Accuracy and precision of loadsol® insole force-sensors for the quantification of ground reaction force-based biomechanical running parameters

Force plates represent the “gold standard” in measuring running kinetics to predict performance or to identify the sources of running-related injuries. As these measurements are generally limited to laboratory analyses, wireless high-quality sensors for measuring in the field are needed. This work analysed the accuracy and precision of a new wireless insole forcesensor for quantifying running-related kinetic parameters. Vertical ground reaction force (GRF) was simultaneously measured with pit-mounted force plates (1?kHz) and loadsol^® sensors (100?Hz) under unshod forefoot and rearfoot running-step conditions. GRF data collections were repeated four times, each separated by 30 min treadmill running, to test influence of extended use. A repeated-measures ANOVA was used to identify differences between measurement devices. Additionally, mean bias and Bland–Altman limits of agreement (LoA) were calculated. We found a significant difference (p?® devices for these parameters. For these same parameters, the LoA analysis showed that 95% of all measurement differences between insole and force plate measurements were less than 12%, demonstrating high precision of the sensors. However, highly dynamic behaviour of GRF, such as force rate, is not yet sufficiently resolved by the insole devices, which is likely explained by the low sampling rate.     

Acute effects of different warm-up protocols on highly skilled golfers’ drive performance

Previous research has highlighted the positive effect that different warm-up protocols have on golf performance (e.g. Sorbie et al., 2016; Tilley & Macfarlane, 2012) with the design of warm-ups and programmes targeting and improving golf performance through the activation and development of specific muscle groups. This study aimed to examine the acute effects of two warm-up protocols on golf drive performance in comparison to a control condition. Using a randomised counterbalanced design over three testing sessions, twenty-three highly skilled golfers completed the control, dynamic and resistance-band warm-up conditions. Following each condition, a GC2 launch monitor was used to record ball velocity and other launch parameters of ten shots hit with the participants’ own driver. A repeated-measures ANOVA found significant increases in ball velocity (η_p² = .217) between the control and both the dynamic and resistance-band warm-up conditions but no difference between these latter two, and a reduction in launch angle between control and dynamic conditions. The use of either a dynamic stretching or resistance-band warm-up can have acute benefits on ball velocity but golfers should liaise with a PGA Professional golf coach to effectively integrate this into their golf driving performance.     

Grip and Forearm Position Effects on Tests of Static and Dynamic Upper Body Endurance

Abstract

The effects of grip and forearm position on two tests of upper body muscular endurance were investigated in 109 male subjects 18–21 years of age. Subjects were systematically presented 12 tasks: six pull-up and six straight-arm hang grip and forearm variations. Each of the six tasks for both endurance tests represented a different combination of grip (thumb over bar and thumb under bar) and forearm position (pronated, supinated and semi-pronated). Task results were analyzed utilizing 2 × 3 (grip × forearm) ANOVA with repeated measures on the two factors. Analysis of pull-up data revealed that the semi-pronated and supinated forearm positions were not statistically different from each other, but superior to the pronated condition. Results of straight-arm hang performance revealed a significant difference between grips at the semi-pronated position, with the “thumb under bar” being superior. Results for forearm positions at grips indicated a significant difference for the “thumb under bar,” with the pronated and semi-pronated positions being superior to the supinated position. For forearm positions at “thumb over bar,” the pronated condition was significantly different from the semi-pronated and supinated positions. Thumb position trends and kinesiological mechanical analysis did foster general recommendations for use of the “thumb over bar” for pull-ups and the “thumb under bar” position for the straight-arm hang.     

