Journal of Science and Medicine in Sport - Articles in Press

Ground hardness and injury in community level Australian football - Corrected Proof

2012-01-19

Abstract: Objective: To describe the risk and details of injuries associated with ground hardness in community level Australian football (AF).Design: Prospective injury surveillance with periodic objective ground hardness measurement.Methods: 112 ground hardness assessments were undertaken using a Clegg hammer at nine locations across 20 grounds, over the 2007 and 2008 AF seasons. Details of 352 injuries sustained by community level players on those grounds were prospectively collected as part of a large randomised controlled trial. The ground location of the injury was matched to the nearest corresponding ground hardness Clegg hammer readings, in gravities (g), which were classified from unacceptably low (<30g) to unacceptably high hardness (>120g).Results: Clegg hammer readings ranged from 25 to 301g. Clegg hammer hardness categories from low/normal to high/normal were associated with the majority of injuries, with only 3.7% (13 injuries) on unacceptably high hardness and 0.3% (1 injury) on the unacceptably low hardness locations. Relative to the preferred range of hardness, the risk of sustaining an injury on low/normal hardness locations was 1.31 (95%CI: 1.06–1.62) times higher and 1.82 (95%CI: 1.17–2.85) times higher on locations with unacceptably high hardness. The more severe injuries occurred with low/normal ground hardness.Conclusions: Despite the low number of injuries, the risk of sustaining an injury on low/normal and unacceptably hard grounds was significantly greater than on the preferred range of hardness. Notably, the severity of the injuries sustained on unacceptably hard grounds was lower than for other categories of hardness.

A population-based study of sport and recreation-related head injuries treated in a Canadian health region - Corrected Proof

Andrew W. Harris, C. Allyson Jones, Brian H. Rowe, Donald C. Voaklander — 2012-01-16

Abstract: Objectives: To report the rates of SR-related HIs presenting to EDs in a Canadian population-based sample.Design: Descriptive epidemiology study.Methods: Using administrative data, sport and recreation-related emergency department presentations for persons 0–35 years of age, from April 1997 through March 2008, were obtained from the Edmonton Zone (formerly the Capital Health Region), Alberta Health Services through the Ambulatory Care Classification System.Results: Of the 3,230,890 visits to the emergency departments of the five hospitals in Edmonton, 63,219 sport and recreation-related injury records and 4935 sport and recreation-head injury records were identified. Head injuries were most frequently treated for the activities of hockey (20.7%), cycling (12.0%), and skiing/snowboarding/sledding. Males accounted for 71.9% (n=3546) and patients less than 18 years of age sustained 3446 (69.8%) sport and recreation-head injuries.Conclusions: Sport and recreation-related head injuries most frequently treated in emergency departments involve common activities such as hockey, cycling, skiing/snowboarding/sledding, and soccer. Males and those less than 18 years of age sustain the majority of sport and recreation-related head injuries treated in emergency departments. These findings underscore the importance of sport-specific policies and safety promotion for the prevention of head injuries, in sports and recreational activities.

The physiological and activity demands experienced by Australian female basketball players during competition - Corrected Proof

Aaron T. Scanlan, Ben J. Dascombe, Peter Reaburn, Vincent J. Dalbo — 2012-01-16

Abstract: Objectives: To describe the physiological and activity demands experienced by Australian female basketball players during competition.Design: A between-subjects (positional comparison) repeated measures (playing periods) observational experimental design was followed.Method: State-level basketball players (n=12; age: 22.0±3.7yr; body mass: 72.9±14.2kg; stature: 174.2±6.9cm; body fat: 17.2±5.6%; estimated ) volunteered to participate. Heart rate (HR) and blood lactate concentration ([BLa]) were collected across eight competitive matches. Overall and positional player activity demands were calculated across three matches using time–motion analysis methodology. Activity frequencies, total durations and total distances were determined for various activity categories.Results: Mean (±SD) HR responses of 162±3bmin−1 (82.4±1.3% HRmax) and 136±6bmin−1 (68.6±3.1% HRmax) were evident across live and total time during matches. A mean [BLa] of 3.7±1.4mmolL−1 was observed across competition. Player activity demands were unchanged across match periods, with 1752±186movements performed and 5214±315m travelled across total live match time. Furthermore, 39±3%, 52±2%, 5±1% and 4±1% of total live time was spent performing low-intensity, moderate-intensity, high-intensity and dribbling activity. Positional comparisons revealed backcourt players performed more ball dribbling (p<0.001) and less standing/walking (p<0.01) and running (p<0.05) than frontcourt players.Conclusions: Together, these findings highlight the high intermittent demands and important contributions of both anaerobic and aerobic metabolic pathways during state-level female basketball competition.

Influence of carbohydrate supplementation on skill performance during a soccer match simulation - Corrected Proof

Mark Russell, David Benton, Michael Kingsley — 2012-01-10

Abstract: Objectives: This study investigated the influence of carbohydrate supplementation on skill performance throughout exercise that replicates soccer match-play.Design: Experimentation was conducted in a randomised, double-blind and cross-over study design.Methods: After familiarization, 15 professional academy soccer players completed a soccer match simulation incorporating passing, dribbling and shooting on two separate occasions. Participants received a 6% carbohydrate–electrolyte solution (CHO) or electrolyte solution (PL). Precision, success rate, ball speed and an overall index (speed-precision-success; SPS) were determined for all skills. Blood samples were taken at rest, immediately before exercise, every 15min during exercise (first half: 15, 30 and 45min; second half: 60, 75 and 90min), and 10min into the half time (half-time).Results: Carbohydrate supplementation influenced shooting (time×treatment interaction: p<0.05), where CHO attenuated the decline in shot speed and SPS index. Supplementation did not affect passing or dribbling. Blood glucose responses to exercise were influenced by supplementation (time×treatment interaction: p<0.05), where concentrations were higher at 45min and during half-time in CHO compared with PL. Blood glucose concentrations reduced by 30±1% between half-time and 60min in CHO.Conclusions: Carbohydrate supplementation attenuated decrements in shooting performance during simulated soccer match-play; however, further research is warranted to optimise carbohydrate supplementation regimes for high-intensity intermittent sports.

