Choice of Pole and Ski Lengths Among Elite Cross-Country Skiers: The Influence of Sex and Performance Level.
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ABSTRACT:
SUBMITTER: Torvik PO
PROVIDER: S-EPMC8100048 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:In elite cross-country skiing, double poling is used in different terrain. This study compared O2-cost and kinematics during double poling with four different pole lengths [self-selected (SS), SS - 5 cm, SS?+?5 cm, SS?+?10 cm] at Low versus Moderate incline.Thirteen highly trained male cross-country skiers (mean?±?SD 23?±?3 years; 182?±?4 cm; 77?±?6 kg) completed eight submaximal trials with roller skis on a treadmill at two conditions: "Low incline" (1.7°; 4.5 m s-1) and "Moderate incline" (4.5°; 2.5 m s-1) with each of the four pole lengths. O2-cost and 3D body kinematics were assessed in each trial.In Low incline, SS?+?10 cm induced a lower O2-cost than all the other pole lengths [P?<?0.05; effect size (ES) 0.5-0.8], whereas no differences were found between the remaining pole lengths (P?>?0.05; ES 0.2-0.4). In Moderate incline, significant differences between all pole lengths were found for O2-cost, with SS - 5 cm?>?SS?>?SS?+?5 cm?>?SS?+?10 cm (P?<?0.05; ES 0.6-1.8). The relative differences in O2-cost between SS and the other pole lengths were greater in Moderate incline than Low incline (SS?-?5 cm; 1.5%, ES 0.8, SS?+?5 cm; 1.3%, ES 1.0, and SS?+?10 cm; 1.9%, ES 1.0, all P?<?0.05). No difference was found in cycle, poling or reposition times between pole lengths. However, at both conditions a smaller total vertical displacement of center of mass was observed with SS?+?10 cm compared to the other pole lengths.Increasing pole length from SS?-?5 cm to SS?+?10 cm during double poling induced lower O2-cost and this advantage was greater in Moderate compared to Low incline.
| S-EPMC5767204 | biostudies-literature
Project description:ObjectiveThis study aimed to describe the endurance training and incidence of illnesses reported by a group of well-trained cross-country (XC) skiers throughout their transition from junior to senior level.MethodsChanges in self-reported training and performance, from 31 well-trained XC skiers, were analyzed from the start of the season they turned 16 y until the end of the season they turned 22 y, using linear mixed-effects models. Differences in the incidence of self-reported illness episodes were analyzed using incidence rate ratios, and the relationships between self-reported illness and training volumes were analyzed using linear mixed-effects models in a sub-group of 23 of the skiers.ResultsIn total, 145 seasons of training data (including 85,846 h of endurance training) and 109 person-years of illness data (including 380 self-reported illness episodes) were analyzed. The athletes progressively increased their annual endurance training volume from age 16 to 22 y in a linear fashion, from ~ 470 to 730 h. Low- and high-intensity training volumes increased by 51.4 ± 2.4 h·y-1 (p < .001) and 4.9 ± 0.6 h·y-1 (p < .001), respectively. Sport-specific and non-specific training increased by 50.0 ± 2.2 h·y-1 (p < .001) and 4.6 ± 2.0 h·y-1 (p < .001), respectively. The athletes reported a median (range) of 3 (0-8) illness episodes and 17 (0-80) days of illness per year, and there was an inverse relationship between self-reported illness days and annual training volume (-0.046 ± 0.013 d·h-1; p < .001).ConclusionsThis group of well-trained XC skiers increased their endurance training volume in a linear fashion by ~ 55 h annually. This was primarily achieved through an increase in low-intensity and sport-specific training. Furthermore, higher training volumes were associated with a lower number of self-reported illness days.
