Does sensorimotor training improve the static balance of young volleyball players?

The aim of this investigation is to assess the effectiveness of a 6-week balance training (BT) protocol, integrated in regular training sessions, on postural sway of young female volleyball players (n = 26, age 13.0 +/- 0.2 years) divided into two groups (intervention and control; 13 per group). Trials were performed for bipedal and unipedal stance conditions before and after the BT protocol, using a pressure platform to collect center-of-pressure (COP) time series that were processed to calculate sway area, COP path length, and maximum displacement range in anteroposterior and mediolateral directions. The intervention group exhibited smaller sway areas in eyes closed conditions (intervention = 42.76 mm2, control = 67.60 mm2; p < 0.05) and Romberg quotients (intervention = 1.11 mm, control = 1.82 mm) in bipedal stance, while all the other parameters were unaffected. BT also reduced sway area (intervention = 122.70 mm2, control = 187.18 mm2) and anteroposterior COP displacements (intervention = 20.18 mm, control = 22.38 mm) of the non-dominant limb for single-leg stance. No significant change was found for the dominant limb. Although it is possible to hypothesize a beneficial effect of BT on young athletes, further investigations are required to clarify its actual effect on balance performance with respect to normal volleyball training.     

太极拳和快走练习对老年女性平衡能力的影响

目的:探索太极拳练习和快走练习对老年人平衡能力的影响效果。方法:31名老年女性被随机分成太极拳组(TC)和快走组(BW)。两组受试者分别接受16周的太极拳练习和快走练习,每周5次,每次1h,随后停止练习跟踪8周。受试者每4周测试一次平衡能力,共测试7次。测试指标包括睁眼(SLO)和闭眼(SLC)状态下的单腿站立时间(TIME)、足底压力中心在左右方向的最大位移量(DX)、足底压力中心在前后方向的最大位移量(DY)。结果:太极拳组(TC)TIME-SLO/SLC从第4周显著性增加,而快走组(BW)从第8周显著性增加;太极拳组DX-SLO/SLC、DY-SLO/SLC从第8周显著性减少,而快走组从第12周显著减少。停练阶段,太极组的平衡能力指标未有显著性变化,但快走组指标中除了DY,其他指标均有明显变化的趋势。结论:太极拳和快走练习均可以提高老年人的平衡能力,太极拳提高的更快(太极vs.快走:8周vs.12周);8周的停练阶段,两种练习方式对平衡能力均有较好的维持作用,但太极拳的维持效果更好。因此,相比于快走练习,老年人可以考虑将太极拳作为首选的练习方式。     

Trampoline Versus Resistance Training in Young Adults: Effects on Knee Muscles Strength and Balance

ABSTRACT

Purpose: Trampoline parks are becoming popular in many countries, providing recreational facilities for children and adults. This study investigated the effects of trampoline training on knee muscles strength and balance in young adults. Methods: Twenty-six participants (14 males, 12 females) were randomized into trampoline training (TT) and resistance training (RT) groups to undergo a 6-week supervised intervention program (2 × 30 min per week). TT group performed basic trampoline exercises while the RT group performed resistance training targeting lower extremities muscles. Peak knee extension and flexion torque, postural sway characteristics, and Y balance test (YBT) performance were evaluated before and after the intervention. A mixed model analysis of variance (group × time) was applied. Results: After training there were significant improvements in knee extension torque (mean difference_post-pre [95% CI], TT: 0.27 [0.00, 0.54] N?m/kg, RT: 0.31 [0.09,0.54] N?m/kg, p = .001), knee flexion torque (TT: 0.25 [0.17,0.33] N?m/kg, RT: 0.21 [0.08,0.34] N?m/kg, p < .001), and dynamic balance (YBT composite scores, mean difference_post-pre [95% CI], TT: 4.9 [?0.3, 10.2]%, RT: 5.2 [2.4,8.0]%, p = .001). No difference between groups was found. Conclusion: Trampoline training can be as effective as resistance training for improving knee muscles strength and dynamic balance in young men and women.     