The epidemiology of injury for an elite junior Australian Football cohort - Corrected Proof

2012-01-05

Abstract: Objectives: To implement an injury recording protocol in a junior elite Australian Football competition and determine the injury profile of this population.Design: Longitudinal cohort study.Methods: Players from an elite Under 18 Australian Football competition were tracked throughout one football season in terms of participation or non-participation in the football competition. Injury reporting forms were collected for all players who were not available for selection as a result of injury.Results: The cohort consisted of 532 players who provided consent for inclusion in the study (100% of players in the competition). There were 256 injuries sustained during the season. Results were normalised to a 40 man team to allow comparison with results from the Australian Football League. The injury incidence was 17.1 new injuries per club (95% CI 14.1–19.4), and prevalence 63.3 missed matches per club (95% CI 59.1–67.1). The category “Ankle joint injuries” was the most commonly reported (n=34) and “Collision with another player” was the main injury mechanism (n=75).Conclusions: The most commonly injured region in junior elite Australian Football was the ankle and collision with another player was the most common injury mechanism. As with previous reports on junior Australian Football, injury incidence was low in comparison to the senior elite competition. Defining the injury profile guides injury prevention strategies. Analysis of injury in junior elite football may provide a unique opportunity to affect both junior and senior injury rates.

Ultrasound measurements on acromio-humeral distance and supraspinatus tendon thickness: Test–retest reliability and correlations with shoulder rotational strengths - Corrected Proof

Hio-Teng Leong, Sammi Tsui, Michael Ying, Vivian Yee-fong Leung, Siu N. Fu — 2012-01-03

Abstract: Objectives: To establish the test–retest reliability of ultrasound measurements on acromio-humeral distance (AHD) and supraspinatus tendon thickness; and to explore their relationships with shoulder rotational strengths.Design: Test–retest observational study.Method: Thirty-seven individuals (age: 21.5±1.4 years) participated in this study. Twenty-four were University volleyball players with 15 healthy and 9 players with shoulder impingement syndrome (SIS). Thirteen participants were healthy untrained individuals. Ultrasound measurements of AHD and supraspinatus tendon thickness were taken, and isokinetic testing of concentric shoulder internal rotation (IR) and external rotation (ER) at a speed of 90°/s was performed.Results: The measurement of the AHD and the supraspinatus tendon thickness indicated excellent reliability (ICC=0.922, and ICC=0.933 respectively), and the minimum detectable difference (MDD) were 2.10mm and 0.64mm respectively. A cut-off AHD distance of 23.9mm had a sensitivity of 0.67 and specificity of 0.71 (area under curve (AUC): 0.70; p=0.05) in identifying individuals with and without SIS. Hence, individuals with AHD larger than 23.9mm had greater possibility of having SIS. Positive correlations were found in AHD with supraspinatus tendon thickness (r=0.36, p<0.05) and shoulder external rotational strengths (r=0.47–0.62, all p<0.05) and ER/IR ratios (r=0.56–0.58, all p<0.05).Conclusion: Ultrasound measurements of AHD and tendon thickness have excellent reliability. The reported cut-off AHD highlighted the potential role of ultrasound measurements in volleyball players for early identification of SIS. The AHD was related to the supraspinatus tendon thickness and shoulder external rotation strengths. Our findings provide a scientific basis for muscle training in overhead athletes such as volleyball players.

Synthetic grass cricket pitches and ball bounce characteristics - Corrected Proof

Kevin Ball, Con Hrysomallis — 2011-12-29

Abstract: The use of synthetic grass cricket pitches is becoming more common at club and sub-elite levels which constitute the majority of cricket participants but there is sparse data on ball bounce characteristics on these surfaces.Objectives: To compare the speed, angle and consistency of ball bounce on two types of synthetic cricket surfaces, the Traditional and the All-Seasons, and compare these ball bounce characteristics with published data for natural turf pitches.Design: Group-based comparison.Methods: High speed motion analysis was used to capture data from balls projected onto the cricket pitches from a bowling machine at three speeds: slow (47kmh−1), medium (72kmh−1) and fast (104kmh−1). Both ends of the cricket pitches were assessed and two types of balls were used: 2-piece and 4-piece leather cricket balls. Digitisation was used to determine the ball speed and angle pre and post bounce and then to calculate the ratios of ball speed and angle. Consistency was determined by the coefficient of variation.Results: The All-Seasons synthetic surface generated a lower speed ratio and a higher angle ratio than the Traditional synthetic surface. The speed ratio for the Traditional surface fell within the range reported for natural turf, whilst the value for the All-Seasons surface was outside the range. Both synthetic surfaces produced angle ratios greater than those for natural turf surfaces.Conclusions: Differences were detected between the different synthetic cricket surfaces and also when compared to natural turf. This variability may have implications for skill development as well as safety.

Relationship between interchange usage and risk of hamstring injuries in the Australian Football League - Corrected Proof

John W. Orchard, Tim Driscoll, Hugh Seward, Jessica J. Orchard — 2011-12-26

Abstract: Objectives: To study risk factors for hamstring injury in the Australian Football League (AFL), in particular the effect of recent changes in match participation (increased use of the interchange bench) on hamstring injury.Design: Analysis of hamstring match injury statistics extracted from an injury database combined with match participation statistics extracted from a player statistics database.Method: 56,320 player matches in the AFL over the period 2003–2010 were analyzed, in which 416 hamstring injuries occurred.Results: In a Generalized Estimating Equation (GEE) analysis accounting for clustering of different teams, significant predictors of hamstring injuries were recent hamstring injury (RR 4.16, 95% CI 3.19–5.43), past history of ACL reconstruction (RR 1.69, 95% CI 1.09–2.60), past history of calf injury (RR 1.58, 95% CI 1.37–1.82), opposition team making 60 or more interchanges during the game (RR 1.38, 95% CI 1.12–1.68) and player having made 7 or more interchanges off the field in the last 3weeks (protective RR 0.74, 95% CI 0.59–0.93).Conclusions: These findings suggest that regular interchanges protect individual players against hamstring injuries, but increase the risk of hamstring injury for opposition players. These findings can be explained by a model in which both fatigue and average match running speed are risk factors for hamstring injury. A player who returns to the ground after a rest on the interchange bench may himself have some short-term protection against hamstring injury because of the reduced fatigue, but his rested state may contribute to increased average running speed for his direct opponent, increasing the risk of injury for players on the opposition team.

