Contribution and effectiveness of ski and pole forces in selected roller skiing techniques on treadmill at moderate inclines

BackgroundMost of the studies about the effects of incline on cross-country skiing are related to the metabolic efficiency. The effective skiing biomechanics has also been indicated to be among the key factors that may promote good performance. The aims of this study were to provide biomechanical characteristics and investigate the relative contribution and effectiveness of ski and pole forces in overcoming the total external resistance with double poling (DP) and Gear 3 (G3) techniques at varying moderate uphill inclines.Methods10 male cross-country skiers participated in this study. Custom-made force measurement bindings, pole force sensors, and an 8-camera Vicon system were used to colle…

Speed control of the V2 skating technique in elite cross-country skiers

The aim was to examine how skiers control skiing speed using V2-skating. Subjects skied with three submaximal and maximal speeds on 100 m 4° uphill. Cycle variables and force parameters form the arms and legs were analysed. Cycle rate increased up to the maximum speed. Cycle length increased from the slowest speed to the all other speeds. Pole force and delta leg force increased up to the maximum speed. Ranges of motions and angular velocities of kick flexion and extension with knee and hip joints increased till highest submaximal speed. Speed was regulated with cycle length and rate while the latter was dominant after ∼5.0 m/s. Higher speed was reached with higher forces from arms and leg…

A Simple Multibody Dynamic Model of Cross-Country Ski-Skating

The purpose of this paper is to present the development of a simple multibody dynamic model matching the observed movements of the center of mass of a skier performing the skating technique in cross-country skiing. The formulation of the equation of motion was made using the Euler–Lagrange equations applied to a multibody tree-type system in three dimensions. The description of the lower limb of the skier and the ski was completed by employing three bodies, one representing the ski, and two representing the natural movements of the leg of the skier. This simple model is able to show an approximation of the movement of the center of mass of the skier and its velocity behavior allowing to stu…

Propulsion Calculated by Force and Displacement of Center of Mass in Treadmill Cross-Country Skiing

This study evaluated two approaches for estimating the total propulsive force on a skier’s center of mass (COM) with double-poling (DP) and V2-skating (V2) skiing techniques. We also assessed the accuracy and the stability of each approach by changing the speed and the incline of the treadmill. A total of 10 cross-country skiers participated in this study. Force measurement bindings, pole force sensors, and an eight-camera Vicon system were used for data collection. The coefficient of multiple correlation (CMC) was calculated to evaluate the similarity between the force curves. Mean absolute force differences between the estimated values and the reference value were computed to evalua…

Arm swing during skating at different skiing speeds affects skiing mechanics and performance

Arm swing has been shown to lead to greater maximal speed and movement economy in cross -country skiing. The current study aimed to investigate how arm swing alters skiing mechanics and contributes to performance and acceleration of the athlete’s centre of mass (COM). While skiing on snow seven highly skilled cross -country skiers simulated V2 -alternate skating without using ski poles and with double or single arm swing and without arm swing . During leg push -off the linear momentum of the body increased due to arm swing. Simultaneously, linear momentum of the arm(s) decreased in arm swing trials, indicating a transfer of momentum from arms to the rest of the body and being more prevalent…

The effect of swinging the arms on muscle activation and production of leg force during ski skating at different skiing speeds

The study investigated the effects of arm swing during leg push-off in V2-alternate/G4 skating on neuromuscular activation and force production by the leg muscles. Nine skilled cross-country skiers performed V2-alternate skating without poles at moderate, high, and maximal speeds, both with free (SWING) and restricted arm swing (NOSWING). Maximal speed was 5% greater in SWING (P<0.01), while neuromuscular activation and produced forces did not differ between techniques. At both moderate and high speed the maximal (2% and 5%, respectively) and average (both 5%) vertical force and associated impulse (10% and 14%) were greater with SWING (all P<0.05). At high speed range of motion and angular …

Arm swing during skating at different skiing speeds affects skiing mechanics and performance

Energy availability during training camp is associated with signs of overreaching and changes in performance in young female cross-country skiers

Abstract Study aim: The aim of this study was to evaluate if young female skiers meet their energy and macronutrient requirements, and how energy availability (EA) and macronutrient intake affects their performance during an intensive training camp. Material and methods: 19 female cross-country skiers (age 16.7 ± 0.7) filled in 48-hour food and training logs during a 5-day training camp. Fasting concentrations of hemoglobin, leptin, triiodothyronine (T3), insulin, insulin-like growth factor 1 (IGF-1), and glucose were measured before (PRE) and after (POST) the camp. Blood lactate (LA), heart rate (HR) and rating of perceived exertion (RPE) from a submaximal treadmill running test, jump heig…

