Roller Skiing Research Articles

Force interaction and 3D pole movement in double poling

The aim of this study was to analyze double poling using combined kinetic and 3D kinematic analysis at high skiing speeds as regards pole force components, pole angles and pole behavior during the poling and swing phase. The hypothesis was that a horizontal pole force is more predictive for maximal skiing speed (V(max)) than the resultant pole force. Sixteen elite skiers performed a double-poling V(max) test while treadmill roller skiing. Pole forces and 3D kinematics of pole movement at a speed of 30 km/h were analyzed and related to V(max). The duration of the "preparation phase" showed the strongest relationship with V(max) (r=0.87, P<0.001). Faster skiers generated longer cycle lengths with longer swing and poling times, had less inclined pole angles at pole plant and a later peak pole force. Horizontal pole forces were not more highly related to V(max) compared with the resultant pole force. Impact force was not related to V(max). At high skiing speeds, skiers should aim to combine high pole forces with appropriate timing of pole forces and appropriate pole and body positions during the swing and poling phase. The emphasis in training should be on the development of specific strength capacities for pole force production and the utilization of these capacities in double-poling training sessions.

Net efficiency of roller skiing with a diagonal stride

The aims of this study were: (a) to determine net efficiency during roller skiing with a diagonal stride at various speeds; (b) to assess the development of net efficiency across speeds; and (c) to examine the characteristics of efficiency in diagonal roller skiing. Two-dimensional kinematics and oxygen uptake were determined in eight male collegiate cross-country ski athletes who roller skied with the diagonal stride at various speeds on a level track. Net efficiency was calculated from rates of internal and external work and net energy expenditure. Individual net efficiency ranged from 17.7% to 52.1%. Net efficiency in the entire group of athletes increased with increasing speed, reached a maximum value of 37.3% at 3.68 m · s−1, before slowly decreasing. These findings indicate that roller skiing with the diagonal stride at high speed is a highly efficient movement and that an optimal speed exists at which net efficiency can be maximally enhanced in diagonal roller skiing.

Classical style constructed roller skis and grip functionality

Roller skis are used by cross-country skiers for snow-free training, with the aim of imitating skiing on snow. The roller skis on the market that are constructed for use in the classical style are equipped with a front and a back wheel, one of which has a ratchet to enable it to grip the surface when diagonal striding and kick double poling. A new type of roller ski was constructed with a function which makes it necessary to use the same kick technique as that used on snow, i.e. the ski has a camber that must be pushed down to obtain grip. Its stiffness can be adjusted based on factors that influence grip, i.e. the skier's bodyweight and technical skiing skills. Thus, our aim was to make comparative measurements as regards grip between ratcheted roller skis and the roller ski with a camber and compare with previous published results for grip waxed skis during cross-country skiing on snow. The measurements were carried out using specially developed equipment, with a bottom plate and an overlying rubber mat of the same type as used on many treadmills and a function for applying different loads and generating traction on the back of the roller ski.

Analysis of a sprint ski race and associated laboratory determinants of world-class performance

This investigation was designed to analyze the time-trial (STT) in an international cross-country skiing sprint skating competition for (1) overall STT performance and relative contributions of time spent in different sections of terrain, (2) work rate and kinematics on uphill terrain, and (3) relationships to physiological and kinematic parameters while treadmill roller ski skating. Total time and times in nine different sections of terrain by 12 world-class male sprint skiers were determined, along with work rate and kinematics for one specific uphill section. In addition, peak oxygen uptake (VO2peak), gross efficiency (GE), peak speed (Vpeak), and kinematics in skating were measured. Times on the last two uphill and two final flat sections were correlated to overall STT performance (r = ~−0.80, P < 0.001). For the selected uphill section, speed was correlated to cycle length (r = −0.75, P < 0.01) and the estimated work rate was approximately 160% of peak aerobic power. VO2peak, GE, Vpeak, and peak cycle length were all correlated to STT performance (r = ~−0.85, P < 0.001). More specifically, VO2peak and GE were correlated to the last two uphill and two final flat section times, whereas Vpeak and peak cycle length were correlated to times in all uphill, flat, and curved sections except for the initial section (r = ~−0.80, P < 0.01). Performances on uphill and flat terrain in the latter part were the most significant determinants of overall STT performance. Peak oxygen uptake, efficiency, peak speed, and peak cycle length were strongly correlated to overall STT performance, as well as to performance in different sections of the race.