The lumbar spine of the young cricket fast bowler: An MRI study - Corrected Proof

Helen Crewe, Bruce Elliott, Gary Couanis, Amity Campbell, Jacqueline Alderson — 2011-12-26

Abstract: Objective: To describe the prevalence and nature of lumbar spinal abnormalities in adolescent cricket fast bowlers.Design: Observational study.Methods: 46 asymptomatic fast bowlers aged 13–18 years participated in the study and were grouped into under-15 (U15), under-17 (U17) and under-19 (U19) classifications. All participants underwent magnetic resonance imaging of the lumbar spine and abnormalities of the pars interarticularis and intervertebral discs were graded according to type and severity. Other abnormalities were also noted.Results: Fifteen bowlers (33%) had at least one pars interarticularis abnormality. Six bilateral and 10 unilateral defects were identified. Of the 10 unilateral pars abnormalities, 6 occurred on the non-dominant side. Nineteen of the abnormalities occurred at the L5 vertebral level, 2 at L4 and 1 at L3. The most common type of pars abnormality was the subtotal stress fracture, which was found in 38% of bowlers aged 16 years and under. Sixteen participants (35%) were found to have degeneration of at least 1 lumbar disc and the prevalence increased with each successive age group (29% U15, 33% U17 and 43% U19). Of the 25 discs with signs of degeneration, 9 occurred at L4/5 and 7 at L5/S1. Eleven of these were classified as mild degeneration, 13 as moderate, and 1 as severe. Disc bulges were found in 33% of participants.Conclusions: Lumbar radiological abnormalities are common in asymptomatic adolescent fast bowlers. Acute bone stress reactions of the lumbar pars interarticularis are visible on magnetic resonance imaging and, in some instances, occur before the onset of activity-related pain.

How diverse was the leisure time physical activity of older Australians over the past decade? - Corrected Proof

Merom Dafna, Cosgrove Carmen, Venugopal Kamalesh, Bauman Adrian — 2011-12-26

Abstract: Objectives: Public health recommendations for older adults highlight the need to engage in a combination of aerobic, muscle strength, flexibility and balance activities. This study characterised leisure time physical activity in older Australians (≥65 years), examining the diversity in reported activities. Design: Cross-sectional monitoring. Methods: The Exercise Recreation and Sport Surveys (2001–2009) were combined and analysed for 22,050 elderly. Results: Walking was reported by 45.6%, of those 53% engaged exclusively in walking. Prevalent sports (i.e., >1%) were bowls (9.4%), aerobics/callisthenics exercise (9.1%), golf (7.7%), swimming (6.4%), gym work (5.2%), cycling (3.2%), tennis (2.9%), dancing (2.1%), fishing (2.0%), tai chi (1.4%), weight lifting (1.2%) and yoga (1.1%). Significant gender differences were apparent. Over time, significant increases were reported in walking, aerobic/callisthenics and gym workout in both genders. In the previous year, 32.0% of older adults participated in “nil” activity, 40.6% engaged in one activity, 19.5% and 8.0% participated in two or three or more activities, respectively. Common combinations were walking with another aerobic activity. Only 2.6% reported a combination of aerobic, balance and strength activities. Multiple-activity participation increased over the years, but declined with increasing age, education and for the most disadvantaged, compared to single-activity participation. Partially or exclusively organised participation, combined, was reported by 42.5% of older adults. Women were more likely to combine mode of participation. Geographic region was associated with multiple-activity participation and organised-only participation. Conclusions: Most elderly people engage in one activity, if at all. An increase in participation in balance enhancing activities and weight training is warranted to maximize health benefits.

Does muscle imbalance affect fatigue after soccer specific intermittent protocol? - Corrected Proof

Sérgio Ricardo de Abreu Camarda, Benedito Sérgio Denadai — 2011-12-23

Abstract: Objectives: This study investigated the muscular strength imbalance dependence of the effect of fatigue induced by an exhaustive laboratory-based soccer-specific exercise on different hamstrings:quadriceps (H:Q) ratios of soccer players.Design: Repeated measures.Method: Twenty-one male professional soccer players (23.2±3.5 years) performed a pre-test to assess the concentric (con) and eccentric (ecc) strength of the knee extensors (KE) and flexors (KF) at 60°s−1 and 180°s−1. Then performed an exhaustive laboratory-based soccer-specific exercise and a post-test similar to the pre-test. The players were allocated into one of two groups in accordance to their conventional Hcon:Qcon (balanced group, BG=Hcon:Qcon>0.60; unbalanced group, UNBG=Hcon:Qcon<0.60).Results: The KEcon (BG=4%, p<0.05; UNBG=6%, p<0.01) and KFcon (BG=7%, p<0.01; UNBG=8%, p<0.01) at 60°s−1 were significantly reduced after exercise for both groups. However, KFecc at 180°s−1 was significantly reduced only in BG (16%, p<0.01). The Hcon:Qcon and Hecc:Qcon were significantly reduced after exercise in BG (0.65±0.03 vs. 0.62±0.04, p<0.05; 1.38±0.2 vs. 1.20±0.2, p<0.01; respectively), but not in UNBG (0.55±0.04 vs. 0.54±0.07; 1.19±0.1 vs. 1.13±0.2, respectively).Conclusions: The effect of fatigue induced by an exhaustive laboratory-based soccer-specific exercise on Hcon:Qcon and Hecc:Qcon in the dominant leg of professional soccer players is dependent on muscular strength balance. Thus, experimental designs and prevention programmes should consider that muscular strength balance might also module the game-induced fatigue of professional soccer players.

