Are declines in physical performance associated with a reduction in skill-related performance during professional soccer match-play?

The aim of this study was to determine whether declines in physical performance in a professional soccer team during match-play were associated with reductions in skill-related performance. Computerized tracking of performance in midfield players (n = 11) showed that total distance and distance covered in high-speed running (>14.4 km · h?1) were greater in the first versus second half of games (both P < 0.001) and in the first versus the final 15 min of play (P < 0.05). Analysis of high-speed running across 5-min periods showed that more distance was covered in the first versus the final game period, and in the peak period of activity compared with the following period and game mean for other periods (all P < 0.05). Analysis of skill-related measures revealed no significant decline between halves, across 15-min intervals or in the 5-min period following that of peak high-speed activity compared with the game mean for other 5-min periods. In contrast, frequencies of passing, ball possessions, and duels were greater in the first 5-min than in the final 5-min period (P < 0.05). Neither physical nor skill-related performance was affected across three consecutive games within a period of ≤7 days. The results suggest that the players were generally able to maintain skill-related performance throughout games and when competing in successive matches within a short time.     

How does buoyancy affect performance during a 200m maximum front crawl swim?

We investigated the rotational effect of buoyant force around the body’s transverse axis, termed buoyant torque, during a 200m front crawl maximal swim. Eleven male swimmers of national or international level participated. One stroke cycle (SC) for each 50m was recorded with two above and four below water cameras. The following variables were analysed: swimming velocity; absolute and normalised buoyant force; minimum, average and maximum buoyant torque; SC and arm recovery times. The average value of buoyant torque was higher in the first 50m (14.2 ± 4.5Nm) than in the following 150m (9.3 ± 4.1Nm~10.9 ± 4.5Nm) and was directed to raise the legs and lower the head throughout the race. The change in its magnitude seemed to be linked to the shorter time spent proportionally in arm recovery (first 50m: 27.6% of SC time; next 150m: 23.3–24.4% of SC time). Most swimmers had periods of the SC where buoyant torque was directed to sink the legs, which accounted to 10% of SC time in the first 50m and about twice this duration in the next 150m. These periods were observed exclusively at some instances when the recovering arm had entered the water while the opposite arm was still underwater.     

The effects of caffeine ingestion on performance time,speed and power during a laboratory-based 1 km cycling time-trial

Abstract

There is little published data in relation to the effects of caffeine upon cycling performance, speed and power in trained cyclists, especially during cycling of ～60 s duration. To address this, eight trained cyclists performed a 1 km time-trial on an electronically braked cycle ergometer under three conditions: after ingestion of 5 mg · kg^?1 caffeine, after ingestion of a placebo, or a control condition. The three time-trials were performed in a randomized order and performance time, mean speed, mean power and peak power were determined. Caffeine ingestion resulted in improved performance time (caffeine vs. placebo vs. control: 71.1 ± 2.0 vs. 73.4 ± 2.3 vs. 73.3 ± 2.7 s; P = 0.02; mean ± s). This change represented a 3.1% (95% confidence interval: 0.7–5.6) improvement compared with the placebo condition. Mean speed was also higher in the caffeine than placebo and control conditions (caffeine vs. placebo vs. control: 50.7 ± 1.4 vs. 49.1 ± 1.5 vs. 49.2 ± 1.7 km · h^?1; P = 0.0005). Mean power increased after caffeine ingestion (caffeine vs. placebo vs. control: 523 ± 43 vs. 505 ± 46 vs. 504 ± 38 W; P = 0.007). Peak power also increased from 864 ± 107 W (placebo) and 830 ± 87 W (control) to 940 ± 83 W after caffeine ingestion (P = 0.027). These results provide support for previous research that found improved performance after caffeine ingestion during short-duration high-intensity exercise. The magnitude of the improvements observed in our study could be due to our use of sport-specific ergometry, a tablet form and trained participants.     

