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IntroductionWhen exercising in the cold, optimizing thermoregulation is essential to maintain performance. However, no study has investigated thermal parameters with wearable-based measurements in a field setting among elite Nordic skiers. Therefore, this study aimed to assess the thermal response and sensation measured at different body parts during exercise in a cold environment in biathletes.MethodsThirteen Swiss national team biathletes (6 females, 7 males) performed two skiing bouts in the skating technique on two consecutive days (ambient temperature: −3.74 ± 2.32 °C) at 78 ± 4% of maximal heart rate. Heat flux (HF), core (Tcore) and skin (Tskin) temperature were measured with sensors placed on the thigh, back, anterior and lateral thorax. Thermal sensation (TS) was assessed three times for different body parts: in protective winter clothing, in a race suit before (PRE) and after exercise (POST).ResultsHF demonstrated differences (p < 0.001) between sensor locations, with the thigh showing the highest heat loss (344 ± 37 kJ/m2), followed by the back (269 ± 6 kJ/m2), the lateral thorax (220 ± 47 kJ/m2), and the anterior thorax (192 ± 37 kJ/m2). Tcore increased (p < 0.001). Tskin decreased for all body parts (p < 0.001). Thigh Tskin decreased more than for other body parts (p < 0.001). From PRE to POST, TS of the hands decreased (p < 0.01).ConclusionBiathletes skiing in a race suit at moderate intensity experience significant heat loss and a large drop in Tskin, particularly at the quadriceps muscle. To support the optimal functioning of working muscles, body-part dependent differences in the thermal response should be considered for clothing strategy and for race suit design.

Purpose: To investigate variability, predictability, and smallest worthwhile performance enhancement in elite biathlon sprint events. In addition, the effects of race factors on performance were assessed. Methods: Data from 2005 to 2015 including >10,000 and >1000 observations for each sex for all athletes and annual top-10 athletes, respectively, were included. Generalized linear mixed models were constructed based on total race time, skiing time, shooting time, and proportions of targets hit. Within-athlete race-to-race variability was expressed as coefficient of variation of performance times and standard deviation (SD) in proportion units (%) of targets hit. The models were adjusted for random and fixed effects of subject identity, season, event identity, and race factors. Results: The within-athlete variability was independent of sex and performance standard of athletes: 2.5-3.2% for total race time, 1.5-1.8% for skiing time, and 11-15% for shooting times. The SD of the proportion of hits was ~10% in both shootings combined (meaning ±1 hit in 10 shots). The predictability in total race time was very high to extremely high for all athletes (ICC .78-.84) but trivial for top-10 athletes (ICC .05). Race times during World Championships and Olympics were ~2-3% faster than in World Cups. Moreover, race time increased by ~2% per 1000 m of altitude, by ~5% per 1% of gradient, by 1-2% per 1 m/s of wind speed, and by ~2-4% on soft vs hard tracks. Conclusions: Researchers and practitioners should focus on strategies that improve biathletes' performance by at least 0.8-0.9%, corresponding to the smallest worthwhile enhancement (0.3 x within-athlete variability). [ABSTRACT FROM AUTHOR]

Biathlon is an Olympic sport combining cross-country skiing with the skating technique and rifle shooting. The sprint (7.5 km for women and 10 km for men) includes 2 shootings between 3 laps of skiing. The aims of the current study were to compare biathletes of different performance levels and sex on total race time and performance-determining factors of sprint races in the biathlon World Cup. The top-10 performers (G1-10) and results in ranks 21-30 (G21-30) in 47 sprint races during the 2011-12 to 2015-16 World Cup seasons were compared regarding total race time, course time, shooting time, range time, shooting performance (rate of hits), and penalty time. G21-30 men and women were on average 3-5% behind G1-10 in total race time, in which course time accounted for 59-65% of the overall performance difference, followed by 31-35% explained by penalty time. The remainder (ie, 4-6%) was explained by differences in shooting time and range time. The G1-10 women exhibited on average 12% slower speeds than the G1-10 men, and course time accounted for 93% of the total time difference of 13% between sexes. The average total hit rates were 92-93% among the G1-10 and 85% among the G21-30 in both sexes. In total, men shot on average 6 s faster than women. Course time is the most differentiating factor for overall biathlon performance between performance levels and sex in World Cup races. No sex difference in shooting performance was found. [ABSTRACT FROM AUTHOR]