Maturity negates the gender-related difference in physical activity among youth. Is this equally justified whatever the accelerometer cut-off point used? - Corrected Proof

Djamel Zitouni, Benjamin C. Guinhouya — 2011-12-22

Abstract: Objectives: To examine the consistency in findings about the influence of maturity on the gender-difference in moderate-to-vigorous physical activity (MVPA) of children using different cut-off points for MVPA.Design: Cross-sectional observation study.Method: The sample involved 253 children (139 boys) of 9.9±0.9 years. Their physical activity was evaluated using an Actigraph accelerometer. The biological age of children was determined with their estimated age at the peak height velocity, and maturity categories were gender-specific defined.Results: Boys spent more time in MVPA than girls (P<0.0001), and no maturity-related differences were obtained on the whole sample. It was only among boys that differences were found between maturity groups with cut-off points of 3000cpm (P=0.034), 3200cpm (P=0.024), and 3600cpm (P=0.011). At a given maturity level, boys spent significantly more time in MVPA than girls, except with the cut-off point of 1000cpm (P=0.07). There were higher proportions of sufficiently active boys, but significances were reached only with cut-off points above 3000cpm. There were no maturity-related differences in the proportion of sufficiently active children as MVPA was computed using cut-off points of 1000cpm, 2000cpm or 3000cpm.Conclusions: The role of maturity in the gender-difference in MVPA seems unclear as one another cut-off point is used among children. Even if a relatively greater consistency was found with the three cut-off points above 3000cpm, data comparison may require a conversion system until a consensus is reached about the exact value to be used among children.

How specific is domain specificity: Does it extend across playing position? - Corrected Proof

Lyndell Bruce, Damian Farrow, Annette Raynor — 2011-12-22

Abstract: Objectives: The current study sought to examine the scope of domain specificity within a sport expertise context through the examination of positional specificity effects in the sport of netball.Design: Skilled goalers, centre court and defenders along with less skilled (novice) participants were tested on a video-based decision making task.Method: Skilled and less skilled netballers completed a video-based decision making task, comprising scenarios from the three different positional areas in netball (goalers, centre court and defence). Participants completed the scenarios from the playing position they were most familiar with, followed by the remaining two positions in a counterbalanced order.Results: Analysis of the goaler and defence scenarios revealed that the skilled goalers and centre court players were significantly more accurate than the novice players, whilst the skilled defenders did not differ to the other three groups (skilled goalers, skilled centre court and novice). For the centre court scenarios the skilled centre court players and defenders were significantly more accurate than the novice players, whilst the skilled goalers did not differ to any of the groups.Conclusions: Limited evidence was shown to support the theory that decision making is specific to the position being played with the goalers and the centre court players most accurate on the attack and centre court scenarios respectively.

Features of sports bras that deter their use by Australian women - Corrected Proof

Kelly-Ann Bowles, Julie R. Steele, Bridget J. Munro — 2011-12-21

Abstract: Objectives: This study aimed to identify features of commercially available sports bras that deter women from wearing them while participating in physical activity.Design: Study results were obtained from a self-administered mail survey, which was posted to participants after gaining their verbal consent via random telephone recruitment.Methods: Four hundred and thirteen women aged 20–35 years were recruited from New South Wales, Australia, with 267 (65%) surveys returned.Results: It was found that the shoulder straps slipping or cutting into the shoulder were the two most disliked features of current sports bras, with 23% of respondents also indicating that the shoulder straps were the first bra feature to fail. Respondents also indicated that the perceived tightness of the sports bra around the chest was a deterrent for their use.Conclusion: Although previous research has found that a correctly fitted sports bra does not impede athletic performance, further research is required to investigate sports bra shoulder strap designs to improve wearer comfort without negatively affecting the ability of a sports bra to reduce breast motion and/or associated breast pain during participation in physical activity.

A qualitative study on overuse injuries: The beliefs of athletes and coaches - Corrected Proof

C.P. van Wilgen, E.A.L.M. Verhagen — 2011-12-21

Abstract: Objective: Preventive approaches for overuse injuries in sports will be more successful when synchronised with athletes’ and coaches’ beliefs. We interviewed athletes and coaches in order to better characterize their beliefs about the definition of an overuse injury, as well as the intrinsic and extrinsic risk factors that underlie overuse injuries.Design: Qualitative study using in-depth interviews in athletes and coaches of different sports.Methods: Athletes who had experienced overuse injuries and coaches who trained athletes who had sustained overuse injuries from sports clubs were invited to participate through interview. We explored each participant's individual definition of an overuse injury and the beliefs concerning the intrinsic and extrinsic risk factors concerning overuse injuries were explored.Results: After nine athletes and nine coaches, sample size saturation was confirmed. Athletes and coaches integrate somatic as well as psychological and sociological factors into the definition of and risk factors for overuse injuries. Intrinsic factors for an overuse injury were related to physical factors, technique, psychological factors and heredity. The extrinsic factors were related to situational, social and training factors, as well as the individual coach.Conclusions: Athletes and coaches have a holistic view on the definition of overuse injuries, and the intrinsic and extrinsic risk factors for overuse injuries. If preventive approaches for overuse injuries are developed and implemented, they should incorporate physical factors, as well as incorporate psychological and social factors. Based on the input of coaches and athletes, the latter are important risk factors for overuse injuries.

