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In cross-country ski skating, both the G2 and G4 sub-techniques involve one pole push for every second ski push but are used at largely different speed-slope ranges. The aim of this study was to compare temporal and kinematic patterns between G2 and G4 at both identical and different speed-slope conditions. A mixed model was used to analyse spatio-temporal parameters, while a combination of dynamic time warping and statistical parametric mapping was used to compare time traces. Main spatio-temporal parameters, such as cycle time, ski contact time and swing time, differed between G2 and G4 (all p < 0.01). Moreover, two forward and more pronounced acceleration phases of the centre of mass (CoM) were visible in G4 while only one acceleration phase was present in G2. The more continuous propulsion in G2 allows for maintaining a more constant speed at steep slopes and low speeds where this sub-technique is preferred. In contrast, the achievement of high speeds while skiing on flatter terrain seem to require more dynamic motion with shorter, more explosive propulsion periods allowed for in G4. In conclusion, G2 and G4 are two unique movements as characterised by fundamentally different CoM motion and should be denoted as two different sub-techniques. [ABSTRACT FROM AUTHOR]

Nature-based winter sports are often framed as a solution to the tension between people's desire for pristine snowy landscapes and their effects on that environment. Low-impact activities such as ski touring and cross-country skiing allow outdoor enthusiasts to visit remote and mountainous locations without the need for hard infrastructure of ski resorts, leaving no permanent marks in the landscape. Yet their growing popularity raises a dilemma about negative effects, especially on wildlife conservation areas. We use the tracks and traces left behind by people as well as animals in Northern Europe and the Alps as a nexus through which to explore how humans and non-humans interact, ignore or avoid each other. Often imagined as ephemeral activities, we argue that the cumulative impacts of nature-based winter sports have significant consequences for wildlife and the way we aim to protect it long after its traces in the snow have disappeared. [ABSTRACT FROM AUTHOR]

Since the introduction of a national system for upper-secondary sport schools in Sweden in the 1970s, these institutions have been an important environment for developments in training and coaching. This is particularly true for cross-country skiing, where these schools quickly became an obligatory passage point. Coaches at the sport schools, often formally employed as PE teachers, were among the first professionalized endurance sport coaches in Sweden. This article examines how communities of practice have influenced the professionalization process of XC ski coaches at Swedish sport schools. The results show how being part of this community is conditioned on personal experience of active learning, historically as a skier yourself and currently as a coach who participates in the everyday work. The strong communities of practice have enabled coaches to maintain a high degree of self--governance and ensured that experiential knowledge remain important in relation to scientific knowledge. [ABSTRACT FROM AUTHOR]

The objective of this study was to test the vectorelectrocardiographic T-wave characteristics for their associations with oxygen consumption (VO2) and physical performance during a maximal cardiopulmonary exercise test (CPET) in highly trained cross-country skiers. Male highly trained cross-country skiers (n = 30) performed the maximal CPET on the bicycle ergospirometric "Oxycon Pro" system with simultaneous oxygen consumption (VO2) and electrocardiogram recording. The measurements were done at rest; the stage preceding anaerobic threshold (preAnT); peak load; and recovery. The anaerobic threshold was estimated by respiratory exchange ratio. Physical performance was estimated by maximal oxygen consumption (VO2max/kg). VECG characteristics were calculated using Kors transformation procedure. During the test, the magnitudes of T-vector, Tx and Ty components decreased until preAnT, then stayed relatively stable until peak load, and reversed during recovery. In univariate linear regression analysis, T-vector amplitude and Tx, Ty and Tz magnitudes were associated with VO2/kg during the test (p < 0.010). The baseline T-vector characteristics were not associated with physical performance. At the preAnT stage, Tx and T-vector amplitude were associated with VO2max/kg (RC 12.70, 95% CI 0.68–24.73, p = 0.039 and RC 10.64, 95% CI 1.62–19.67, p = 0.023, respectively). [ABSTRACT FROM AUTHOR]

The old adage has two people out hiking who run into a bear. One starts running while the other asks 'why are you running? You can't outrun a bear'. To which the other responds, 'I don't have to outrun the bear. I only have to outrun you'. Hiking/trekking is not typically a competitive endeavor characterized by contests but, like many endeavors/pursuits/activities, competition can be injected into it; thereby sportifying it. Swimming is a sport (under certain conditions). At the same time, it is also a recreational activity and a form of physical exercise; likewise angling/fishing, climbing, cross-country skiing, mountain biking, kayaking, rowing, surfing, et al. The categorization of many activities under the umbrella of sport has it uses to understand the wider concept of what is sport, but the purpose of why one engages in 'physical activities taking place in a natural environment' can sometimes be more important than whether some activities might or might not qualify to be classified under the rubric of sports at all. Indicators exist to show whether participants are actually engaged toward—driven in a way, even—to further their skills in their focused activity (if it is a focused activity at all!––i.e. a 'serious leisure' pursuit or just a recreational hobby). From this perspective (of looking at sport-like and sporting activities in other than Olympic-style forms) this paper explores the differentiations between sport (including nature sport) contests, nature challenge activities (NCAs) and outdoor recreation from the standpoint of the most relevant factors that distinguish them: rules, skill development, purpose for engaging in them. This paper also makes the case that differentiating participants in the above activities by purpose (as either nature challenge recreationalists or nature sport devotees) has utility; to better help research into people's engagement in physical activities in natural environments. [ABSTRACT FROM AUTHOR]

The article explores the realm of sport from an aesthetic point of view. Making a sustained physical effort regularly may have a positive impact on our psycho-somatic being and can sustain our health and well-being. But what exactly is this aesthetic component in sport and is it possible that this aesthetic component prevails over other components when it comes to individual sport? Moreover, is this aesthetic component complex in its nature or can it be reduced to some unique underlying principle? These are the main philosophical questions that this article strives to answer by exploring the aesthetic experience proper to sport. Abandoning the much-acclaimed perspective of the spectator (which consists of seeing sport as a spectacle or drama to be enjoyed and judged from a distance) entails that the aesthetic in sport has to be studied from the perspective of an active and individual participator. Ultimately, the article makes the claim that sport is both a way of interacting with one's environment and a way of aesthetic self-fulfilment which allows the individual to lead a meaningful life rich in aesthetic experiences and events. [ABSTRACT FROM AUTHOR]

