INTRODUCTION: Double poling (DP) is one of the most used techniques in cross-country skiing and very reliable model to study biomechanical and physiological performance characteristics. Increasing speed and inclination significantly affects mechanical and neuromuscular output (Holmberg et al., 2005; Lindinger et al., 2011; Sandbakk et al., 2010). The purpose of this study is to investigate the strategy of neuromuscular patterns with respect to the variation of external load. METHODS: Muscular activity for triceps brachii (TRI) pectoralis major (PE), deltoid posterior (DP), biceps brachii (BI), rectus abdominis (RA), teres major (TM) and erector spinae (ES) was recorded at 2000 Hz using sEMG (Cometa) according to SENIAM protocol. Force applied to the poles was recorded at 100 Hz by strain-gauge sensors. Gas exchanges and lactate concentration were measured by Quark device (Cosmed and Biosens C-line) for every load condition. Nine skiers participated in the study (24.3 ± 3.9 years, 173.0 ± 4.9 cm; 68.0 ± 5.2 kg): five elite cross country (CCS) and four elite biathletes (BIA). Subjects performed an incremental test on a treadmill at four rolling velocities (12, 15, 18 and 21 km h -1) and four inclines (1, 3, 5 and 7°). For each step, they performed DP sequences for 30 s duration followed by a one-minute recovery. All the subjects used the same pair of roller skis. For each step, cycle frequency (CF) and length (CL), average force and power (Fave, Prel), and muscular activity (RMS) were calculated for 20 cycles and normalized with respect to body weight and to MVC. A neuromuscular-mechanical gross efficiency index (GME) was defined as the Prel divided by the cumulative amount of RMS of propulsive muscles. RESULTS: For all the subjects, GME decreased according to increasing incline. At an incline of 1° and from V18 it shows a significant increase (fig.1). For BIA skiers GME shows a moderate increase from V15 and up to an incline of 5°. Indeed, CCS skiers had a much more constant GME behavior but with greater values than for BIA. DISCUSSION/CONCLUSION: Results are discussed with respect to different modulations of CF and CL, and VO2 for both subgroups. According to this model, it is possible to differentiate the strategy of neuromuscular coordination pattern and overall metabolic and mechanical output
© Copyright 2023 9th International Congress on Science and Skiing, March 18 - 22, 2023, Saalbach-Hinterglemm, Austria. Published by University of Salzburg. All rights reserved.