Cross‐country skiing movement factorization to explore relationships between skiing economy and athletes' skills

Abstract

We investigated the relationships between the biomechanics of the double poling (DP) technique in cross-country skiing, its economy, and athletes' skill. To this aim, skiers' motion has been factorized into components through principal component analysis (PCA). Eight high-level (HL) and eight regional level (RL) male cross-country skiers performed a 5-minute submaximal DP trial while roller skiing on a treadmill at 14 km h and 2° incline. Whole-body kinematics was recorded with a motion capture system. PCA was applied to markers coordinates to extract principal movements (PM ), which were ranked by their variance. Energy cost (EC) of locomotion was calculated from ergospirometric measurements. Results showed that 96.7%±0.6% of total skiing pattern variance can be described with the first three PM (Shoulder and trunk flexion-extension are described PM and PM and elbow flexion-extension are mainly represented in PM and PM The variance of further components, consisting of residual movements (eg, slow postural changes or high-frequency vibrations), was greater for the RL than the HL skiers (4.0%±0.5% vs 2.6%±0.3%; P<.001) and was positively correlated with EC (R =.646; P<.001). PCA permitted to describe the biomechanics of the DP technique through a limited set of principal movements. Skiing skills and economy appeared to be related to a skier's ability to simplify movement complexity, suggesting that an efficient skier is better able to reduce superfluous movement components during DP.

The Effects of Six-Month Subalpine Training on the Physical Functions and Athletic Performance of Elite Chinese Cross-Country Skiers

“…The first five levels of the test were all 5 min long, all at a speed of 9 km/h, with the inclination angle of the running platform increasing by one degree from 3 • to 7 • ; the last four levels were all 4 min long, with speeds of 11 km/h, 7 km/h, 7 km/h and 11 km/h, respectively. During the test, the average heart rate (b/min) at the end of each minute was recorded and the athletes used the V2 technique [25][26][27]. The athletes' blood lactate (mmol/L) levels were measured using an EKF blood lactate tester (Biosen, EKF Industrial Electronics, Magdeburg, Germany) and the athletes' average heart rates (b/min) and rating of perceived exertion (RPE) values were recorded for the entire level [28][29][30] (Figure 1).…”

“…The main reasons are: exercise stretch and increase metabolites increase the permeability of muscle cells, increased catecholamines, and tissue cell damage. Both exercise intensity and load affected serum creatine kinase activity, and it is generally accepted that the effect of load intensity on CK activity is greater than that of load, with the most pronounced increase when both are increased [27]. In this study, serum CK was significantly increased in both male and female athletes during the first month of subalpine training, due to increased permeability of the body's cell membranes caused by hypoxic stimulation [43], followed by a gradual adaptation to subalpine training conditions.…”

Stronger Is Better: The Impact of Upper Body Strength in Double Poling Performance

“…Previous studies have focused on determining factors for performance in cross-country skiing and have found strong correlations between VO 2 max and performance (Bergh, 1987; Ingjer, 1991; Mahood et al, 2001; Larsson et al, 2002; Alsobrook and Heil, 2009; Ainegren et al, 2013; Sandbakk and Holmberg, 2014). Pellegrini et al (2018) have shown that high-level skiers have better work economy than regional level skiers. Even though an important factor for work economy is the skiers technical skills, several studies have found improvements in performance corresponding to a better work economy after maximal strength training (Østerås et al, 2002; Mikkola et al, 2007; Losnegard et al, 2011).…”

The Modern Double-Poling Technique Is Not More Energy Efficient Than the Old-Fashioned Double-Poling Technique at a Submaximal Work Intensity

“…Hence, from a biomechanical perspective the DP OLD and DP MOD differ, and it was previously reported that the CoM displacement within the DP MOD explains differences in energy cost between groups with different levels of performance ability (Zoppirolli et al, 2015 ). Recently, it was shown that a pronounced trunk inclination was related to an increased energy cost during DP (Pellegrini et al, 2018b ). They also proposed that, during the last three decades, the DP technique among elite skiers has evolved from a technique characterized by pronounced trunk flexion toward a technique with greater emphasis on shoulder motion during the propulsion phase (Pellegrini et al, 2018b ).…”

“…Recently, it was shown that a pronounced trunk inclination was related to an increased energy cost during DP (Pellegrini et al, 2018b ). They also proposed that, during the last three decades, the DP technique among elite skiers has evolved from a technique characterized by pronounced trunk flexion toward a technique with greater emphasis on shoulder motion during the propulsion phase (Pellegrini et al, 2018b ). However, no previous study has investigated whether these biomechanical differences are reflected by physiological differences between techniques.…”