This study compared performance strategies and sub-technique selection in cross-country skate skiing sprint races, specifically individual time-trial (ITT) and head-to-head (H2H) formats. Fourteen male cross-country skiers from the Chinese national team participated in the FIS-sanctioned sprint race day. GNSS and heart rate sensors recorded positioning, skiing speeds, heart rate, sub-technique usage, and skiing kinematics. Statistical parametric mapping (SPM) was used to determine the course positions (clusters) where instantaneous skiing speed was significantly associated with section time. One-way analyses of variance were used to examine differences between the ITT and H2H. H2H race speeds were 2.4 ± 0.2% faster than the ITT race (p < 0.05).Variations in sub-technique and skiing kinematics were observed between race formats, indicating different strategies and tactics employed by athletes. SPM identified specific clusters (primarily uphill) where the fastest athlete gained significant time over the slowest. The greatest time gains were associated with higher G3 sub-technique usage and longer G3 cycle length on steep uphill terrain (9–13% gradients). Integrating SPM analyses and sub-technique assessments can help optimise performance and tactics in sprint races. This study enhances our understanding of cross-country skiing dynamics and performance variations among elite competitors. [ABSTRACT FROM AUTHOR]

This cross-sectional study aimed to compare clinical oral conditions as well as the self-reported oral health status of biathletes and cross-country skiers (A) to age- and gender-matched non-athletic controls (C). Thirty-one A and 68 C were examined in 2020 regarding caries experience (DMF-T), partially erupted wisdom teeth, non-carious tooth wear (erosion), dental plaque biofilm, gingival inflammation, periodontal screening (PSI), salivary active matrix-metalloproteinase-8 (aMMP-8) test and screening for temporomandibular disorders (TMD). Questionnaires recorded periodontal symptoms, TMD symptoms and oral health behaviour. Group A had a lower prevalence of carious teeth and positive aMMP-8 tests, but more of them had severe gingivitis and signs of periodontitis. Both groups reported similar oral health behaviour. Only in group C, associations between aMMP-8 and periodontal findings as well as clinical findings and self-reported symptoms of TMD were identified. Group A showed a high prevalence of oral inflammation and seemed to be less aware of oral symptoms. Clinical examination seems to be necessary for periodontal/TMD screening of athletes. [ABSTRACT FROM AUTHOR]

L'année 1932 marque le passage en France d'une pratique confidentielle à des formes multiples du ski de randonnée qui se détachent dans cette période. À une voie militaire du ski de randonnée qui persiste et où la domination de la Nature est recherchée symboliquement pour la formation des soldats, se développe une seconde voie, celle de l'« aventure », illustrée par la recherche de l'excellence et de la performance symbolisée plus particulièrement par l'essor des raids. Enfin, une voie « conviviale » vient compléter cette pluralité des formes de pratique du ski de randonnée en plaçant au cœur des préoccupations de ces pratiquants la recherche de loisirs où la logique contemplative de la Nature est valorisée. À travers cet article, il s'agit donc de montrer que la dynamique du ski de randonnée, présentée par les médias de cette époque, est non seulement exponentielle dans la France de l'entre-deux-guerres, mais aussi plurielle en termes de représentations sociales des formes de pratique de ce sport de montagne. The year 1932 marks the transition in France from a confidential practice to multiple forms of ski touring which stand out in this period. Alongside a military way of ski touring which persists and where the domination of Nature is symbolically sought for the training of soldiers, a second way is developing, the "adventure" way, illustrated by the search for excellence and the performance symbolized more particularly by the rise of raids. Finally, a "friendly" way completes this plurality of forms of ski touring by placing at the heart of the practitioners' concerns the search for leisure where the contemplative logic of Nature is valued. Through this article, it is therefore a question of showing that the dynamics of ski touring, presented by the media of this period, are not only exponential in France between the two wars but also plural in terms of representational forms of practice of this mountain sport. [ABSTRACT FROM AUTHOR]

Environmental sustainability in sport is an increasingly important issue. In this paper, we want to highlight a specific phenomenon, namely artificially constructed landscapes and the outdoor sport activities that take place therein. More specifically, we are interested in the logics that govern peoples' practice of sport in such artificial landscapes and what challenges with regards to environmental sustainability that follow from these logics. The purpose of this paper is to identify what individual athletes perceive as meaningful logics when practicing sport in artificial landscapes and to analyse and discuss potential environmental consequences of these logics. The sports we focus on are cross-country skiing and canoe slalom, two sports that historically have been dependent on specific geographies and contexts. We build on two research questions: What logics of practice govern individual athletes' practice of sport in artificial landscapes? And what environmental challenges are potential consequences of the logics that are expressed by the athletes? Our findings indicate that the logic of performance is dominant for the sport practitioners who train in artificial landscapes, at the expense of perspectives such as nature experience and environmental sustainability. If performance is key, then the role of the training landscape is also first and foremost to present the best possible conditions for performance. But if the athlete/exerciser see their training as a means of experiencing nature, then other values than performance and comparability can become more important. When the environmental impact of individual athletes and of the artificial landscapes in which they do their training come under increased scrutiny, the role of logics of practice in the sport and movement culture needs further attention. Being aware of nature and the environment is also a logic that could be found meaningful in the process of making sports more sustainable. [ABSTRACT FROM AUTHOR]

The impact of high-nitrate beetroot juice (BRJ) supplementation has seen a recent explosion of interest in sports science. This study examined the potential influence of 7-day BRJ supplementation on the endurance performance of winter triathletes. Eighty young active winter triathletes (44 males, age = 21.50 ± 1.15 yrs; 36 females, age = 20.66 ± 1.45 yrs) participated in this study and were provided with either BRJ (6.5 mmol NO3−/70 mL) or a placebo (PL, 0.065 mmol NO3−/70 mL) for 7 days (a dose of ×3 per day) in a randomized, double-blind design. The athletes then completed a submaximal treadmill run, intraday cycling exhaustion testing, and a 10-km cross country (XC) skiing competition on the second day. There was a significant decrease in the oxygen uptake, respiratory exchange ratio, and blood lactic acid level (p < 0.05) between the BRJ and PL treatment groups during V3 speed running (males: 13.3 km·h−1, females: 11.6 km·h−1). BRJ treatment also remarkably increased the time to exhaustion (TTE) during cycling exhaustion testing (males: p = 0.02, females: p = 0.04). No significant differences were observed in medium- or low-speed submaximal treadmill runs and 10-km XC skiing performance. One week of daily nitrate-rich BRJ supplementation improved running economy at high speed during the submaximal treadmill running test and extended the TTE of athletes during cycling exhaustion testing. However, BRJ supplementation did not improve the performance in 10-km on-snow time trials in XC skiing. Regarding nutritional strategies to improve endurance performance in exercise training and competition, these results should be carefully considered owing to the different motor skill levels and competitive abilities of participants. [ABSTRACT FROM AUTHOR]