Test–retest reliability of the Tekscan® F-Scan® 7 in-shoe plantar pressure system during treadmill walking in healthy recreationally active individuals

In-shoe plantar pressure systems are commonly used in clinical and research settings to assess foot function during functional tasks. Recently, Tekscan® has updated their F-Scan® in-shoe plantar pressure system; however, this system’s test–retest reliability has not been established. Therefore, the purpose of this study was to determine the test–retest reliability of the F-Scan® 7 system in recreationally active individuals during treadmill walking. Seventeen healthy adults completed 2 sessions of treadmill walking. For each session, participants were fitted for shoes and pressure insoles and walked on a treadmill at a self-selected pace for 30 s. Following the sessions, the test–retest reliability peak pressure, pressure time integral, average pressure and pressure contact area over 4 regions of the foot (heel, mid-foot, forefoot and toes) was assessed by calculating intraclass coefficients (ICC 2,k) and coefficient of variation percentage (CoV%). Pressure contact area consistently had the highest ICCs and lowest CoV% (ICCs: 0.91–0.98; CoV%: 2.7–7.8%). Whereas, the forefoot and toe regions had the highest ICCs for all 4 measures (ICCs: 0.83–0.98; CoV%: 3.1–13.4%). During treadmill walking in healthy recreationally active individuals, the reliability of the new Tekscan F-Scan® ranged from poor to high and was dependent on the measure and region of the foot.     

Combined effects of sleep deprivation and strenuous exercise on cognitive performances during The North Face® Ultra Trail du Mont Blanc® (UTMB®)

This study investigated the effects of combined sleep deprivation and strenuous exercise on cognitive and neurobehavioral performance among long-distance runners completing one of the most difficult ultramarathons in the world. Seventeen runners participated. Each had a wrist-worn actigraph throughout the race to record their sleep time. In addition, each individual’s performance in 10-min response-time tests before and after the race was recorded and a questionnaire enabled participants to report any difficulties they experienced during the competition. During race completion times of 27 to 44 h, combined acute lack of sleep (12 ± 17 min of rest during the race) and strenuous exercise (168.0 km) had marked adverse effects on cognitive performances ranging from mere lengthening of response time to serious symptoms such as visual hallucinations. This study suggests that regardless of rest duration and time in race, cognitive performances of ultramarathoners are adversely affected.     

The effect of limb dominance on lower limb functional performance – a systematic review

Lower limb dominance (or lateral preference) could potentially effect functional performance. Clinicians are often asked to make judgements as to when a patient has sufficiently “recovered” from an injury, typically using strength and dynamic performance outcome measures. The primary purpose of this study was to systematically review the literature in relation to limb dominance within active adult populations and discuss some limitations to current methods and relate this to current clinical practice. A search of MEDLINE and CINAHL and EMBASE databases and reference lists of those articles identified was performed. Eleven articles were selected for meta-analysis. There was no statistical effect of limb dominance for any of the functional tests: isokinetic quadriceps and hamstring tests, hamstring:quadriceps ratios, single-leg hop for distance, single-leg vertical jump and vertical ground reaction force following a single-leg vertical jump. Pooled symmetry values varied from 94.6% to 99.6% across the tests, above the clinically accepted benchmark of 90% used in clinical practice. Although the results of this study must be used with discretion, asymmetries in the tasks described in this analysis should be viewed as undesirable and remedied accordingly. Further research is needed to quantify asymmetries, particularly in relation to sport-specific contexts.     

The Governor has a sweet tooth – Mouth sensing of nutrients to enhance sports performance

Abstract

The oral–pharyngeal cavity and the gastrointestinal tract are richly endowed with receptors that respond to taste, temperature and to a wide range of specific nutrient and non-nutritive food components. Ingestion of carbohydrate-containing drinks has been shown to enhance endurance exercise performance, and these responses have been attributed to post-absorptive effects. It is increasingly recognised, though, that the response to ingested carbohydrate begins in the mouth via specific carbohydrate receptors and continues in the gut via the release of a range of hormones that influence substrate metabolism. Cold drinks can also enhance performance, especially in conditions of thermal stress, and part of the mechanism underlying this effect may be the response to cold fluids in the mouth. There is also some, albeit not entirely consistent, evidence for effects of caffeine, quinine, menthol and acetic acid on performance or other relevant effects. This review summarises current knowledge of responses to mouth sensing of temperature, carbohydrate and other food components, with the goal of assisting athletes to implement practical strategies that make best use of its effects. It also examines the evidence that oral intake of other nutrients or characteristics associated with food/fluid intake during exercise can enhance performance via communication between the mouth/gut and the brain.     