视觉和前庭功能对自由式滑雪空中技巧运动员姿势控制能力的影响

目的:探讨视觉、前庭功能对自由式滑雪空中技巧运动员姿势控制能力的影响。方法:利用多功能旋转椅和芬兰Metitur平衡分析系统,对18名(男、女各9名)运动员进行姿势控制的抗干扰测试。选取人体压力中心的侧方稳定性Vx、前后方向稳定性Vy和多方稳定性R为测试指标。按性别(男、女性)、站立方式(左腿和右腿站立)和感觉条件(6种)分为3个因素,采用3因素(2×2×6)重复测量方差分析检验不同因素对姿势控制能力差异性的影响。结果:1)各因素的主效应均存在显著性差异(P<0.05),站立方式×感觉条件的交互作用在Vy指标上具有显著性差异(P<0.05);2)各种感觉条件均造成姿势控制能力显著性降低(P<0.01),降低程度为:闭眼+抬头>睁眼+右转>睁眼+左转>闭眼>睁眼+抬头>睁眼;3)侧方稳定性Vx干扰显著性>前后方稳定性Vy(P<0.01);4)向右旋转干扰显著性>向左旋转(P<0.01);抬头条件下干扰男子显著性>女子(P<0.01);5)双重感觉干扰显著性>单一感觉干扰(P<0.01)。结论:前庭旋转的干扰严重降低运动员的姿势控制能力,该项目运动员在前庭旋转的干扰时存在特异性。     

优秀跆拳道运动员静态平衡特征定量分析

目的:对比跆拳道运动员静息状态和模拟第二回合比赛一分钟后的静态姿势摆动频谱、稳定性及体重分配,分析影响第三回合比赛平衡能力的风险因素。方法:选择山东省男子跆拳道运动员12名,采用Tetrax平衡测试系统测试受试者静息状态和模拟第二回合比赛一分钟后睁眼自然站立状态(NO)、闭眼自然站立状态(NC)、睁眼站在6cm软垫(PO)、闭眼站在6cm软垫(PC)下的姿势摆动频谱、稳定性指数(ST)和体重分配指数(WDI)。结果:模拟第二回合比赛一分钟后运动员的ST值显著高于静息状态的ST值(P=0.047)。NO姿势摆动频谱分析,静息状态和模拟第二回合比赛一分钟后,跆拳道运动员姿势摆动从F1到F8呈递减趋势,在F3频段模拟第二回合比赛一分钟后运动员摆动强度显著高于静息状态(P=0.036)。体重分配分析模拟第二回合比赛一分钟后NO、NC、PO、PC的WDI值显著(P<0.05)或极显著(P<0.01)高于静息状态。结论:跆拳道运动员正常姿势维持表现为高强度低频率的姿势摆动特点,模拟第二回合比赛一分钟后运动员存在因外周前庭功能异常引起的稳定性下降,体重分布从不同程度上都出现异常。     

Analysis of lower limb internal kinetics and electromyography in elite race walking

Abstract

The aim of this study was to analyse lower limb joint moments, powers and electromyography patterns in elite race walking. Twenty international male and female race walkers performed at their competitive pace in a laboratory setting. The collection of ground reaction forces (1000 Hz) was synchronised with two-dimensional high-speed videography (100 Hz) and electromyography of seven lower limb muscles (1000 Hz). As well as measuring key performance variables such as speed and stride length, normalised joint moments and powers were calculated. The rule in race walking which requires the knee to be extended from initial contact to midstance effectively made the knee redundant during stance with regard to energy generation. Instead, the leg functioned as a rigid lever which affected the role of the hip and ankle joints. The main contributors to energy generation were the hip extensors during late swing and early stance, and the ankle plantarflexors during late stance. The restricted functioning of the knee during stance meant that the importance of the swing leg in contributing to forward momentum was increased. The knee flexors underwent a phase of great energy absorption during the swing phase and this could increase the risk of injury to the hamstring muscles.     

