Reliabilities of leg and vertical stiffness during treadmill running

The aim of this study was to determine the intra-participant variabilities (i.e. intra-day and inter-day reliabilities) in leg and vertical stiffness, as well as related kinematic parameters, during treadmill running using the sine-wave method. Twenty-two healthy men ran on a treadmill at 4.44 m/s, and the flight and contact times were measured with a high-speed video camera. Three 30-s running bouts with 2-min inter-bout rests were performed to examine the intra-day reliability, and single 30-s running bouts on three separate days with 24- to 48-h inter-bout intervals were performed to examine the inter-day reliability. The reliability statistics included repeated-measure analyses of variance, average inter-trial correlations, intra-class correlation coefficients (ICCs), Cronbach's α reliability coefficient, and the coefficient of variation. Both leg and vertical stiffness produced high ICCs within 0.972 and 0.982, respectively, and between 0.922 and 0.873 days, respectively. High values were also observed for all of the reliability coefficients. Similar results were found regarding contact time, flight time, step length, and step rate. It was concluded that the measurements of leg and vertical stiffness, as well as related kinematic parameters, obtained using the sine-wave method during treadmill running at 4.44 m/s, were highly reliable, both within and across days.     

原地摆臂纵跳和抱头纵跳动力学特征的比较

运用三维测力台(Kistler)和红外光点自动捕捉测试系统(Qualisys-MCU500)对北京体育大学男子排球队9名运动员分别进行了摆臂纵跳和抱头纵跳的测试,结果表明:摆臂纵跳蹬伸过程中最大力值大于抱头纵跳,但是由于蹬伸后半段时间的延长使后半段蹬伸力的梯度值没有明显增加;落地时地面最大冲击力与纵跳高度无关;摆臂纵跳的冲量值大于抱头纵跳,但研究结果发现纵跳高度与冲量并没有显著性相关关系.     

800 m跑下肢垂直刚度与腿刚度的变化特征

利用弹簧质量模型对广东省第7届大学生运动会男子乙组800 m跑过程中,支撑腿垂直刚度及腿刚度进行探讨,结果表明:腿垂直刚度、腿刚度及跑速在100～200 m区间内达到峰值,并从此开始直到最后均呈连续下降;垂直刚度及腿刚度与跑速均存在显著的线性正相关,这种关联性也体现在与步频及步幅上;垂直刚度与支撑时间、腾空时间存在显著负相关,但却与腾空时间与支撑时间比值呈显著正相关,其深层原因有待于进一步探讨;800 m跑后期阶段,要想保持跑速,通过保持较高的垂直刚度来维持较高的步频最为关键.     

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.     

Contribution of the lower extremity joints to mechanical energy in running vertical jumps and running long jumps

The energy contribution of the lower extremity joints to vertical jumping and long jumping from a standing position has previously been investigated. However, the resultant joint moment contributions to vertical and long jumps performed with a running approach are unknown. metatarsophalangeal joint to these activities has not been investigated. The objective of this study was to determine the mechanical energy contributions of the hip, knee, ankle and metatarsophalangeal joints to running long jumps and running vertical jumps. A sagittal plane analysis was performed on five male university basketball players while performing running vertical jumps and four male long jumpers while performing running long jumps. The resultant joint moment and power patterns at the ankle, knee and hip were similar to those reported in the literature for standing jumps. It appears that the movement pattern of the jumps is not influenced by an increase in horizontal velocity before take-off. The metatarsophalangeal joint was a large energy absorber and generated only a minimal amount of energy at take-off. The ankle joint was the largest energy generator and absorber for both jumps; however, it played a smaller relative role during long jumping as the energy contribution of the hip increased.     

振动力量训练对女子铅球运动员支撑腿膝关节屈伸肌肉力量影响的实验研究

以上海体育学院竞技体育系10名女子铅球运动员为研究对象,对她们实施了6周两种不同方法的力量训练后发现:振动力量训练结合传统力量训练方法的实验组,其CYBEX等动练习机上的峰力矩、每次作功、平均作功、到峰力矩时间等指标均优于只进行传统力量训练方法的对照组.提示振动力量训练能够更有效的提高女子铅球运动员支撑腿的最大力量和快速力量.     

