Different durations within the method of best practice affect the parameters of the speed–duration relationship

AbstractThe aim of the study was to determine whether estimates of the speed–duration relationship are affected using different time-trial (TT) field-based testing protocols, where exhaustive times were located within the generally recommended durations of 2–15 min. Ten triathletes (mean ± SD age: 31.0 ± 5.7 years; height: 1.81 ± 0.05 m; body mass: 76.5 ± 6.8 kg) performed two randomly assigned field tests to determine critical speed (CS) and the total distance covered above CS (D). CS and D were obtained using two different protocols comprising three TT that were interspersed by 60 min passive rest. The TTs were 12, 7, and 3 min in Protocol I and 10, 5, and 2 min in Protocol II. A linear relationship of speed vs. the inverse of time (s = D × 1/t + CS) was used to determine parameter estimates. Significant differences were found for CS (p = 0.026), but not for D (p = 0.123). The effect size for CS (d = 0.305) was considered small, while that for D was considered moderate (d = 0.742). CS was significa...