优秀武术运动员指定动作训练损伤的调查分析

采取填表和座谈两种方式对武术专业５３ 名优秀运动员指定动作训练损伤及其它损伤进行了调查,结果表明,武术运动员损伤以膝、踝关节、胫骨膜、腰肌、小腿肌内为主;动作难度大,身体素质要求高是指定性动作损伤的主要原因;落地支撑腿的膝、踝关节损伤、胫骨膜炎症等疲劳性疾病,与指定动作练习有关,局部负重过大、过度疲劳、身体素质不够等,是构成指定动作训练损伤的主要因素。     

超重肥胖老年女性下肢肌力及平衡能力的运动干预实验研究

目的：针对超重肥胖老年人进行循环训练运动干预设计,探讨循环训练对超重肥胖老年人下肢肌力及平衡能力的影响。方法：以34名老年女性为受试者,分为超重组和对照组,均坚持12周循环训练干预,比较干预前后两组受试者双侧下肢膝踝屈伸等速肌力、静动态平衡能力、计时"起立-行走"时间和Berg平衡量表得分情况。结果：运动干预12周后,两组下肢膝踝屈伸肌标准化峰值力矩、屈伸肌肌力比值和双侧肌力比值、静态与动态平衡能力、Berg平衡量表得分及计时"起立-行走"时间均有显著提高;且超重组的右膝伸肌标准化峰值力矩的提高程度明显高于对照组。结论：循环训练可以显著提高老年人的下肢肌力和平衡能力,且对提高超重肥胖老年人下肢伸肌肌力有更明显的改善效果,是预防老年人跌倒的有效运动方法。     

Control of propulsion and body lift during the first two stances of sprint running: a simulation study

The aim of this study was to relate the contribution of lower limb joint moments and individual muscle forces to the body centre of mass (COM) vertical and horizontal acceleration during the initial two steps of sprint running. Start performance of seven well-trained sprinters was recorded using an optoelectronic motion analysis system and two force plates. Participant-specific torque-driven and muscle-driven simulations were conducted in OpenSim to quantify, respectively, the contributions of the individual joints and muscles to body propulsion and lift. The ankle is the major contributor to both actions during the first two stances, with an even larger contribution in the second compared to the first stance. Biarticular gastrocnemius is the main muscle contributor to propulsion in the second stance. The contribution of the hip and knee depends highly on the position of the athlete: During the first stance, where the athlete runs in a forward bending position, the knee contributes primarily to body lift and the hip contributes to propulsion and body lift. In conclusion, a small increase in ankle power generation seems to affect the body COM acceleration, whereas increases in hip and knee power generation tend to affect acceleration less.     

Influence of a proprioceptive training on functional ankle stability in young speed skaters – a prospective randomised study

The influence of a 12-week-proprioceptive training on functional ankle stability was investigated in young speed skaters. Twenty-eight speed skaters were randomly divided into an intervention (n = 14) and into a control group (n = 14). A 15-min circle training was performed 5 times per week over a 12-week period. Measurements were taken prior to the training, after 6 and 12 weeks of training. Kinaesthesia was evaluated with the Isomed2000 in all movements of the ankle joint. Dynamic balance was tested with the Biodex Stability System at the stable level 8 and at the unstable level 2, measuring the overall stability index, the anterior/posterior and the medial/lateral scores. Static single-leg stance was evaluated using the Kistler force platform. Kinaesthesia of the intervention group improved significantly for plantarflexion of the right foot (P = 0.001) after 12 weeks. Dynamic balance showed significant differences in the intervention group after 12 weeks in comparison with the first measurement for each foot in the overall stability index, the anterior/posterior and the medial/lateral scores (P ≤ 0.017, respectively) at the unstable level 2. Functional ankle stability improved in terms of dynamic balance after 12 weeks of proprioceptive training. Therefore, inclusion of proprioceptive exercises in the daily training programme is recommended for young speed skaters.     