The aim was to investigate whether rifle carriage affects gear distribution during on-snow skiing in highly-trained biathletes, and whether there were any associated sex differences. Twenty-eight biathletes (11 women, 17 men) skied a 2230-m lap at competition speed twice, one lap with the rifle (WR) and the other lap without the rifle (NR). The biathletes wore a portable 3D-motion analysis system while skiing, which enabled characterisation of distance and time in different gears. Skiing WR increased lap time compared to NR (412 (90) vs. 395 (91) s, p < 0.001). The biathletes used gear 2 to a greater extent WR compared to NR (distance: 413 ± 139 vs. 365 ± 142 m; time: 133 (95) vs. 113 (86) s; both p < 0.001) and gear 3 less (distance: 713 ± 166 vs. 769 ± 182 m, p < 0.001; time: 141 ± 33 vs. 149 ± 37 s, p = 0.008), with similar patterns for women and men. Differences between WR and NR in the use of gears 3 and 2 were more extensive for moderate compared to steeper uphill terrain. Rifle carriage increased the use of gear 2, which was negatively associated with performance. Therefore, preparing biathletes to be able to cover more distance in gear 3 WR, especially in moderate uphill terrain, may improve biathlon skiing performance. [ABSTRACT FROM AUTHOR]

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To examine the effects of kinesio taping on lower back muscle soreness immediately after its application and after 24 h during a cross-country skiing camp in collegiate students. The present study followed a double-blind, randomized, placebo-controlled trial design. Out of the 60 participants in a winter skiing camp, 54 volunteered to participate in the study (aged 21.3 years old, 20 females and 34 males). After 3 days of practical cross-country ski lessons (4 h per day), volunteers were, balanced by sex, randomly divided into three groups. One group had kinesio taping applied on the lower back, another had placebo tape applied and the third group nothing. The two-way ANOVA with the Bonferroni adjustment showed that the lower back muscle soreness levels in the kinesio taping group decreased statistically significantly from baseline to after 24 h of the kinesio taping application (p= 0.020). Kinesio taping reduced low back muscle soreness 24 h after its application produce by several days of cross-country skiing in physically active collegiate students. Kinesio taping method may be beneficial in reducing post-exercise delayed onset muscle soreness in healthy sport collegiate students. [ABSTRACT FROM AUTHOR]

The International Paralympic Committee Classification Code requires sports to develop evidence-based, sports-specific classification systems. This project aimed to determine the minimum eligibility criteria for Para nordic and Para alpine skiing by simulating vision impairments and measuring the impact of the impairments on performance in twenty-two nordic (28.09 ± 9.68 years; 16 male) and eleven alpine (37.91 ± 18.9 years, 11 male) able-sighted skiers. Eight visual acuity (VA)/contrast sensitivity (CS) (Cambridge Simulation Glasses, University of Cambridge) and six visual field (VF) impairments (bespoke goggles; University of Waterloo) were simulated. VA, CS and VF were measured in each participant before they completed an on-snow session, skiing short competition-style courses with each of the 14 simulated impairments in a randomized order. Clear goggle (no impairment) trials were used as controls. Receiver Operating Characteristic (ROC) and decision tree analyses were conducted to determine the optimum VA, CS and VF cut-offs for classifying performance based on differences from baseline in real time. Moderate impairments in VA, CS and VF negatively affect skiing performance. The recommended cut-off criteria based on both analyses were VA ≥0.90 logMAR and ≤48% VF extent for nordic and VA of ≥0.60 logMAR and VF extent of ≤59.0% for alpine. [ABSTRACT FROM AUTHOR]

The International Ski Federation (FIS) instituted sex testing protocols in 1967. In doing so, it followed the example set by the International Amateur Athletic Federation (IAAF) and became the second international federation to institute some form of compulsory sex control, before the International Olympic Committee implemented its sex verification policy in 1968. Despite initially looking to the track and field federation for guidance, the FIS eventually diverged in procedure, method, and timing. It required testing occur in women skiers' home countries before competition, introduced testosterone levels into the equation, and continued mandatory checks until 2000, after the IAAF had abandoned routine, on-site controls. An analysis of the FIS sex verification policies exposes a deep and long-lasting anxiety about the appropriateness of women in all sports, not just in track and field; identifies the introduction of hormonal analysis into sex verification; and shows the unintended consequences of sex testing when done at the national level. [ABSTRACT FROM AUTHOR]

Objective: The prevalence of asthma among elite endurance athletes is high, but less is known about the incidence of asthma among athletes. The aim of this study was to examine the incidence rate of physician-diagnosed asthma among elite endurance athletes. Method: An annual postal questionnaire was sent to an open prospective cohort of elite endurance athletes between 2011 and 2015. Athletes from Swedish National teams, students at universities with elite sport partnership, and pupils at Swedish National elite sport schools, competing in cross-country skiing, biathlon, ski orienteering, or orienteering were invited (n = 666). Incidence rate of physician-diagnosed asthma was calculated among those without asthma at baseline (n = 449). Risk factors for incident physician-diagnosed asthma were identified using a multivariate logistic regression analysis. Results: Response rate was 88.7% (n = 591) at baseline. The median age of participants was 17 (range 15–36) years at inclusion. The study population included 407 (69%) skiers and 184 (31%) orienteers. The prevalence of asthma at baseline was 23.9% (n = 141). Incidence rate (95% confidence interval [CI]) of physician-diagnosed asthma was 61.2 (45.7–80.3) per 1,000 person-years. Risk factors (odds ratio [OR (95% CI)]) for incident physician-diagnosed asthma were family history of asthma (1.97 [1.04–3.68]), being a skier (3.01 [1.42–7.21]), and wheezing without having a cold (4.15 [1.81–9.26]). Conclusion: The incidence rate of physician-diagnosed asthma is high among Swedish elite endurance athletes. [ABSTRACT FROM AUTHOR]

Biathlon is an Olympic winter sport combining the endurance sport of cross-country skiing with precision rifle shooting. Here, the need to prepare the body for upcoming events is particularly evident. As a high heart rate can be detrimental to shooting performance, it might be beneficial for biathletes to decrease their heart rate when approaching the shooting range, whereas heart rate should ideally be increased at the start and when facing an uphill section to cater for physiological demands. Ten national-level, junior male biathletes skied 6–8 laps in a standardized 2 km biathlon course with competition intensity, where each lap was followed by 5 shots in the standing position. Electrocardiography was continuously measured, and changes in heart rate during the 30 s leading up to the start, the uphill section, and the shooting event were analyzed. Instantaneous heart rate (IHR) increased significantly before the start and before the beginning of the uphill, whereas IHR decreased significantly before arriving at the shooting range. These findings provide evidence that biathletes anticipate forthcoming events by prospectively adjusting their heart rate upwards and downwards depending on task demands. Being able to use perceptual predictive information to optimally prepare the body for challenges that lie ahead, may have implications for expert performance in several different sports, as well as in other fields where purposeful regulation of heart rate is important for success. [ABSTRACT FROM AUTHOR]

