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Ski Simulator

Keizo Yamamoto, Makoto Tsubokura, Jun Ikeda, Keiji Onishi, Sophie Baleriola
The purpose of this study was to investigate the effects of posture of a ski jumper on aerodynamic characteristics during the take-off using computational fluid dynamics (CFD). The CFD method adopted for this study was based on Large-Eddy Simulation. Body surface data were obtained by 3-D laser scanning of an active ski jumper. Based on video analysis of the actual take-off movement, two sets of motion data were generated (world-class jumper A and less-experienced jumper B). The inlet flow velocity that corresponds to the in-run velocity in actual ski jumping was set to 23...
October 6, 2016: Journal of Biomechanics
Robert Eberle, Dieter Heinrich, Peter Kaps, Michael Oberguggenberger, Werner Nachbauer
A common anterior cruciate ligament (ACL) injury situation in alpine ski racing is landing back-weighted after a jump. Simulated back-weighted landing situations showed higher ACL-injury risk for increasing ski boot rear stiffness (SBRS) without considering muscles. It is well known that muscle forces affect ACL tensile forces during landing. The purpose of this study is to investigate the effect of different SBRS on the maximal ACL tensile forces during injury prone landings considering muscle forces by a two-dimensional musculoskeletal simulation model...
July 26, 2016: Journal of Sports Sciences
Erik Andersson, Hans-Christer Holmberg, Niels Ørtenblad, Glenn Björklund
PURPOSE: To examine the metabolic responses and pacing strategies during the performance of successive sprint time trials (STTs) in cross-country skiing. METHODS: Ten well-trained male cross-country skiers performed four self-paced 1300-m STTs on a treadmill, each separated by 45 min of recovery. The simulated STT course was divided into three flat (1°) sections (S1, S3 and S5) involving the double poling sub-technique interspersed with two uphill (7°) sections (S2 and S4) involving the diagonal stride sub-technique...
July 12, 2016: Medicine and Science in Sports and Exercise
Melissa I Gomis, Robin Vestergren, Helena Nilsson, Ian T Cousins
The contribution of direct (i.e., uptake of perfluorooctanoic acid (PFOA) itself) and indirect (i.e., uptake of 8:2 fluorotelomer alcohol (FTOH) and metabolism to PFOA) exposure to PFOA serum concentrations was investigated using a dynamic one-compartment pharmacokinetic (PK) model. The PK model was applied to six occupationally exposed ski waxers for whom direct and indirect exposures via inhalation were characterized using multiple measurements with personal air sampling devices. The model was able to predict the diverging individual temporal trends of PFOA in serum with correlation coefficients of 0...
July 5, 2016: Environmental Science & Technology
Hyo Taek Lee, Hyo Lyun Roh, Yoon Sang Kim
[Purpose] Efficient management using exercise programs with various benefits should be provided by educational institutions for children in their growth phase. We analyzed the heart rates of children during ski simulator exercise and the Harvard step test to evaluate the cardiopulmonary endurance by calculating their post-exercise recovery rate. [Subjects and Methods] The subjects (n = 77) were categorized into a normal weight and an overweight/obesity group by body mass index. They performed each exercise for 3 minutes...
January 2016: Journal of Physical Therapy Science
Hyo Taek Lee, Hyo Lyun Roh, Yoon Sang Kim
[Purpose] Currently, various simulators are produced and used for athlete's exercise, rehabilitation, and training. In this study, we analyzed the kinematic factors of sectional and total movements in healthy participants by providing group-dependent information during simulated exercise. [Subjects and Methods] Participants in this study included 26 male adults (non-experts and experts); experts held a certificate issued by the Korea Ski Instructors Association. The elapsed times in each phase, the difference in the lower extremity angles, and muscle activity were computed through analysis of kinematic factors...
