Effects of balance training on postural sway, leg extensor strength, and jumping height in adolescents

Deficits in strength of the lower extremities and postural control have been associated with a high risk of sustaining sport-related injuries. Such injuries often occur during physical education (PE) classes and mostly affect the lower extremities. Thus, the objectives of this study were to investigate the effects of balance training on postural sway, leg extensor strength, and jumping height in adolescents. Twenty high school students participated in this study and were assigned to either an intervention (n = 10) or control group (n = 10). The intervention group participated in a 4-week balance-training program integrated in their physical education lessons. Pre- and posttests included the measurements of postural sway on a balance platform, jumping height on a force platform, and maximal isometric leg extension force on a leg-press. Balance training resulted in significantly improved postural control, increased jumping height, and enhanced rate of force development of the leg extensors. Physiological adaptations rather than learning effects seem to be responsible for the observed findings. These results could have an impact on improving the performance level in various sports and on reducing the injury prevalence of the lower extremities.     

Video-based training to improve perceptual-cognitive decision-making performance of Australian football umpires

Decision-making is a central component of the in-game performance of Australian football umpires; however, current umpire training focuses largely on physiological development with decision-making skills development conducted via explicit lecture-style meetings with limited practice devoted to making actual decisions. Therefore, this study investigated the efficacy of a video-based training programme, aimed to provide a greater amount of contextualised visual experiences without explicit instruction, to improve decision-making skills of umpires. Australian football umpires (n = 52) were recruited from metropolitan and regional Division 1 competitions. Participants were randomly assigned to an intervention or control group and classified according to previous umpire game experience (i.e., experienced; less experienced). The intervention group completed a 12-week video-based decision-making training programme, with decision-making performance assessed at pre-training, and 1-week retention and 3-week retention periods. The control group did not complete any video-based training. Results indicated a significant Group (intervention; Control) × Test interaction (F(1, 100) = 3.98; P = 0.02, partial ?² = 0.074), with follow-up pairwise comparisons indicating significant within-group differences over time for the intervention group. In addition, decision-making performance of the less experienced umpires in the intervention group significantly improved (F(2, 40) = 5.03, P = 0.01, partial ?² = 0.201). Thus, video-based training programmes may be a viable adjunct to current training programmes to hasten decision-making development, especially for less experienced umpires.     

Exercise training increases the S-Klotho plasma levels in sedentary middle-aged adults: A randomised controlled trial. The FIT-AGEING study

ABSTRACT

This study aimed to investigate the effects of different training modalities on the soluble Klotho (S-Klotho) plasma levels in sedentary middle-aged adults. A total of 74 middle-aged adults (53.4 ± 5.0 years old; 52.7% women) were enrolled in the FIT-AGEING study. We conducted a 12-week randomised controlled trial. The participants were randomly assigned to 4 different groups: (i) a control group (no exercise), (ii) a physical activity recommendation from the World Health Organization group (PAR), (iii) a high intensity interval training group (HIIT), and (iv) a high intensity interval training group adding whole-body electromyostimulation training group (HIIT-EMS). S-Klotho plasma levels, anthropometric measurements, and body composition variables were measured before and after the intervention programme. All exercise training modalities induced an increase in the S-Klotho plasma levels (all P ≤ 0.019) without statistical differences between them (all P ≥ 0.696). We found a positive association between changes in lean mass index and changes in the S-Klotho plasma levels, whereas a negative association was reported between changes in fat mass outcomes and changes in the S-Klotho plasma levels after our intervention study. In conclusion, our results suggest that the link between exercise training and the increase in S-Klotho plasma levels could be mediated by a decrease of fat mass and an increase of lean mass.     

Exercise training modifies walking kinematics and energy cost in obese adolescents: A pilot controlled trial

Abstract

The aim of this study was to investigate the effects of a weight loss intervention based on physical exercise on the relationship between energy cost and stride frequency during walking in obese teenagers. Participants aged 13–16 years old were assigned to a training (n?=?14) and control (n?=?10) groups. During eight weeks, the training group performed three 60-min weekly sessions of high-intensity intermittent activities coupled with aerobic training. Body composition, gait parameters and energy cost during 4-min walking bouts at participants’ most comfortable speed and preferred stride frequency (PSF), PSF-10%, PSF?+?10%, PSF-20% and PSF?+?20% were measured before and after intervention. The effects of training and stride frequencies on the energy cost of walking were analysed by an ANOVA with repeated measures. The main results showed that the exercise intervention induced a significant increase in walking speed (+23.2%), and significant decreases in body mass (?1.4%), body fat percentage (?2.1%) and energy cost of walking at various frequencies (decreases ranging from ?10.5% to ?20.4%, p?<?.05). In addition, significantly greater decreases were shown at high frequencies (p?<?.05). No significant differences were shown in the control group (p?>?.05). These results suggest that this type of training is beneficial to reduce walking energy cost of obese teenagers, in particular at high frequencies. This should improve their well-being during daily activities.     