The social environment within individual sport teams can have a significant influence on the success, development, and well-being of athletes. We explored elite individual sport athletes' group experiences through the lens of social identity theorising. Participants were six members (4 male, 2 female, Mage = 21.5 years) of a National Development Nordic Ski team. At two time points in the competitive season, we used Social Identity Mapping (Bentley et al., 2020) in combination with semi-structured interviews to explore athletes' experiences as a member of the ski team. Social Identity Mapping provided a visual representation of each participant's social identities and was used to facilitate athletes' views of their group experiences in the semi-structured interviews. Interview data were thematically analysed to explicate participants' perceptions of social identity and cohesion, and their perceived relevance to success and development in elite individual sport. Major themes included social group memberships and identities, the presence of subgroups, the ebb and flow of cohesion and conflict, and teammate and coach influence on the group. On this basis, we argue that social identity mapping can be a valuable resource for athletes and coaches seeking to create a positive and cohesive team environment within an elite individual sport team. [ABSTRACT FROM AUTHOR]

A talent identification index system for male and female cross-country skiers in four age groups (11–12 years old, 13–14 years old, 15–16 years old, and 17–18 years old) was established. The system comprises five body shape indexes ( i =5): Leg-to-Body Ratio (LBR), body fat percentage, maturity status, spreaded brachia index, and upper extremity length. The physiological function indexes ( i =2) are VO2max and haemoglobin mass (Hb). The psychological indexes ( i =5) cover reaction time, perception speed, a quality-of-will scale, an attention test, and operational thinking. The physical fitness indexes ( i =11) comprise upper limb explosiveness, vertical jump, 3000-metre run, orthostatic forward flexion, closed-eyes single-leg stand, standing long jump, 20-metre sprint, pull-ups (males), flexed arm hang (females), hexagon jump, and a Functional Movement Screen (FMS) test. The athletic performance indexes ( i =3) comprise on-snow time trials for 1.2 km, 5 km, and 10 km. The talent identification evaluation model was created using automated evaluation software. The talent identification index system and evaluation standard table for cross-country skiers passed the P60 shortlist and P90 elite boundaries established using the percentile method. Thus, the results of this test profile verify that the evaluative model is objectively effective. [ABSTRACT FROM AUTHOR]

Cross-country skiing is a complex endurance sport requiring technical skills, in addition to considerable physiological and tactical abilities. This review aims to identify biomechanical factors that influence the performance of cross-country skiers. Four electronic databases were searched systematically for original articles in peer-reviewed journals addressing the relationship between biomechanical factors (including kinematics, kinetics, and muscle activation) and performance while skiing on snow or roller skiing. Of the 46 articles included, 22 focused exclusively on the classical technique, 18 on the skating technique, and six on both. The indicators of performance were: results from actual or simulated races (9 articles); speed on specific tracts (6 articles); maximal or peak speed (11 articles); skiing economy or efficiency (11 articles); and grouping on the basis of performance or level of skill (12 articles). The main findings were that i) cycle length, most often considered as a major determinant of skiing speed, is also related to skiing economy and level of performance; ii) higher cycle rate related with maximal speed capacity, while self-selected cycle rate improves skiing economy at sub-maximal speeds; iii) cross-country skiing performance appears to be improved by joint, whole-body, ski, and pole kinematics that promote forward propulsion while minimizing unnecessary movement. [ABSTRACT FROM AUTHOR]

This research draws upon pedagogical experimentation on a ski-touring journey in the Australian Alps, building upon place-responsive pedagogies in outdoor environmental education with insight from new materialist and posthuman theory. In particular, this research focusses on the generative potential of considering co-productions and assemblages that include the materiality of a more-than-human world. Combining place-responsive and new materialist ideas, the concept of more-than-human stories is offered as a pedagogical strategy that may challenge anthropocentrism and develop different ways of thinking about and with more-than-human places. An example of these ideas in practice is offered, where Ya, an undergraduate student, presents her more-than-human story—One Single Moment—a picture-story book created on the ski-touring journey. Following her picture-story book, she maps the conditions of possibility, the various pedagogical influences that led to the creation of One Single Moment. Our aim through this research is to offer methodological and pedagogical insight into using new materialist theories in creative and productive ways. [ABSTRACT FROM AUTHOR]

The present study investigates the relationship between birth rank and academic achievement of children in a cross-country study to examine whether firstborn children perform better in primary school than later-born children when controlling for individual, social and parental characteristics. Data were drawn from the School Children Mental Health in Europe (SCMHE) study, which included samples from Bulgaria, Germany, Italy, Netherlands, Lithuania, Romania and Turkey (n = 7,518). Children's academic performance in reading and mathematics was evaluated by teachers and parents reported sociodemographic variables including birth rank and parental attitudes. Controlling for individual, sociodemographic variables and parental attitudes in multinomial regressions, first- or second-born children displayed greater performance in mathematics and in reading as compared to children whose birth rank was third or above. Children from large families, especially when they are not first- or second-born appear to be at greater risk for academic difficulties and should benefit from targeted prevention efforts. [ABSTRACT FROM AUTHOR]

We aimed to evaluate the changes in double poling (DP) kinematics due to a long-distance cross-country skiing race in athletes with different performance levels. A total of 100 cross-country skiers, belonging to 10 different performance groups, were filmed on flat terrain 7 and 55 km after the start line, during a 58-km classical race. Cycle velocity, frequency and length decreased from the best to the lower-ranked group, while duty cycle increased (all P <.001). Between track sections, cycle velocity and length decreased, duty cycles increased (all P <.001) while frequency was unaltered (P =.782). Group*section interactions resulted for cycle velocity (P =.005). Considering all the participants together, % change in cycle velocity between sections correlated with % change in length and duty cycle (all P <.001). Thus i) skiers in better groups showed longer and more frequent cycles as well as shorter duty cycles than skiers in slower groups; ii) throughout the race all the groups maintained the same cycle frequency while decreasing cycle velocity and length; iii) better groups showed a lower reduction in cycle velocity. Individually, a low reduction in cycle velocity during the race related to the capacity to maintain long cycles and short duty cycles. [ABSTRACT FROM AUTHOR]

The recommendation problem has been widely studied and researchers are constantly searching for better methods. Recommending events is an even more difficult problem because there is no information such as ratings from past events. In this paper, we introduce a method for recommending activity events: activities hosted by one or more individuals which involve movement: walking, running, cycling, cross-country skiing, and driving to users who have location history such as trajectories, meetings, POI visits, and geo-tagged photos. We tested the method in a real environment in Mopsi platform: . Although there are many location-based event recommendation systems in literature, this is to our knowledge the first system that recommends activity events like bicycle and skiing trips. The experiments show that we can predict whether a user is attending the event or not with 80% accuracy, which is significantly better than random chance (50%). [ABSTRACT FROM AUTHOR]