White Paper: functionality and efficacy of wrist protectors in snowboarding—towards a harmonized international standard

The wrist is the most frequently injured body region among snowboarders. Studies have shown that the risk of sustaining a wrist injury can be reduced by wearing wrist protection. Currently, there are a wide variety of wrist protection products for snowboarding on the market that offer a range of protective features. However, there are no minimum performance standards for snowboarding wrist protectors worldwide. The International Society for Skiing Safety convened a task force to develop a White Paper to evaluate the importance and necessity of a minimum performance for all wrist protectors used in snowboarding. The White Paper outlines the need for a general framework for a harmonized international standard and reviews the existing evidence. Therefore, this White Paper may serve as a common base for future discussions. The broader goal of developing and implementing such a standard is to reduce the incidence and the severity of wrist injuries in snowboarding without increasing the risk of adverse events, such as upper arm or shoulder injury. The European standard for inline skating wrist protectors (EN 14120) can serve as a starting point for efforts related to a standard for snowboard wrist protectors, but certain modifications to the standard would be required. It is hypothesized that implementation of a snowboarding wrist protector standard would result in fewer and less severe wrist injuries in the sport and could translate into more riding days for healthy snowboarders and significant health-care costs savings.     

The effect of caffeine ingestion on 8 km run performance in a field setting

Abstract

The aim of this study was to assess the effect of caffeine ingestion on 8 km run performance using an ecologically valid test protocol. A randomized double-blind crossover study was conducted involving eight male distance runners. The participants ran an 8 km race 1 h after ingesting a placebo capsule, a caffeine capsule (3 mg · kg^?1 body mass) or no supplement. Heart rate was recorded at 5 s intervals throughout the race. Blood lactate concentration and ratings of perceived exertion were recorded after exercise. A repeated-measures analysis of variance (ANOVA) identified a significant treatment effect for 8 km performance time (P < 0.05); caffeine resulted in a mean improvement of 23.8 s (95% confidence interval [CI] = 13.1 to 34.5 s) in 8 km performance time (1.2% improvement, 95% CI = 0.7 to 1.8%). In addition, a two-way (time × condition) repeated-measures ANOVA identified a significantly higher blood lactate concentration 3 min after exercise during the caffeine trial (P < 0.05). We conclude that ingestion of 3 mg · kg^?1 body mass of caffeine can improve absolute 8 km run performance in an ecologically valid race setting.     

The role of viewing distance and viewing angle on referees’ decision-making performance during the FIFA World Cup 2014

The present study aims to reveal the effects of positioning on decision-making performance in top-level refereeing in association football. To this end, for all 64 matches of the FIFA World Cup 2014, potential foul-play situations were videometrically analysed in terms of the referee’s position relative to the infringement. Contrary to earlier studies, viewing angles were analysed in addition to viewing distances and error rates were considered for not only falsely whistled but also falsely non-whistled events. Moreover, direct logistic regression analysis was applied to detect position-dependent differences. For the total of 1,527 potential foul play situations, an overall low error rate of 6.9% was found. The similar numbers of total whistle (n = 52) and non-whistle errors (n = 54) reflect referees’ ability to balance both types of errors. Regarding the overall viewing-distance effect, referees were 2.58 times (95% CI 1.47–4.54) more likely to commit a whistle error at 10–15 m and 5.51 times (95% CI 1.35–22.47) more likely to commit a non-whistle error at 0–5 m, corresponding to the position ranges occurring with the highest (10–15 m: 30.3%) and lowest (0–5 m: 5.8%) frequencies. In contrast, no significant effects of viewing-angle on decision-making accuracy could be revealed.     