Analysis of sprint cross-country skiing using a differential global navigation satellite system

The purpose was to examine skiing velocities, gear choice (G2-7) and cycle rates during a skating sprint time trial (STT) and their relationships to performance, as well as to examine relationships between aerobic power, body composition and maximal skiing velocity versus STT performance. Nine male elite cross-country skiers performed three tests on snow: (1) Maximum velocity test (V (max)) performed using G3 skating, (2) V (max) test performed using double poling (DP) technique and (3) a STT over 1,425 m. Additional measurements of VO(2max) during roller skiing and body composition using iDXA were made. Differential global navigation satellite system data were used for position and velocity and synchronized with video during STT. The STT encompassed a large velocity range (2.9-12.9 m s(-1)) and multiple transitions (21-34) between skiing gears. Skiing velocity in the uphill sections was related to gear selection between G2 and G3. STT performance was most strongly correlated to uphill time (r = 0.92, P < 0.05), the percentage use of G2 (r = -0.72, P < 0.05), and DP V (max) (r = -0.71, P < 0.05). The velocity decrease in the uphills from lap 1 to lap 2 was correlated with VO(2max) (r = -0.78, P < 0.05). V (max) in DP and G3 were related to percent of racing time using G3. In conclusion, the sprint skiing performance was mainly related to uphill performance, greater use of the G3 technique, and higher DP and G3 maximum velocities. Additionally, VO(2max) was related to the ability to maintain racing velocity in the uphills and lean body mass was related to starting velocity and DP maximal speed.

Determinants of a Simulated Cross-Country Skiing Sprint Competition using V2 Skating Technique on Roller Skis

The present study investigated the performance-predicting factors of a simulated cross-country (XC) skiing sprint competition on roller skis, on a slow surface. Sixteen elite male XC skiers performed a simulated sprint competition (4 x 850 m heat with a 20-minute recovery) using V2 skating technique on an indoor tartan track. Heat velocities, oxygen consumption, and peak lactate were measured during or after the heats. Maximal skiing velocity was measured by performing a 30-m speed test. Explosive and maximal force production in the upper body was determined by bench press (BP). Subjects also performed maximal anaerobic skiing test (MAST) and the 2 x 2-km double poling (DP) test. The maximal velocity of MAST (VMAST) and velocities at 3 (V3), 5 (V5), 7 (V7) mmol.L lactate levels in MAST were determined. In the 2 x 2-km test, DP economy (VO2SUBDP) and maximal 2-km DP velocity (VDP2KM) were determined. The best single performance-predicting factors for the sprint performance were VDP2KM (r = 0.73, p < 0.01), V7 (r = 0.70, p < 0.01), and VO2SUBDP (r = -0.70, p < 0.01). Faster skiers in sprint simulation had a higher absolute VO2 (L.min) (p < 0.05-0.01) during sprint heats, and higher anaerobic skiing power (VMAST, p < 0.05) and better anaerobic skiing economy (V3, V5, V7, p < 0.05-0.001) than slower skiers. Faster skiers were also stronger in BP, with regard to both absolute (p < 0.01) and relative (p < 0.05) values. In addition, anaerobic characteristics seem to be of importance at the beginning of the XC skiing sprint competition, whereas the aerobic characteristics become more important as the XC skiing sprint competition progressed. This study indicates that sprint skiers should emphasize sport-specific upper body training, and training skiing economy at high speeds.