Movement patterns in rugby sevens: Effects of tournament level, fatigue and substitute players - Corrected Proof

Dean G. Higham, David B. Pyne, Judith M. Anson, Anthony Eddy — 2011-12-21

Abstract: Objective: Understanding of the physical demands and the effects of fatigue and substitute players in rugby sevens is limited. This study quantified the differences in movement patterns between domestic and international rugby sevens tournaments, the effects of fatigue within and between matches during tournaments, and movement patterns of second half substitute players.Design: Movement patterns of 19 international-level male rugby sevens players were recorded using a Global Positioning System (GPS) device during 11 international and 16 domestic matches (n=174 files).Methods: Maximum velocity, total distance covered, distance covered in velocity zones and number of moderate and high accelerations and decelerations are reported per min of match time. Movement patterns were compared between international and domestic matches, first and second half, first and last tournament match and substitute and full-match players.Results: Substantially greater distance was covered at high velocity (∼27% at ≥6ms−1) and 4–39% more accelerations and decelerations were performed in international than domestic matches. The relative distance covered by players at velocities >2ms−1 and the number of changes in velocity were reduced by 1–16% from first to second half. Small differences were observed in activity at <5ms−1 (−8–8%) and moderate accelerations (−18%) from first to last tournament match. All movement variables were higher (2–123%) for substitute players.Conclusions: International rugby sevens competition is more intense than domestic matches. Despite reductions in work-rate within individual matches, there is little indication of accumulated fatigue over a multi-day tournament.

Alcohol-related aggression and antisocial behaviour in sportspeople/athletes - Corrected Proof

2011-12-19

Abstract: Objective: There is no empirical research on alcohol-related aggression and antisocial behaviour in non-US collegiate athletes. The present study addressed this gap by examining these behaviours in Australian university sportspeople. Design: Cross-sectional. Methods: University sportspeople and non-sportspeople completed questionnaires on alcohol consumption, aggressive and antisocial behaviours (e.g., abused, hit or assaulted someone, made unwanted sexual advance, damaged property) when intoxicated. Participants also reported whether they had been the victim of similar aggressive or antisocial behaviours. Demographic data and known confounders were collected. Results: Hierarchical logistic regression models accounting for confounders and alcohol consumption scores found that university sportspeople were significantly more likely than non-sportspeople to have displayed aggressive behaviour (i.e., insulted or assaulted someone; OR 1.65, 95% CI: 1.19, 2.28, p=.003), and damaged property (OR 1.98, 95% CI: 1.38, 2.84, p<.0005) in the past year when intoxicated. Sportspeople were no more likely to have received aggression, had property damaged due to others intoxication (OR 1.21, 95% CI: .90, 1.62, p=.20; and OR 1.10, 95% CI: .79, 1.53, p=.57, respectively), or to have made unwanted sexual advances (OR 1.10, 95% CI: .65, 1.83, p=.74). Sportspeople were less likely to have reported being sexually assaulted when intoxicated (OR .44, 95% CI: .23, .83, p<.01). Conclusions: Consistent with work from the US alcohol-related aggressive and antisocial behaviours were greater in male Australian university sportspeople/athletes than in their female and non-sporting counterparts. There is a need for research explicating the interaction between alcohol, contextual and cultural aspects of sport, and sport participants.

Physical activity levels and movement skill instruction in secondary school physical education - Corrected Proof

Dean A. Dudley, Anthony D. Okely, Wayne G. Cotton, Phil Pearson, Peter Caputi — 2011-12-15

Abstract: The purpose of this study was to determine the levels of physical activity (PA), lesson context and teacher interaction students receive during physical education (PE) in secondary schools in New South Wales, Australia. A baseline cross-sectional study was performed using systematic direct observation of Year 7 PE classes over a six-month period. Eighty-one (81) PE lessons across six schools were observed. Results were the mean (SD) percentage of class time spent in moderate to vigorous physical activity (MVPA) was 56.9% (18.7). However, only 60% of the 81 met the recommended 50% of class time spent in moderate to vigorous physical activity (MVPA). Just over 6% of class time was spent in skill instruction. Game play made up nearly half of the lesson context (44%) and teachers spent just under one-third (31%) of class time promoting PA. Conclusions from this baseline study indicate that substantial variations in the PA, lesson context and teacher interaction exist within PE. As a large proportion of classes, especially girls’ only classes, did not meet the Centers of Disease Control and Prevention (CDC) recommendation of 50% of class time in MVPA, ways need to be found to promote PA in PE classes. Levels of skill instruction and practice were well below international comparisons and may have implications for PA participation later in life. Numerous possibilities exist for improving PE in Australia as a way of improving the activity levels and experiences of our young people.

Differences in markers of cardiovascular disease between professional football players of West-Asian and Black African descent - Corrected Proof

M.G. Wilson, B. Hamilton, A.L. Sandridge, O. Salah, H. Chalabi — 2011-12-14

Abstract: Objectives: To examine the cardiovascular risk factors of professional football players of West-Asian and Black African descent competing in the 2010/11 Qatar Stars League.Design: Ten out of twelve professional football clubs attended pre-participation screening. 100 West-Asian males from seven Gulf States and six Middle-Eastern countries and 90 Black males from seven African countries.Methods: All players were screened using the FIFA pre-competition medical assessment, incorporating a physical examination, resting 12-Lead ECG, echocardiogram, with determination of total cholesterol, high and low density lipoprotein (HDL/LDL) and triglycerides.Results: West-Asian football players had a higher prevalence of a family history (FH) of coronary heart disease (CHD) (25% vs. 12%, p=0.025) compared to Black African players predominantly due to CHD in their fathers (14% vs. 6%, p<0.05). West-Asian players had higher total cholesterol levels (4.4 vs. 4.2mmol/L, p=0.025) and lower HDL levels (1.3 vs. 1.4mmol/L, p=0.004) than Black African players; remaining significant after adjusting for a FH of CHD. Positively, all lipid levels were clinically acceptable for both ethnicities. Finally, one in eight West-Asian and one in eleven Black African football players were regular smokers.Conclusions: The prevalence of cardiovascular disease in West-Asia is increasing. This study observed clinically acceptable blood lipid profiles for both West-Asian and Black African football players. However, West-Asian players had a greater number of markers for CVD than their Black African counterparts despite being matched for physical activity levels. Targeted education with regards to diet, lifestyle and tobacco use is required for both ethnicities.