The influence of a 6.5% carbohydrate-electrolyte solution on performance of prolonged intermittent high-intensity running at 30°C

Nine male student games players consumed either flavoured water (0.1 g carbohydrate, Na⁺ 6 mmol · l^?1), a solution containing 6.5% carbohydrate-electrolytes (6.5 g carbohydrate, Na⁺ 21 mmol · l^?1) or a taste placebo (Na⁺ 2 mmol · l^?1) during an intermittent shuttle test performed on three separate occasions at an ambient temperature of 30°C (dry bulb). The test involved five 15-min sets of repeated cycles of walking and variable speed running, each separated by a 4-min rest (part A of the test), followed by 60 s run/60 s rest until exhaustion (part B of the test). The participants drank 6.5 ml · kg^?1 of fluid as a bolus just before exercise and thereafter 4.5 ml · kg^?1 during every exercise set and rest period (19 min). There was a trial order effect. The total distance completed by the participants was greater in trial 3 (8441 ± 873 m) than in trial 1 (6839 ± 512, P < 0.05). This represented a 19% improvement in exercise capacity. However, the trials were performed in a random counterbalanced order and the participants completed 8634 ± 653 m, 7786 ± 741 m and 7099 ± 647 m in the flavoured water (FW), placebo (P) and carbohydrate-electrolyte (CE) trials, respectively (P = 0.08). Sprint performance was not different between the trials but was impaired over time (FW vs P vs CE: set 1, 2.41 ± 0.02 vs 2.39 ± 0.03 vs 2.39 ± 0.03 s; end set, 2.46 ± 0.03 vs 2.47 ± 0.03 vs 2.47 ± 0.02 s; main

effect time, P < 0.01). The rate of rise in rectal temperature was greater in the carbohydrate-electrolyte trial (rise in rectal temperature/duration of trial, °C · h^?1; FW vs CE, P < 0.05; P vs CE, N.S.). Blood glucose concentrations were higher in the carbohydrate-electrolyte than in the other two trials (FW vs P vs CE: rest, 4.4 ± 0.1 vs 4.3 ± 0.1 vs 4.2 ± 0.1 mmol · l^?1; end of exercise, 5.4 ± 0.3 vs 6.4 ± 0.6 vs 7.2 ± 0.5 mmol · l^?1; main effect trial, P < 0.05; main effect time, P < 0.01). Plasma free fatty acid concentrations at the end of exercise were lower in the carbohydrate-electrolyte trial than in the other two trials (FW vs P vs CE: 0.57 ± 0.08 vs 0.53 ± 0.11 vs 0.29 ± 0.04 mmol · l^?1; interaction, P < 0.01). The correlation between the rate of rise in rectal temperature (°C · h^?1) and the distance completed was ?0.91, ?0.92 and ?0.96 in the flavoured water, placebo and carbohydrate-electrolyte conditions, respectively (P < 0.01). Heart rate, blood pressure, plasma ammonia, blood lactate, plasma volume and rate of perceived exertion were not different between the three fluid trials. Although drinking the carbohydrate-electrolyte solution induced greater metabolic changes than the flavoured water and placebo solutions, it is unlikely that in these unacclimated males carbohydrate availability was a limiting factor in the performance of intermittent running in hot environmental conditions.     

From processing efficiency to attentional control: a mechanistic account of the anxiety–performance relationship

The aim of this paper is to outline the development of Eysenck and Calvo's (1992) processing efficiency theory (PET) and to summarise research testing its predictions in the sporting domain. PET provides a mechanistic explanation for how anxiety may influence performance through its impact on attentional resources. The central tenet of PET is that as well as pre-empting resources in working memory, increased anxiety provides a motivational function, leading to the allocation of additional effort to attempt to maintain task performance. Research in sport settings has been supportive of the predictions of PET, adopting a range of measures of processing efficiency; including self-reported effort, secondary task performance and psychophysiological indices. Furthermore, cognitive sport psychologists have recently examined direct influences of anxiety on the efficiency of information processing via gaze behaviour analyses. These findings are particularly relevant in the light of a recent update and development of PET; attentional control theory (ACT; Eysenck, Derakshan, Santos, & Calvo, 2007). ACT purports that anxiety reduces attentional control by increasing the influence of the stimulus-driven attentional system at the cost of goal directed control. It is evident that ACT may provide a useful framework for examining the relationship between anxiety, attention and performance in sport skills.     