Endurance Training and Sprint Performance in Elite Junior Cross-Country Skiers

The purpose of the present study was to investigate the relationship between aerobic characteristics and sprint skiing performance, and the effects of high-intensity endurance training on sprint skiing performance and aerobic characteristics. Ten male and 5 female elite junior cross-country skiers performed an 8-week intervention training period. The intervention group (IG, n = 7) increased the volume of high-intensity endurance training performed in level terrain, whereas the control group (CG, n = 8) continued their baseline training. Before and after the intervention period, the skiers were tested for 1.5-km time-trial performance on roller skis outdoors in the skating technique. Maximal oxygen uptake (VO₂max) and oxygen uptake at the ventilatory threshold (VO₂VT) were measured during treadmill running. VO₂max and VO₂VT were closely related to sprint performance (r = ~0.75, both p < 0.008). The IG improved sprint performance, VO₂max, and VO₂VT from pre to posttesting and improved sprint performance and VO₂VT when compared to the CG (all p < 0.01). This study shows a close relationship between aerobic power and sprint performance in cross-country skiing and highlights the positive effects of high-intensity endurance training in level terrain.

Kinematic Determinants and Physiological Response of Cross-Country Skiing at Maximal Speed

The scope of the study was to a) transfer the maximal anaerobic running test (MART) to a treadmill-based cross-country roller skiing test protocol for skating and classic style, b) analyze the development and determinants of kinematic and physiological parameters from submaximal to maximal skiing speeds, c) analyze the effects of fatigue on skiing technique, and d) test the hypotheses that maximal skiing speed is related to cycle length and that the fastest skiers show shorter thrust combined with longer swing phases. Up to 24 elite skiers performed MART tests in double poling, diagonal stride and V2 skating, with roller skis on a treadmill. Anthropometrics, blood lactate, HR, and kinematics were determined. When compared with former studies, faster skiing speeds of up to 34% were reported. Skiers improved speed by increasing cycle rate while trying to maintain cycle length. In the diagonal stride and V2 skating at maximal skiing speeds, skiers used contrary technical strategies to maintain the speed, whereas in double poling, a tendency toward an optimum in cycle length and cycle rate was established. Duration for the pole thrusts was around 180 ms for V2 skating and 210 ms for double poling. Highest relation to performance was found for the duration of the swing phases of arms and legs. The increase in skiing speed and cycle length, compared with former studies and the positive relation between swing phase duration, stresses the importance of effective thrust phases within a short period. Therefore, it is recommended to increase the proportion of training aimed at the improvement of specific explosive strength and maximal power to increase the impulse of force.

Roller ski rolling resistance and its effects on elite athletes’ performance

Modern ski-treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical fitness in a laboratory environment whilst performing classical and freestyle (skating) techniques on roller skis. For elite athletes, the differences in performance between test occasions are quite small, thus emphasising the importance of knowing the roller skis’ rolling resistance in order to allow the correct comparison between the results of different test occasions. In this study, the roller skis’ rolling resistance was measured on the ski-treadmill’s surface using a roller ski rolling resistance measurement system specially produced for this purpose. The study investigated the influence of significant changes in rolling resistance on physiological variables. The results showed that during submaximal exercise, power, oxygen uptake, heart rate and blood lactate were significantly changed by different rolling resistances, while there were no significant or only small changes to cycle rate, cycle length and ratings of perceived exertion. Incremental maximal tests showed that time to exhaustion was significantly changed by different rolling resistances and this occurred without significant changes in maximal power, maximal oxygen uptake, maximal heart rate and blood lactate, and that the influence on ratings of perceived exertion were insignificant or small.

Modeling Oxygen Uptake during V1 Treadmill Roller Skiing

Modeling Oxygen Uptake during V1 Treadmill Roller Skiing

Comparison of Heart Rate Deflection and Ventilatory Threshold During a Field Cross-Country Roller-Skiing Test