Differences in wrist mechanics during the golf swing based on golf handicap - Corrected Proof

2011-12-12

Abstract: Variation in swing mechanics between golfers of different skill levels has been previously reported. To investigate if differences in three-dimensional wrist kinematics and the angle of golf club descent between low and high handicap golfers. A descriptive laboratory study was performed with twenty-eight male golfers divided into two groups, low handicap golfers (handicap=0–5, n=15) and high handicap golfers (handicap≥10, n=13). Bilateral peak three-dimensional wrist mechanics, bilateral wrist mechanics at ball contact (BC), peak angle of descent from the end of the backswing to ball contact, and the angle of descent when the forearm was parallel to the ground (DEC-PAR) were determined using an 8 camera motion capture system. Independent t-tests were completed for each study variable (α=0.05). Pearson correlation coefficients were determined between golf handicap and each of the study variables. The peak lead arm radial deviation (5.7°, p=0.008), lead arm radial deviation at ball contact (7.1°, p=0.001), and DEC-PAR (15.8°, p=0.002) were significantly greater in the high handicap group. In comparison with golfers with a low handicap, golfers with a high handicap have increased radial deviation during the golf swing and at ball contact.

Is the six-minute walk test appropriate for detecting changes in cardiorespiratory fitness in healthy elderly men? - Corrected Proof

2011-12-12

Abstract: Objective: The purpose of this study was to determine whether the six-minute walk test (6-MWT) can detect changes in cardiorespiratory fitness (CRF) induced by exercise training in healthy elderly men.Design: Randomized and prospective controlled trial.Methods: Thirty-two healthy untrained men, between 65 and 75 years of age, were randomly assigned to one of three groups: control (C, n=12), endurance training (E, n=10), or concurrent training (ER, n=10). Training groups underwent 24weeks of exercise, 3 times a week. All participants were subjected to cardiopulmonary exercise testing and the 6-MWT, before and after the training period.Results: At follow-up, the E and ER groups had significantly higher peak oxygen uptake (15.0±9.1 and 12.6±10.4%, respectively) and 6-MWT distances (5.5±5.3 and 4.6±2.8%, respectively) compared to the C group. In pre-intervention (n=32), the 6-MWT distance correlated positively with (r=0.51, p=0.001) and at anaerobic threshold (r=0.39, p=0.010). On the other hand, there was no significant correlation between the changes (after–before) in the 6-MWT distance and peak (E and ER groups: r=0.38, p=0.097).Conclusion: The 6-MWT is not appropriate to evaluate changes in CRF in healthy elderly men who performed endurance and concurrent training for 24weeks.

Use of pedometers to identify less active children and time spent in moderate to vigorous physical activity in the school setting - Corrected Proof

2011-12-09

Abstract: To examine in the context of a school day whether a pedometer, compared to an accelerometer, was an effective tool to identify children with low physical activity levels. Additionally, to characterise within the school day, patterns of variation in level and timing of activity of the most active and least active children. Observational study to compare two methods (accelerometer and pedometer) of identifying less active children and intensity of activity. During school hours, for three consecutive days, children (n=47, aged 8–11years) in two classes wore an accelerometer and sealed pedometer. Accelerometers were programmed to record at 15s epochs and the number of pedometer steps taken were recorded at the end of each school day. Patterns of activity by total accelerometer counts, and with cutoffs applied, were examined against time and the number of steps taken. Based on the accelerometer (>1500counts/min), the majority (68%) of children spent more than 60min in moderate to vigorous physical activity (MVPA) during the school day. Overall, time spent in MVPA was three times greater during break times compared to classroom time, with no apparent differences by class/age or gender. Total accelerometer counts and pedometer steps were correlated (r=0.60). One minute of MVPA was equivalent to 45 (95% CI 20–70) pedometer steps. The pedometer, a practical, relatively inexpensive tool, is suitable for the identification of less active children and has some utility to assess the relative intensity of activities in the context of a school day.

Changes in practice task constraints shape decision-making behaviours of team games players - Corrected Proof

2011-12-08

Abstract: This study examined the effects of manipulating relative positioning between defenders (initial distance apart) on emergent decision-making and actions in a 1 vs. 2 rugby union performance sub-phase. Twelve experienced youth players performed 80 trials of a 1 (attacker) vs. 2 (defenders) practice task in which the starting distance between defenders was systematically decreased. Movement displacement trajectories of participants were video recorded to obtain 2D positional data. The independent variable was the starting distance between defenders and dependent variables were: (i) performance outcome (try or tackle), (ii) mean speed of all players during performance, and (iii) time between the first crossover and the end of the trial. Repeated measures ANOVA was used to compare the effects of different starting distances on performance. Shorter starting distances between defenders were associated with a higher frequency of effective tackle outcomes, lower mean speeds of all participants, and a greater time period between the first crossover and the end of the trial. Decision-making behaviours emerged as a function of changes in participants’ spatial location during performance. This observation supports the importance of manipulating key spatial-temporal variables in designing representative practice task constraints that induce functional player–environment interactions in team sports training.

Post-match changes in neuromuscular function and the relationship to match demands in amateur rugby league matches - Corrected Proof

Rob Duffield, Alistair Murphy, Alanna Snape, Geoffrey M. Minett, Melissa Skein — 2011-12-05

Abstract: The current study investigated the change in neuromuscular contractile properties following competitive rugby league matches and the relationship with physical match demands. Eleven trained, male rugby league players participated in 2–3 amateur, competitive matches (n=30). Prior to, immediately (within 15min) and 2h post-match, players performed repeated counter-movement jumps (CMJ) followed by isometric tests on the right knee extensors for maximal voluntary contraction (MVC), voluntary activation (VA) and evoked twitch contractile properties of peak twitch force (Pt), rate of torque development (RTD), contraction duration (CD) and relaxation rate (RR). During each match, players wore 1Hz Global Positioning Satellite devices to record distance and speeds of matches. Further, matches were filmed and underwent notational analysis for number of total body collisions. Total, high-intensity, very-high intensity distances covered and mean speed were 5585±1078m, 661±265m, 216±121m and 75±14mmin−1, respectively. MVC was significantly reduced immediately and 2h post-match by 8±11 and 12±13% from pre-match (p<0.05). Moreover, twitch contractile properties indicated a suppression of Pt, RTD and RR immediately post-match (p<0.05). However, VA was not significantly altered from pre-match (90±9%), immediately-post (89±9%) or 2h post (89±8%) (p>0.05). Correlation analyses indicated that total playing time (r=−0.50) and mean speed (r=−0.40) were moderately associated to the change in post-match MVC, while mean speed (r=0.35) was moderately associated to VA. The present study highlights the physical demands of competitive amateur rugby league result in interruption of peripheral contractile function, and post-match voluntary torque suppression may be associated with match playing time and mean speeds.