全面建成小康社会背景下体育的发展理念--基于对体育休闲的认识

全面建成小康社会是我国现阶段的发展历程,体育在这一时期也面临新的转型。群众体育朝体育休闲的方向发展是符合我国的现状,有利于人民与社会进步的一种发展方式。研究以休闲为基础,认识体育休闲,论述体育休闲：健康性、自然性、实践性、愉悦性、超越性、价值性六种属性,从“自然发展状态的构建”、“和谐社会氛围的营造”、“美好生活方式的建立”、“文化价值品味的呈现”四个方面阐述体育休闲对全面建成小康社会中的价值,旨在对我国体育的发展提供一点参考。     

Between-Day Reliability and Usefulness of a Fitness Testing Battery in Youth Sport Athletes: Reference Data for Practitioners

This study aimed to evaluate the between-day reliability and usefulness of a fitness testing battery in a group of youth sport athletes. Fifty-nine youth sport athletes (age = 17.3 ± 0.7 years) undertook a fitness testing battery including the isometric mid-thigh pull, counter-movement jump, 5–40 m sprint splits, and the 5–0-5 change of direction test on two occasions separated by 7 days. Usefulness was assessed by comparing the reliability (typical error) to the smallest worthwhile change. The typical error was 5.5% for isometric mid-thigh pull and 3.8% for counter-movement jump. The typical error values were 2.7, 2.5, 2.2, 2.2, and 1.8% for the 5, 10, 20, 30, and 40 m sprint splits, and 4.1% (left) and 5.4% (right) for the 5–0-5 tests. The smallest worthwhile change ranged from 1.1 to 6.1%. All tests were identified as having “good” or “acceptable” reliability. The isometric mid-thigh pull and counter-movement jump had “good” usefulness, all other tests had “marginal” usefulness.     

Comment on “Talent identification and promotion programmes of Olympic athletes”

Abstract

Waist girth is recognised as a better predictor of obesity, particularly abdominal obesity, compared to other measures. Although several protocols for waist girth exist, arm position is either ignored, or not specified in unambiguous terms. Therefore, the purpose of this study was to determine if arm position influenced anthropometric waist girth measurement. Waist girth was measured in 92 adults (19 males, 73 females) with arms relaxed, abducted, horizontal, folded across the chest (three variations) and raised vertically. Duplicate measures, in all positions, were recorded by a single International Society for the Advancement of Kinanthropometry (ISAK)-trained technician to a precision of 0.2% technical error of measurement (TEM). Arm position had a significant effect (P < 0.001) on waist girth. Male participants had greater waist girth than females (P < 0.001) and the waist girth differences across the varying arm positions exhibited a significant position-by-gender interaction (P < 0.001). The arm position-by-body mass index (BMI) category interaction was also significant (P = 0.016) with greater differences observed at higher BMI. These findings suggest caution in comparing results of different studies where arm position is not specified and indicate that the arm position corresponding to the ISAK protocol has the lowest error and is therefore recommended.     

The off-break and “doosra”: Kinematic variations of elite and sub-elite bowlers in creating ball spin in cricket bowling

This study sought to identify kinematic differences in finger-spin bowling actions required to generate variations in ball speed and spin between different playing groups. A 12-camera Vicon system recorded the off-spin bowling actions of six elite and 13 high-performance spin bowlers, and the “doosra” actions of four elite and two high-performance players. Forearm abduction and fixed elbow flexion in the bowling arm were higher for the elite players compared with the high-performance players. The elite bowlers when compared with the high-performance players delivered the off-break at a statistically significant higher velocity (75.1 and 67.1 km/hr respectively) and with a higher level of spin (26.7 and 22.2 rev/s respectively). Large effect sizes were seen between ball rotation, pelvic and shoulder alignment rotations in the transverse plane. Elbow extension was larger for elite bowlers over the period upper arm horizontal to ball release. Compared to the off-break, larger ranges of shoulder horizontal rotation, elbow and wrist extension were evident for the “doosra”. Furthermore, the “doosra” was bowled with a significantly longer stride length and lower ball release height. Although not significantly different, moderate to high effect size differences were recorded for pelvis rotation, elbow extension and elbow rotation ranges of motion.     