Purpose: To assess the net effects of strength training on middle- and long-distance performance through a meta-analysis of the available literature. Methods: Three databases were searched, from which 28 of 554 potential studies met all inclusion criteria. Standardized mean differences (SMDs) were calculated and weighted by the inverse of variance to calculate an overall effect and its 95% confidence interval (CI). Subgroup analyses were conducted to determine whether the strength-training intensity, duration, and frequency and population performance level, age, sex, and sport were outcomes that might influence the magnitude of the effect. Results: The implementation of a strength-training mesocycle in running, cycling, cross-country skiing, and swimming was associated with moderate improvements in middle- and long-distance performance (net SMD [95%CI] = 0.52 [0.33-0.70]). These results were associated with improvements in the energy cost of locomotion (0.65 [0.32-0.98]), maximal force (0.99 [0.80-1.18]), and maximal power (0.50 [0.34-0.67]). Maximal-force training led to greater improvements than other intensities. Subgroup analyses also revealed that beneficial effects on performance were consistent irrespective of the athletes' level. Conclusion: Taken together, these results provide a framework that supports the implementation of strength training in addition to traditional sport-specific training to improve middle- and long-distance performance, mainly through improvements in the energy cost of locomotion, maximal power, and maximal strength. [ABSTRACT FROM AUTHOR]

The higher education sector was affected by this pandemic, managing enduring challenges since early 2020. Institutions of higher learning (IHL) are prepared to address unsurmountable challenges to ensure that students are not deceived and are being given the proper nurture, coupled with adherence to syllabuses. Simultaneously, the COVID-19 pandemic has caused unscrupulous pressure on students of these institutions. The psychological waves are creating mammoth consequences, affecting the beneficiaries of the higher education system and their families. In recent years, with limited studies on psychological impact among tertiary students on a cross-country basis, general self-efficacy, and the degree of coping strategies, we were motivated to investigate the degree of depression, anxiety, and stress (DAS), among this cohort of students encompassing the pre-university/Diploma, 1st–4thyear undergraduate, and postgraduate students from private universities in Malaysia, Indonesia, India, Southern Africa, and China, representing the emerging economies. A cross-sectional survey was conducted, followed by quantitative analysis. The objective of this study was to recognize whether there is a relationship between the psychological impact of DAS and the coping strategies adopted by the undergraduate students responding during the lockdown. The findings of this study revealed that with a sample size of 397, DAS lacked any severe impact on students across gender, country, household income, and level of education. DAS was established to be well managed with a coping strategy and self-efficacy established. This study resulted in a deeper understanding of DAS among undergraduates in emerging economies and their degree of coping behavior, providing a glimpse of the approach of millennials to handle DAS during the pandemic. [ABSTRACT FROM AUTHOR]

Cross-country skiing is one of the most important competitive events in the Winter Olympics, and it is also the earliest competitive sports event in China's winter snow events. However, due to the influence of factors such as economic development, climatic conditions, and regional resources, cross-country skiing has developed slowly in China and is still in a relatively backward position compared with developed countries such as Europe and the United States. In this paper, the modeling and analysis of the attitude calculation system is proposed, and the attitude recognition technology is applied to the high-intensity resistance training system of cross-country skiing. Several training elements such as special endurance training goals, training content, training methods, and training monitoring are presented. It demonstrates the rationality and feasibility of the high-intensity resistance training system for excellent cross-country skiers in cross-country skiing and arranges the strengthening training of the upper and lower limbs and waist and abdominal muscles of the athletes in a targeted manner. For 6–9 times a week, each endurance training is about 1–4 hours or strength training is about 15–90 minutes. The fastest time for men is 31 minutes 29 seconds 21, which is 1 second 88 higher than that before training, and the average score has improved by 6 seconds 80; the women's fastest time was 24 minutes 06 seconds 21, which was 4 seconds 22 higher than that before training, and the average score increased by 7 seconds 70. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop and validate a method using inertial measurements units (IMUs) to determine inner-cycle parameters (e.g., cycle, poles and skis contact, and swing time) and the main sub-techniques (i.e., G2, G3 and G4) in cross-country roller ski skating on a treadmill. The developed method is based on the detection of poles and skis initial and final contacts with the ground during the cyclic movements. Thirteen well-trained athletes skied at different combinations of speed (6–24 km∙h-1) and incline (2–14%) on a treadmill using the three different sub-techniques. They were equipped with IMUs attached to their wrists and skis. Their movements were tracked using reflective markers and a multiple camera infrared system. The IMU-based method was able to detect more than 99% of the temporal events. It calculated the inner-cycle temporal parameters with a precision ranging from 19 to 66 ms, corresponding to 3.0% to 7.8% of the corresponding inner-cycle duration. The obtained precision would likely allow differentiation of skiers on different performance levels and detection of technique changes due to fatigue. Overall, this laboratory validation provides interesting possibilities also for outdoor applications. [ABSTRACT FROM AUTHOR]

