高山滑雪初学者运动损伤原因调查分析

运用文献资料法、实地观察法和数理统计法等,对沈阳白清寨高山滑雪的初学者运动损伤情况进行调查,分析其损伤的原因,以期为大众初学者安全地进行滑雪提供参考。     

自由式滑雪空中技巧运动员姿势控制训练及效果评价研究

目的:对我国自由式滑雪空中技巧队运动员姿势控制能力进行训练和评价,为后期的专项训练实践提供指导和参考。方法:对13名国家运动员(男性6名,女性7名)进行3种不同的姿势控制能力训练,利用METITUR平衡能力测试系统在训练前后对13名国家运动员进行平衡能力测试,一个训练周期后,对2017年和2018年两个赛季运动员的技术动作进行对比分析。结果:通过METITUR平衡能力测试,13名运动员静态平衡能力在前后方向上(Y轴向)的稳定性升高,说明运动员在控制重心能力上有所提高。通过训练前后运动员的动态平衡能力测试人体重心曲线图,运动员训练后在支撑面左右方向的自动态平衡能力有所有提高。技术动作对比分析的结果显示,运动员的着陆成功率也有了较大幅度的提高。结论:通过为期6个月的姿势控制能力的训练,运动员的静态平衡能力在支撑面前后方向上明显提高,动态平衡能力在支撑面后的左右方向上有显著提升。     

对辽宁省首届高山滑雪社会指导员现状的研究

采用文献资料法,观察法等对辽宁省首届高山滑雪社会指导员的现状进行研究,旨在为推动滑雪运动的发展提供参考。     

第24届大冬会的成功举办对我国高山滑雪运动的促进作用

通过对我国高山滑雪运动现状的分析,指出目前我国高山滑雪运动存在政府和有关部门对雪上项目的投入有待提高、宣传力度不够使人们对高山滑雪运动认识不足、经费短缺与开展高山滑雪运动需较高投入存在矛盾以及缺乏完善高山滑雪后备人才培养体制等问题,并总结出大冬会改善了地方经济、扩大了高山滑雪运动的社会影响、增加了政府对高山滑雪运动项目的经济投入、改善了我国高山滑雪运动硬件设施、有助于完善高山滑雪运动人才培养体制、有利于推广普及高山滑雪运动、有利于教练员提高执教水平等促进项目发展的途径,为高山滑雪项目的快速发展提供理论依据。     

Effect of ski boot rear stiffness (SBRS) on maximal ACL force during injury prone landing movements in alpine ski racing: A study with a musculoskeletal simulation model

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. Injury prone situations for ACL-injuries were generated by the musculoskeletal simulation model using measured kinematics of a non-injury situation and the method of Monte Carlo simulation. Subsequently, the SBRS was varied for injury prone landings. The maximal ACL tensile forces and contributing factors to the ACL forces were compared for the different SBRS. In the injury prone landings the maximal ACL tensile forces increased with increasing SBRS. It was found that the higher maximal ACL force was caused by higher forces acting on the tibia by the boot and by higher quadriceps muscle forces both due to the higher SBRS. Practical experience suggested that the reduction of SBRS is not accepted by ski racers due to performance reasons. Thus, preventive measures may concentrate on the reduction of the quadriceps muscle force during impact.     

竞技高山滑雪运动交换区及回转动作技术原理

技术因素是制约我国竞技高山滑雪运动水平提高的一个主要因素。为加快我国竞技高山滑雪运动技术水平的发展,通过理论研究和运动实践等方法,从运动生物力学的角度出发,对竞技高山滑雪回转中轨迹交换区进行设定,并对回转技术的基本坐标系及滑雪板的受力情况进行分析,进一步探讨了交换区的滑行技术动作,提出了交换区和滑行姿态应是等腰三角形或椎体型运动姿态等理论,以期为提高高山滑雪运动员的技术水平和训练效果提供一定的参考。     

Time course of the acute effects of core stabilisation exercise on seated postural control

Core stabilisation exercises are often promoted for purposes ranging from general fitness to high-performance athletics, and the prevention and rehabilitation of back troubles. These exercises, when performed properly, may have the potential to enhance torso postural awareness and control, yet the potential for achieving immediate gains has not been completely studied. Fourteen healthy young participants performed a single bout of non-fatiguing core stabilisation exercise that consisted of repeated sets of 2 isometric exercises, the side bridge and the four-point contralateral arm-and-leg extension. Seated postural control, using an unstable balance platform on top of a force plate, was assessed before and after exercise, including multiple time points within a 20-minute follow-up period. Nine standard postural control variables were calculated at each time point, including sway displacement and velocity ranges, root mean squares and cumulative path length. Statistical analysis showed that none of the postural control variables were significantly different at any time point following completion of core stabilisation exercise. Thus, we conclude that a single bout of acute core stabilisation exercise is insufficient to immediately improve seated trunk postural control in young healthy individuals.     

