(10) Modelling the Early and Late Acceleration Phases of the Sprint Start in Elite Long Track Speed Skaters

Purpose: This study established the reliability of an exponential function to model the change in velocity during the speed skating sprint start, and the validity of associated model parameters in a group of sub-elite and elite long track speed skaters.

Methods: Long track speed skaters (n=38) performed maximal effort 50 m on-ice accelerations from a standing start while tethered to a horizontal robotic resistance device that sampled position and time data continuously. An exponential function was applied to the raw data to model the change in velocity throughout the acceleration phase (Figure 1) and compute the maximal skating speed (MSS), maximal acceleration (MAC), maximum relative net horizontal power (P_Max) and an acceleration-time constant (τ).

Results: All constructed models provided a sufficient fit of the raw data (R² > 0.95, mean bias < 2%). Intra-day reliability of all model parameters ranged from good to excellent (ICC > 0.8, CV < 5%). Strong negative correlations (r: -0.72 to -0.96) were observed between MSS and P<sub>Max and the 10 m and 20 m split times measured with the robotic resistance and with 100 split times obtained from 500 m races. Moderate to large between-group differences were observed in MSS, MAC, and P<sub>Max between the elite vs. sub-elite speed skaters (Cohen d effect sizes: 1.18-3.53).

Conclusions: Our results indicate that monoexponential modelling is a valid and reliable method of monitoring initial acceleration performance in elite level long track speed skaters. PRACTICAL APPLICATIONS: Model parameters (MSS, MAC, P_Max­) offer a promising method of better characterizing on-ice acceleration with respect to the independent movement phases of running and gliding that warrant consideration in other skating sports. These measures may assist coaches with the prescription of on-ice programming or could be used in relation with off-ice tests to better identify key performance indicators (KPIs) in skating sports.

Acknowledgements: This study was supported by the Canadian Sport Institute Calgary, the Olympic Oval at the University of Calgary, Speed Skating Canada, the Killam Foundation, and the Canadian Institutes of Health Research (CIHR: 950-200955).