| S-EPMC8121355 | biostudies-literature
Project description:Rationale:The main purposes of this study were to compare mitochondrial respiration in M. triceps brachii and M. vastus lateralis between elite cross-country (XC) skiers and physically active controls (CON), and to explore the associations between mitochondrial respiration in these muscles and peak oxygen uptake ( V˙ O2peak) in arm- and leg-dominant exercise modes. Methods:Thirteen male elite XC skiers (age: 25 ± 4; peak oxygen uptake ( V˙ O2peak): 75.5 ± 4.2 mL⋅kg-1⋅min-1) and twelve CON (age: 26 ± 3; V˙ O2peak: 57.2 ± 6.4 mL⋅kg-1⋅min-1) had microbiopsies taken from M. vastus lateralis and M. triceps brachii, which were analyzed for various measures of mitochondrial respiration using high-resolution respirometry. Thereafter, all participants tested V˙ O2peak in both running (RUN) and upper body poling (UBP). Results:XC skiers had generally higher mitochondrial respiration in M. triceps brachii compared to CON (P < 0.001), whereas no significant group-differences in mitochondrial respiration in M. vastus lateralis were revealed. XC skiers had higher mitochondrial respiration in M. triceps brachii compared to M. vastus lateralis (P = 0.005-0.058), whereas in CON, most mitochondrial respiration measures were higher in M. vastus lateralis than in M. triceps brachii (P < 0.01). When all athletes were pooled, there was a strong positive correlation between V˙ O2peak in UBP and mitochondrial respiration in M. triceps brachii on several measures (P < 0.01), whereas no correlation was found for RUN. Conclusion:The higher mitochondrial respiration found in M. triceps brachii compared to M. vastus lateralis among our elite XC skiers demonstrates the potential for the arm muscles to adapt to aerobic endurance training. The opposite pattern found in CON, clearly showed lower mitochondrial respiration in M. triceps brachii compared to XC skiers, whereas respiration in M. vastus lateralis did not differ between groups. The strong positive correlation between mitochondrial respiration in M. triceps brachii and V˙ O2peak in UBP indicate that arm muscles' respiratory function may be a limiting factor for V˙ O2peak in arm-dominant exercise modes.
| S-EPMC6461012 | biostudies-other
Project description:Elite hospitals represent the highest level of Chinese hospitals in medical service and management, medical quality and safety, technical level and efficiency, which are also one of the important indicators reflecting high-quality medical resources in the region, and their spatial allocation is directly related to the fairness of health resource allocation. We explored the allocation pattern of high-quality resources and its influencing factors in the development of China's health system using geographic weighted regression (GWR), Multi-scale Geographically Weighted Regression (MGWR), GWR and MGWR with Spatial Autocorrelation(GWR-SAR and MGWR-SAR), spatial lag model (SLM), and spatial error model (SEM). The results of OLS regression showed that city level, number of medical colleges, urbanization rate, permanent population and GDP per capita were its significant variables. And spatial auto-correlation of elite hospitals in China is of great significance. Further, its spatial agglomeration phenomenon was confirmed through SLM and SEM. Among them, the city level is the most important factor affecting the spatial allocation of elite hospitals in China. Its action intensity shows a solid and weak mosaic trend in the Middle East, relatively concentrated in some areas with medium intensity and concentrated in the West China. Obviously, China's elite hospitals are unevenly distributed and have evident spatial heterogeneity. Therefore, we suggest that we should pay attention to the spatial governance of high-quality medical resources, attract medical elites in the region, increase investment in medical education in the scarce areas of elite hospitals and develop tele-medicine service.
| S-EPMC8481595 | biostudies-literature
Project description:BackgroundIn the last decade, a growing body of research has focused on the many aspects and challenges of combining parenthood with elite sport. Although the number of father-athletes is significantly higher than the number of mother-athletes, few studies to date have focused on male athletes' experiences in a parenting context.AimThe aims of the present study were to explore how father-athlete challenges manifest among elite Nordic skiers in Norway, and to better understand how male athletes balance their priorities as they initiate, maintain, and/or discontinue their athletic career as a father-athlete.MethodsQualitative data were collected through semi-structured interviews with 10 world-class male Nordic skiers in Norway (3 athletes without a child, 4 current father-athletes and 3 former father-athletes) and the content was analyzed using thematic analysis.ResultsFour main stages were identified in the father-athlete transition: (a) Expecting incompatibility (b) Taking the step, (c), The first blow, and (d) Finding the optimal balance. Through these stages the informants expected/had experienced challenges such as performance decline, disturbed sleeping patterns, fear of sickness and role conflicts. To manage these challenges, the father-athletes had developed various strategies to balance their dual roles (e.g., adapting training and competition seasons). Among the benefits, the father-athletes mentioned that they had become more structured, time efficient and ruthless with their priorities, enhanced motivation to train and a better work-life balance.ConclusionThis study offers valuable insights into father-athlete challenges that can be used to support career longevity and work-life balance among male athletes.
