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https://www.readbyqxmd.com/read/28810170/the-role-of-speed-and-incline-in-the-spontaneous-choice-of-technique-in-classical-roller-skiing
#1
Gertjan Ettema, Espen Kveli, Magne Øksnes, Øyvind Sandbakk
Cross-country skiers change technique depending on terrain (incline) and effort (work rate; speed at a particular incline or resistance). The literature is not unequivocal about the influence of incline or speed on the choice of technique, i.e., which of these act as a 'control parameter'. Identifying task related control parameters for spontaneous technique shifts assists elucidating which mechanisms are active for triggering technique transitions. The aim of this study was to investigate whether speed or incline acted as such control parameter for technique shifts during classic style roller skiing...
August 12, 2017: Human Movement Science
https://www.readbyqxmd.com/read/28782598/physiological-and-performance-effects-of-nitrate-supplementation-during-roller-skiing-in-normoxia-and-normobaric-hypoxia
#2
Linn Nybäck, Caroline Glännerud, Gustav Larsson, Eddie Weitzberg, Oliver Michael Shannon, Kerry McGawley
The present study examined the effects of acute nitrate (NO3(-)) supplementation ingested in the form of concentrated beetroot juice on cross-country roller-ski performance in normoxia (N) and normobaric hypoxia (H). Eight competitive cross-country skiers (five males: age 22 ± 3 years, V·O2max 71.5 ± 4.7 mL kg(-1)·min(-1); three females: age 21 ± 1 years, V·O2max 58.4 ± 2.5 mL kg(-1)·min(-1)) were supplemented with a single dose of NO3(-)-rich beetroot juice (BRJ, ∼13 mmol NO3(-)) or a NO3(-)-depleted placebo (PL, ∼0 mmol NO3(-)) and performed 2 x 6-min submaximal exercise bouts and a 1000-m time-trial (TT) on a treadmill in N (20...
August 4, 2017: Nitric Oxide: Biology and Chemistry
https://www.readbyqxmd.com/read/28769849/an-inverse-relative-age-effect-in-male-alpine-skiers-at-the-absolute-top-level
#3
Øyvind Bjerke, Arve Vorland Pedersen, Tore K Aune, Håvard Lorås
The Relative Age Effect (RAE) can be described as the advantage of being born early after a certain cut-off date within a group of selection. The effect has been found across a wide range of sports and is particularly evident in pre-elite sports and team sports with a high selection pressure. At the absolute top level in team elite sports, the advantage of being relatively older has been reported to disappear, and even reverse, so that the relatively younger athletes are advantaged. In order to further examine such a reversal of the RAE, we investigated the performance of the overall top 50 skiers each year in the alpine World Cup, over a period of 20 years, among men (N = 234) and women (N = 235)...
2017: Frontiers in Psychology
https://www.readbyqxmd.com/read/28763504/full-course-macro-kinematic-analysis-of-a-10-km-classical-cross-country-skiing-competition
#4
Finn Marsland, Colin Mackintosh, Hans-Christer Holmberg, Judith Anson, Gordon Waddington, Keith Lyons, Dale Chapman
In this study micro-sensors were employed to analyse macro-kinematic parameters during a classical cross-country skiing competition (10 km, 2-lap). Data were collected from eight male participants during the Australian championship competition wearing a single micro-sensor unit (MinimaxX™, S4) positioned on their upper back. Algorithms and visual classification were used to identify skiing sub-techniques and calculate velocities, cycle lengths (CL) and cycle rates (CR) over the entire course. Double poling (DP) was the predominant cyclical sub-technique utilised (43 ± 5% of total distance), followed by diagonal stride (DS, 16 ± 4%) and kick double poling (KDP, 5 ± 4%), with the non-propulsive Tuck technique accounting for 24 ± 4% of the course...
2017: PloS One
https://www.readbyqxmd.com/read/28746948/-factors-associated-with-safety-knowledge-on-alpine-ski%C3%A2-slopes
#5
Gerhard Ruedl, Elena Pocecco, Friedrich Brunner, Klaus Greier, Carolin Hildebrandt, Christian Raschner
Background The jurisdiction after a winter sport accident including a third party fault considers the 10 rules for safe skiing/snowboarding introduced by the International Ski Federation (FIS) to clarify the question of liability. A previous study revealed that beginners, young skiers and those who were not local residents displayed insufficient safety knowledge in given situations. The aim of this study was to evaluate additional factors associated with safety knowledge on ski slopes, e. g. type of winter sport, helmet use, risk taking behavior, and a previous injury occurred on a ski slope...