Four weeks of running sprint interval training improves cardiorespiratory fitness in young and middle-aged adults

The purpose of this study was to determine the effectiveness of a 4-week running sprint interval training protocol to improve both aerobic and anaerobic fitness in middle-aged adults (40–50 years) as well as compare the adaptations to younger adults (20–30 years). Twenty-eight inactive participants – 14 young 20–30-year-olds (n = 7 males) and 14 middle-aged 40–50-year-olds (n = 5 males) – completed 4 weeks of running sprint interval training (4 to 6, 30-s “all-out” sprints on a curved, self-propelled treadmill separated by 4 min active recovery performed 3 times per week). Before and after training, all participants were assessed for maximal oxygen consumption (VO_2max), 2000 m time trial performance, and anaerobic performance on a single 30-s sprint. There were no interactions between group and time for any tested variable, although training improved relative VO_2max (young = 3.9, middle-aged = 5.2%; P < 0.04), time trial performance (young = 5.9, middle-aged = 8.2%; P < 0.001), peak sprint speed (young = 9.3, middle-aged = 2.2%; P < 0.001), and average sprint speed (young = 6.8, middle-aged = 11.6%; P < 0.001) in both young and middle-aged groups from pre- to post-training on the 30-s sprint test. The current study demonstrates that a 4-week running sprint interval training programme is equally effective at improving aerobic and anaerobic fitness in younger and middle-aged adults.     

Psychosocial wellbeing in active older adults: A systematic review of qualitative literature

Physical activity and wellbeing in older adults is a global priority in combating negative economic consequences associated with population aging. Quantitative research using a medicalized model clearly associates physical activity with physiological health benefits. However, it is argued that a review of qualitative literature exploring individual experiences of active older adults can provide important insights into physical activity, aging, and wellbeing – specifically, how discourses of ageing and self-identity may interact with physical activity levels. A literature search on electronic databases PsycARTICLES, PsycINFO, SPORTDiscus, and ProQuest was used to identify qualitative studies of older adults who exercise or engage in competitive sport. Findings reveal that both groups tend to resist dominant negative stereotypes of ageing and view physical activity as central to self- identity. Yet approaches to ageing varied with the competitive sport group adopting a more negative view of the ageing process. Whilst results suggest that different levels of physical activity may impact on the psychosocial wellbeing of older adults, inconsistent definitions of exercise and competitive sport make it impossible to group these differences according to specific physical activity levels. More precise definitions of physical activity constructs in future research may provide a better understanding of these differences.     

The effect of foot orthoses and insoles on running economy and performance in distance runners: A systematic review and meta-analysis

ABSTRACT

Foot orthoses and insoles are prescribed to runners, however their impact on running economy and performance is uncertain. The aim of this systematic review and meta-analysis was to determine the effect of foot orthoses and insoles on running economy and performance in distance runners. Seven electronic databases were searched from inception until June 2018. Eligible studies investigated the effect of foot orthoses or insoles on running economy (using indirect calorimetry) or running performance. Standardised mean differences (SMDs) were computed and meta-analyses were conducted using random effects models. Methodological quality was assessed using the Quality Index. Nine studies met the criteria and were included: five studies investigated the effect of foot orthoses on running economy and four investigated insoles. Foot orthoses were associated with small negative effects on running economy compared to no orthoses (SMD 0.42 [95% CI 0.17,0.72] p = 0.007). Shock absorbing insoles were also associated with negative effects on running economy, but an imprecise estimate (SMD 0.26 [95% CI ?0.33,0.84] p = 0.83). Quality Index scores ranged from 4 to 15 out of 17. Foot orthoses and shock absorbing insoles may adversely affect running economy in distance runners. Future research should consider their potential effects on running performance.     