January 2016: Journal of Physical Therapy Science
Caroline Praz, Benedikt Fasel, Philippe Vuistiner, Kamiar Aminian, Bengt Kayser
PURPOSE: The purpose of this study was to estimate the energy cost of linear (EC) and vertical displacement (ECvert), mechanical efficiency and main stride parameters during simulated ski mountaineering at different speeds and gradients, to identify an optimal speed and gradient that maximizes performance. METHODS: 12 subjects roller skied on a treadmill at three different inclines (10, 17 and 24 %) at three different speeds (approximately 70, 80 and 85 % of estimated peak heart rate)...
May 2016: European Journal of Applied Physiology
E Andersson, G Björklund, H-C Holmberg, N Ørtenblad
To improve current understanding of energy contributions and determinants of sprint-skiing performance, 11 well-trained male cross-country skiers were tested in the laboratory for VO2max , submaximal gross efficiency (GE), maximal roller skiing velocity, and sprint time-trial (STT) performance. The STT was repeated four times on a 1300-m simulated sprint course including three flat (1°) double poling (DP) sections interspersed with two uphill (7°) diagonal stride (DS) sections. Treadmill velocity and VO2 were monitored continuously during the four STTs and data were averaged...
February 29, 2016: Scandinavian Journal of Medicine & Science in Sports
Teatske M Altenburg, Mai J M Chinapaw, Amika S Singh
OBJECTIVES: Evidence suggests that physical activity is positively related to several aspects of cognitive functioning in children, among which is selective attention. To date, no information is available on the optimal frequency of physical activity on cognitive functioning in children. The current study examined the acute effects of one and two bouts of moderate-intensity physical activity on children's selective attention. DESIGN: Randomized controlled trial (ISRCTN97975679)...
October 2016: Journal of Science and Medicine in Sport
Ivan Demšar, Jože Duhovnik, Blaž Lešnik, Matej Supej
The purpose of the study was to analyse the flexion angles of the ski boot, ankle and knee joints of an above-knee prosthesis and to compare them with an intact leg and a control group of skiers. One subject with an above-knee amputation of the right leg and eight healthy subjects simulated the movement of a skiing turn by performing two-leg squats in laboratory conditions. By adding additional loads in proportion to body weight (BW; +1/3 BW, +2/3 BW, +3/3 BW), various skiing regimes were simulated. Change of Flexion Angle (CoFA) and Range of Motion (RoM) in the ski boot, ankle and knee joints were calculated and compared...
December 2015: Journal of Sports Science & Medicine
Jeheon Moon, Dohoon Koo, Kitae Kim, Insik Shin, Hyeyoung Kim, Jinhae Kim
[Purpose] This study aimed to verify the effectiveness of an augmented reality-based ski simulator through analyzing the changes in movement patterns as well as the engagement of major muscles of the lower body. [Subjects] Seven subjects participated in the study. All were national team-level athletes studying at "K" Sports University in Korea who exhibited comparable performance levels and had no record of injuries in the preceding 6 months (Age 23.4 ± 3.8 years; Height 172.6 ± 12.1 cm; Weight 72.3 ± 16...
August 2015: Journal of Physical Therapy Science
B Stocks, J A Betts, K McGawley
This study investigated carbohydrate ingestion of varied doses and frequencies during a simulated cross-country skiing time trial. Ten men and three women (age: 30 ± 7 years; V ˙ O 2 m a x : 59.6 ± 5.7 mL/kg/min) completed four, 30-km classic technique roller skiing time trials on a treadmill. A 1:1 maltodextrin-fructose carbohydrate solution was provided at high (2.4 g/min; HC) and moderate (1.2 g/min; MC) ingestion rates, each at high (six feeds; HF) and low (two feeds; LF) frequencies. In the LF trials, blood glucose was elevated following carbohydrate ingestion (at 4 and 19 km) but was reduced at 14 and 29 km compared with HF strategies (P ≤ 0...
September 2016: Scandinavian Journal of Medicine & Science in Sports
Jørgen Danielsen, Øyvind Sandbakk, Hans-Christer Holmberg, Gertjan Ettema
PURPOSE: This study aims to investigate fluctuations in total mechanical energy of the body (Ebody) in relation to external ergometer work (Werg) during the poling and recovery phases of simulated double-poling cross-country skiing. METHODS: Nine male cross-country skiers (mean ± SD age, 24 ± 5 yr; mean ± SD body mass, 81.7 ± 6.5 kg) performed 4-min submaximal tests at low-intensity, moderate-intensity, and high-intensity levels and a 3-min all-out test on a ski ergometer...