July 26, 2017: Sportverletzung Sportschaden: Organ der Gesellschaft Für Orthopädisch-Traumatologische Sportmedizin
https://www.readbyqxmd.com/read/28744166/intramyocellular-lipids-of-muscle-type-in-athletes-of-different-sport-disciplines
#6
Yoshinao Nakagawa, Masaaki Hattori
The present study used magnetic resonance spectroscopy ((1)H-MRS) to examine quantitative differences in intramyocellular lipid (IMCL) contents in various muscle types at rest for individual athletes from different sport disciplines. Five groups consisting of sprinters, alpine skiers, cross-country skiers, endurance runners and untrained healthy male subjects volunteered for this study. Data were acquired using (1)H-MRS from the tibialis anterior (TA), medial gastrocnemius (MG) and soleus (SOL) muscles. No significant difference was found in the cross-sectional area (CSA) of the TA, MG and SOL muscles, whereas the CSA of subcutaneous fat was significantly lower (p<0...
2017: Open Access Journal of Sports Medicine
https://www.readbyqxmd.com/read/28738884/health-status-and-health-behaviors-among-citizen-endurance-nordic-skiers-in-the-united-states
#7
Paul J Anderson, Ralph S Bovard, Mohammad Hassan Murad, Timothy J Beebe, Zhen Wang
BACKGROUND: More than two-thirds of Americans are overweight or obese (69%) placing them at high risk for a wide array of chronic diseases. Physical activity anchors most approaches to obesity prevention and weight management, but physical activity levels remain low in the general US population. As a group, citizen athletes who compete in Nordic skiing events such as the American Birkebeiner participate in fitness cultures that promote physical activity. METHODS: During October-November 2014, we emailed a 48 question online survey to 23,611 individuals who had participated in the American Birkebeiner ski event, the largest citizen ski race in North America...
July 24, 2017: BMC Research Notes
https://www.readbyqxmd.com/read/28713458/trunk-strength-characteristics-of-elite-alpine-skiers-a-comparison-with-physically-active-controls
#8
Carolin Hildebrandt, Lisa Müller, Christian Heisse, Christian Raschner
Core muscle imbalances and weak trunk strength are relevant for injury prevention and performance. Information regarding core strength requirements and ideal flexion/extension ratios in alpine skiing is limited. We aimed to compare trunk strength capacities in elite alpine skiers with those of a matched control group. The concentric maximal trunk flexion and extension of 109 elite skiers and 47 active controls were measured at 150°/s in a ballistic mode using the CON-TREX® TP 1000 test system. The relative flexion peak torque was higher in male ski racers (p = 0...
June 2017: Journal of Human Kinetics
https://www.readbyqxmd.com/read/28713454/balance-basic-anthropometrics-and-performance-in-young-alpine-skiers-longitudinal-analysis-of-the-associations-during-two-competitive-seasons
#9
Blaz Lesnik, Damir Sekulic, Matej Supej, Michael R Esco, Milan Zvan
Balance is hypothesized to be important in alpine skiing, while it is known that balance depends on anthropometric indices. The aim of this investigation was to explore the association between balance, anthropometrics and skiing-results over two competitive seasons among youth alpine-skiers. Eighty-one skiers (40 females) participated in this study. The participants were tested twice over two competitive seasons: when they were 12-13 years old (U14) and when they were 14-15 years old (U16). The variables consisted of anthropometrics (body height and body mass) and three balance indexes (medio-lateral-, anterio-posterior- and overall-stability-index)...
June 2017: Journal of Human Kinetics
https://www.readbyqxmd.com/read/28689164/head-impact-velocities-in-fis-world-cup-snowboarders-and-freestyle-skiers-do-real-life-impacts-exceed-helmet-testing-standards
#10
Sophie E Steenstrup, Kam-Ming Mok, Andrew S McIntosh, Roald Bahr, Tron Krosshaug
INTRODUCTION: Prior to the 2013-2014 season, the International Ski Federation (FIS) increased the helmet testing speed from a minimum requirement of 5.4 to 6.8 m/s for alpine downhill, super-G and giant slalom and for freestyle ski cross, but not for the other freestyle disciplines or snowboarding. Whether this increased testing speed reflects impact velocities in real head injury situations on snow is unclear. We therefore investigated the injury mechanisms and gross head impact biomechanics in four real head injury situations among World Cup (WC) snowboard and freestyle athletes and compared these with helmet homologation laboratory test requirements...