Absolute reliability of five clinical tests for assessing hamstring flexibility in professional futsal players - Corrected Proof

Francisco Ayala, Pilar Sainz de Baranda, Mark De Ste Croix, Fernando Santonja — 2011-11-21

Abstract: Objectives: To examine the absolute reliability of five methods for estimating hamstring flexibility in professional futsal players.Design: Absolute reliability laboratory study (k=4).Method: A total of 46 male futsal players (172.9±4.5cm; 69.7±7.5Kg) completed the study. All participants performed each measurement test twice in a randomized order on four different occasions. Absolute reliability was examined through typical percentage error, percentage change in the mean and intraclass correlations (ICC) as well as their respective confidence limits.Results: The findings showed high reliability for the sit and reach test (SRT) (4.48% typical error; 0.84% change in the mean, 0.95 ICC), toe touch test (TT) (5.89% typical error; 2.31% change in the mean, 0.89 ICC) and back-saver sit and reach test (BSSR) (3.73% typical error; 0.51% change in the mean, 0.97 ICC) compared to the passive straight leg raise test (PSLR) (7.6% typical error; 8.86% change in the mean, 0.77 ICC) and modified sit and reach test (MSR) (11.87% typical error; 7.64% change in the mean, 0.84 ICC) which showed moderate reliability.Conclusion: An observed change larger than 6.72%, 7.55% and 5.59% for baseline SRT, TT and BSSR scores respectively would indicate that a real improvement in hamstring flexibility has occurred. In addition, the clinical reliability of PSLR and MSR are questioned and should be re-evaluated in future research studies.

Changes in bone turnover markers during the close season in elite football (soccer) players - Corrected Proof

Richard Weiler, Richard Keen, Roger Wolman — 2011-11-07

Abstract: Bone turnover marker changes in response to physical activity are well documented. There is, however, little information on the extent and severity of skeletal de-conditioning in athletes in response to rest periods. This study analyses changes in markers of bone resorption and bone formation during the close season within the squad of an English Football Association Championship club. Evaluation was performed on the first team football squad just before the end of the 2007/2008 football season and again 8 weeks later before pre-season testing and training. Bone resorption was measured by serum concentration of C-terminal telopeptide (CTx) and bone formation by serum concentration of the N-terminal propeptide of type I procollagen (PINP). Twenty football players aged from 18 to 36 years (mean 23.6 years) were included in the study. The mean change in CTx during the close season was +0.14ng/ml (95% CI: 0.21–0.06, p=0.001). The mean change in PINP was −10.8ng/ml (95% CI: −3.9 to −17.7, p=0.004). In professional football players, a close season rest of 8 weeks results in an increase in bone resorption and a decrease in bone formation markers. This imbalance between formation and resorption may have negative effects on bone mass and structure. Future research should focus on understanding the many factors that could contribute to the changes found in the study during the close season.

Validity of a brief self-report instrument for assessing compliance with physical activity guidelines amongst adolescents - Corrected Proof

Nicola D. Ridgers, Anna Timperio, David Crawford, Jo Salmon — 2011-11-04

Abstract: Objectives. To examine the validity of a brief self-report questionnaire for assessing physical activity, and compliance and non-compliance with moderate-to-vigorous physical activity (MVPA) recommendations in Australian adolescents against accelerometry. Design. Cross-sectional study. Methods. MVPA of 203 adolescents (124 females, 79 males) aged 15–17 years was objectively assessed for 8 consecutive days using uni-axial accelerometers and calculated using age-specific cut-points. Adolescents self-reported the number of days (0–7) they were physically active for a total of at least 60min/day (1) over the past 7 days and (2) over a typical week. Compliance with physical activity recommendations was defined as (1) 5 and (2) 7 days of self-reported MVPA (of at least 60min/day), and (3) ≥60min MVPA per average day, and (4) >60min MVPA on every day according to accelerometry. Spearman's Rho correlations analysed the association between accelerometry-derived MVPA/day and self-reported MVPA days/week for the whole sample, sex and weight status. Percent agreement determined the proportion of adolescents correctly identified as not meeting physical activity recommendations (specificity) or as meeting physical activity recommendations (sensitivity) according to the self-report questionnaire. Results. Moderate to large correlations were found between the self-report and accelerometer data (0.2–0.51) across population subgroups. The percent agreement between the self-report and accelerometry data was good for specificity; however, the sensitivity was low, potentially due to poor compliance with recommendations. Conclusions. Compared to accelerometry, the brief MVPA self-report questionnaire appears to have acceptable validity for measuring non-compliance with physical activity recommendations in 15–17 year old adolescents.

Relationship between sports participation and the level of motor coordination in childhood: A longitudinal approach - Corrected Proof

2011-11-03

Abstract: This study examined the stability of motor coordination and the relationship between motor coordination and organized sports participation over time. A longitudinal approach was followed. A total of 371 children between six and nine years of age at initial testing completed a test battery measuring motor coordination in three consecutive years and a questionnaire on their club sports participation in year 1 and year 3 of testing. Correlation coefficients revealed the motor coordination of children to be a highly stable factor, ranging from 0.662 (6–8 years) to 0.873 (7–9 years). Results of the Repeated Measures ANOVA indicated that children who consistently practiced sports in a club environment over the three years of testing displayed better coordination levels than children who only partially participated or did not participate in a club environment at all. Moreover, stability was further indicated as consistent sports participation over time and changes or lack thereof did not substantially influence the development of motor coordination over time. In addition, the basic level of motor coordination and the amount of club sports participation significantly predicted sports participation two years later. The importance of the stability of motor coordination levels in childhood and its role in determining organized sports participation may have implications for talent identification purposes as well as potential health-related benefits in childhood and throughout the lifespan.