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Aerodynamic drag plays an important role in high-speed skiing. The wind-induced thrust or resistance of athletes, the sliding speed, and the work to overcome the aerodynamic drag are greatly affected by wind; therefore, reducing wind-induced drag is a focus of sport science. This paper proposes a method for evaluating the influence of wind on cross-country skiing performance, which is based on the athlete's aerodynamic-drag-work relative to the environmental wind field and the establishment of a racetrack wind field model. Aiming at an athlete's typical sport posture in the Yabuli Ski Field, the impact of field wind on the skier's speed, the work done by the athlete to overcome aerodynamic drag, and the ratio of the field wind-induced work to the athlete's total work are analyzed. Through the analysis of the athlete's work to overcome aerodynamic drag and the wind resistance energy dissipation ratio in three training cases, it is shown that the field wind has a great influence on the athlete's performance during sliding, which verified the effectiveness of the method. This method will provide coaches and sport researchers with accurate wind resistance energy dissipation data and provide a scientific basis for routine athletic training. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the effects of aerodynamic drag and drafting on propulsive force (F PROP), drag area (C D A), oxygen cost (V˙O2), metabolic rate (E ˙), and heart rate (HR) during roller skiing on a treadmill in a wind tunnel using the double poling technique. A secondary aim was to investigate the effects of wind versus no-wind test conditions on the same physiological parameters. Methods: Ten subjects of each gender participated in the experiments. One pair of skiers of the same gender roller skied simultaneously in line with the air flow; the distance between the skiers was ~2.05 m. Each pair was tested as follows: I) with wind, leading; II) with wind, drafting; and III) without wind. The treadmill inclination was 0° throughout the tests. For the wind conditions, the air velocity was similar to the treadmill belt speed: 3 to 7 m·s−1 for men and 3 to 6 m·s−1 for women. Results: Drafting resulted in significantly (P < 0.05) lower F PROP, C D A , V˙O2, and E ˙, compared with leading, for both genders at racing speed but not at lower speeds, whereas HR was only affected for the male skiers at racing speed. The test without wind resulted in significantly lower F PROP, V˙O2, and E ˙ at all tested speeds compared with the tests with wind present, whereas HR was lower only at higher speeds. Conclusions: At racing speed, but not at lower speeds, the positive effects of drafting behind a skier during double poling were obvious and resulted in a lower F PROP, C D A , V˙O2, E ˙, and HR. Tests without wind present put even lower demands on the skiers' physiology, which was also evident at lower speeds. [ABSTRACT FROM AUTHOR]

Snowsports education is crucial to the sustainability of the snowsports industry as it connects the participants to the sport through formal instruction. Investing in the development of snowsports education professionals who have the skills and knowledge can contribute to creating lifelong participants. The purpose of this study is to understand what is known about snowsports education in an effort to guide future research toward a more thorough theoretical, practical, and interdisciplinary understanding. Through a scoping review, this paper summarizes the current body of knowledge and identifies gaps in extant literature. Primary findings suggest snowsports education programs and instructors have significant impacts on a participant's attitude toward snowsports and toward their skill acquisition. A notable gap is that while researchers have suggested instructor-participant interactions are valuable to the snowsports education experience, few studies have explicitly explored such interaction. Guided by the current knowledge and existing gaps, potential research opportunities are discussed. [ABSTRACT FROM AUTHOR]

Purpose: The primary purpose was to test the effect of heat suit training on hemoglobin mass (Hbmass) in elite cross‐country (XC) skiers. Methods: Twenty‐five male XC‐skiers were divided into a group that added 5 × 50 min weekly heat suit training sessions to their regular training (HEAT; n = 13, 23 ± 5 years, 73.9 ± 5.2 kg, 180 ± 6 cm, 76.8 ± 4.6 ml·min−1·kg−1) or to a control group matched for training volume and intensity distribution (CON; n = 12, 23 ± 4 years, 78.4 ± 5.8 kg, 184 ± 4 cm, 75.2 ± 3.4 ml·min−1·kg−1) during the five‐week intervention period. Hbmass, endurance performance and factors determining endurance performance were assessed before and after the intervention. Results: HEAT led to 30 g greater Hbmass (95% CI: [8.5, 51.7], p = 0.009) and 157 ml greater red blood cell volume ([29, 285], p = 0.018) post‐intervention, compared to CON when adjusted for baseline values. In contrast, no group differences were observed for changes in work economy, running velocity, and fractional utilization of maximal oxygen uptake (V̇O2max) at 4 mmol·L−1 blood lactate, V̇O2max or 15‐min running distance performance trial during the intervention. Conclusion: HEAT induced a larger increase in Hbmass and red blood cell volume after five weeks with five weekly heat suit training sessions than CON, but with no detectable group differences on physiological determinants of endurance performance or actual endurance performance in elite CX skiers. [ABSTRACT FROM AUTHOR]