July 8, 2017: British Journal of Sports Medicine
https://www.readbyqxmd.com/read/28684013/cervical-spine-alignment-in-helmeted-skiers-and-snowboarders-with-suspected-head-and-neck-injuries-comparison-of-lateral-c-spine-radiographs-before-and-after-helmet-removal-and-implications-for-ski-patrol-transport
#11
Jared Murray, David A Rust
OBJECTIVE: Current protocols for spine immobilization of the injured skier/snowboarder have not been scientifically validated. Observing changes in spine alignment during common rescue scenarios will help strengthen recommendations for rescue guidelines. METHODS: Twenty-eight healthy volunteers (18 men, 10 women) age 47±17 (range 20-73) (mean ±SD with range) underwent a mock rescue in which candidate patrollers completing an Outdoor Emergency Care course performed spine immobilization and back boarding in 3 scenarios: 1) Ski helmet on, no c-collar; 2) helmet on, with c-collar; and 3) helmet removed, with c-collar...
July 3, 2017: Wilderness & Environmental Medicine
https://www.readbyqxmd.com/read/28659826/no-additional-benefits-of-block-over-evenly-distributed-high-intensity-interval-training-within-a-polarized-microcycle
#12
Kerry McGawley, Elisabeth Juudas, Zuzanna Kazior, Kristoffer Ström, Eva Blomstrand, Ola Hansson, Hans-Christer Holmberg
Introduction: The current study aimed to investigate the responses to block- versus evenly-distributed high-intensity interval training (HIT) within a polarized microcycle. Methods: Twenty well-trained junior cross-country skiers (10 males, age 17.6 ± 1.5 and 10 females, age 17.3 ± 1.5) completed two, 3-week periods of training (EVEN and BLOCK) in a randomized, crossover-design study. In EVEN, 3 HIT sessions (5 × 4-min of diagonal-stride roller-skiing) were completed at a maximal sustainable intensity each week while low-intensity training (LIT) was distributed evenly around the HIT...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28649805/cross-country-skiing-movement-factorization-to-explore-relationships-between-skiing-economy-and-athletes-skills
#13
Barbara Pellegrini, Chiara Zoppirolli, Gennaro Boccia, Lorenzo Bortolan, Federico Schena
We investigated the relationships between the biomechanics of the double poling (DP) technique in cross-country skiing, its economy and athletes' skill. To this aim, skiers' motion has been factorized into components through principal component analysis (PCA).Eight high-level (HL) and eight regional level (RL) male cross-country skiers performed a 5-min submaximal DP trial while roller skiing on a treadmill at 14 km h(-1) and 2° incline. Whole-body kinematics was recorded with a motion capture system. PCA was applied to markers coordinates to extract principal movements (PMk ), which were ranked by their variance...
June 26, 2017: Scandinavian Journal of Medicine & Science in Sports
https://www.readbyqxmd.com/read/28639688/pronounced-limb-and-fibre-type-differences-in-subcellular-lipid-droplet-content-and-distribution-in-elite-skiers-before-and-after-exhaustive-exercise
#14
Han-Chow E Koh, Joachim Nielsen, Bengt Saltin, Hans-Christer Holmberg, Niels Ørtenblad
KEY POINTS: Although lipid droplets in skeletal muscle are an important energy source during endurance exercise, our understanding of lipid metabolism in this context remains incomplete. Using transmission electron microscopy, two distinct subcellular pools of lipid droplets can be observed in skeletal muscle - one beneath the sarcolemma and the other between myofibrils. At rest, well-trained leg muscles of cross-country skiers contain 4- to 6-fold more lipid droplets than equally well-trained arm muscles, with a 3-fold higher content in type 1 than in type 2 fibres...
June 22, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28603377/effect-of-prolonged-racing-on-muscle-activity-and-spatiotemporal-variables-double-poling-technique
#15
Kitae Kim, Siddhartha Bikram Panday, In-Sik Shin, Jin-Hae Kim, Hye-Young Kim, Gwang-Jae Yu
[Purpose] The purpose of this study was to examine the effect of a 40-minute race on muscle activity and spatiotemporal cycle variables at four-time points during a 12-km roller skiing test using the double-poling technique. [Subjects and Methods] Five elite cross-country (XC) skiers on the Korean National reserve team participated in the study. Part of a biathlon course that consisted of both flat land and slopes was selected, and three measurements were recorded after every 4-km lap. Spatiotemporal variables, mean frequency and mean amplitude of 6 muscles were the chosen computational parameters...