The effects of maximal and submaximal arm crank ergometry and cycle ergometry on postural sway

Abstract

This study aimed to determine whether arm crank ergometry (ACE) disturbed postural sway to the same extent as cycle ergometry (CE). Nine healthy, none specifically trained adults undertook posturographic tests before and after five separate exercise trials consisting of: two incremental exercise tests to exhaustion for ACE and CE to examine postural sway responses to maximal exercise and to determine peak power output (W_max); two subsequent tests of 30 min duration for ACE and CE at a relative workload corresponding to 50% of the ergometer-specific W_max (ACE_rel; 53 ± 8 W and CE_rel; 109 ± 16 W). A final CE trial was performed at the same absolute power output (CE_abs) as the submaximal ACE trial to match absolute exercise intensity (i.e., 53 ± 8 W). The centre of pressure (COP) displacement was recorded using a force platform before, immediately after exercise and during a 30-min recovery period. ACE had no effects on postural sway (P > 0.05). An increase in mediolateral COP displacement was observed following maximal CE only (P = 0.001), while anteroposterior COP displacement and COP path length increased following maximal and submaximal CE (P < 0.05). These differences in postural sway according to exercise mode likely stem from the activity of postural muscles when considering that CE recruits lower limb muscles involved in balance. This study provides evidence of an exercise mode which does not elicit post-exercise balance impairments, therefore possesses applications to those at an increased risk of falling.     

The role of path length- and speed-related factors for the enhancement of section performance in alpine giant slalom

Knowing how to enhance alpine skiing performance is essential for effective coaching. The purpose of this study was to explore the role of path length- and speed-related factors for performance enhancement, while skiing on a homogeneously set/constantly inclined giant slalom course section (average gate distance: 27?m; offset: 8?m; slope inclination: 26°). During a video-based three-dimensional kinematic field-experiment, the data of six athletes who skied a two-gate section on four different types of skis were collected. The performance parameter analysed was section time. The performance predictors analysed were centre of mass (CoM), path length and the change in specific mechanical energy per entrance speed along the analysed section. Furthermore, since the current study examined alpine skiing performance within short sections, the skier’s entrance speed was also considered. Classified as a high-performance and a low-performance group based on section time, slow and fast trials significantly differed in CoM path length, the change in specific mechanical energy per entrance speed and entrance speed. The entrance speed of all trials analysed ranged between 15.25 and 17.66?m/s. In trials with both high and low entrance speed, the change in specific mechanical energy per entrance speed was found to be more relevant for the prediction of section time than CoM path length. However, further studies should investigate whether such a prioritization can be unrestrictedly generalized to other situations, such as entrance speeds, course sets, slope inclinations and competition disciplines different to those assessed in the current study.     

高山滑雪运动技能学习过程中的技能迁移与信息反馈

采用文献资料法和实地观察法,探讨了高山滑雪运动中技能学习过程中的技能迁移和信息反馈两方面的内容。根据技能迁移和信息反馈的特点,提出了适合高山滑雪运动技能迁移方法及建立合理的信息反馈体系,以促进高山滑雪运动技能的学习。     

Effect of Kinesio Taping and balance exercises on postural control in amateur soccer players: A randomised control trial

ABSTRACT

The objective of this study was to determine the effect of Kinesio Taping (KT), alone or together with balance exercises (BE), on parameters related to postural control, such as dynamic balance, static balance and flexibility. Forty-four male amateur soccer players (mean age 24.45 (4.79) years) were randomly allocated to 3 groups: KT+BE that received KT and BE (n = 16); KT_p+BE, in which the KT was used as a placebo (n = 15) and KT alone (n = 13). The intervention period lasted 4 weeks. Star Excursion Balance Test (SEBT), Unipedal Stance Test (UST) and the Toe Touch Test (TTT) were assessed at baseline (pre), two weeks after beginning the treatment (mid) and after the intervention (post). We observed a significant improvement on the SEBT (mid and post-treatment) and the UST (post-treatment), but not on the TTT in either KT+BE or KT_p+BE groups post treatment. No differences were found either in KT group at any time point or between groups in any variable studied. In conclusion, KT functional correction technique does not improve static and dynamic balance when applied alone, whereas BE alone or combined with KT significantly improves these variables. None of these techniques has any effect on flexibility.

