Individual Acceleration-Speed Profile Variables: Comparison and Reliability Between Linear and Curvilinear Sprints.

Miras-Moreno, S, García-Ramos, A, Sašek, M, Cvjetičanin, O, Šarabon, N, Kavčič, I, and Smajla, D. Individual acceleration-speed profile variables: comparison and reliability between linear and curvilinear sprints. J Strength Cond Res XX(X): 000-000, 2024-The aim of this study was to compare linear sprint (LS) and curvilinear sprint (CS) to provide (a) the goodness-of-fit of individual acceleration-speed profile (ASP) and (b) the magnitude and within- and between-session reliability of the ASP variables (A0 [theoretical maximal acceleration], S0 [theoretical maximal velocity], and ASslope [slope of the linear ASP]). Twenty-one sports science students performed 2 identical experimental sessions composed of 3 LS trials and 6 CS trials (3 for each testing side). The individual ASP was modeled considering only the fastest or combining the 3 trials of each sprint type. The individual ASP presented a very high goodness-of-fit for the 3 sprint types, but slightly higher for best (range r2 = 0.98 [0.75-1.00]) compared with combined trials (range r2 = 0.95 [0.84-0.99]). Linear sprints revealed higher S0 (effect size [ES] ≥ -1.88; p < 0.001) and ASslope (ES ≥ -2.80; p < 0.001) but lower A0 (ES ≥ 1.15; p < 0.001) compared with CS. The ASP variables generally showed an acceptable within-session absolute reliability (range coefficient of variation [CV] = 4.5% [2.4-6.9%]) but an overall poor relative reliability for ASslope (range intraclass correlation coefficient = 0.44 [0.24-0.69]). The between-session reliability was greater for the combined trials (range CV = 4.7% [1.9-8.6%]) compared with the best trial (range CV = 6.1% [2.9-8.7%]). This study opens the possibility of using the ASP to monitor CS, preferably by combining multiple trials to increase its between-session reliability.