May 2017: Journal of Physical Therapy Science
https://www.readbyqxmd.com/read/28597103/the-effects-of-strength-training-versus-ski-ergometer-training-on-double-poling-capacity-of-elite-junior-cross-country-skiers
#16
Tomas Carlsson, Lars Wedholm, Johnny Nilsson, Magnus Carlsson
PURPOSE: To compare the effects of strength training versus ski-ergometer training on double-poling gross efficiency (GE), maximal speed (V max), peak oxygen uptake ([Formula: see text]) for elite male and female junior cross-country skiers. METHODS: Thirty-three elite junior cross-country skiers completed a 6-week training-intervention period with two additional 40-min training sessions per week. The participants were matched in pairs and within each pair randomly assigned to either a strength-training group (STR) or a ski-ergometer-training group (ERG)...
August 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28559075/impact-of-prehospital-transportation-on-survival-in-skiers-and-snowboarders-with-traumatic-brain-injury
#17
Hai Sun, Navdeep S Samra, Piyush Kalakoti, Kanika Sharma, Devi Prasad Patra, Rimal H Dossani, Jai Deep Thakur, Elizabeth A Disbrow, Kevin Phan, Sreenivas P Veeranki, Aqueel Pabaney, Christina Notarianni, John T Owings, Anil Nanda
INTRODUCTION: Prehospital helicopter use and its impact on outcomes in snowboarders and skiers incurring traumatic brain injury (TBI) is unknown. The present study investigates the association of helicopter transport with survival of snowboarders and skiers with TBI, in comparison with ground emergency medical services (EMS), by using data derived from the National Trauma Data Bank (2007-2014). METHODS: Primary and secondary endpoints were defined as in-hospital survival and absolute risk reduction based upon number needed to transport (treat) respectively...
August 2017: World Neurosurgery
https://www.readbyqxmd.com/read/28558914/numerical-investigation-of-the-early-flight-phase-in-ski-jumping
#18
N Gardan, A Schneider, G Polidori, H Trenchard, J M Seigneur, F Beaumont, F Fourchet, R Taiar
The purpose of this study is to develop a numerical methodology based on real data from wind tunnel experiments to investigate the effect of the ski jumper's posture and speed on aerodynamic forces in a wide range of angles of attack. To improve our knowledge of the aerodynamic behavior of the ski jumper and his equipment during the early flight phase of the ski jump, we applied CFD methodology to evaluate the influence of angle of attack (α=14°, 21.5°, 29°, 36.5° and 44°) and speed (u=23, 26 and 29m/s) on aerodynamic forces in the situation of stable attitude of the ski jumper's body and skis...
July 5, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28552919/methods-for-acquiring-data-on-terrain-geomorphology-course-geometry-and-kinematics-of-competitors-runs-in-alpine-skiing-a-historical-review
#19
Włodzimierz S Erdmann, Vassilis Giovanis, Piotr Aschenbrenner, Vaios Kiriakis, Andrzej Suchanowski
PURPOSE: This paper aims at the description and comparison of methods of topographic analysis of racing courses at all disciplines of alpine skiing sports for the purposes of obtaining: terrain geomorphology (snowless and with snow), course geometry, and competitors' runs. METHODS: The review presents specific methods and instruments according to the order of their historical appearance as follows: (1) azimuth method with the use of a compass, tape and goniometer instruments; (2) optical method with geodetic theodolite, laser and photocells; (3) triangulation method with the aid of a tape and goniometer; (4) image method with the use of video cameras; (5) differential global positioning system and carrier phase global positioning system methods...
2017: Acta of Bioengineering and Biomechanics
https://www.readbyqxmd.com/read/28538302/physiological-demands-of-elite-cross-country-skiing-during-a-real-competition
#20
Cristina Gonzalez-Millan, Dario Perez-Brunicardi, Juan J Salinero, Beatriz Lara, Javier Abián-Vicen, Francisco Areces, Diana Ruiz-Vicente, Lidon Soriano, Juan Del Coso
The aim of this study was to assess different physiological variables before and after a 5-km (women) and 10-km (men) cross-country skiing competition to determine potential mechanisms of fatigue. Fourteen elite-level skiers competed in an official cross-country skiing competition using the classical style (9 men and 5 women). Instantaneous skiing velocity was measured during the race by means of 15-Hz global positioning system devices. Before and after the race, a sample of venous blood was obtained to assess changes in blood lactate and serum electrolyte and myoglobin concentrations...
June 2017: Journal of Strength and Conditioning Research
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