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

Christoph Triska,Alfred Nimmerichter,Bernd Heidegger,Bettina Karsten,Bernhard Prinz,Harald Tschan,Bernhard Koller-Zeisler,Alessandro Zagatto

doi:10.1371/journal.pone.0189776

Christoph Triska, Alfred Nimmerichter + Show 6 more

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https://doi.org/10.1371/journal.pone.0189776

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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.

Highlights

A reliable determination of critical power (CP) and the total amount of work accomplished above CP until task failure (W) has long been a question of interest
Mean PO for each TT was plotted against the inverse-of-time using a linear regression where PO is the mean power output (W), Wis the total amount of work accomplished above CP until task failure (J) and CP is the critical power (W): PO 1⁄4 W0 Á 1 þ CP
Results demonstrate a notable improvement for intra-class correlation coefficient (ICC) and coefficient of variation (CoV) values related to both parameter estimates after familiarization using TT of equal duration (i.e. 12, 7, and 3 min)

Summary

Introduction

A reliable determination of critical power (CP) and the total amount of work accomplished above CP until task failure (W) has long been a question of interest. Reliability of critical power testing work rate that can be sustained for a long time without a continuous loss of metabolic (e.g. pH, phosphocreatine) and systemic (blood lactate concentration, V_ O2) homeostasis [1], Wis an equivalent for a finite amount of work that can be accomplished above CP [2, 3]. The determination of CP and Wrequires 3 to 5 constant-power time-to-exhaustion trials (TTE) on a cycle ergometer, leading to exhaustion within 2–15 min [e.g. 4, 5–7]. It should be noted that small differences in time-to-exhaustion between repeated trials might alter the parameter estimates (in particular W) [11, 12]. TTE efforts should be used with caution when trying to detect small training induced changes in an athlete’s performance [13]

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