“假球”：一种博弈论解释

“假球”现象背后存在着两个层次的博弈过程,一是俱乐部之间的合作博弈;二是俱乐部与公众之间的非合作博弈。由于信息不对称的存在,越注重短期利益的俱乐部其打假球的动机也越强烈。因此如要消除“假球现象．使俱乐部成为长期参与人将是必然。     

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.     

Identification of types of landings after blocking in volleyball associated with risk of ACL injury

Landing with a low knee flexion angle after volleyball block jumps may be associated with an increased risk of anterior cruciate ligament (ACL) injury. The aim of the present study was to identify the types of volleyball landings after blocks where the knee flexion angle is found to be under a critical knee flexion angle value of 30° at the instant of the first peak of the ground reaction force (GRF). Synchronized kinematic and kinetic data were collected for each trial. T-tests were used to determine if each knee flexion angle at the instant of the peak GRF was significantly different from the critical value of 30°. A repeated measures ANOVA was used to compare knee flexion angle, time to first peak and the magnitude of the first peak of the resultant GRF and knee stiffness. Significantly lower knee flexion angles were found in the “go” landing (p?=?.01, ES?=?0.6) and the “reverse” landing (p?=?.02, ES?=?0.6) only. The results for knee flexion angle and GRF parameters indicated a significant difference between a “reverse” and “go” and other types of landings, except the “side stick” landing for GRF. The “reverse” and “go” landings may present a risk for ACL injury due to the single-leg landing of these activities that have an associated mediolateral movement.     

A systematic review on small-sided games in football players: Acute and chronic adaptations

Small-sided games (SSG) are played on a small pitch, often using modified rules and involving a smaller number of players. This article aimed to critically analyse the literature to determine how small-sided games affect the performance of football players in the short- and long term. Electronic databases were searched for literature dating from January 2000 to July 2018. The methodological quality of the studies was evaluated using the modified Downs and Black Quality Index (cross-sectional studies) and the Physiotherapy Evidence Database (PEDro) scale (intervention studies). Fifty-three studies, 44 cross-sectional and 9 intervention studies, met the inclusionary criteria for review. Most of the cross-sectional studies focused on describing the differences between SSG protocols, whereas 4 studies focused on making a comparison between “interval” and “continuous” SSG training regimes. On the other hand, intervention studies focused on making a comparison between SSG-based protocols and high-intensity intermittent training (HIIT)-based running protocols, in addition to determine the effect of a SSG-based training programme alone. SSG-based football plans (2 to 4 SSG sessions per week) show athletic performance improvements in football players by improving sprint, repeated sprint ability (RSA) and change of direction (COD) along with muscular and physiological adaptation.     

Measurement Schedules of Sprint Running

Abstract

Four measures of elapsed time were secured on a sample of 76 male physical education majors during a 50-yd. sprint. The subjects were timed during two sprints and measurements were secured at 20, 30, 40, and 50 yd. Ten different measurement schedules were developed from the four measurements. Data revealed that the greatest source of measurement error existed in the first 20 yd. of the sprint. The intraclass reliability estimates of the 10 measurement schedules ranged from .79 to .98.     

Estimation versus falsification approaches in sport and exercise science

There has been a recent resurgence in debate about methods for statistical inference in science. The debate addresses statistical concepts and their impact on the value and meaning of analyses’ outcomes. In contrast, philosophical underpinnings of approaches and the extent to which analytical tools match philosophical goals of the scientific method have received less attention. This short piece considers application of the scientific method to “what-is-the-influence-of x-on-y” type questions characteristic of sport and exercise science. We consider applications and interpretations of estimation versus falsification based statistical approaches and their value in addressing how much x influences y, and in measurement error and method agreement settings. We compare estimation using magnitude based inference (MBI) with falsification using null hypothesis significance testing (NHST), and highlight the limited value both of falsification and NHST to address problems in sport and exercise science. We recommend adopting an estimation approach, expressing the uncertainty of effects of x on y, and their practical/clinical value against pre-determined effect magnitudes using MBI.     