Background: Whilst the ergogenic effects of carbohydrate intake during prolonged exercise are well-documented, few investigations have studied the effects of carbohydrate ingestion during cross-country skiing, a mode of exercise that presents unique metabolic demands on athletes due to the combined use of large upper- and lower-body muscle masses. Moreover, no previous studies have investigated exogenous carbohydrate oxidation rates during cross-country skiing. The current study investigated the effects of a 13C-enriched 18% multiple-transportable carbohydrate solution (1:0.8 maltodextrin:fructose) with additional gelling polysaccharides (CHO-HG) on substrate utilization and gastrointestinal symptoms during prolonged cross-country skiing exercise in the cold, and subsequent double-poling time-trial performance in ~ 20 °C. Methods: Twelve elite cross-country ski athletes (6 females, 6 males) performed 120-min of submaximal roller-skiing (69.3 ± 2.9% of V ̇ O2peak) in −5 °C while receiving either 2.2 g CHO-HG·min− 1 or a non-caloric placebo administered in a double-blind, randomized manner. Whole-body substrate utilization and exogenous carbohydrate oxidation was calculated for the last 60 min of the submaximal exercise. The maximal time-trial (2000 m for females, 2400 m for males) immediately followed the 120-min submaximal bout. Repeated-measures ANOVAs with univariate follow-ups were conducted, as well as independent and paired t-tests, and significance was set at P < 0.05. Data are presented as mean ± SD. Results: Exogenous carbohydrate oxidation contributed 27.6 ± 6.6% to the total energy yield with CHO-HG and the peak exogenous carbohydrate oxidation rate reached 1.33 ± 0.27 g·min− 1. Compared to placebo, fat oxidation decreased by 9.5 ± 4.8% with CHO-HG, total carbohydrate oxidation increased by 9.5 ± 4.8% and endogenous carbohydrate utilization decreased by 18.1 ± 6.4% (all P < 0.05). No severe gastrointestinal symptoms were reported in either trial and euhydration was maintained in both trials. Time-trial performance (8.4 ± 0.4 min) was not improved following CHO-HG compared to placebo (− 0.8 ± 3.5 s; 95% confidence interval − 3.0 to 1.5 s; P = 0.46). No sex differences were identified in substrate utilization or relative performance. Conclusions: Ingestion of an 18% multiple-transportable carbohydrate solution with gelling polysaccharides was found to be well-tolerated during 120 min of submaximal whole-body exercise, but did not improve subsequent maximal double-poling performance. [ABSTRACT FROM AUTHOR]

It has been previously observed that athletes of certain origin nationality dominate particular sports; however, this phenomenon has been less studied in cross-country (XC) skiing, especially with regards to performance-related aspects, such as pacing. The aim of the present study was to examine the effect of nationality on pacing strategies of XC skiers who finished the "Vasaloppet" from 2004 to 2017. We studied 183,919 finishers (19,465 women and 164,454 men), classified into 15 nationalities, i.e. nationalities with number of finishers larger than 0.25% of the total number of finishers. In women, athletes from Russia (7:47:46 h:min:s) were the fastest and athletes from Denmark (10:01:03 h:min:s) the slowest (p < 0.001, η2 = 0.057). In men, athletes from Russia (6:33:03 h:min:s) were the fastest and athletes from Denmark (9:03:27 h:min:s) the slowest (p < 0.001, η2 = 0.069). In women and men, a small nationality× split interaction on speed was observed (p < 0.001, η2 = 0.016–0.019) with Russians presenting a more even pacing compared to their slower counterparts. It was concluded that fast nationalities present a more even pacing, which should be attributed to the general trend of fast athletes for a more even pacing. [ABSTRACT FROM AUTHOR]

Biomechanical differences in double poling (DP) between sex and performance level were investigated in female and male cross-country skiers during a classical race (10/15 km). Skiers were divided into faster and slower on basis of race performance: females faster (n=20), females slower (n=20), males faster (n=20), and males slower (n=20). Based on video analysis while DP in a flat section of the track, joint and pole angles at pole plant (PP) and pole-off, cycle characteristics and the use and coordination pattern of heel-raise (raise of heels from the ground to have a higher body position at PP) were analysed. Faster females and males had 4.3% and 7.8% higher DP velocity than their slower counterparts (both P<0.001). Faster males had 6.5% longer cycles than slower males (P<0.001). Faster skiers stopped heel-raise later than slower skiers (females: 2.0±3.4% vs. −1.0±3.5%, P<0.05; males: 3.9±2.4% vs. 0.8±3.2% of cycle time in relation to PP, P<0.001). At PP, faster skiers and male skiers had a smaller pole angle and greater ankle to hip and ankle to shoulder angle with respect to vertical, resulting in a more distinct forward body lean. However, the majority of the differences are likely due to higher DP velocity. [ABSTRACT FROM AUTHOR]

The aim of the present study was to examine the performance× age interaction on pacing in cross-country (XC) skiing. We analyzed all finishers (n = 79,722) who competed in "Vasaloppet" from 2012 to 2017 grouped in performance quartiles according to their race time with Q1 as the fastest and Q4 as the slowest. Women (44.1 ± 10.2%) had larger pace range than men (40.9 ± 11.8%; p < 0.001, η2 = 0.014). The pace range ranged from 29.8 ± 7.1% (Q1) to 49.0 ± 10.1% (Q4; p < 0.001, η2 = 0.179). In women and men, smaller differences in pace range among age groups for the faster performance groups were observed (p < 0.001, η2 = 0.014, η2 = 0.008, respectively). In summary, fast XC skiers adopted relatively even pacing independent of their age, and the older XC skiers adopted more even pacing than their younger counterparts of similar performance level suggesting that differences among age groups are performance-dependent. [ABSTRACT FROM AUTHOR]

Pacing strategies in cross-country skiing have been investigated in several studies. However, none of the previous studies have been verified by collected skiing data giving the skiing velocities along a measured track. These can be used to calculate the propulsive power output. Collected real-time positioning data from a cross-country sprint skiing race were used to estimate the propulsive power by applying a power balance model. Analyses were made for the time-trial and the final for one female and one male skier. The average propulsive power over the whole race times were 311 and 296 W during the time trial and 400 and 386 W during the final, for the female and male skier, respectively. Compared to the average propulsive power over the whole race, the average active propulsive phases were calculated as 33 and 44% higher in the time trials and 36 and 37% higher in the finals for the female and male, respectively. The current study presents a novel approach to use real-time positioning data to estimate continuous propulsive power during cross-country sprint skiing, enabling in-depth analyses of power output and pacing strategies. [ABSTRACT FROM AUTHOR]