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.     

舞蹈式柔韧训练对提升青少年花样游泳运动员动作表现的影响研究

研究目的:运动员青少年时期的柔韧素质发展是成年后提高运动成绩的关键因素之一。本文通过舞蹈式柔韧训练对提高动作表现影响的实验研究,为花样游泳的陆上训练提供实践方法和理论依据。研究方法:选取广州市花样游泳队20名9-12岁运动员,分实验组10人、对照组10人。实验组进行为期4个月的舞蹈式柔初训练干预,对照组开展一般柔初训练。干预前后分别对两组的四个动作指标进行测试评价,数据采用SPSS分析系统进行T检验,组内纵向比较,组间横向比较。研究结果:实验组经过舞蹈式柔初训练干预后,指标数据呈明显变化趋势,显著性优于对照组(P<0.01)。在竖高叉、横高叉、前腿踢搬、紫金冠四个动作的表现中,实验组比对照组的动作提升幅度大。研究结论:经过舞蹈式柔軔训练教学干预后,柔韧动作干预的实验组各指标显著高于对照组。训练能够显著提升运动员的比赛动作表现能力。广州市花样游泳队夺得2016年鄂尔多斯全国青少年花样游泳锦标赛陆上柔初操项目第一名,优异的成绩与4个月的舞蹈式柔初训练有着紧密联系。     

Effects of dynamic resistance training on fascicle length and isometric strength

The aims of this study were to assess changes in muscle architecture, isometric and dynamic strength of the leg extensor muscles, resulting from dynamic resistance training, and the relationships between strength and muscle architecture variables. The participants (n = 30) were randomly assigned to one of two groups. The training group (n = 16; age 21.8 +/- 2.3 years, body mass 74.8 +/- 9.2 kg, height 1.75 +/- 0.08 m) performed dynamic resistance training for 13 weeks. The control group (n = 14; age 19.9 +/- 1.5 years, body mass 74.0 +/- 8.5 kg, height 1.76 +/- 0.05 m) did not perform any resistance training. Maximal dynamic and isometric strength were tested in both groups, before and after the training period. The members of the training group used the free-weight squat lift (90 degrees ) as their training exercise. The concentric phase of the squat was performed explosively. Skeletal muscle architecture of the vastus lateralis was visualized using ultrasonography. At the end of the study, significant increases in vastus lateralis muscle thickness (+6.9%, P < 0.001), fascicle length (+10.3%, P < 0.05), one-repetition maximum (+8.2%, P < 0.05), rate of force development (+23.8%, P < 0.05) and average force produced in the first 500 ms (+11.7%, P < 0.05) were seen only in the training group. Adaptations to the muscle architecture in the training group limited the loss of fibre force, and improved the capacity for developing higher velocities of contraction. The architectural changes in the training group were similar to those seen in studies where high-speed training was performed. In conclusion, dynamic resistance training with light loads leads to increases in muscle thickness and fascicle length, which might be related to a more efficient transmission of fibre force to the tendon.     

Visual-perceptual training with motor practice of the observed movement pattern improves anticipation in emerging expert cricket batsmen

ABSTRACT

This study addressed the paucity of evidence of whether visual anticipation can be improved in emerging experts in striking sports. Twelve emerging expert batsmen from a state cricket squad were equally randomised into intervention and control groups. They were pre-and-post tested on a video temporal occlusion test of a fast bowler, as well as transfer tests of different fast and slow bowlers. The intervention group received two sessions per week of point-light display temporal occlusion training with motor practice of the observed bowler’s action over a 4-week period. The control group completed only the testing phases. Batting averages before, during, and after the study were recorded for both groups. The intervention group, but not the control group, improved anticipation to significantly above chance level across pre-to-post-tests based upon pre-ball flight information. The intervention, but not the control, transferred their learning to anticipate significantly above chance level based upon pre-ball flight information across different fast and slow (spin) bowlers. Batting average of the intervention group was higher than the control group during the study. Findings indicate that the intervention can improve anticipation in emerging expert batsmen, beyond sport-specific practice. This improvement may benefit competition performance, but further evidence is required.     