Neuromuscular control and coordination during cycling

The neuromuscular control aspect of cycling has been investigated through the effects of modifying posture and cadence. These studies show that changing posture has a more profound influence on neuromuscular coordination than does changing slope. Most of the changes with standing posture occur late in the downstroke: increased ankle and knee joint moment, reduced hip joint moment and greater activity in specific muscles. Due to the influence of lower extremity inertial properties, higher pedaling frequency induces more neuromuscular changes at the hip than at the knee or ankle joints. These neuromuscular adaptations to environmental and task constraints are discussed with regard to the contributions of the central nervous system and the solution provided by peripheral anatomical structure--mono- and biarticular muscles. The results indicate that training and related movement analysis should be specific to the motion, supporting the notion of task-specific training.     

跆拳道训练对学龄儿童静态平衡能力的影响

研究目的：通过对比正常学龄儿童与跆拳道训练的学龄儿童平衡能力,以探索跆拳道训练对学龄儿童静态平衡能力的影响。研究方法：选取参加跆拳道训练的学龄儿童10名作为实验组,匹配10名无跆拳道训练、武术及其他专项练习的学龄儿童作为对照组。采用win-pod平衡功能检测系统对受试者进行单足和双足平衡能力测试。研究结果：双足睁眼或闭眼测试时,有跆拳道训练的学龄儿童与无跆拳道训练、武术及其他静力练习的学龄儿童相比静态平衡能力差异有统计学意义（P＜0.05）;在睁眼左足测试时,实验组与对照组差异有统计学意义（P＜0.05）主要体现在重心动摇轨迹长、重心平均动摇速度、Y轴动摇速度这些指标上;而在睁眼右足测试时,实验组与对照组各项指标中除了Y轴平均摆幅这项指标,其他指标在两组之间差异都有统计学意义（P＜0.05）;闭眼单足测试时,从左右足依次来看,实验组与对照组分别在Y轴动摇速度和Y轴平均摆幅差异有统计学意义（P＜0.05）。研究结论：跆拳道训练能够有效增强学龄儿童在双足和右足站立静态站立的静态平衡能力,提高站立的姿势稳定性。     

Effects of stance width on performance and postural stability in national-standard pistol shooters

The aim of the present study was to determine whether changing stance width would result in a corresponding change in postural and/or pistol stability. Twelve national-standard male air pistol shooters performed 10 shots each at five stance widths (30 cm, 45 cm, 60 cm, 75 cm, and 90 cm). Postural stability was determined by measuring centre-of-pressure changes with a dual force-platform system. Shooting mechanics measures were determined by a NOPTEL ST-2000 optoelectronic training system. Medial-lateral centre-of-pressure excursion (F?,?? = 7.17, P < 0.001, effect size = 0.99) and speed (F?,?? = 77.03, P < 0.001, effect size = 3.88) were reduced as stance width decreased. Centre of gravity fine (the percentage of time held within an area the size of the ten-ring) improved during narrower stance widths (F?,?? = 12.49, P < 0.001, effect size = 0.71). Our findings suggest that stance width affects postural and pistol stability in national-standard air pistol athletes. Moreover, the current method of suggesting a wider stance to improve shooting performance should be reconsidered and perhaps air-pistol shooters should use a 30-cm stance width to improve postural stability and shooting performance.     

The effect of Tai Chi intervention on balance in older males

PurposeThe purpose of the present study was to examine the effects of a 24-week Tai Chi exercise intervention on balance and other physical changes such as flexibility and reaction time (RT) among healthy older males.MethodsThirty-eight male subjects aged 55–65 years without prior Tai Chi experience were recruited from a local community in Shanghai, China. A 60-min Tai Chi exercise session was performed three times a week for 24 weeks. Changes in RT, sit-and-reach flexibility and balance (static balance with eyes open and closed respectively) were measured before and after the Tai Chi intervention.ResultsAfter the 24-week Tai Chi intervention, the choice RT (p < 0.05) decreased, and sit-and-reach flexibility improved (p < 0.01) over the pre-test (7.8±6.2 vs. 7.1±3.0cm). Sway length, area, X-axis deviation amplitude and Y-axis deviation amplitude performance decreased significantly after the intervention with a double-foot stance with eyes open (p < 0.05). Sway length, area and average sway speed showed a statistically significant decrease after the intervention with the double-foot stance with eyes closed. In the single-foot stance with eyes open condition, sway length and average sway speed showed a statistically significant decrease (p < 0.05).ConclusionThe 24-week Tai Chi exercise intervention had a positive influence on balance control in older males.     