Graph The sad news came to us of Peter Sleight's passing on 7 October 2020. He suffered from a stroke few years ago and a note reached us from Christopher Sleight, Peter's oldest son: 'My sad news is that Peter died peacefully on Wednesday evening at The Old Prebendal House. In 1964, consultant cardiologist Peter Sleight in conjunction with cardiac surgeon Alf Gunning from South Africa performed one of the first pioneering operations to install an external Lucas cardiac pacemaker in a patient in her early 30s at the Radcliffe Infirmary in Oxford. [Extracted from the article]

Objectives: Pacing strategies have mainly been investigated for runners, but little is known for cross-country skiers. The aim of the present study was to investigate whether differences in pacing strategies do exist between younger and older cross-country skiers competing in the 42 km ‘Engadin Ski Marathon’. Methods: Pacing was studied in 105,565 cross-country skiers (classified in 5-year age groups) competing between 1998 and 2016 in this race by examining changes of mean section velocity in 10 km (Change A, i.e. 100×(velocity in the 10-20 km section - velocity in the 0-10 km section)/velocity in the 0-10 km section), 20 km (Change B) and 35 km (Change C). Results: A small sex×distance (i.e. Change A versus Change B versus Change C) interaction on change of velocity was shown (P < .001, η2 = 0.016), with women showing a less even pacing than men. In women, there was a trivial main effect of age group on Change A (P < .001, η2 = 0.008) with a smaller decrease in velocity in age group <20 (−7.4%) and larger decrease in velocity in age group 75-79 (−12.8%), and Change B (P = .006, η2 = 0.004) with smaller increase in velocity in age group 75-79 (+30.6%) and larger increase in velocity in age group 40-44 (+37.7%), but not on Change C (P = .784, η2 = 0.003). In men, a small main effect of age group on Change A was shown (P < .001, η2 = 0.019), with a smaller decrease of velocity in age group <20 (−3.5%) and larger in age group 70-74 (−10.5%). Trivial main effects of age group on Change B (P < .001, η2 = .002), with a smaller increase of velocity in age group 85-89 (+25.8%) and larger increase in age group 70-74 (+33.0%), and Change C (P < .001, η2 = 0.003), with smaller decrease of velocity in age group 85-89 (−38.2%) and larger decrease in age group 80-84 (−41.0%), were found. Conclusions: Based on these findings, it was concluded that men and young cross-country skiers had a more even pacing than women and older cross-country skiers, which was in contrast with previous findings in other endurance sports, suggesting that the sex- and age-related differences in pacing might be sport-dependent. [ABSTRACT FROM AUTHOR]

Demographic and performance data from 197,825 athletes competing in "Engadin Ski Marathon" between 1998 and 2016 were analysed. When all finishers per age group were considered, there was no gender difference in time (2:59:00 in women versus 2:59:09 h:min:s in men; P = 0.914, η2 < 0.001) and the main effect of age group on time was trivial (P < 0.001, η2 = 0.007). When the top 10 finishers per age group were considered, men were faster than women (1:27:32 versus 1:34:19 h:min:s, respectively; P < 0.001, η2 = 0.373), there was a large effect of age group on time (P < 0.001, η2 = 0.590) and the gender difference was larger in the older than in the younger age groups (P < 0.001, η2 = 0.534). The age of peak performance for all finishers by 1-year interval age group was 40.3 and 39.6 years in all women and men, respectively. The top 10 finishers by 1-year interval age group achieved their peak performance in the age of 38.4 and 42.2 years in women and men, respectively. The age of peak performance was older and the age-related performance decline occurred earlier in marathon cross-country skiing, compared to road-based marathon running. [ABSTRACT FROM AUTHOR]

The aim of this study was to advance current movement analysis methodology to enable a technique analysis in sports facilitating (1) concurrent comparison of the techniques between several athletes; (2) identification of potentially beneficial technique modifications and (3) a visual representation of the findings for feedback to the athletes. Six elite cross-country skiers, three world cup winners and three national elite, roller ski skated using the V2 technique on a treadmill while their movement patterns were recorded using 41 reflective markers. A principal component analysis performed on the marker positions resulted in multi-segmental "principal" movement components (PMs). A novel normalisation facilitated comparability of the PMs between athletes. Additionally, centre of mass (COM) trajectories were modelled. We found correlations between the athletes' performance levels (judged from race points) and specific features in the PMs and in the COM trajectories. Plausible links between COM trajectories and PMs were observed, suggesting that better performing skiers exhibited a different, possibly more efficient use of their body mass for propulsion. The analysis presented in the current study revealed specific technique features that appeared to relate to the skiers' performance levels. How changing these features would affect an individual athlete's technique was visualised with animated stick figures. [ABSTRACT FROM AUTHOR]

To characterise timing of movements and evaluate performance effects of technique alterations in V2 ski skating, 13 elite male cross-country skiers (age, 23 ± 2 years; stature, 182 ± 6 cm; body mass, 76 ± 8 kg; V2 VO2max, 79.3 ± 4.4 mL · kg-1 · min-1) were tested four times during the preparation and competition phase on a roller ski treadmill. Each test consisted of submaximal intensities of exercise for determination of oxygen cost followed by one 1000-m performance test. Hip movement (from accelerometer data) and joint angles (2D video) were determined for high-intensity exercise (6° and 3.5 m · s-1; ~ 97-100% of VO2peak). Each ski thrust consisted of three phases: gliding phase (18-50% of cycle time), poling phase (50-70% of cycle time), and kick phase (70-78% of cycle time). Flexion/extension of the hip initiated all phases, followed by the respective joints in legs and arms. Mixed-model analysis, adjusting for systematic time-point effects, identified that both reduced vertical hip acceleration and increased cycle time gave a small likely reduction in oxygen cost and 1000-m time. In conclusion, well-developed hip movement is a key characteristic of the V2 technique for elite-standard skiers' long-term performance development. [ABSTRACT FROM AUTHOR]

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Skiing underwent substantial changes during the post-war years when the sport turned into a multi-billion dollar industry and a leisure activity for the masses. Despite its global nature and popularity, skiing in academic writing has not gained much recognition. This paper explores the role of knowledge transfer during the pioneering phase of post-war skiing in Australia. It describes the life of Charles William Anton, an Austrian refugee from theAnschlusswho migrated to Sydney and subsequently became one of the founding fathers of Australian post-war skiing. The following pages show the multi-layered nature of skiing as a global sport by exemplifying how ideas spread from pre-war Europe to post-war Australia. The paper will also provide a case study about refugee knowledge transfer and the ‘productive process of absorption, adoption or rejection of knowledge’ that takes place once an idea has been introduced into a new environment. [ABSTRACT FROM AUTHOR]