This study was to assess whether the point of deflection from linearity of heart rate (HRd) could be an accurate predictor of ventilatory threshold (VT2) during a specific cross-country roller-skiing (RS) test. Ten well-trained cross-country skiers performed a maximal and incremental RS test in the field and a standardized maximal and incremental treadmill running (TR) test in the laboratory. Values of oxygen uptake (VO2) and heart rate (HR) were continuously recorded during all exercises by a portable breath-by-breath gas exchange measurement system and a wireless Polar monitoring system, respectively. The VT2 and HRd points were individually determined by visual analysis during RS. Maximal VO2 (VO2 max) and HR were higher (p < 0.05) during TR (67.1 +/- 7.3 ml x min(-1) x kg(-1) and 196.0 +/- 14.1 bpm, respectively) compared with RS (64.2 +/- 7.3 ml x min(-1) x kg(-1) and 191.5 +/- 13.1 bpm, respectively). However, a high correlation (r = 0.94, p < 0.01) between TR and VO2 max was observed. Paired t-tests showed no significant differences in HR (183.6 +/- 15.1 vs. 185.2 +/- 13.9 bpm) and VO2 (55.5 +/- 7.1 vs. 55.8 +/- 6.1 ml x min(-1) x kg(-1)) at intensities corresponding to HRd and VT2 during the RS test, respectively; Pearson product-moment correlation coefficients demonstrated significant relationships for HR at the HRd and VT2 points (r = 0.99, p < 0.001) as well as for VO2 (r = 0.95, p < 0.001). Our results indicate that the specific incremental RS test is effective in eliciting HRd in the field for all skiers and is an accurate predictor of VT2. These findings give very interesting practical applications to cross-country coaches and skiers to evaluate and control specific aerobic training loads.

Rolling resistance for treadmill roller skiing

Modern treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical performance under laboratory conditions using classical and freestyle techniques on roller skis. T ...

Assessment of United States Biathletes: Lab based Physiological testing and Performance data

PURPOSE: To investigate the relationship between, sports specific laboratory based physiological assessments and performance data of United States national Biathlon athletes. METHODS: Physiological and performance data was collected from twelve US national biathlon athletes (7 females and 5 males) with a mean age of 24 + 5 years, stature of 173+ 8 cm and body mass of 68+ 9 kg. Each athlete completed two incremental treadmill tests to exhaustion on separate days in random order, one running (run) and one roller skiing using poles (ski). During both tests the following physiological variables were recorded, oxygen uptake (VO2) using a breath-by-breath metabolic measurement system (Parvo-Medics), heart rate (HR) using Polar Vantage XL, and blood lactate (LA) using YSI 2300. LA was taken two minutes post exercise to determine peak blood lactate (p-LA). The data collected from the physiological tests were compared with performance data from the 2003/04 competitive season to determine the relationship between the annual physiological tests and the athletes 10K biathlon performance. RESULTS: The data showed a significant correlation (p<0.05) between treadmill ski p-LA and 10-km biathlon performance (r= 0.960). However there was no significant correlation between run p-LA and 10-km biathlon performance. A paired t-test showed significant difference between treadmill run and treadmill ski p-LA (p = 0.03) while a Bland and Altman 95% limits of agreement analysis indicated a small significant bias but large variation within the data set for p-LA (0.5 + 7.6 mmol). In addition, there was a significant correlation between treadmill ski VO2peak and 10-km biathlon performance(r=0.684), but no significant correlation between treadmill run VO2peak. and 10-km biathlon performance. CONCLUSIONS: This data clearly shows the importance of using sports specific protocols such as roller skiing when assessing physiological characteristics of biathlon athletes.

Biomechanical pole and leg characteristics during uphill diagonal roller skiing

Diagonal skiing as a major classical technique has hardly been investigated over the last two decades, although technique and racing velocities have developed substantially. The aims of the present study were to 1) analyse pole and leg kinetics and kinematics during submaximal uphill diagonal roller skiing and 2) identify biomechanical factors related to performance. Twelve elite skiers performed a time to exhaustion (performance) test on a treadmill. Joint kinematics and pole/plantar forces were recorded separately during diagonal roller skiing (9°; 11 km/h). Performance was correlated to cycle length (r = 0.77; P < 0.05), relative leg swing (r = 0.71), and gliding time (r = 0.74), hip flexion range of motion (ROM) during swing (r = 0.73) and knee extension ROM during gliding (r = 0.71). Push-off demonstrated performance correlations for impulse of leg force (r = 0.84), relative duration (r = − 0.76) and knee flexion (r = 0.73) and extension ROM (r = 0.74). Relative time to peak pole force was associated with performance (r = 0.73). In summary, diagonal roller skiing performance was linked to 1) longer cycle length, 2) greater impulse of force during a shorter push-off with larger flexion/extension ROMs in leg joints, 3) longer leg swing, and 4) later peak pole force, demonstrating the major key characteristics to be emphasised in training.

