Abstract
All‐out exercise testing (AOT) has emerged as a method for quantifying critical speed (CS) and the curvature constant (D′). The AOT method was recently validated for shuttle running yet how that method compares with linear running is unknown. In the present study, we utilized a novel bi‐exponential model that derives CS and D′ with additional new parameters from the AOT method. Fourteen male athletes (age = 21.6 ± 2.2 years; height = 177 ± 70 cm; weight = 83.0 ± 11.8 kg) completed a graded exercise test (GXT) to derive maximum oxygen uptake (V˙O2max) and the average speed between gas exchange threshold and V˙O2max (sΔ50%), a linear AOT, and two shuttle AOTs. Measurement agreement was determined using intraclass correlation coefficient (ICC α), typical error (TE), and coefficient of variation (CV). The y‐asymptote (S0) of the speed‐time curve (3.52 ± 0.66 m·sec−1) did not differ from sΔ50% (3.49 ± 0.41 m·sec−1) or CS (3.77 ± 0.56 m·sec−1) (P = 0.34). Strong agreement was observed for estimates of CS (ICC α = 0.92, TE = 0.18 m·sec−1, and CV = 5.7%) and D′ (ICC α = 0.94, TE = 16.0 m, CV = 7.6%) with significant (P < 0.01) correlations observed between V˙O2max and CS and between S0 and V˙O2max (r values of 0.74 and 0.84, respectively). The time constant of the decay in speed (τd) and the amplitude between maximal speed and S0 (Ad) emerged as unique metrics. The Ad and τd metrics may glean new insights for prescribing and interpreting high‐intensity exercise using the AOT method.
Highlights
High-intensity running is characterized by a hyperbolic relationship between running speeds and performance times (Hill 1925)
Multiple linear regression was used to derive a composite metric of S0 whereby that value versus D0 was compared using a paired samples t test
Separate analyses of variance with repeated measures were used to evaluate differences of the critical speed (CS) and D0 metrics between the three all-out exercise test (AOT), whereas as D50% was added as a 4th level of the independent variable for CS
Summary
High-intensity running is characterized by a hyperbolic relationship between running speeds and performance times (tLIM) (Hill 1925). The tLIM (x-axis) associated with running different distances (y-axis) may be used to derive critical speed (CS, slope) and the finite capacity for running speeds exceeding CS (D0, intercept) (i.e., the distance-tLIM model, or D-tLIM) (Fukuba and Whipp 1999). Using speed (y-axis) and the inverse time (x-axis), or the speedinverse time (S-1/tLIM) model, the CS and D0 are the intercept and slope, respectively With the AOT method, the CS is derived theoretically by expending D0 completely via all-out running within a span of 150 sec (i.e., D0 = zero in eq 1), resulting in an average speed during the last 30 of 180 sec equaling and a 2019 The Authors.
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