Does sensorimotor training improve the static balance of young volleyball players?

The aim of this investigation is to assess the effectiveness of a 6-week balance training (BT) protocol, integrated in regular training sessions, on postural sway of young female volleyball players (n = 26, age 13.0 ± 0.2 years) divided into two groups (intervention and control; 13 per group). Trials were performed for bipedal and unipedal stance conditions before and after the BT protocol, using a pressure platform to collect center-of-pressure (COP) time series that were processed to calculate sway area, COP path length, and maximum displacement range in anteroposterior and mediolateral directions. The intervention group exhibited smaller sway areas in eyes closed conditions (intervention = 42.76 mm², control = 67.60 mm²; p < 0.05) and Romberg quotients (intervention = 1.11 mm, control = 1.82 mm) in bipedal stance, while all the other parameters were unaffected. BT also reduced sway area (intervention = 122.70 mm², control = 187.18 mm²) and anteroposterior COP displacements (intervention = 20.18 mm, control = 22.38 mm) of the non-dominant limb for single-leg stance. No significant change was found for the dominant limb. Although it is possible to hypothesize a beneficial effect of BT on young athletes, further investigations are required to clarify its actual effect on balance performance with respect to normal volleyball training.     

The influence of wearing ski-boots with different rigidity characteristics on postural control

Abstract

External supports that reduce ankle joint mobility such as ski-boots can impair postural control of healthy participants. Although this disruptive effect has been attributed to the rigidity of the external supports, the results remained controversial and no study has been conducted in order to evaluate the influence of ski-boots rigidity. Hence, the question about the influence of ankle support rigidity on postural control remains open. This study was therefore undertaken in order to investigate the effect of ski-boots rigidity on postural control. Ten healthy active participants were recruited. The wearing of soft and rigid ski-boots was compared to barefoot while standing on a seesaw generating mediolateral and anteroposterior instability. Centre of pressure displacements were sampled with a force platform. The surface electromyographic activity of the main muscles from the leg, thigh and trunk was recorded. A motion analysis system was also used to calculate the ankle, knee and hip angles. The results did not reveal any negative influence of ski-boot rigidity on postural control but rather suggest a less active postural control with the rigid ski-boots which offered a higher mechanical contribution.     

Effects of balance and resistance training in children, adolescents, and seniors

Background and aims

Over the last few decades, demographic change has affected the German population in terms of a decreasing proportion of young people and an increasing proportion of elderly people. Both age groups have deficits in motor performance in common, either due to maturation and secular declines (children and adolescents) or due to biologic aging (seniors). As a consequence, deficits in postural control and muscle strength can be observed in children, adolescents, and seniors. Given these functional limitations, it is not surprising that risk of falling and, thus, medical care is particularly high in these age groups. Therefore, the objectives of this work were to investigate whether resistance or balance training have an effect on intrinsic fall risk factors (i.e., deficits in balance and strength) in children, adolescents, and seniors.

Methods

Healthy prepubertal, adolescent, and elderly subjects participated in a series of longitudinal studies. Muscle strength of the lower extremities was assessed by means of an isokinetic device and/or force plates. Postural control was determined during quiet and perturbed stance on a balance platform, during unperturbed multitask walking on a pressure sensitive walkway, as well as during perturbed walking on a treadmill. In addition, activity of lower extremity muscles was recorded.

Results

Balance training significantly improved postural sway, the ability to compensate for stance and gait perturbations, and strength performance of the lower extremities in adolescents, and seniors, however not in prepubertal children. Resistance training significantly enhanced strength performance, but not performance in biomechanic tests assessing postural control in adolescents and seniors.