Special requirements, such as super-maximally filled glycogen stores, short regeneration times, correct meal timing or appropriate weight specifications for ski jumping are particularly useful for endurance athletes such as cross-country skiers. A deficiency could have a fatal effect on performance and possibly a negative influence on health. While cross-country skiing is clearly one of endurance sports, ski jumping and alpine skiing are considered to be fast-strength sports or technical (acrobatic) sports. The proven advantages of carbohydrate loading (supercompensation), a nutritional technique for classic endurance loads, also apply to cross-country skiing. A drop in performance, concentration and coordination disorders as well as overheating threaten if fluid loss exceeds 2% of the total body water. Vitamin additives or sweeteners in sports drinks are inefficient. Since the higher need is actually compensated by the increased food intake with a balanced mixed diet, there is, in principle, no over-proportional need for individual vitamins in athletes. As the maximum oxygen uptake is already 15% lower from 3000 m altitude, a drop in performance is clearly noticeable there. When skiing (snowshoeing, ski touring, etc.), it should be noted that an ascent of 100 meters in altitude alone requires an additional 100-150 kcal. At moderate activity, the additional energy requirement at high altitudes compared to the sea level is estimated to be 250-290 kcal per day for men and 180-200 kcal per day for women. Top athletes in cross-country skiing can liberate 170-210 kJ/min (40-50 kcal/min) in a dominant anaerobic manner within 2-3 minutes. The respective energy consumption is modified by numerous personal as well as external factors (for cross-country skiing, for example, the outside temperature, the friction resistance of the snow, the technique, the height profile of the route and the headwind). In cross-country skiers, the average values of body fat range between 4.8 and 12.7% in males and from 10.6 to 22.7% in females, while the average values of lean body mass (LBM) vary between 58.2 and 68.8 kg in males and from 45.6 to 48.6 kg in females. In alpine skiers, the mean values of body fat are between 9.7 and 15.8% in males and from 16.2 to 26.7% in females, and the LBM values in males range between 59.9 and 74.7 kg, in females from 42.1 to 52.8 kg. The span of body fat in male ski jumpers ranges from 8.6 to 16% with an LBM of 59.7 kg. Since 2012, a BMI of at least 21 kg/m² including suit and shoes has been a condition for ski jumpers to be able to use full-length skis (145% of body height). Otherwise, shorter skis have to be used, which reduces the wing area and is intended to reduce the jump distance as a penalty. The average values of body fat in male athletes of Nordic Combined range between 8.9 and 11.2%, and the corresponding LBM values are between 62.0 and 64.1 kg. When comparing these parameters of body composition, it must always be remembered that different methods of determining the body fat percentage have been used in corresponding studies and that possible differences do not represent a development of the skiing somatotypes over time but could also have methodological reasons. [ABSTRACT FROM AUTHOR]

In winter sports, the equipment often comes into contact with snow or ice, and this contact generates a force that resists motion. In some sports, such as cross-country skiing, this resistive force can significantly affect the outcome of a race, as a small reduction in this force can give an athlete an advantage. Researchers have examined the contact between skis and snow in detail, and to fully understand this friction, the entire ski must be studied at various scales. At the macro scale, the entire geometry of the ski is considered and the apparent contact between the ski and the snow is considered and at the micro-scale the contact between the snow and the ski-base textures. In the present work, a method for characterising the contact between the ski-base texture and virtual snow will be presented. Six different ski-base textures will be considered. Five of them are stone-ground ski bases, and three of them have longitudinal linear textures with a varying number of lines and peak-to-valley heights, and the other two are factory-ground “universal” ski bases. The sixth ski base has been fabricated by a steel-scraping procedure. In general, the results show that a ski base texture with a higher Spk value has less real contact area, and that the mutual differences can be large for surfaces with similar Sa values. The average interfacial separation is, in general, correlated with the Sa value, where a “rougher” surface exhibits a larger average interfacial separation. The results for the reciprocal average interfacial separation, which is related to the Couette type of viscous friction, were in line with the general consensus that a “rougher” texture performs better at high speed than a “smoother” one, and it was found that a texture with high Sa and Spk values resulted in a low reciprocal average interfacial separation and consequently low viscous friction. The reciprocal average interfacial separation was found to increase with increasing real contact area, indicating a correlation between the real area of contact and the Couette part of the viscous friction.