A simple method for assessment of muscle force,velocity, and power producing capacities from functional movement tasks

A range of force (F) and velocity (V) data obtained from functional movement tasks (e.g., running, jumping, throwing, lifting, cycling) performed under variety of external loads have typically revealed strong and approximately linear F–V relationships. The regression model parameters reveal the maximum F (F-intercept), V (V-intercept), and power (P) producing capacities of the tested muscles. The aim of the present study was to evaluate the level of agreement between the routinely used “multiple-load model” and a simple “two-load model” based on direct assessment of the F–V relationship from only 2 external loads applied. Twelve participants were tested on the maximum performance vertical jumps, cycling, bench press throws, and bench pull performed against a variety of different loads. All 4 tested tasks revealed both exceptionally strong relationships between the parameters of the 2 models (median R = 0.98) and a lack of meaningful differences between their magnitudes (fixed bias below 3.4%). Therefore, addition of another load to the standard tests of various functional tasks typically conducted under a single set of mechanical conditions could allow for the assessment of the muscle mechanical properties such as the muscle F, V, and P producing capacities.     

Relationship of running economy, ventilatory threshold, and maximal oxygen consumption to running performance in high school females

The purpose of the study was to relate three determinants of distance running success, (a) maximal oxygen consumption (VO2max), (b) ventilatory threshold (VT), and (c) running economy (RE), to actual running time in a 5-km race (ART). Twenty-four female runners (M age = 15.9 years) from four high school teams that competed at the Massachusetts All-State 5-km Cross Country Championship Meet and placed 1st, 7th, 19th, and 20th were tested in the laboratory. The mean VO2max of these runners was 61.7 ml.kg-1.min-1, HRmax 201 b.min-1, VEmax 100 L.min-1, and RER 1.10. The VT occurred at 79% of the VO2max, and HR of 184 b.min-1 (92% of HRmax). The velocity at VT (vVT) and velocity at VO2max (vVO2max) was correlated with ART, r(22) = .78 and .77 (p less than .001), respectively. The VO2 at VT and at maximal exercise was correlated with ART by r(22) = -.66 and -.69 (p less than .001), respectively. The VO2 at 215 m.min-1 (8 mph) was poorly related to ART, r(22) = -.05, p greater than .05. It was concluded that either of the derived variables vVT and vVO2max appear to explain significant variation in distance running performance among adolescent female cross country runners.     

Role of objectively measured sedentary behaviour in physical performance,frailty and mortality among older adults: A short systematic review

Sedentary behaviour (SB) has recently emerged as an independent risk factor for different health outcomes. Older adults accumulate long time in SB. Understanding the role that SB plays on health is crucial for a successful aging. This short systematic review summarizes the current evidence related to the effects of objectively measured SB on frailty, physical performance and mortality in adults ≥60?years old. The literature search produced 271 records for physical performance (n?=?119), frailty (n?=?31), and mortality (n?=?121). Finally, only 13 articles fulfilled the inclusion criteria and were included in this review. All articles but one included in the physical performance section (n?=?9) showed a negative association between longer time spent in SB and physical performance. A significant association of SB with higher odds of frailty was found, however this association disappeared after adjusting for cognitive status. Lastly, two of the three included studies showed positive associations between SB and mortality, but this effect decreased or even disappeared in the more adjusted models. In conclusion, there is consistency that SB is negatively associated with physical performance. However, the relationship between objectively measured SB and frailty incidence and mortality rates remains unclear and deserves further research. The use of homogenous criteria to assess SB and the inclusion of more robust research designs will help clarifying the independent effects that SB could have on physical performance, frailty, and mortality. This will ultimately help designing more efficient and comprehensive physical activity guidelines for older adults.     

Effects of strengthening and stretching exercise programmes on kinematics and kinetics of running in older adults: a randomised controlled trial

The aim of this study was to investigate the effects of strengthening and stretching exercises on running kinematics and kinetics in older runners. One hundred and five runners (55–75 years) were randomly assigned to either a strengthening (n = 36), flexibility (n = 34) or control (n = 35) group. Running kinematics and kinetics were obtained using an eight-camera system and an instrumented treadmill before and after the eight-week exercise protocol. Measures of strength and flexibility were also obtained using a dynamometer and inclinometer/goniometer. A time effect was observed for the excursion angles of the ankle sagittal (P = 0.004, d = 0.17) and thorax/pelvis transverse (P < 0.001, d = 0.20) plane. Similarly, a time effect was observed for knee transverse plane impulse (P = 0.013, d = 0.26) and ground reaction force propulsion (P = 0.042, d = ?0.15). A time effect for hip adduction (P = 0.006, d = 0.69), ankle dorsiflexion (P = 0.002, d = 0.47) and hip internal rotation (P = 0.048, d = 0.30) flexibility, and hip extensor (P = 0.001, d = ?0.48) and ankle plantar flexor (P = 0.01, d = 0.39) strength were also observed. However, these changes were irrespective of exercise group. The results of the present study indicate that an eight-week stretching or strengthening protocol, compared to controls, was not effective in altering age-related running biomechanics despite changes in ankle and trunk kinematics, knee kinetics and ground reaction forces along with alterations in muscle strength and flexibility were observed over time.     

