Little is known about the true extent and severity of overuse injuries in sport, largely because of methodological challenges involved in recording them. This study assessed the prevalence of overuse ...injuries among Norwegian athletes from five sports using a newly developed method designed specifically for this purpose. The Oslo Sports Trauma Research Center Overuse Injury Questionnaire was distributed weekly by e‐mail to 45 cross‐country skiers, 98 cyclists, 50 floorball players, 55 handball players, and 65 volleyball players for 13 weeks. The prevalence of overuse problems at the shoulder, lower back, knee, and anterior thigh was monitored throughout the study and summary measures of an injury severity score derived from athletes' questionnaire responses were used to gauge the relative impact of overuse problems in each area. The area where overuse injuries had the greatest impact was the knee in volleyball where, on average, 36% of players had some form of complaint (95% CI 32–39%). Other prevalent areas included the shoulder in handball (22%, 95% CI 16–27%) the knee in cycling (23%, 95% CI 17–28%), and the knee and lower back in floorball (27%, 95% CI 24–31% and 29%, 95% CI 25–33%, respectively).
Skiing into modernity Denning, Andrew
2014., 20141126, 2014, 2014-11-26, Letnik:
3
eBook
Skiing into Modernityis the story of how skiing moved from Europe's Scandinavian periphery to the mountains of central Europe, where it came to define the modern Alps and set the standard for skiing ...across the world.Denning offers a fresh, sophisticated, and engaging cultural and environmental history of skiing that alters our understanding of the sport and reveals how leisure practices evolve in unison with our changing relationship to nature. Denning probes the modernist self-definition of Alpine skiers and the sport's historical appeal for individuals who sought to escape city strictures while achieving mastery of mountain environments through technology and speed-two central features distinguishing early twentieth-century cultures.Skiing into Modernitysurpasses existing literature on the history of skiing to explore intersections between work, tourism, leisure, development, environmental destruction, urbanism, and more.
(1) Background: In alpine skiing, senior athletes and especially women have a high risk of knee injury. This may also be related to muscular fatigue (MF) of the knee-stabilizing thigh muscles. This ...study investigates both the evolution of muscle activity (MA) and of MF of the thighs throughout an entire skiing day. (2) Methods:
= 38 female recreational skiers over 40 years of age performed four specific skiing tasks (plough turns, V-steps uphill, turns with short, and middle radii) at specific times, while freely skiing the rest of the day. Surface EMG of the thigh muscle groups (quadriceps and hamstrings) was measured using special wearables (EMG pants). Apart from standard muscle activity parameters, the EMG data were also processed in the frequency domain to calculate the mean frequency and its shift over the day as a metric of muscle fatigue. (3) Results: The EMG pants showed reliable signal quality over the entire day, with BMI not impacting this. MF increased during skiing before and for both muscle groups significantly (
< 0.006) during lunch. MF, however, was not reflected in the quadriceps-hamstrings ratio. The plough manoeuvre seems to require significantly (
< 0.003) more muscle dynamics than the three other tasks. (4) Conclusion: MF may be quantified over an entire skiing day and thus fatigue information could be given to the skier. This is of major importance for skiers at the beginner level dominantly performing plough turns. Crucial for all skiers: There is no regenerative effect of a 45-min lunch break.
