Abstract
PurposeWe compared a new locomotor-specific model to track the expenditure and reconstitution of work done above critical power (W´) and balance of W´ (W´BAL) by modelling flat over-ground power during exhaustive intermittent running.MethodNine male participants completed a ramp test, 3-min all-out test and the 30–15 intermittent fitness test (30–15 IFT), and performed a severe-intensity constant work-rate trial (SCWR) at the maximum oxygen uptake velocity (vV̇O2max). Four intermittent trials followed: 60-s at vV̇O2max + 50% Δ1 (Δ1 = vV̇O2max − critical velocity [VCrit]) interspersed by 30-s in light (SL; 40% vV̇O2max), moderate (SM; 90% gas-exchange threshold velocity [VGET]), heavy (SH; VGET + 50% Δ2 [Δ2 = VCrit − VGET]), or severe (SS; vV̇O2max − 50% Δ1) domains. Data from Global Positioning Systems were derived to model over-ground power. The difference between critical and recovery power (DCP), time constant for reconstitution of W´ (tau_{{W^{prime}}}), time to limit of tolerance (TLIM), and W´BAL from the integral (W´BALint), differential (W´BALdiff), and locomotor-specific (OG-W´BAL) methods were compared.ResultsThe relationship between tau_{{W^{prime}}} and DCP was exponential (r2 = 0.52). The tau_{{W^{{prime}}}} for SL, SM, and SH trials were 119 ± 32-s, 190 ± 45-s, and 336 ± 77-s, respectively. Actual TLIM in the 30–15 IFT (968 ± 117-s) compared closely to TLIM predicted by OG-W´BAL (929 ± 94-s, P > 0.100) and W´BALdiff (938 ± 84-s, P > 0.100) but not to W´BALint (848 ± 91-s, P = 0.001).ConclusionThe OG-W´BAL accurately tracked W´ kinetics during intermittent running to exhaustion on flat surfaces.
Highlights
The curvilinear relationship between athletic performance and time was originally described by Hill (1925), where constant power output maintained to the limit of tolerance (TLIM) declined as a function of exercise duration
Whilst the critical power (CP) or Vcrit is typically measured over several days and bouts of constant load exercise, it has been shown that the finite work capacity above CP (W’) can be completely utilized in a single all-out, three-min exercise test (3 MT) (Vanhatalo et al 2007)
Nonlinear regression analysis conducted on W′ as a function of difference between critical and recovery power (DCP) (Fig. 3) yielded a moderate relationship with s in light (SL), SM, and SH trials (r2 = 0.52)
Summary
The curvilinear relationship between athletic performance and time was originally described by Hill (1925), where constant power output maintained to the limit of tolerance (TLIM) declined as a function of exercise duration. The asymptote of the hyperbolic power–duration relationship has since been termed critical power (CP; critical metabolic rate; associated external power output measured in watts [W]), while the curvature constant represents the finite work capacity above CP and is termed W (measured in kilojoules [kJ]) (Monod and Scherrer 1965). This relationship holds across various species (Lauderdale and Hinchcliff 1999; Billat et al 2004) and, among humans, extends to a variety of locomotive modalities, including over-ground running. Parameters derived from the power–time relationship can be used to describe a ‘gold standard’ demarcation of the metabolic steady state (CP; Jones et al 2019) and the finite work capacity of individuals’ > CP (W’), which can be used in combination to determine exercise performance (Jones et al 2010; Jones and Vanhatalo 2017)
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