Validity and reliability of a new method for measuring putting stroke kinematics using the TOMI® system

Abstract

The purpose of this study was to determine the validity and reliability of a new method for measuring three-dimensional (3D) putting stroke kinematics using the TOMI® device. A putting robot and a high-speed camera were used to simultaneously collect data for the validity evaluation. The TOMI® device, when used in conjunction with standard 3D coordinate data processing techniques, was found to be a valid and reliable method for measuring face angle, stroke path, putter speed, and impact spot at the moment of ball contact. The validity of the TOMI® measurement system was quantified using the 95% limits of agreement method for each aforementioned variable. The practical significance of each validity score was assessed by incorporating the maximum estimated measurement error into the stroke of the putting robot for 10 consecutive putts. All putts were executed from a distance of 4 m on a straight and flat synthetic putting surface. Since all putts were holed successfully, the measurement error for each variable was deemed to be negligible for the purposes of measuring putting stroke kinematics. The influence of key kinematic errors, at impact, on the outcome of a putt was also determined.     

Accuracy of pacing during breaststroke swimming using a novel pacing device,the Aquapacer™

Generally, swimmers pace themselves using their own judgement and the poolside clock during swimming training, fitness testing protocols or scientific investigation. The Aquapacer? is a new pacing device that can be used to pace the swimming speed or stroke rate of the swimmer. The aims of this study were to determine if breaststroke swimmers could pace accurately during submaximal swimming using a poolside clock (Study 1) and the Aquapacer? (Study 2), at swimming speeds at, just above and just below maximal 200 m time-trial speeds (using the Aquapacer?, Study 3) and under three different race pacing conditions (using the Aquapacer?, Study 4). Between 8 and 15 male national or club standard 200 m breaststroke swimmers participated in each of the studies. The swimmers in Study 2, despite being less well trained than the swimmers in Study 1 and part of a more heterogeneous group in terms of swimming performance, repeatedly demonstrated less random error in pacing, suggesting that the Aquapacer? may be preferable to the poolside clock when swimmers are being required to pace accurately. The Aquapacer? also enabled swimmers to pace accurately at racespecific swimming speeds (until fatigue precluded them from holding pace) (Study 3), and through a change in pace at race-specific speeds (Study 4), which suggests that it may be of use in entraining racing strategies.     

Looking for a Refuge of ‘Normalcy’ during the Argentine Dictatorship: The Case of Atlanta Football Club

Abstract

This article examines the history of Club Atlético Atlanta of Buenos Aires during the years of the military dictatorship (1976–1983) within the framework of efforts to reconsider the impact of repression on everyday life. Club Atlético Atlanta is a microcosm of Argentine society, and it contained everything: from victims of repression, to the son of genocidal general Roberto Eduardo Viola. Conformism, indifference, adaptation, support for the military authorities, or opposition to them, as well as resistance strategies, were a mosaic of expressions showing that various attitudes coexisted while facing the impact of state terror on daily life. The advent of dictatorship did not mean the same rupture for everyone, and did not alter in the same way certain dimensions of everyday life and routines for different individuals and groups. The story of a neighbourhood club such as Atlanta and the perceptions and memories of its fans may help us move forward on this path, to ascertain the links between the ‘micro’ level of social life and the great narratives of politics and the State.     

Sports participation and health during periods of educational transition: a study of 30–35-year-olds in north-west England

In view of the persistence of health inequalities and declines in leisure-sport participation over the life course, several quantitative investigations have explored the links between participation and other leisure activities, which have their foundations in childhood and youth, as a means of understanding adults’ health behaviours. This paper presents new qualitative evidence to examine the largely under-explored relationship between leisure-sport participation and health within the context of educational transitions among a sample of 30–35-year-olds in north-west England. Drawing on semi-structured interviews conducted with 19 participants between July and August 2009, the paper illuminates the differential impact that gender and social class had on sports participation, and other health-related behaviours (e.g. drinking and smoking), among different groups of adults during the inherently transitional life-stage of youth. The findings suggest that while significant, the length of time spent in education and the differential educational experiences recalled by adults cannot adequately explain the observed differences in health and leisure-sport participation. The major sources of difference, while associated with educational transitions, appeared to lie instead in the broader inequalities that characterized adults’ lives and it is argued that simply enhancing leisure-sport participation and individual lifestyle change, as a means of health promotion, is a futile endeavour that does little to tackle the socio-economic structural determinants of health. We conclude by suggesting that until this is recognized by government and those both inside and outside of the health and sport policy communities, stubborn differences in leisure-sport participation rates and health inequalities—that have their foundations in childhood and youth, but extend over the life course—are likely to remain intact, and the unequal lives people currently lead are likely to become even more unequal in the future.     