TDP提高肌肉力量训练效果的实验研究

为期九周的实验训练结果表明:TDP复合元素板在热激发下发射的特定电磁波用于肌肉力量训练,其最大力量和爆发力的增长率有明显提高,这种有效性与TDP在医用方面的良好生物学效应是相吻合的。而TDP在肌肉内部产生作用的机理,可以在医学领域相应的研究成果中找到一些依据,但更深入细致的研究,尤其是TDP对肌细胞兴奋——收缩内在过程的影响,还需设计新的实验方法以便能在细胞水平上加以探索。     

Can anti-gravity running improve performance to the same degree as over-ground running?

This study examined the changes in running performance, maximal blood lactate concentrations and running kinematics between 85%BM anti-gravity (AG) running and normal over-ground (OG) running over an 8-week training period. Fifteen elite male developmental cricketers were assigned to either the AG or over-ground (CON) running group. The AG group (n = 7) ran twice a week on an AG treadmill and once per week over-ground. The CON group (n = 8) completed all sessions OG on grass. Both AG and OG training resulted in similar improvements in time trial and shuttle run performance. Maximal running performance showed moderate differences between the groups, however the AG condition resulted in less improvement. Large differences in maximal blood lactate concentrations existed with OG running resulting in greater improvements in blood lactate concentrations measured during maximal running. Moderate increases in stride length paired with moderate decreases in stride rate also resulted from AG training. The use of AG training to supplement regular OG training for performance should be used cautiously, as extended use over long periods of time could lead to altered stride mechanics and reduced blood lactate.     

Investigation of an experimental weight-training programme.

The aim of this study was to compare the effects of conventional weight-training (control) with an experimental programme. The training programme consisted of 12 sessions, 3 a week for 4 weeks. The experimental group (n = 12) performed sets of forearm flexion with a barbell until a 20% decline in maximal force was noted. The controls (n = 11) trained according to established weight-training principles. Isometric tests were performed on both the right and left forearm flexors and during forearm flexion with a barbell: the tests were continued for a 3-week post-experimental period. The subjects were matched on all tests at the start of the experiment. Larger reductions in muscle torque within the training sessions were noted among the experimental subjects--19.8 +/- 2.0, 16.9 +/- 1.9 and 18.0 +/- 1.8% for right, left and combined elbow flexion respectively, compared to 11.8 +/- 2.7, 14.9 +/- 4.1 and 13.4 +/- 3.1% for the controls. The volume of training (number of lifts) was 30.4% higher for the experimental subjects. Muscle strength increased in both groups (P less than 0.05). The controls improved by 12.7 +/- 6.9, 24.9 +/- 22.1, 18.3 +/- 12.3 and 30.3 +/- 11.1% for right, left, combined isometric strength and the barbell test respectively. These did not differ significantly from the corresponding results for the experimental group--7.6 +/- 8.8, 17.0 +/- 12.4, 11.8 +/- 9.3 and 29.1 +/- 10.6% (P greater than 0.05). Neither the decrease in force during a single training session nor the volume of training were related to the training effect expressed as an increase in muscle force (P greater than 0.05). The effectiveness of the conventional programme in producing similar improvements in muscle strength to the experimental programme suggests that a high volume of training is unnecessary for strength gains.     

Effects of aerobic exercise on overweight children's cognitive functioning: a randomized controlled trial

The study tested the effect of aerobic exercise training on executive function in overweight children. Ninety-four sedentary, overweight but otherwise healthy children (mean age = 9.2 years, body mass index 85th percentile) were randomized to a low-dose (20 min/day exercise), high-dose (40 min/day exercise), or control condition. Exercise sessions met 5 days/week for 15 weeks. The Cognitive Assessment System (CAS), a standardized test of cognitive processes, was administered individually before and following intervention. Analysis of covariance on posttest scores revealed effects on executive function. Group differences emerged for the CAS Planning scale (p = .03). Planning scores for the high-dose group were significantly greater than those of the control group. Exercise may prove to be a simple, yet important, method of enhancing aspects of children's mental functioning that are central to cognitive and social development.     