Linear Regression Analysis for Prediction of VO2 during Treadmill Roller Skiing Using the V1 Technique

Linear Regression Analysis for Prediction of VO2 during Treadmill Roller Skiing Using the V1 Technique

Evaluation of Required Motor Abilities in Commonly Practiced Exercise Modes and Potential Training Effects Among Adults

There is a lack of knowledge of the motor abilities required in different exercise modes which are needed when counseling sedentary middle-aged people to start a physically active lifestyle. Nominal group technique was used to establish the consensus statement concerning motor abilities and physical fitness in 31 exercise modes. Walking, running, jogging, and calisthenics were regarded as the most suitable exercise modes for most people with no specific requirements. The most demanding exercise modes of evaluated exercise modes were roller skating, downhill skiing, and martial arts, requiring all five motor abilities. Four abilities were necessary in skating, jazz dance, and ice hockey. When exercising is target-oriented, endurance is trained evidently in 27 out of 31 and muscle strength in 22 out of 31 exercise modes. The consensus statement gives theoretical basis for the components of motor abilities and physical fitness components in different exercise modes. The statement is instructive in order to promote health-enhancing physical activity among sedentary people. This study completes the selection of the exercise modes more detailed than current PA recommendation and guidelines for public health. A variety of exercise modes with one or none motor requirements is available to start. When amount and intensity of exercise is increased the training effects can be found in most components of motor ability and physical fitness.

Validation of Simple Tests of Biathlon Shooting Ability

The aim of this study was to validate three simple ttests of biathlon shooting abilities. Twelve expert biathletes performed vis.ual reaction time tests adapted for the rifle in the stranding (RT-S) and prone positions (RT-P), and a tremometer test adapted for the rifle in the standing position (TT-S). Six cons.ecutive days measurements showed an acceptable reproducibiility for these tests (coefficient of variation = 1.2 % for RT-S, 1.1 %for RT-P and 6.5 % for TT-S). A significant difference was observed between TT-S at rest and after roller skiing 2.1 km at 90 % of maximal heart rate. This finding demonstrates the sensitivity of TT-S to discriminate the effects of fatigue on postural icontrol. Among 24 biathletes of regional to expert level, significant correlations were observed between resting RT-P and pronte shooting performance after roller skiing (r2 = 0.23; p = 0.01) and between resting TT-S and shooting performance in the standing position after roller skiing (r2 = 0.68; p = 0.0001), demonistrating the specificity of these tests. From these results, we conclude that TT-S is a valid field test of biathlon shooting performance.

Concurrent Endurance and Explosive Type Strength Training Increases Activation and Fast Force Production of Leg Extensor Muscles in Endurance Athletes

The purpose of this experiment was to examine the effects of concurrent endurance and explosive strength training on electromyography (EMG) and force production of leg extensors, sport-specific rapid force production, aerobic capacity, and work economy in cross-country skiers. Nineteen male cross-country skiers were assigned to an experimental group (E, n = 8) or a control group (C, n = 11). The E group trained for 8 weeks with the same total training volume as C, but 27% of endurance training in E was replaced by explosive strength training. The skiers were measured at pre- and post training for concentric and isometric force-time parameters of leg extensors and EMG activity from the vastus lateralis (VL) and medialis (VM) muscles. Sport-specific rapid force production was measured by performing a 30-m double poling test with the maximal velocity (V(30DP)) and sport-specific endurance economy by constant velocity 2-km double poling test (CVDP) and performance (V(2K)) by 2-km maximal double poling test with roller skis on an indoor track. Maximal oxygen uptake (Vo(2)max) was determined during the maximal treadmill walking test with the poles. The early absolute forces (0-100 ms) in the force-time curve in isometric action increased in E by 18 +/- 22% (p < 0.05), with concomitant increases in the average integrated EMG (IEMG) (0-100 ms) of VL by 21 +/- 21% (p < 0.05). These individual changes in the average IEMG of VL correlated with the changes in early force (r = 0.86, p < 0.01) in E. V(30DP) increased in E (1.4 +/- 1.6%) (p < 0.05) but not in C. The V(2K) increased in C by 2.9 +/- 2.8% (p < 0.01) but not significantly in E (5.5 +/- 5.8%, p < 0.1). However, the steady-state oxygen consumption in CVDP decreased in E by 7 +/- 6% (p < 0.05). No significant changes occurred in Vo(2)max either in E or in C. The present concurrent explosive strength and endurance training in endurance athletes produced improvements in explosive force associated with increased rapid activation of trained leg muscles. The training also led to more economical sport-specific performance. The improvements in neuromuscular characteristics and economy were obtained without a decrease in maximal aerobic capacity, although endurance training was reduced by about 20%.