Comparison of Exclusive Double Poling to Classic Techniques of Cross-country Skiing

Introduction: This study aimed to 1) determine basic physiological demands during a simulated on-snow cross-country skiing (XCS) race when using grip-waxed skis (all classic XCS techniques [CLASSIC]), versus glide-waxed skis for exclusive double poling (DP) and 2) analyze in which track sections DP is different from CLASSIC under controlled gliding conditions in elite junior and senior skiers. Methods: Nineteen male and female elite XC skiers performed 1) two randomized simulated XCS races over 5.3 km using DP or CLASSIC measuring section times, V˙ O2, HR, blood lactate, and RPE; and 2) V˙ O2peak tests using diagonal stride and DP on treadmill. Results: The total group showed no differences…

Forward acceleration of the centre of mass during ski skating calculated from force and motion capture data

The purpose of this paper was to present and evaluate a methodology to determine the contribution of bilateral leg and pole thrusts to forward acceleration of the centre of mass (COM) of cross-country skiers from multi-dimensional ground reaction forces and motion capture data. Nine highly skilled cross-country (XC) skiers performed leg skating and V2-alternate skating (V2A) under constant environmental conditions on snow, while ground reaction forces measured from ski bindings and poles and 3D motion with high-speed cameras were captured. COM acceleration determined from 3D motion analyses served as a reference and was compared to the results of the proposed methodology. The obtained value…

Technique detection of cross-country ski classical race using kinematic GNSS

Validation of 2D Force Measurement Roller Ski and Practical Application.

Several methods could be used to measure the forces from skis or roller skis in cross-country skiing. Equipment that could measure medio-lateral forces may be of good help for investigating the relevant skating techniques. The aim of this study was to validate a pair of newly designed two-dimensional force measurement roller skis. The vertical and medio-lateral forces which were perpendicular to the body of the roller ski could be measured. Forces were resolved into the global coordinate system and compared with the force components measured by a force plate. A static and dynamic loading situation for the force measurement roller ski was performed to reveal the validity of the system. To de…

Biomechanical analysis of different starting strategies utilized during cross-country skiing starts

The present study was designed to analyse and compare the kinetics and kinematics associated with three different starting strategies during classic cross-country ski racing. Inside a ski tunnel, 12 elite male skiers performed three sets of three 38 m starts. Each set included one start using: double poling only (DP), diagonal stride only (DIA) and freely chosen (FREE) (i.e. where subjects used the strategy or combination of strategies they felt was fastest) in random order. The first 18 m was performed on a series of force plates that measured horizontal and vertical forces followed by 20 m of a standard snow track. Additionally, cycle characteristics and joint angles were measured. DIA an…

The effect of ski gliding properties on the force production of V2-technique

Ohtonen, Olli 2010. Suksen luisto-ominaisuuksien vaikutukset V2-tekniikan voiman-tuottoon. Biomekaniikan pro gradu -työ, syksy 2010. Liikuntabiologian laitos, Jyväsky-län yliopisto, 64 s. Perinteisen hiihdon voimantuottoa on tutkittu paljon (esim. Komi 1985/1987, Vä-häsöyrinki 2008, Lindinger 2009), mutta 3D-voimamittauksia luisteluhiihdosta ei ole juurikaan tehty. Suksen luisto-ominaisuuksien vaikutuksista suorituskykyyn ja biome-kaanisiin ominaisuuksiin puhutaan paljon mutta, niitä ei ole vielä tutkittu. Tämän tutki-muksen tavoitteena oli suunnitella ja rakentaa toimiva 3D-voimanmittauslaitteisto ja tutkia kuinka erilailla voidellut sukset vaikuttavat luisteluhiihdon sykliin sekä käsien j…

Effects of Gliding Properties of Cross-Country Skis on the Force Production during Skating Technique in Elite Cross-Country Skiers

The aim of the present study was to examine how different gliding conditions of skis affect performance, cycle characteristics and leg and pole force production during V2 skating. Ten elite skiers skied on 100 m uphill (4°) at three different constant speeds (4.0, 4.8 and 5.6 m/s) and maximum speed using two differently prepared skating skis (fast and slow ski). With the slow ski, maximum speed was 6.4 % slower than with the fast ski. With constant speeds, cycle time got shorter due to a decrease in the recovery time of the leg and pole. Peak pole force and average cycle force increased as well as lateral leg forces while there were no changes in the vertical leg forces. A strategy for how…