Technical performance effectiveness subsequent to complex motor skills training in young boxers

Abstract

Boxing is a sport that comprises a wide variety of integrated offensive, defensive and counter-attack skills performed in an unpredictable environment. Mastering the variety of complex motor skills (CMS) that are required in a boxing match allows the player to employ the best motor performance in most positions of the actual game. This study aimed to assess the associations between implementing CMS versus simple motor skill (SMS) training and the subsequent changes in physical, technical and technical performance effectiveness (TPE) variables in junior boxers. We employed an experimental design that comprised two groups (each 20 males, mean age = 15.22±0.62 years). For 12 weeks, intervention boxers received CMS training, while controls received traditional SMS training. Physical, technical and TPE variables were measured before and after the training programs. Although the two groups were of similar abilities at baseline, there were statistically significant differences (P<0.05) between the intervention and control boxers in the post measures, to the advantage of the intervention group. In terms of absolute (i.e. differences in) or relative (i.e. ratios of) improvements, the intervention group exhibited more favourable values across the variables, and better performance. Developing CMS of junior boxers could contribute positively to their physical and technical abilities, and enhance their TPE.     

The biomechanical characteristics of high-performance endurance running

The biomechanical profile of high-level endurance runners may represent a useful model that could be used for developing training programmes designed to improve running style. This study, therefore, sought to compare the biomechanical characteristics of high-performance and recreational runners. Kinematic and kinetic measurements were taken during overground running from a cohort of 14 high-performance (8 male) and 14 recreational (8 male) runners, at four speeds ranging from 3.3 to 5.6?m?s^?1. Two-way ANOVA analysis was then used to explore group and speed effects and principal component analysis used to explore the interdependence of the tested variables. The data showed the high-performance runners to have a gait style characterised by an increased vertical velocity of the centre of mass and a flight time that was 11% longer than the recreational group. The high-performance group were also observed to adopt a forefoot strike pattern, to contact the ground with their foot closer to their body and to have a larger ankle moment. Importantly, although observed group differences were mostly independent of speed, the tested variables showed a high degree of interdependence suggesting an underlying unitary phenomenon. This is the first study to compare high-performance and recreational runners across a full range of kinematic and kinetic variables. The results suggest that high-performance runners maintain stride length with a prolonged aerial phase, rather than by landing with a more extended knee. These findings motivate future intervention studies that should investigate whether recreational runners could benefit from instruction to decrease shank inclination at foot contact.     

Maximal isometric force and muscle cross‐sectional area of the forearm in fencers

The maximal isometric force (MIF) of a muscle is directly related to its cross‐sectional area (CSA). Strength training produces an increase in muscular force while muscular hypertrophy becomes appreciable at a later time; in asymmetric sports, training causes significant increases in force and muscular mass of the dominant limb of the athlete. The aim of this study was to analyse the differences in muscular force and trophism between the dominant and non‐dominant forearms in fencers and in controls.

The data of 17 male distance runners (age 21.4±2.4 years, body mass 74.0±5.0 kg, height 180 ± 6 cm) were compared with those of 58 male fencers (age 23.0 ± 6.7 years, body mass 71.9±9.3 kg, height 178 ± 7 cm) drawn from the ranking lists of the National Fencing Committee. They trained for a mean of 11.4±6.0 (range 2–36) years, commencing at 10.7 ± 4.5 years of age.

Cross‐sectional area (muscle plus bone) was estimated in the dominant and non‐dominant forearm using a simplified anthropometric method. Maximal isometric force was determined using a mechanical handgrip dynamometer. The differences in CSA and isometric force between the two limbs and between fencers and controls were tested using paired and unpaired Student's i‐tests, respectively. Significant differences in CSA and maximal force were observed between the dominant and non‐dominant forearm in fencers (both P<0.001) and in controls (P<0.005 and P<0.001, respectively). The fencers showed a greater CSA (P<0.001) and force (P< 0.001) in the dominant forearm compared with the control group. Furthermore, the differences between the dominant and non‐dominant limb of the fencers were significantly greater than the differences between the dominant and non‐dominant limb of the controls (P<0.001 for CSA and P<0.05 for force). No significant differences in stress ratio (force/CSA) were obtained in either group.

The results of this study suggest that asymmetric sports training at submaximal intensities produces significant asymmetries in force and CSA which are independent of technical level and years of training. Despite this, the force/CSA ratio is constant and independent of training.     

Effects of a verbal and visual feedback system on running technique, perceived exertion and running economy in female novice runners

The purpose of this study was to determine the effects of a verbal and visual feedback system on running technique, ratings of perceived exertion (RPE), and running economy. Twenty-two female novice runners were randomly assigned to experimental (n = 11) and control (n = 11) groups. The experimental subjects received verbal and visual feedback concerning their running technique prior to and during each training run. Training involved 15 20-min treadmill running sessions over a 5-week period. The control group adhered to the same training routine but did not receive feedback concerning their running technique. High-speed (100 Hz) photography was used to collect biomechanical data. A submaximal oxygen consumption test and Borg's RPE scale were used to collect data concerning running economy and perceived exertion, respectively. Statistical analysis using ANCOVA revealed that the proposed feedback system had a significant (P less than 0.01) effect on the experimental group's running technique by affecting the following desired changes relative to the control group: greater relative stride lengths, shorter support time, greater ankle dorsiflexion during support and greater knee flexion during support and non-support. There were no significant differences between the groups in submaximal VO2 or RPE. The results of this study suggest that verbal and visual feedback are effective means of eliciting modifications in running style in female novice runners. The link between modifications in running style and improvements in running economy and perceived exertion remains unclear.     