Micro-sensors were used to quantify macro kinematics of classical cross-country skiing techniques and measure cycle rates and cycle lengths during on-snow training. Data were collected from seven national level participants skiing at two submaximal intensities while wearing a micro-sensor unit (MinimaxX™). Algorithms were developed identifying double poling (DP), diagonal striding (DS), kick-double poling (KDP), tucking (Tuck), and turning (Turn). Technique duration (T-time), cycle rates, and cycle counts were compared to video-derived data to assess system accuracy. There was good reliability between micro-sensor and video calculated cycle rates for DP, DS, and KDP, with small mean differences (Mdiff% = −0.2 ± 3.2, −1.5 ± 2.2 and −1.4 ± 6.2) and trivial to small effect sizes (ES = 0.20, 0.30 and 0.13). Very strong correlations were observed for DP, DS, and KDP for T-time (r = 0.87–0.99) and cycle count (r = 0.87–0.99), while mean values were under-reported by the micro-sensor. Incorrect Turn detection was a major factor in technique cycle misclassification. Data presented highlight the potential of automated ski technique classification in cross-country skiing research. With further refinement, this approach will allow many applied questions associated with pacing, fatigue, technique selection and power output during training and competition to be answered. [ABSTRACT FROM PUBLISHER]

An effective start enhances an athlete's chances of success in ski cross competitions. Accordingly, this study was designed to investigate the biomechanics of start techniques used by elite athletes and assess the influence of different start environments. Seven elite ski cross athletes performed starts indoors on a custom-built ramp; six of these also performed starts on an outdoor slope. Horizontal and vertical forces were measured by force transducers located in the handles of the start gate and a 12-camera motion capture system allowed monitoring of the sagittal knee, hip, shoulder, and elbow kinematics. The starting movement involved Pre, Pull, and Push phases. Significant differences between body sides were observed for peak vertical and resultant forces, resultant impulse, and peak angular velocity of the shoulder joint. Significantly lower peak vertical forces (44 N), higher resultant impulse (0.114 Ns/kg), and knee joint range of motion (12°) were observed indoors. Although movement in the ski cross start is generally symmetrical, asymmetric patterns of force were observed among the athletes. Two different movement strategies, i.e. pronounced hip extension or more accentuated elbow flexion, were utilised in the Pull phase. The patterns of force and movement during the indoor and outdoor starts were similar. [ABSTRACT FROM PUBLISHER]

Elite sport organizations invest considerable efforts in continuous evaluation of training and development. A key challenge is to promote athletes’′ reliable learning. This requires critical reflection. In this paper we look at how highly successful elite cross-country skiers reflect on their training. The theoretical framework of organizational mindfulness and reliable learning directs attention to three key mechanisms that influence reflection: socialization, sensemaking and interpretation. We identified an inherent tension in the way athletes are socialized into elite athletes. On the one hand, they internalize strong beliefs in key success factors. Such beliefs serve as a normative framework that provides commitment and enthusiasm. However, strong beliefs may weaken the athletes’ ability to notice ambiguous feedback signals in complex training situations. We found four different styles of reflection, but only one of them is consistent with requirements for reliable learning. [ABSTRACT FROM PUBLISHER]

The aim of this study was to observe the cardiovascular demands by monitoring the heart rate (HR) and the pacing strategy by evaluating the speed during a simulated cross-country skiing race. Eleven skiers (16.45 ± 1.67 yrs; 21.32 ± 2.03 kg m–2; 72.35 ± 4.69 mL min–1kg–1) competed in a 10km event divided into four laps. The HR profile was classified into four intensity zones. The skiers spent 66.84 ± 23.64% and 31.82 ± 23.77% of the total time above 90% and at 80 – 90% of the HRmaxrespectively, whereas the lower zones were negligible. During the event, a progressive increase in intensity was observed: HRmeanraised by 2.42% in the last versus the first lap (p< 0.001). The skiers decreased their speed in the second (p= 0.017) and the third laps (p< 0.001) compared to with the first lap. In the fourth lap the skiers increased the speed slightly but without statistical difference. The speed maintained by the skiers resulted in the adoption of a reverse J-shaped pacing strategy. [ABSTRACT FROM AUTHOR]

Cycle and force characteristics were examined in 11 elite male cross-country skiers using the diagonal stride technique while skiing uphill (7.5°) on snow at moderate (3.5 ± 0.3 m/s), high (4.5 ± 0.4 m/s), and maximal (5.6 ± 0.6 m/s) velocities. Video analysis (50 Hz) was combined with plantar (leg) force (100 Hz), pole force (1,500 Hz), and photocell measurements. Both cycle rate and cycle length increased from moderate to high velocity, while cycle rate increased and cycle length decreased at maximal compared to high velocity. The kick time decreased 26% from moderate to maximal velocity, reaching 0.14 s at maximal. The relative kick and gliding times were only altered at maximal velocity, where these were longer and shorter, respectively. The rate of force development increased with higher velocity. At maximal velocity, sprint-specialists were 14% faster than distance-specialists due to greater cycle rate, peak leg force, and rate of leg force development. In conclusion, large peak leg forces were applied rapidly across all velocities and the shorter relative gliding and longer relative kick phases at maximal velocity allow maintenance of kick duration for force generation. These results emphasise the importance of rapid leg force generation in diagonal skiing. [ABSTRACT FROM PUBLISHER]

Although today's ski waxing chemicals and micro-machining techniques of the ski base are highly sophisticated, objective procedures for testing and verification of the results have not yet been developed and evaluation is based on comparison of subjective experience. The purpose of the present study was thus to compare different setups for testing the glide of cross-country skis. Two differently waxed ski pairs were tested for glide inside a ski tunnel. Inertial measurement units (IMUs) were attached to each ski; instantaneous velocities monitored by three different speed-traps; the velocities during the acceleration phase determined by Doppler radar. Kinetic, potential and total energy, giving the energy dissipation, were calculated for four representative trials during the acceleration phase. No reliable data were obtained from the IMUs due to high drift. The mean maximal velocity for the two ski pairs were 6.97,s = 0.09 and 6.70,s = 0.09 m·s − 1, respectively. Higher differences between the skis were identified during the retardation phase compared to the acceleration phase. The mean difference between the velocities determined by the speed-trap and Doppler radar was 0.6,s = 1%, demonstrating that the latter provides accurate data for evaluation of gliding characteristics and performance. However, theoretical confirmation of the friction coefficient, on the basis of data provided by Doppler radar and energy calculations requires exact measurements of the inclination and topography of the track in question. [ABSTRACT FROM PUBLISHER]