Changes in biomechanics of skiing at maximal velocity caused by simulated 20 km skiing race using V2 skating technique

This study investigated how the fatigue caused by a 20 km simulated skating cross-country skiing race on snow affects the final spurt performance from a biomechanical perspective. Subjects performed a 100 meter maximal skiing trial before and at the end of the simulated race. Cycle characteristics, ground reaction forces from skis and poles, and muscle activity from eight muscles were recorded during each trial. Results showed that subjects were in a fatigued state after the simulated race manifested by 11.6% lower skiing speed (P < 0.01). The lower skiing speed was related to an 8.0% decrease in cycle rate (P < 0.01) whereas cycle length was slightly decreased (tendency). In temporal patte…

Methodological Guidelines Designed to Improve the Quality of Research on Cross-Country Skiing

AbstractCross-country (XC) ski races involve a variety of formats, two different techniques and tracks with highly variable topography and environmental conditions. In addition, XC skiing is a major component of both Nordic combined and biathlon competitions. Research in this area, both in the laboratory and field, encounters certain difficulties that may reduce the reliability and validity of the data obtained, as well as complicate comparisons between studies. Here, 13 international experts propose specific guidelines designed to enhance the quality of research and publications on XC skiing, as well as on the biathlon and Nordic combined skiing. We consider biomechanical (kinematic, kinet…

Race course profiling of the cross country ski using kinematic GNSS

Changes in biomechanics of skiing at maximal velocity caused by simulated 20 km skiing race using V2 skating technique

This study investigated how the fatigue caused by a 20-km simulated skating cross-country skiing race on snow affects the final spurt performance from a biomechanical perspective. Subjects performed a 100-m maximal skiing trial before and at the end of the simulated race. Cycle characteristics, ground reaction forces from skis and poles, and muscle activity from eight muscles were recorded during each trial. Results showed that subjects were in a fatigued state after the simulated race manifested by 11.6% lower skiing speed (P<.01). The lower skiing speed was related to an 8.0% decrease in cycle rate (P<.01), whereas cycle length was slightly decreased (tendency). In temporal patterns, rela…

Measurement of Head Motion during Double-Poling Technique in Cross-Country Ski Classical Race using Kinematic GNSS

The Development and Precision of a Custom-Made Skitester

In the sport of cross-country skiing, equipment has a direct influence on results. Ski teams do extensive testing of different ski base grinds and products on a yearly basis. To achieve reliable results, the quality of methods used for testing skis needs to be taken in to account in addition to factors including the physical characteristics of testing personnel and changes in weather conditions. The aim of this study was to introduce a custom-made skitester, that was developed for testing skis on real snow, in laboratory conditions, and to evaluate its precision. The current skitester is capable of glide testing both classic and skate skis as well as kick simulation for the testing of grip …

Validation of portable 2D force binding systems for cross-country skiing

The aim of the present study was to design, construct and scientifically validate a two-dimensional force measurement binding system for cross-country skiing. The system consists of two force measurement bindings. One binding was designed for analysing classic skiing (vertical and anterior–posterior [along the ski] force components) and the other one for skate (freestyle) skiing (vertical and medio-lateral [transverse to the ski] force components). Validation was accomplished using a three-step process: (1) accuracy tests for the sensors in two temperatures, (2) sport-specific imitation jump test on standard force plates in a laboratory and (3) comparing the system against force measurement…

Sensors / Cross-country skiing analysis and ski technique detection by high-precision kinematic global navigation satellite system

Cross-country skiing (XCS) embraces a broad variety of techniques applied like a gear system according to external conditions, slope topography, and skier-related factors. The continuous detection of applied skiing techniques and cycle characteristics by application of unobtrusive sensor technology can provide useful information to enhance the quality of training and competition. (1) Background: We evaluated the possibility of using a high-precision kinematic global navigation satellite system (GNSS) to detect cross-country skiing classical style technique. (2) Methods: A world-class male XC skier was analyzed during a classical style 5.3-km time trial recorded with a high-precision kinemat…

A Simple Mechanical Model for Simulating Cross-Country Skiing Propulsive Force

In this paper, a three-dimensional multibody dynamic model of a cross-country skier is developed and presented where a single propulsion phase is modeled to obtain the kinetic parameters involved in the movement. A professional Olympic-level skier performed the skating technique without poles in a ski tunnel under controlled conditions and on an incline plane. Then, with the use of a force acquisition system attached to the ski bindings and a motion capture system set on site, the leg resultant forces and the movement of specific points of the skier’s lower body were acquired. The data obtained from the motion capture system was used as the prescribed kinematic input data in the multibody m…