BackgroundA limited number of long-term prospective studies have investigated health problems in competitive cross-country skiers. Moreover, limited information exists regarding differences in the ...prevalence and severity of health problems between senior and development female and male cross-country skiers.ObjectiveTo compare the prevalence and severity of health problems between senior and development female and male national team cross-country skiers.DesignComparative, prospective, observational cohort study.SettingSenior and development national cross-country ski teams.ParticipantsEighteen (9 women, 9 men) senior and 22 (9 women, 13 men) development national team skiers.InterventionSkiers self-reported their health problems weekly for 17 weeks throughout the 2019/2020 competitive cross-country ski season using the Oslo Sports Trauma Research Center Questionnaire on Health Problems (OSTRC-H2).Main Outcome MeasurementsWe calculated weekly prevalence and severity measures for illnesses, acute and overuse injuries, substantial health problems (i.e., health problems leading to moderate or severe reductions in training volume or sports performance, or a complete inability to participate) and all health problems combined.ResultsWeekly response rate to the OSTRC-H2 was 90% (SD 7%). Average weekly prevalence of substantial (~12%) and all (~25%) health problems were similar between senior and development team skiers. However, illness prevalence was lower in senior vs. development skiers (8%, 95% CI 3%, 13% vs. 13%, 95% CI 9%, 17%, respectively; p = .026) and injuries were higher (12%, 95% CI 9%, 15% vs. 5%, 95% CI 3%, 7%; p < .001). There were no differences in severity measures (all p > .05).ConclusionsHealth problems were relatively common among the skiers, with one quarter affected by at least one problem at any given time. While the prevalence of all health problems was similar, illnesses were less prevalent in the senior compared to the development team skiers and injuries were more prevalent.
The subacromial impingement syndrome is a high-incidence injury for cross-country sit-skiing skier, which is often accompanied by muscle imbalance. However, at present, no musculoskeletal model has ...been identified for this sport. Thus, this research aimed to establish a bilateral upper extremity trunk (BUET) musculoskeletal model suitable for cross-country sit-skiing based on OpenSim software and verify the function of the model. By splicing three existing OpenSim models, an upper limb model with 17 segments, 35 degrees of freedom, and 472 musculotendon actuators was established. The clavicle and scapula were modeled as individual bodies and then connected to the torso through a three-degrees-of-freedom rotational joint and to the clavicle through a weld joint, respectively. The five lumbar vertebrae were established separately and coupled into a three-degree-of-freedom joint. Kinematics, kinetic, and EMG signal data of five 15-s maximal effort interval tests were obtained by using seven cameras, ergometers, and surface EMG synchronous collection. Based on the resulting rotator cuff muscle geometry of the model, simulated muscle activation patterns were comparable to experimental data, and muscle-driven ability was proven. The model will be available online (
https://simtk.org/projects/bit
) for researchers to study the muscle activation of shoulder joint movement.
Graphical Abstract
This study aimed to: (i) analyze the load characteristics of 4 weeks cross-country skiing altitude training; (ii) analyze the relationships between methods of monitoring training load and ...physiological indicators changes of elite male Chinese cross-country skiers during this period. Practitioners collected load data during 4 weeks of altitude training camp. Participants performed maximal oxygen uptake, lactate threshold, body composition, and skierg power test before and after the training camp to investigate the changes in physiological performance. Edwards TRIMP, Lucia TRIMP, and session rating of perceived exertion were collected as internal load. Training distance, time recorded by the Catapult module were collected as external load. The result revealed a " pyramid " pattern in the load characteristics during the altitude training camp. The correlation between luTRIMP and percent change in physiological indicators was highest. Percentage changes in lactate threshold velocity (r = .78 95% CI -.01 to .98), percentage changes in lactate threshold HR (r = .71 95% CI .14- .99), percentage changes in maximum HR (r = .83 95% CI .19-1.00), percentage changes in skierg power-to-weight ratio (r = .75 95% CI -.28 to .98) had very large relationships with luTRIMP. In cross-country skiing altitude training, training loads should be reasonably controlled to ensure that athletes do not become overly fatigued. Methods of training load monitoring that combine with athletes' physiological characteristics and program characteristics have the highest dose-response relationships, it is an important aspect of cross-country ski training load monitoring. The luTRIMP could be a good monitoring tool in cross-country skiing altitude training.