Test-retest reliability of jump execution variables using mechanography: a comparison of jump protocols

Mechanography during the vertical jump may enhance screening and determining mechanistic causes underlying physical performance changes. Utility of jump mechanography for evaluation is limited by scant test-retest reliability data on force-time variables. This study examined the test-retest reliability of eight jump execution variables assessed from mechanography. Thirty-two women (mean±SD: age 20.8 ± 1.3 yr) and 16 men (age 22.1 ± 1.9 yr) attended a familiarization session and two testing sessions, all one week apart. Participants performed two variations of the squat jump with squat depth self-selected and controlled using a goniometer to 80º knee flexion. Test-retest reliability was quantified as the systematic error (using effect size between jumps), random error (using coefficients of variation), and test-retest correlations (using intra-class correlation coefficients). Overall, jump execution variables demonstrated acceptable reliability, evidenced by small systematic errors (mean±95%CI: 0.2 ± 0.07), moderate random errors (mean±95%CI: 17.8 ± 3.7%), and very strong test-retest correlations (range: 0.73–0.97). Differences in random errors between controlled and self-selected protocols were negligible (mean±95%CI: 1.3 ± 2.3%). Jump execution variables demonstrated acceptable reliability, with no meaningful differences between the controlled and self-selected jump protocols. To simplify testing, a self-selected jump protocol can be used to assess force-time variables with negligible impact on measurement error.     

Testgütekriterien des Fragebogens AnMS-Sport zur Erfassung des Anschlussmotivs im Sportkontext

In this paper the test control criteria of the sport-specific Affiliation Motives Scale-Sport are reported. Theoretical background for the development of the scale is the affiliation motive, which is composed of the two factors “hope for affiliation”and “fear of rejection” (Mehrabian and Ksionzkys, A theory of affiliation, 1974). The factor analysis, which was conducted after an item analysis, displayed a two-factor structure and identified the two scales “hope for affiliation” and “fear of rejection” in sports. These two factors could be confirmed by a Confirmatory Factor Analyses. Furthermore, the questionnaire shows satisfactory Cronbach’s alpha. Construct validity is shown through correlations with two general questionnaires to measure the affiliation motive (Krippl, Itemanalytische Untersuchungen zur Selbstbeschreibung von Emotion und Motivation, 1999; Teubel, Eine deutsche Übersetzung der Mehrabian-Skala zur Erfassung des Anschlussmotivs, 2009) and two scales of the German Personality Research Form (Stumpf et al., Deutsche Personality Research Form(PRF), 1985). Validity is additionally shown through significant group differences between team and individual athletes as well as by significant differences between top-level and recreational volleyball players.     

中外比较视域下的体育小镇认知反思与重构

在城市化发展类型和模式趋于多元的背景下,体育小镇建设在西方发达国家早已积累了大量的实践案例和丰富经验,有一整套完善且成熟的建构体系和发展模式。体育小镇的理论溯源和认知基础可从“田园城市理论”“城市区域核理论”和“城市文化资本理论”角度予以重新理解,其价值再认知应从产业转型与文化再造、社会融合与社区营造以及地域生产力空间交汇、建构小镇市民生活新方式等维度展开,生成脉络遵循经济与文化的双重价值取向,而非单一的资本导向和政策驱动。在此基础上,以中外对比的视野将体育小镇置于长时段历史进行纵深式考察,剖析中西方体育小镇形成的背景差异和发展动因,并从产业和文化的二元维度做出要点解析,提出政策性建议。     

Concerns and issues in Studying and Assessing Motor Learning

This study was designed to test measurement error in a digital pedometer. Twenty-four Yamax MLS-2000 digital pedometers were tested using a walking test and a shake test before and after heavy use in a large study. The mean deviation from 100 steps for the walking test was 2.26 ± .80 (M ± SD) and 1.71 ± .88 on pretest and posttest, respectively. Mean deviation from 100 shakes for the shake test was 0.39 ± 0.29 and 0.60 ± 0.62 for the pretest and posttest, respectively. No pedometer exceeded 5% error (i.e., 5 steps out of 100) on any of the tests. No significant differences were found between the pretest and posttest, F(1, 46) = 1.49, p ? .229, but significant differences were found between the walking and the shake tests, F(1, 46) = 109.04, p < .01. The interaction was significant, F(1, 46) = 7.76, p £ .008. This study demonstrated that very little measurement error existed in the Yamax MLS-2000 digital pedometer. Researchers can have confidence that the scores obtained using this pedometer are accurate.     