The purpose of this study was to: 1) establish the optimal body-mass exponent for maximal oxygen uptake (O2max) to indicate performance in elite-standard men cross-country skiers; and 2) evaluate the influence of course inclination on the body-mass exponent. Twelve elite-standard men skiers completed an incremental treadmill roller-skiing test to determineO2max and performance data came from the 2008 Swedish National Championship 15-km classic-technique race. Log-transformation of power-function models was used to predict skiing speeds. The optimal models were found to be: Race speed = 7.86 ·O2max ·m−0.48and Section speed = 5.96 ·O2max ·m−(0.38 + 0.03 · α)· e−0.003 · Δ(wheremis body mass, α is the section’s inclination and Δ is the altitude difference of the previous section), that explained 68% and 84% of the variance in skiing speed, respectively. A body-mass exponent of 0.48 (95% confidence interval: 0.19 to 0.77) best describedO2max as an indicator of performance in elite-standard men skiers. The confidence interval did not support the use of either “1” (simple ratio-standard scaled) or “0” (absolute expression) as body-mass exponents for expressingO2max as an indicator of performance. Moreover, results suggest that course inclination increases the body-mass exponent forO2max. [ABSTRACT FROM PUBLISHER]

The purpose of this study was to evaluate the behaviour of cross-country ski poles during double poling on a treadmill using three-dimensional kinematics. The results were compared with standard laboratory tests of the pole manufacturers. A total of 18 skiers were analysed at two speeds (85% and 95% of the maximal speed) at grades of 1.5% and 7%. Variables describing cycle characteristics, bending stiffness, bending behaviour, and trajectories of the pole markers were analysed. Triangular-shaped poles demonstrated the greatest stiffness and lowest variability in maximal bending. Softer poles demonstrated greater variability in bending behaviour and lost ground contact at high skiing speeds, which for some skiers resulted in failure to complete high-speed tests. Considerable variations in pole behaviour for similar poles between skiers were observed, which might be attributed to differences in technique, indicating that mechanical properties of the poles did not exclusively determine pole behaviour in the dynamic situation. The greatest magnitude of pole bending was in the middle part of the pole, which differed from the standard static pole analysis of the manufacturer. Increases in grade demonstrated the greatest effect on pole bending. Distinct differences from the pole manufacturers' laboratory measures were apparent, suggesting that basic pole testing might be adapted. [ABSTRACT FROM PUBLISHER]

In this study, changes in skiing performance and poling kinetics during a simulated cross-country sprint skiing competition were investigated. Twelve elite male cross-country skiers performed simulated sprint competition (4 × 1,150 m heat with 20 min recovery between the heats) using the double-poling technique. Vertical and horizontal pole forces and cycle characteristics were measured using a force plate system (20-m long) during the starting spurt, racing speed, and finishing spurt of each heat. Moreover, heat and 20-m phase velocities were determined. Vertical and horizontal pole impulses as well as mean cycle length were calculated. The velocities of heats decreased by 2.7 ± 1.7% (p = 0.003) over the simulated competition. The 20-m spurting velocity decreased by 16 ± 5% (p < 0.002) and poling time increased by 18 ± 9% (p < 0.003) in spurt phases within heats. Vertical and horizontal poling impulses did not change significantly during the simulation; however, the mean forces decreased (p < 0.039) (vertical by 24 ± 11% and horizontal by 20 ± 10%) within heats but not between the heats. Decreased heat velocities over the simulated sprint and spurting velocities within heats indicated fatigue among the skiers. Fatigue was also manifested by decreased pole force production and increased poling time. [ABSTRACT FROM PUBLISHER]

The purpose of this study was to investigate teammate interpersonal influence in individual sport. Fourteen elite individual sport athletes (i.e., 6 mid- to long-distance runners, 6 cross country skiers, 1 mountain biker, and 1 wrestler) participated in semi-structured qualitative interviews exploring their sport experiences with teammates. Athletes suggested that teammates were a primary source of motivation, social facilitation, social comparisons, and teamwork. Athletes also described how concepts such as cohesion and competitiveness acted as determinants of interpersonal influence. Group experiences are influential for individual sport athletes, and the management of group processes is an important concern for coaches and practitioners. [ABSTRACT FROM PUBLISHER]

This study is on how leg utilisation may affect skiing efficiency and performance in double-poling ergometry. Three experiments were conducted, each with a different style of the double-poling technique: traditional with small knee range-of-motion and fixed heels (TRAD); modern with large knee range-of-motion and fixed heels (MOD1) and modern with large knee range-of-motion and free heels (MOD2). For each style, motion data were extracted with automatic marker recognition of reflective markers and applied to a 3D full-body musculoskeletal simulation model. Skiing efficiency (skiing work divided by metabolic muscle work) and performance (forward impulse) were computed from the simulation output. Skiing efficiency was 4.5%, 4.1% and 4.1% for TRAD, MOD1 and MOD2, respectively. Performance was 111, 143 and 149 Ns for TRAD, MOD1 and MOD2, respectively. Thus, higher lower body utilisation increased the performance but decreased the skiing efficiency. These results demonstrate the potential of musculoskeletal simulations for skiing efficiency estimations. [ABSTRACT FROM AUTHOR]

Recent developments in cross-country ski racing should promote the use of kick double poling. This technique, however, has not been the focus in athletes' training and has barely been investigated. The aims of the present study were to develop a function-based phase definition and to analyse speed adaptation mechanisms for kick double poling in elite cross-country skiers. Joint kinematics and pole/plantar forces were recorded in 10 athletes while performing kick double poling at three submaximal roller skiing speeds. A speed increase was associated with increases in cycle length and rate, while absolute poling and leg push-off durations shortened. Despite maintained impulses of force, the peak and average pole/leg forces increased. During double poling and leg push-off, ranges of motion of elbow flexion and extension increased (p < 0.05) and were maintained for hip/knee flexion and extension. Cycle length increase was correlated to increases in average poling force (r = 0.71) and arm swing time (r = 0.88; bothp < 0.05). The main speed adaptation was achieved by changes in double poling technique; however, leg push-off showed high variability among elite skiers, thus illustrating important aspects for technique training. [ABSTRACT FROM PUBLISHER]

The purpose of the present study was to establish the most appropriate allometric model to predict mean skiing speed during a double-poling roller skiing time-trial using scaling of upper-body power output. Forty-five Swedish junior cross-country skiers (27 men and 18 women) of national and international standard were examined. The skiers, who had a body mass (m) of 69.3 ± 8.0 kg (mean ± s), completed a 120-s double-poling test on a ski ergometer to determine their mean upper-body power output (W). Performance data were subsequently obtained from a 2-km time-trial, using the double-poling technique, to establish mean roller skiing speed. A proportional allometric model was used to predict skiing speed. The optimal model was found to be: Skiing speed = 1.057 ·W 0.556·m−0.315, which explained 58.8% of the variance in mean skiing speed (P < 0.001). The 95% confidence intervals for the scaling factors ranged from 0.391 to 0.721 forWand from −0.626 to −0.004 form. The results in this study suggest that allometric scaling of upper-body power output is preferable for the prediction of performance of junior cross-country skiers rather than absolute expression or simple ratio-standard scaling of upper-body power output. [ABSTRACT FROM PUBLISHER]