Effects of a power-focussed resistance training intervention on backward grinding performance in America's Cup sailing

This study determined whether backward grinding performance in America's Cup sailing could be improved using a training intervention to increase power capability in the upper-body pull movement. Fourteen elite male sailors (34.9 ± 5.9 years; 98.1 ± 14.4 kg; 186.6 ± 7.7 cm) were allocated into experimental (speed-focussed) and control groups. Grinding performance was assessed using a grinding ergometer and an instrumented Smith machine measured force, velocity and power during the bench pull exercise. Conventional training produced significant improvements in bench pull 1 RM (5.2 ± 4.0%; p = 0.016) and maximum force production (5.4 ± 4.0%; p = 0.014). Speed-focussed training improved maximum power (7.8 ± 4.9%; p = 0.009), power at 1RM (10.3 ± 8.9%; p = 0.019) and maximum velocity (8.4 ± 2.6%; p = 0.0002). Backward grinding performance showed greater improvements in the experimental group than the control group for moderate (+1.8%) and heavy load (+6.0%) grinding. Changes in maximum power output and power at 1 RM had large correlations (r = 0.56–0.61) with changes in both moderate and heavy load grinding performance. Time to peak force had the strongest relationship, explaining 70% of the change in heavy load grinding performance. Although the performance benefit was not entirely clear the likelihood of a detrimental effect was low ( < 5%) and therefore implementation could be recommended.     

Effects of 16 - week Tai Chi intervention on postural stability and associated physiological factors in older people

One of the challenges faced by aging people is de-creased postural stability and increased risks for falls.Thereis general agreement that postural control involves manysen-sory and motor systems,and a number of investigators havefound that ageis relatedto declinesin visual,vestibular,andsensorimotor functions[1].With increasing age,the timerequired to process and integrate sensory information andmotor reactionincreases[2].Proprioception,the afferent infor-mationregarding body position and bala…     

Effects of Aerobic Exercise on Overweight Children's Cognitive Functioning

The study tested the effect of aerobic exercise training on executive function in overweight children. Ninety-four sedentary, overweight but otherwise healthy children (mean age = 9.2 years, body mass index ? 85th percentile) were randomized to a low-dose (20 min/day exercise), high-dose (40 min/day exercise), or control condition. Exercise sessions met 5 days/week for 15 weeks. The Cognitive Assessment System (CAS), a standardized test of cognitive processes, was administered individually before and following intervention. Analysis of covariance on posttest scores revealed effects on executive function. Group differences emerged for the CAS Planning scale (p = .03). Planning scores for the high-dose group were significantly greater than those of the control group. Exercise may prove to be a simple, yet important, method of enhancing aspects of children's mental functioning that are central to cognitive and social development.     

Balance and proprioception responses to FIFA 11+ in amateur futsal players: Short and long-term effects

ABSTRACT

Background: The FIFA 11+ has shown positive effects on balance and proprioception parameters in football players. As there have been very few research studies involving futsal, we examined the short and long term effects of the FIFA 11+ on static and dynamic balance, as well as proprioception in male amateur futsal players.

Methods: Seventy-one male futsal players were randomized to two groups (FIFA 11+: n = 37, age: 27.33 ± 4.33 years; Control: n = 34, age: 25.55 ± 4.65 years). Intervention lasted 10 weeks, 2 sessions per week, succeeded by a 10-week follow-up period. For balance testing, we assessed the single-legged postural sway with a force platform (static balance) and the Y balance test (dynamic balance). Proprioception was assessed with active joint position sense testing.

Results: Complete pre-post intervention and follow-up tests were available for 61 players. The FIFA 11+ group showed higher training exposure and lower body mass index and body weight. After adjustment for baseline differences, no significant differences between groups were observed in the pre-post changes for centre of pressure measures, Y-balance and proprioception parameters both at short and long-term.

Conclusions: Performing FIFA 11+ for 10 weeks did not improve static and dynamic balance as well as proprioception in amateur futsal players.