Abbreviation: KT: Kinesiotaping; BE: Balance exercises; KTp: Placebo Kinesiotaping; UST: Unipedal Stance Test; SEBT: Star Excursion Balance Test; TTT: Toe Touch Test     

Altered visual focus on sensorimotor control in people with chronic ankle instability

The purpose of this investigation was to examine the effects of the combination of chronic ankle instability (CAI) and altered visual focus on strategies for dynamic stability during a drop-jump task. Nineteen participants with self-reported CAI and 19 healthy participants performed a drop-jump task in looking-up and looking-down conditions. For the looking-up condition, participants looked up and read a random number that flashed on a computer monitor. For the looking-down condition, participants focused their vision on the force plate. Sagittal- and frontal-plane kinematics in the hip, knee and ankle were calculated at the time points of 100 ms pre-initial foot contact to ground and at IC. The resultant vector time to stabilisation was calculated with ground reaction force data. The CAI group demonstrated less hip flexion at the point of 100 ms pre-initial contact (P < 0.01), and less hip flexion (P = 0.03) and knee flexion at initial contact (P = 0.047) compared to controls. No differences in kinematics or dynamic stability were observed in either looking-up or looking-down conditions (P > 0.05). Altered visual focus did not influence movement patterns during the drop-jump task, but the presence of CAI did. The current data suggests that centrally mediated changes associated with CAI may lead to global alterations in the sensorimotor control.     

我国滑雪产业发展现状研究

近些年,滑雪运动在我国迅速发展,吸引越来越多的人参与到这项运动。伴随着滑雪运动的兴起,作为一个新兴的产业——滑雪产业也快速的发展起来。本文通过对我国滑雪产业发展现状的研究,预测其未来的发展趋势,力求为此领域的发展提供理论依据。     

Strength,power, and postural control in seniors: Considerations for functional adaptations and for fall prevention

Abstract

The ageing neuromuscular system is affected by structural and functional changes that lead to a general slowing down of neuromuscular performance and an increased risk of falling. As a consequence, the process of ageing results in a reduced ability to develop maximal and explosive force, as well as in deficits in static and dynamic postural control. A decrease in the number and size of type II fibres in particular accounts for the age-related decline in muscle mass (sarcopaenia) and strength performance. Multiple denervation and re-innervation processes of muscle fibres seem to be responsible for the reduced number of muscle fibres. Recently, it has been suggested that it is not the decline in motoneurons that accounts for the loss in number of muscle fibres but the disturbed potential of fibre regeneration and re-innervation. Furthermore, an age-related reduction in the number of satellite cells has also been associated with sarcopaenia. The ability to compensate for platform and gait perturbations deteriorates with ageing as reflected in longer onset latencies and inefficient postural responses. All sites within the somatosensory system are affected by ageing and therefore contribute to postural instability. However, morphological changes of muscle spindles appear primarily to be responsible for the impaired ability to compensate for balance threats in old age. Given these neuromuscular limitations in old age, it is important to apply adequate training interventions that delay or even reverse the onset of these constraints. Strength training has the potential to enhance maximal as well as explosive force production capacity. This is accomplished by neural factors, including an improved recruitment pattern, discharge rate, and synchronization of motor units. Furthermore, an increase in number of satellite cells most likely accounts for training-induced muscle hypertrophy. Recent studies have investigated the impact of balance training in old age on the ability to develop maximal and explosive force. In addition, the effects of balance training on reflex activity during gait perturbations were also examined. Increases in maximal and explosive force production capacity and an improved ability to compensate for gait perturbations were observed. It is evident from the literature that researchers are increasingly studying the effects of more specifically designed training programmes on performance in populations of older adults. Thus, in the near future, strength training could be replaced by high-velocity forms of power training and balance training by perturbation-based training programmes. It is hypothesized that this new approach is more efficient in terms of fall prevention than the traditional approach.     