Conclusion

The investigated effects of balance and resistance training on postural control and strength together with data from epidemiologic studies imply that the combination of balance and resistance training is best suited for fall prevention, because it effectively counteracts a large number of intrinsic fall risk factors.     

How does practise of internal Chinese martial arts influence postural reaction control?

The aim of this study was to determine the effects of Chinese martial arts practice on postural reaction control after perturbation. Participants standing in Romberg tandem posture were subjected to an unexpected lateral platform translation with the eyes open or closed at two translation amplitudes. The peak displacement of the centre of pressure and of the centre of mass, and the onset latency of muscular activity (tibialis anterior, gastrocnemius, lumbodorsal muscular group, and rectus abdominis), were evaluated for martial arts practitioners and for sport and non-sport participants. Compared with the sport and non-sport participants, the martial arts group showed lower maximal centre of pressure and centre of mass peak displacements in both the lateral and anterior - posterior directions, but no difference was found in the onset of muscular responses. We conclude that martial arts practice influences postural reaction control during a fixed-support strategy in a tandem task. The martial arts group used the ankle joint more frequently than the sport and non-sport participants, especially in the eyes-closed conditions. Our results suggest that the better balance recovery in the martial arts group is a consequence of better control of biomechanical properties of the lower limbs (e.g. through muscular response by co-contraction), not a change in the neuromuscular temporal pattern.     

超等长阻力训练对下肢各关节角动力学的影响

为测试超等长阻力训练前后原地垂直纵跳动作下肢各关节角速度及角加速度,计算下肢各关节角刚度,观察超等长阻力训练对下肢各关节角动力学的影响。将16名青年男子篮球运动员随机分成超等长阻力训练组和常规训练对照组。采用VICON和三维测力台采集每个动作的运动学和动力学数据,计算下肢各关节角速度及角加速度,并经逆动力学方法计算下肢净关节力矩。结果可见,超等长阻力训练组髋、踝关节角速度和角刚度明显高于对照组,膝关节角速度及角刚度两组没有明显差异;超等长阻力训练组髋、膝、踝关节角加速度均显著高于对照组。结果说明超等长阻力训练可降低拉长-缩短周期支撑时间、缩短摊还期、增强肌肉-肌腱复合体能量转换能力、提高下肢肌肉爆发力。适于需要关节角速度、角加速度及爆发力的项目。     

Chronic ankle instability is associated with proprioception deficits: A systematic review and meta-analysis

BackgroundAcute ankle injury causes damage to joint mechanoreceptors and deafferentation and contributes to proprioception deficits in patients with chronic ankle instability (CAI). We aimed to explore whether deficits of proprioception, including kinesthesia and joint position sense (JPS), exist in patients with CAI when compared with the uninjured contralateral side and healthy people. We hypothesized that proprioception deficits did exist in patients with CAI and that the deficits varied by test methodologies.MethodsThe study was a systematic review and meta-analysis. We identified studies that compared kinesthesia or JPS in patients with CAI with the uninjured contralateral side or with healthy controls. Meta-analyses were conducted for the studies with similar test procedures, and narrative syntheses were undertaken for the rest.ResultsA total of 7731 studies were identified, of which 30 were included for review. A total of 21 studies were eligible for meta-analysis. Compared with the contralateral side, patients with CAI had ankle kinesthesia deficits in inversion and plantarflexion, with a standardized mean difference (SMD) of 0.41 and 0.92, respectively, and active and passive JPS deficits in inversion (SMD = 0.92 and 0.72, respectively). Compared with healthy people, patients with CAI had ankle kinesthesia deficits in inversion and eversion (SMD = 0.64 and 0.76, respectively), and active JPS deficits in inversion and eversion (SMD = 1.00 and 4.82, respectively). Proprioception deficits in the knee and shoulder of patients with CAI were not statistically significant.ConclusionProprioception, including both kinesthesia and JPS, of the injured ankle of patients with CAI was impaired, compared with the uninjured contralateral limbs and healthy people. Proprioception varied depending on different movement directions and test methodologies. The use of more detailed measurements of proprioception and interventions for restoring the deficits are recommended in the clinical management of CAI.