| S-EPMC11291440 | biostudies-literature
Project description:Small differences in turn cycle structure, invisible to the naked eye, could be decisive in improving descent performance. The aim of this study was to assess the influence of turn cycle structure on the performance of elite alpine skiers using an inertial measurement unit (IMU) in different slalom (SL) course settings. Four SL courses were set: a flat-turned (FT), a steep-turned (ST), a flat-straighter (FS) and a steep-straighter (SS). Five elite alpine skiers (21.2 ± 3.3 years, 180.2 ± 5.6 cm, 72.8 ± 6.6 kg) completed several runs at maximum speed for each SL course. A total of 77 runs were obtained. Fast total times correlate with a longer initiation (INI) time in FT, a shorter steering time out of the turn (STEOUT) in the FT and FS and a shorter total steering time (STEIN+OUT) in the FT and SS courses. The linear mixed model used for the analysis revealed that in the FT-course for each second increase in the INI time, the total time is reduced by 0.45 s, and for every one-second increase in the STEOUT and STEIN+OUT times, the total time increases by 0.48 s and 0.31 s, respectively. Thus, to enhance descent performance, the skier should lengthen the INI time and shorten the STEOUT and STEIN+OUT time. Future studies could use an IMU to detect turn phases and analyze them using the other built-in sensors.
| S-EPMC8838443 | biostudies-literature
Project description:IntroductionIn cross-country skiing, the repetitive ventilation of large amounts of cold and dry air strains the airways. The aim of this systematic review was to establish an overview of the current literature on asthma in cross-country skiers, biathletes and ski-orienteers.MethodsSix databases were searched on August 29, 2019. The search yielded 2161 articles. Thirty articles fulfilled the search criteria and were pooled together for a qualitative synthesis. Eight articles were included in the meta-analysis on the prevalence of asthma and the use of asthma medication.ResultsAccording to the meta-analysis, the prevalence of self-reported physician-diagnosed asthma in skiers was 21% (95% CI 14-28%). The onset age of asthma was higher in skiers than in non-skiers with asthma. The prevalence of asthma medication use was on average 23% (CI 95% 19-26%). Several studies reported that asthma was underdiagnosed in skiers, as previously healthy skiers without a prior asthma diagnosis or medication use were frequently found to fulfill diagnostic criteria for asthma according to lung function tests. Studies using bronchial biopsy demonstrated that eosinophilic asthma is not detected in skiers with asthma as often as it is in non-skiers with asthma and that there are signs of airway inflammation even in non-asthmatic skiers.ConclusionOur findings suggest that the accuracy and coverage of diagnosing asthma in skiers has improved over the recent decades. However, the optimal treatment and natural course of asthma in this population remain unclear. Future research should investigate how the intensity of training, airway infections and their treatment affect the development of asthma among skiers.Prd registration numberCRD42017070940.