步行平衡控制研究的现状及发展

从人体基本的生物力学结构出发，阐述了步行中平衡控制的基本理论及最近的发展动态；从运动控制的原理出发，讨论了随着年龄的增加步行控制的变化特征；比较分析了多种实验结果，揭示了现有步行控制研究中的问题，同时指明了今后研究的方向。     

The hip control test is a valid and reliable measure of hip neuromuscular control

Abstract

Insufficient hip neuromuscular control may contribute to non-contact sport injuries. However, the current evaluative test of hip neuromuscular control, the single-leg squat, requires hip abductor muscle strength to complete. The purpose of this study was to develop the hip control test (HCT) and determine the test’s reliability and construct validity. Nineteen healthy adults visited the laboratory twice. The HCT is a 10-s test of reciprocal toe-tapping accuracy. Both automated and manual HCT ratings were recorded simultaneously during each visit. Additionally, eccentric hip abductor torque was measured. HCT reliability was assessed with intra-class correlation coefficients (ICC). Agreement between automated and manual ratings was determined with Bland–Altman plots. Construct validity was established if HCT performance significantly decreased with a secondary cognitive task (p < 0.05). Bivariate regression determined the relationship between HCT performance and eccentric hip abductor torque. Automated and manual HCT ratings both had moderate reliability (ICC = 0.72) and yielded similar results (limits of agreement = ?1 to 2 taps). The HCT had construct validity (p = 0.001), and no correlation with hip abductor muscle strength (r = 0.213). Thus, the HCT is a reliable and valid test. The HCT is simple to administer and measures hip neuromuscular control separately from strength.     

高山滑雪运动员的生化监控和营养补充

通过对高山滑雪运动员供能特点进行探讨和分析,提出血清睾酮、血清肌酸激酶、血乳酸和尿肌酐系数等适用于高山滑雪运动员机能评定的生化指标,并阐述了营养补充的重要性及比赛前期、比赛当日和比赛后的饮食营养建议,旨在通过科学合理生化指标的监控和营养物质的补充来促进运动员身体机能的提高,进而提高运动员的训练效果和竞赛成绩。     

The effects of a high-intensity free-weight back-squat exercise protocol on postural stability in resistance-trained males

The purpose of this study was to investigate the effects of a high-intensity free-weight back-squat exercise on postural stability characteristics in resistance-trained males. Eighteen college-aged (mean ± SD: age = 22.9 ± 2.9 years; height = 175.8 ± 6.4 cm; mass = 86.3 ± 9.3 kg), resistance-trained males performed postural stability testing before and after completing five sets of eight repetitions of back-squat exercises at 80% of one-repetition maximum. A commercial balance testing device was used to assess sway index at pre- and at 0, 5, 10, 15 and 20 min post-exercise. Each balance assessment consisted of four, 20-s static stance conditions: eyes-open firm surface, eyes-closed firm surface, eyes-open soft surface and eyes-closed soft surface. Sway index was greater (P = 0.001–0.020) at Post 0 than at all other time points. No differences (P > 0.05) were observed between any other time phases. Sway index was greater (P < 0.001) for eyes-closed soft surface than all other conditions. These findings revealed sway index for all conditions significantly increased following completion of the back-squat; however, sway index recovered within 5 min of exercise. Higher sway index values as a result of neuromuscular fatigue induced by a back-squat exercise may have performance and injury risk consequences to subsequent activities that rely on postural stability. However, these findings suggest balance impairments may recover in ~5 min following high-intensity lower body resistance exercise.     

The effect of unilateral balance training on postural control of the contralateral limb

To investigate the impact of unilateral balance training on postural control of the trained and contralateral limb in healthy elderly. Fifty-one healthy old adults were randomly assigned into training group (TG) and control group (CG). Participants of the TG performed unilateral balance training (dominant (DOM) leg) over 4 weeks (4×/week). Centre of pressure analysis was performed at baseline, 5 weeks follow-up and 9 weeks follow-up under the following conditions: (1) one-leg stance without additional task, (2) one-leg stance with motor task and (3) one-leg stance with cognitive task. From baseline to 5 weeks follow-up, a mixed analysis of variance detected a significant time × group interaction for the DOM leg (P < 0.05), indicating higher improvement of the TG in comparison to CG. No significant interaction effect was found for the non-DOM leg. Within the TG, the non-DOM leg significantly improved in mean velocity (P = 0.001) and anterior–posterior range (P < 0.001). Unilateral balance training was effective to improve postural control of the trained leg. The effect on the contralateral leg was small and not significant within this study design. Improvements were retained after 4 weeks without training. A tendency is given that unilateral balance training might be beneficial to improve postural control of the contralateral leg.     

The effects of skiing velocity on mechanical aspects of diagonal cross-country skiing

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.