December 2015: Medicine and Science in Sports and Exercise
Grega Logar, Marko Munih
This study uses inertial sensors to measure ski jumper kinematics and joint dynamics, which was until now only a part of simulation studies. For subsequent calculation of dynamics in the joints, a link-segment model was developed. The model relies on the recursive Newton-Euler inverse dynamics. This approach allowed the calculation of the ground reaction force at take-off. For the model validation, four ski jumpers from the National Nordic center performed a simulated jump in a laboratory environment on a force platform; in total, 20 jumps were recorded...
2015: Sensors
Tina Habota, Skye N McLennan, Jan Cameron, Julie D Henry, Chantal F Ski, David R Thompson, Peter G Rendell
Although cognitive deficits are common in patients with chronic heart failure (CHF), no study to date has investigated whether these deficits extend to the capacity to execute delayed intentions (prospective memory, PM). This is a surprising omission given the critical role PM plays in correctly implementing many important CHF self-care behaviors. The present study aimed to provide the first empirical assessment of PM function in people with CHF. The key dependent measure was a laboratory measure of PM that closely simulates PM tasks in daily life - Virtual Week...
March 2015: Journal of the International Neuropsychological Society: JINS
Nicolas Fabre, Laurent Mourot, Chiara Zoppirolli, Erik Andersson, Sarah J Willis, Hans-Christer Holmberg
Here, we tested the hypothesis that aerobic energy expenditure (AEE) is higher during a simulated 6-km (2 loops of 3-km each) "skiathlon" than during skating only on a treadmill and attempted to link any such increase to biomechanical and neuromuscular responses. Six elite male cross-country skiers performed two pre-testing time-trials (TT) to determine their best performances and to choose an appropriate submaximal speed for collection of physiological, biomechanical and neuromuscular data during two experimental sessions (exp)...
April 2015: Human Movement Science
Damiano Formenti, Alessio Rossi, Giovanna Calogiuri, Tor Oskar Thomassen, Raffaele Scurati, Andi Weydahl
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(-1) kg(-1)) competed in a 10 km 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 HRmax respectively, whereas the lower zones were negligible...
2015: Research in Sports Medicine
Déborah Nourrit-Lucas, Adaté Olivier Tossa, Grégory Zélic, Didier Delignières
Long-range correlations have been evidenced in a number of experiments, generally using overlearned and overpracticed tasks. The authors hypothesized that long-range correlation could represent the byproduct of learning. They analyzed the series of periods produced by a group of expert and a group of novices during prolonged trials on a ski simulator. Results showed a very low variability in expert's series, as compared to novices. Fractal analyses showed that fluctuations were significantly more structured and correlated in experts...
2015: Journal of Motor Behavior
Kjell Hausken
PURPOSE: A model was developed for cross-country skiing where locomotive power depends on speed and slope as variables, and further depends on snow friction, gravitation, mass, air drag, wind, and air density. Model parameters were estimated experimentally. METHODS: Two differential equations were developed for how locomotive power depends on speed and slope. The equations are of the logistic form with a threshold determined by the skier's technique, intensity, mass, metabolic rate, gross efficiency, and lactate threshold...
December 2014: Human Movement Science
Hans Kristian Stadheim, Matthew Spencer, Raymond Olsen, Jørgen Jensen
PURPOSE: Performance improvements after caffeine (CAF) ingestion are well documented when using a 1-d protocol. In numerous competitions such as the Tour de France, Tour de Ski, world championships, and National College Athletic Association championships, athletes compete for several days in a row. To date, no studies have investigated the effects of CAF when competing for consecutive days in a row. This study aimed to investigate the effects of placebo (PLA) and two different CAF doses (3 and 4...
September 2014: Medicine and Science in Sports and Exercise
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