| S-EPMC7575483 | biostudies-literature
Project description:PurposeThe objective of this study is to compare the physiological capacity and training characteristics of the world's six highest ranked female cross-country skiers (world class (WC)) with those of six competitors of national class (NC).MethodsImmediately before the start of the competition season, all skiers performed three 5-min submaximal stages of roller skiing on a treadmill for measurement of oxygen cost, as well as a 3-min self-paced performance test using both the double poling (DP) and diagonal stride (DIA) techniques. During the 3-min performance tests, the total distance covered, peak oxygen uptake (V˙O2peak), and accumulated oxygen deficit were determined. Each skier documented the intensity and mode of their training during the preceding 6 months in a diary.ResultsThere were no differences between the groups with respect to oxygen cost or gross efficiency at the submaximal speeds. The WC skiers covered 6%-7% longer distances during the 3-min tests and exhibited average V˙O2peak values of ∼70 and ∼65 mL·min·kg with DIA and DP, respectively, which were 10% and 7% higher than the NC skiers (all P < 0.05). However, the accumulated oxygen deficit did not differ between groups. From May to October, the WC skiers trained a total of 532 ± 73 h (270 ± 26 sessions) versus 411 ± 62 h (240 ± 27 sessions) for the NC skiers. In addition, the WC skiers performed 26% more low-intensity and almost twice as much moderate-intensity endurance and speed training (all P < 0.05).ConclusionsThis study highlights the importance of a high oxygen uptake and the ability to use this while performing the different skiing techniques on varying terrains for female cross-country skiers to win international races. In addition, the training data documented here provide benchmark values for female endurance athletes aiming for medals.
| S-EPMC5642331 | biostudies-literature
Project description:Purpose: To investigate the interaction between exercise modality (i.e., upper- and lower-body exercise) and sex in physiological responses and power output (PO) across the entire intensity spectrum (i.e., from low to maximal intensity). Methods: Ten male and 10 female cross-country (XC) skiers performed a stepwise incremental test to exhaustion consisting of 5 min stages with increasing workload employing upper-body poling (UP) and running (RUN) on two separate days. Mixed measures ANOVA were performed to investigate the interactions between exercise modalities (i.e., UP and RUN) and sex in physiological responses and PO across the entire exercise intensity spectrum. Results: The difference between UP and RUN (ΔUP-RUN), was not different in the female compared with the male XC skiers for peak oxygen uptake (18 ± 6 vs. 18 ± 6 mL·kg-1·min-1, p = 0.843) and peak PO (84 ± 18 vs. 91 ± 22 W, p = 0.207). At most given blood lactate and rating of perceived exertion values, ΔUP-RUN was larger in the male compared with the female skiers for oxygen uptake and PO, but these differences disappeared when the responses were expressed as % of the modality-specific peak. Conclusion: Modality-differences (i.e., ΔUP-RUN) in peak physiological responses and PO did not differ between the female and male XC skiers. This indicates that increased focus on upper-body strength and endurance training in female skiers in recent years may have closed the gap between upper- and lower-body endurance capacity compared with male XC skiers. In addition, no sex-related considerations need to be made when using relative physiological responses for intensity regulation within a specific exercise modality.
| S-EPMC8724206 | biostudies-literature
Project description:Simple Summary The adjustment of ski attitude during the flight period of ski jumping aims to improve the aerodynamic performance and thus enlarges the flying distance. Previous studies have measured the aerodynamic forces of an isolated ski through wind tunnel experiments; however, less information on the aerodynamic moment and underlying flow structures was provided. The biomechanic relation between the aerodynamics of the ski and the athlete’s ankle was also unknown. Using Computational Fluid Dynamics (CFD) methods, this research investigated the aerodynamic characteristics and related flow structures of a full-scale ski jumping ski in 125 attitudes. A convenient database for the aerodynamic forces and moments of the ski was established and the association between the aerodynamics of the ski and the control of the athlete’s ankle is discussed. Abstract The performance of ski jumping is underpinned by multi-disciplinary principles, in which the aerodynamics of the ski dominates the flying distance and affects the biomechanics of the athletes’ ankle during the flight period. Conventional research on this topic was supported by wind tunnel experiments. Here, the aerodynamics of a full-scale ski jumping ski was calculated via Computational Fluid Dynamics (CFD) methods and good agreement with experimental data was achieved. The impacts of the angle of attack, yaw angle, and roll angle on the aerodynamic performance are explained. The inclusion of yaw angle can enhance the lift generation, which originates from the formation of a tilted multi-vortex system and the induced low-pressure footprints on the upper surface of the ski. Our results thus establish a database for the aerodynamic forces and moments of the ski and the associations between our findings and the skills in ankle control are discussed.
| S-EPMC9138498 | biostudies-literature