Can changes in midsole bending stiffness of shoes affect the onset of joint work redistribution during a prolonged run?

Purpose:This study aimed to investigate if changing the midsole bending stiffness of athletic footwear can affect the onset of lower limb joint work redistribution during a prolonged run.Methods:Fifteen trained male runners(10-km time of <44 min) performed 10-km runs at 90% of their individual speed at lactate threshold(i.e.,when change in lactate exceeded 1 mmol/L during an incremental running test) in a control and stiff shoe condition on 2 occasions.Lower limb joint kinematics and kinetics...     

A comparison of the agreement,internal consistency,and 2-day test stability of the InBody 720, GE iDXA,and BOD POD® gold standard for assessing body composition

The study compared the agreement, internal consistency, and measurement stability of the GE iDXA, BOD POD, and InBody 720. Body composition of 43 men and 37 women (31.4 ± 10.7 years; 90% Caucasian and 10% other) was assessed in triplicate using each method over two different days. Mean percent body fat (% BF) of the participants was different for all three machines (27.6 ± 10.0% [GE iDXA)] 25.6 ± 10.4% [BOD POD], and 21.3 ± 10.6% [InBody 720]; p < .05). The coefficient of variation for same day repeated measures was 1.06% (GE iDXA), 3.29% (BOD POD), and 2.97% (InBody 720). The coefficient of variation for 2-day repeated measures was 1.81% (GE iDXA), 4.61% (BOD POD), and 4.24% (InBody 720). The difference between the GE iDXA and BOD POD was within acceptable variability, while the InBody 720 significantly underestimated % BF. The internal consistency was highest for the GE iDXA, followed by the InBody 720, and then the BOD POD.     

Assimilating to a boy’s body shape for the sake of performance: three female athletes’ body experiences in a sporting culture

This paper explores three female swimmers’ relationships with their male coaches and the body practices they were exposed to within Australian swimming. Particular attention is given to how the relationships and practices might relate to gender. Additionally, the article examines how (if at all) the conduct contributed to the social construction of an accepted female swimmer body. Through narrative accounts, the three adolescent female athletes articulate hierarchical male coach–female athlete relationships and specific body encounters they were exposed to and/or engaged with. Their experiences reveal how a sexually maturing body (growing breasts, female body shape and menstruating) was deemed unsuitable for performance and the swimmers were thus encouraged to transform their bodies and behaviours towards that of the boys. Using a feminist Foucauldian perspective, these accounts points to how the three swimmers came to regulate their diet, training and appearance in order to fulfil expectations. This self-regulation is problematic in two ways: first, no scientific evidence shows that a boy like physique is essential for best performance. Second, the stress from being pressured to achieve a particular body, as well as the shame that resulted from being unable to achieve the idealised physique, eventually caused the swimmers to develop an unhealthy relationship with their developing bodies. We highlight how those immersed in sporting contexts should recognise the serious implications of gender practices and power relations underpinning the male coach–female athlete dynamic in competitive sport.     

Choice of sprint start performance measure affects the performance-based ranking within a group of sprinters: which is the most appropriate measure?

Sprint start performance has previously been quantified using several different measures. This study aimed to identify whether different measures could influence the performance-based ranking within a group of 12 sprinters, and if so, to identify the most appropriate measure. None of the 10 performance measures ranked all sprinters in the same order; Spearman's rho correlations between different block phase measures ranged from 0.50 to 0.94, and between block phase measures and those obtained beyond block exit from 0.66 to 0.85. Based on the consideration of what each measure quantifies, normalised average horizontal external power was identified as the most appropriate, incorporating both block velocity and the time spent producing this velocity. The accuracy with which these data could be obtained in an externally valid field setting was assessed against force platform criterion data. For an athlete producing 678 +/- 40 W of block power, a carefully set-up manual high-speed video analysis protocol produced systematic and random errors of +5 Wand +/- 24 W, respectively. Since the choice of performance measure could affect the conclusions drawn from a technique analysis, for example the success of an intervention, it is proposed that external power is used to quantify start performance.