The influence of the vaulting table on the handspring front somersault

The traditional “horse” was replaced by a new vaulting “table” in artistic gymnastics competitions in 2001.The aim of this study was to determine whether the table led to a change in vaulting technique. This was achieved by comparing three-dimensional video-based analyses (50 Hz) of selected biomechanical discrete and continuous variables across four elite male gymnasts performing a series of handspring front somersault vaults on the traditional horse and the new table. Individual joint and inter-segment coupling (continuous relative phase) were used to quantify techniques used on the two apparatuses. Differences were attributed in part to the design and construction of the new table. No differences were observed for the approach and take-off from the board. Significant differences in hip flexion at board take-off and strike angle on the table were observed. One of the effects of the latter was an increase in vertical take-off velocity compared with the horse. Individual strategies were observed in hip and shoulder coordination patterns that were obscured when group data were considered. Close monitoring of the evolution of skill on this new apparatus is paramount for gymnastics coaching, and further studies of current elite competitive vaulting techniques are required.     

Physical Performance and Body Form as Related to Physical Activity of College Women

Abstract

The problems of this study were to investigate the interrelationship of selected functional and body form measures, and to examine the differences between groups varying in activity levels. The volunteers for the study, 35 college women, were placed in activity groups termed “most active” and “least active” according to their response on an activity history-recall questionnaire. Functional measures included strength and flexibility. Strength was measured with a cable tensiometer and followed the procedures outlined by H. H. Clarke. Flexibility was measured using a Leighton Flexometer. Body form measures included height, weight, percent body fat, fat free body weight, specific gravity, and ponderal index. The range, mean, and standard deviation were computed for all parameters. The Pearson product-moment correlation was employed to determine interrelationships of all variables. Equality of variances among selected parameters was determined by the F test; Cochran-Cox and two sample t tests were used to determine the equality of means among selected parameters in the activity groups. Significant differences at the .05 level were found between the means of weight, fat free body weight, trunk extension flexibility, with the most active group exhibiting higher values. The least active group showed significantly greater shoulder extension flexibility, shoulder inward rotation flexibility, and ankle flexion flexibility.     

不同力量水平运动员激活后增强效应的时域特征

目的探究不同力量水平运动员激活后增强效应(post-activation potentiation,PAP)的时域特征。方法 PAP诱导练习采用90%1 RM重复3次杠铃半蹲,使用三维测力台对13名受试者静态半蹲跳前测值和跳后(15 s、3min、6 min、9 min、12 min)测值进行采集。采用双变量重复测量设计,运用重复测量方差分析和成对比较对腾空高度、峰值冲量和峰值功率进行分析。结果①腾空高度(P<0.01)和峰值冲量(P<0.05)在3、6和9 min时较基线值显著增加,峰值功率3 min(P<0.01)和6 min(P<0.05)时较基线值显著增加,组间均无显著差异(P>0.05)。②普通组各指标峰值出现在3 min,强壮组各指标峰值出现在6 min,且强壮组各指标峰值均大于普通组。结论不同力量水平运动员经90%1 RM强度重复3次杠铃半蹲诱导练习后,腾空高度和峰值冲量显著增加的时域均为3～9 min,峰值功率显著增加的时域均为3～6 min;但其PAP表现出不同时域特征相关,通常力量水平较高者腾空高度、峰值冲量和峰值功率的增长速率高于力量...