Reliability and Validity of Test Concepts for the Cross-Country Skiing Sprint

This study was conducted, first, to develop a test concept for the new cross-country (XC) skiing sprint and to check test reliability and validity, and, secondly, to test the hypothesis that short-duration maximal speed in double poling (DP) predicts DP sprint performance over race distance (1000-1500 m). A total of 31 elite XC skiers performed test-retest of a 50-m DP sprint test (DP50m) and a subgroup (N = 17) performed test-retest of a DP sprint speed test (DPVmax) and a 1000-m DP sprint test (DP1000m), both on a treadmill. Additionally, 17 subjects performed all three tests to check validity, whereas six subjects performed an additional 1000-m DP field test. All tests were performed on roller skis. The DP50m, DPVmax, and DP1000m were reliable (r = 0.78-0.99, P < 0.001, CV = 0.79-6.18). The 50-m time (t50) and maximal velocity (Vmax50) of DP50m correlated to the maximal velocity (Vmax) in the DPVmax-test (r = -0.90; r = 0.86; P < 0.001), and time in the DPfield-test (tfield) correlated (r = 0.96, P < 0.01) to time in the DP1000m-test (t1000), showing validity of all treadmill tests. t50, Vmax50, Vmax, and fatigue index (FI) correlated to t1000 (r = 0.87; r = -0.85; r = -0.95; r = 0.86, P < 0.001). Cross-country skiing DP sprint tests appear reliable, valid, and standardizable. The relationship of maximal DP speed on DP sprint performance over race distance suggests (a) to integrate short-time sprint tests as predictors for XC sprint skiing performance, and (b) to reconsider the role of XC skiing specific speed training as an additional instrument to improve XC skiing sprint performance.

Biomechanical validation of a specific upper body training and testing drill in cross‐country skiing

The aim of this study was to perform a biomechanical validation of a double poling imitation drill on a rollerboard. Six elite cross‐country skiers performed three imitation drill trials at maximal speed at 13° inclination and in double poling on roller skis on a paved road of 3°. Pole and strap forces, elbow and hip angles and EMG activity of eight upper body muscles were measured. Force curves showed similar characteristics, except for impact force occurring only at pole plant in double poling on roller skis. Double poling on a rollerboard includes an eccentric roll‐down phase not appearing in double polling on roller skis. Forces on the rollerboard were similar to those on roller skis. Courses of the elbow angles indicated similar shapes, except for the angle at the start of the propulsion phase and, consequently, during flexion (p < 0.01). Propulsion time and cycle duration were longer and frequency lower on the rollerboard (all p < 0.001). Muscle activities were not significantly different, except for stronger biceps brachii (p < 0.01) and weaker erector spinae activation (p < 0.05) on the rollerboard. Muscle coordination patterns showed similar onset and offset points of each muscle and comparable activations in both activities, except for biceps brachii. Two movement strategies on the rollerboard were found, which led to small differences in measured variables. The biomechanical validity of double poling on a rollerboard can be judged as moderately high, being aware of the differences in some variables that might be considered in training sessions on the rollerboard, particularly when using intervals with high number of repetitions.