The main goal of this study was to identify potential external risk factors for injury in recreational skiers through a survey questionnaire. Subjects were divided into injured skiers and a control ...group who never had an injury. Injured skiers (N=212) answered questions that helped define potential risk factors. The control group (N=206) completed the same questionnaire but without questions about injury. Common questions were used to determine the possibility of injury using Chi-Square test, and additional questions were used to determine the influence on injury severity using Fisher’s test. An analysis of external factors showed that formal ski school was not statistically related to the possibility and severity of injury, but significantly increased knowledge of skiing. Skiing with another person did not decrease the possibility of injury but did increase the severity of injury. Visibility, field of vision, condition of the slope, temperature, and weather conditions are not statistically related to injury severity, but when combined, they could be an important factor in the possibility of injury.
Purpose
To investigate performance, physiological, and perceptual responses of an entire sprint cross-country skiing competition in the skating style.
Methods
Eighteen national-level male junior ...skiers participated in a simulated competition comprising an individual time trial (TT), followed by three heats (quarterfinals QF, semifinals SF, and final F). Participants’ heart rate (HR) was continuously monitored while perceived readiness (RED, 1–10), rating of perceived exertion (RPE, 6–20), and blood lactate La- were assessed at standardized time points.
Results
The total duration and distance covered were 03:30 ± 00:06 h and 25.2 ± 2.9 km, respectively. The participants spent 02:19 ± 00:27 h > 60% of their maximal HR (HR
max
) and 00:16 ± 00:04 h > 85% of HR
max
. Average HR decreased from TT to F (89.3 ± 2.0% vs. 86.9 ± 3.0% of HR
max
,
P
< 0.01). La- levels were highest before (4.6 ± 2.0 vs. 2.9 ± 1.2, 3.2 ± 2.0 and 2.5 ± 1.3 mmol·L
−1
, all P < 0.01) and after (10.8 ± 1.4 vs. 9.8 ± 1.6, 9.1 ± 1.8 and 8.7 ± 1.7 mmol·L
−1
, all
P
< 0.05) F compared to TT, QF, and SF, respectively. RED was lowest before F compared to TT, QF, and SF (6.6 ± 1.4 vs. 7.9 ± 1.1, 7.6 ± 1.1, and 7.4 ± 1.4, respectively, all
P
< 0.05) while RPE was highest after TT compared to QF, SF, and F (17.8 ± 0.9 vs. 15.1 ± 2.0, 16.5 ± 1.2 and 16.6 ± 1.8, respectively, all
P
< 0.01). The six best-performing skiers demonstrated higher RED before F (7.2 ± 0.9 vs. 5.3 ± 1.2,
P
< 0.05) and higher La- after F (11.2 ± 0.2 vs. 10.2 ± 0.3, mmol·L
−1
,
P
< 0.05) than lower-performing competitors.
Conclusion
This study provides novel insights into physiological demands of an entire sprint cross-country skiing competition, which involves repeated 3-min high-intensity efforts interspersed with > 2 h (25 km) of low- to moderate-intensity exercise.
Learning underlying patterns from sensory data is crucial in the Human Activity Recognition (HAR) task to avoid poor generalization when coping with unseen data. A key solution to such an issue is ...representation learning, which becomes essential when input signals contain activities with similar patterns or when patterns generated by different subjects for the same activity vary. To address these issues, we seek a solution to increase generalization by learning the underlying factors of each sensor signal. We develop a novel multi-channel asymmetric auto-encoder to recreate input signals precisely and extract indicative unsupervised futures. Further, we investigate the role of various activation functions in signal reconstruction to ensure the model preserves the patterns of each activity in the output. Our main contribution is that we propose a multi-task learning model to enhance representation learning through shared layers between signal reconstruction and the HAR task to improve the robustness of the model in coping with users not included in the training phase. The proposed model learns shared features between different tasks that are indeed the underlying factors of each input signal. We validate our multi-task learning model using several publicly available HAR datasets, UCI-HAR, MHealth, PAMAP2, and USC-HAD, and an in-house alpine skiing dataset collected in the wild, where our model achieved 99%, 99%, 95%, 88%, and 92% accuracy. Our proposed method shows consistent performance and good generalization on all the datasets compared to the state of the art.
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