (P = W´ ∙ 1/t + CP). A repeated-measures ANOVA was used to detect differences in CP and W´ and reliability was assessed using the intra-class correlation coefficient (ICC) and the coefficient of variation (CoV). CP and W´ values were not significantly different between repeated tests (P = 0.171 and P = 0.078 for CP and W´, respectively). The ICC between Familiarization and Test I was r = 0.86 (CP) and r = 0.58 (W´) and between Tests I and II it was r = 0.94 (CP) and r = 0.95 (W´). The CoV notably decreased from 4.1% to 2.6% and from 25.3% to 8.2% for CP and W´, respectively. Despite the non-significant differences for both parameter estimates between Familiarization, Test I, and Test II, ICC and CoV values improved notably after the familiarization trial. Our novel findings indicate that for both, CP and W´ a familiarization trial increased reliability. It is therefore advisable to familiarize well-trained athletes when determining the power-duration relationship using TT under laboratory conditions.

Reliability of the Functional Threshold Power in Competitive Cyclists

“…Interestingly, despite the high variability in each part of the warm-up and the moderate CV for the overall warm-up (5.5 %), the reliability of the mean PO of the 20-min TT does not seem to be affected (▶Table 1). This is in accordance with the variability found in the TTs of different durations using shorter standardized warm-ups (CV = 2.0-3.4 %) [30][31][32].…”

“…A meta-analysis showed that between the first two trials the CV is 1.3 × higher than the CV between subsequent trials; there is a reduction in the change in the mean (1.2-0.2 % [3]). Additionally, a study showed an increase in the ICC between familiarization-test and test-retest comparisons [32]. In the present study, the CV between test and familiarization was 1.1 × higher than between test-retest.…”

Methodological Approaches and Related Challenges Associated With the Determination of Critical Power and Curvature Constant

“…A final point to consider is the test-retest reliability of estimations of CP and W' using TT. Recently, Triska et al(103) performed three identical TT to determine CP and W' using a single-day protocol with the first TT used as familiarisation. The authors noted that the CV of CP and W' between the familiarisation and the first subsequent TT were 4.1% and 25.3%, respectively.…”

Comparison of Critical Speed and D′ Derived From 2 or 3 Maximal Tests

“…Previous research has suggested an upper SEE limit for CS/CP of 2% and 10% for D'/W'. 15 The SEE of the regression model may be reduced when more trials (data points) are included in the model. Consequently, when using a 3-point model, it has been suggested that a fourth or fifth prediction trial should be added when the SEE exceeds these limits.…”