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 < 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 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.     

排球运动员急停起跳动作中跖趾关节的生物力学分析

以20名女排队员急停起跳动作中的跖趾关节为研究对象,通过三维测力台、高速摄像机和肌电仪多机同步测试来收集运动员急停起跳中跖趾关节的运动学、动力学以及肌电数据。结果表明：1）排球运动员在急停起跳动作中,跖趾关节角度变化幅度在50°~60°之间时,运动员的起跳高度较高。建议排球运动员将急停起跳动作中的跖趾关节进行专项化训练,并采用50°~60°的跖趾关节角度变化幅度;2）排球运动员在急停起跳动作初采用足尖着地能够取得较好的起跳高度。建议排球运动员在训练及比赛中进行急停起跳动作初采用足尖着地;3）训练中,应利用跖趾关节力量训练器进行针对性训练,提高趾长伸肌、第三腓骨肌、拇长伸肌的力量值,提高跖趾关节的活化程度,进而提高运动员的起跳高度。     

A wireless accelerometer node for reliable and valid measurement of lumbar accelerations during treadmill running

This study investigated the reliability of a wireless accelerometer and its agreement with optical motion capture for the measurement of root mean square (RMS) acceleration during running. RMS acceleration provides a whole-body metric of movement mechanics and economy. Fifteen healthy college-age participants performed treadmill running for two 60-s trials at 2.22, 2.78, and 3.33 m/s and one trial of 150 s (five 30-s epochs) at 2.78 m/s. We assessed between-trial and within-trial reliability, and agreement in each axis between a trunk-mounted wireless accelerometer and a reflective marker on the accelerometer measured by optical motion capture. Intraclass correlations assessing between-trial repeatability were 0.89–0.97, depending on the axis, and intraclass correlations assessing within-trial repeatability were 0.99–1.00. Bland–Altman analyses assessing agreement indicated mean difference values between ?0.03 and 0.03 g, depending on the axis. Anterio-posterior acceleration had the greatest limits of agreement (LOA) (±0.12 g) and vertical acceleration had the smallest LOA (±0.03 g). For measuring RMS acceleration of the trunk, this wireless accelerometer node provides repeatable and valid measurement compared with the standard laboratory method of optical motion capture.     

论大众体育运行的公共治理:内涵、基础及实现途径

大众体育公共治理的运行基础是建立有效的体育社会化的组织结构、运行机制和运行模式.研究认为：现阶段应优先确立政府的主导作用，积极拓展新型消费与消费服务的供给领域，积极培育大众体育市场，健全城镇社区的体育组织管理体系.当前体育社会化的发展要克服传统体育的运行模式，关键的问题是建立政府、社会、企业三位一体的社会体育治理结构.政府应该从管理经济、社会、环境领域的全部公共事务，转变为提供基础性的公共物品和服务，尽快发展一些功能健全的行业协会，使之成为承担政府下放的社会职能的载体.在此基础上提出了：强化政府公共职能，变革体育管理体制，优化社会体育资源配置;形成以社会大众为对象的多样化体育服务网络;调整体育产业结构，推动传统体育产业向服务业转移以及服务结构、服务项目及服务方式创新等构建内容，以进一步适应社会转型和体育体制的改革发展。     

无累进递增负荷与有累进递增负荷测定无氧阈 结果的对比研究

通过10名体育专业健康男性大学生在Jacger程控跑台上分别进行有累进递增负荷与无累进递增负荷，并在实验中测定各档跑速时的相应心率(HR)和血乳酸值(HLa)。结果无累进递增负荷的AT值明显推迟出现；进一步研究发现采用无累进递增负荷测定的AT值更能科学地反映机体的实际水平，能对评价运动员有氧耐力水平和指导运动训练提供更科学的依据。