Landing technique affects knee loading and position during athletic tasks - Corrected Proof

Nelson Cortes, Steven Morrison, Bonnie L. Van Lunen, James A. Onate — 2011-10-31

Abstract: Anterior cruciate ligament (ACL) injuries have been reported to occur with the ankle in a dorsiflexed position at initial contact. Few studies have attempted to quantify the biomechanical parameters related with such landing patterns during athletic tasks. The purpose of this study was to evaluate the effects that two landing techniques have in lower extremity biomechanics while performing two tasks. Single-group repeated measures design. Twenty female soccer athletes from a Division I institution performed two landing techniques (forefoot and rearfoot) during two unanticipated tasks (sidestep cutting and pivot). Repeated measures analyses of variance were conducted to assess differences in the kinematic and kinetic parameters between landing techniques for each task. The forefoot landing technique had significantly higher internal knee adductor moment than the rearfoot for both the pivot and sidestep cutting task (p<0.001 and p=0.003, respectively). For the sidestep cutting task, participants had increased knee valgus angle with the rearfoot, whereas for the pivot they had increased knee valgus with the forefoot landing technique (p<0.05). The results of this study highlighted that there are inherent differences in biomechanical outcomes between foot-landing techniques. The forefoot landing technique increasingly affects knee adduction moment loading, which can potentially place a higher strain on the ACL. Essentially, the demands of the landing technique on lower extremity biomechanics (e.g., hip and knee) are task dependent.

Neural conduction and excitability following a simple warm up - Corrected Proof

Alan J. Pearce, Grant S. Rowe, Douglas G. Whyte — 2011-10-24

Abstract: Objective: This study examined the effect of a generic, active warm up on neural and muscular conduction time. Design: Single group, pre-post design. Method: Central and peripheral neuromuscular conduction time was quantified in the abductor pollicis brevis (APB) and gastrocnemius muscles of 18 healthy participants (mean age 25.9±5.8 years, 12 males) using transcranial magnetic stimulation (TMS) and M-wave techniques, prior to and immediately following an active warm up consisting of 5min running at 65% of maximum heart rate. Neural conduction time, for both TMS and M-wave, was quantified as the time between stimulus artefact and deflection of the wave form, whilst muscle conduction time for TMS and M-wave, was quantified from the stimulus artefact to the absolute peak twitch response. Results: Following the warm up protocol, a significant reduction in muscle conduction time was found in both TMS and M-wave of 0.43ms (P=0.02) and 0.30ms (P=0.001) for the APB; and 0.29ms (P<0.001) and 0.87ms (P=0.003) for the gastrocnemius, respectively. No change was found in neural conduction using either TMS or M-wave techniques. Conclusions: These findings support previous data which demonstrate an improvement in muscular conduction time and subsequent improvement in athletic performance post warm up. The data also make evident that changes in muscular conduction time are a global response to warm up and are not directly related to muscular activity. In contrast, neural conduction time did not change and should not be confused with changes in muscular conduction time in the literature.

Changes in drive phase lower limb kinematics during a 60min cycling time trial - Corrected Proof

Mark G.L. Sayers, Amanda L. Tweddle, Joshua Every, Aaron Wiegand — 2011-10-24

Abstract: Objectives: The aim of this study was to evaluate changes in the three dimensional lower limb kinematics during a simulated cycling time trial. Design: Repeated measures. Methods: Ten experienced male road cyclists performed a 60min cycling test at a workload based on previous onset of blood lactate accumulation (OBLA) testing. The time trial (TT) was divided into six 10min periods consisting of 8min cycling at steady state (88% of OBLA) followed by a 90s effort phase (140% of OBLA) and a 30s recovery phase (60% of OBLA). Three-dimensional kinematic data (200Hz) were recorded in the last minute of each steady state phase with specific attention directed at changes in range of motion (ROM) and consistency of orientation at the hip, knee and ankle joints during drive phase.Results: from repeated measures ANOVA indicated a mean effect for test duration on the drive phase ROM in both hip extension (p=0.027) and ankle dorsi flexion (p<0.001). The SD of the mean tibial rotation during the drive phase was the only measure of movement consistency that showed an effect for test duration (p=0.031). Conclusion: These findings indicated that participants tended to increase the ROM in hip extension and ankle flexion during drive phase at the end of a TT. Changes in the consistency of tibial rotation during the drive phase may be an important indicator of fatigue and should be monitored by coaches during training due to its possible relationship with injury and fatigue.

Effects of exercise on bone density and falls risk factors in post-menopausal women with osteopenia: A randomised controlled trial - Corrected Proof

2011-10-13

Abstract: Objectives and design: This randomised, single-blind controlled trial aimed to determine the efficacy of an exercise program for post-menopausal women with osteopenia undertaken in community exercise facilities. Methods: Thirty-nine community volunteers with hip osteopenia and not taking bone-enhancing medication were randomly allocated to an exercise (EX) or control (CON) group. EX participants attended an exercise facility in Melbourne, Australia, three times/week for 52 weeks (with a 2 week break) for partially supervised exercises targeting hip bone strength, muscle strength and balance. They also performed daily jumping exercises at home. CON participants continued with their usual care. All participants were given calcium supplementation. Assessment at baseline and 52 weeks measured bone mineral density (BMD) at the proximal femur and lumbar spine. Health-related quality of life (QOL) and objective measures of strength and balance were also collected. Results: ANCOVA adjusting for baseline values revealed a small benefit of exercise in mean total hip BMD (the primary outcome) with a significant mean difference in change between groups of −0.012g/cm2 (95% CI −0.022 to −0.002g/cm2). EX participants improved 0.5% compared with a 0.9% loss for CON participants. The only other between-group differences were in QOL and a test of trunk and upper limb endurance, which both favoured the EX group. Conclusion: This exercise program appears to have modest benefits for post-menopausal women with osteopenia who are not taking bone-enhancing medication. This mode of exercise delivery has adherence and progression limitations but may be appropriate to recommend for some people.

Normalizing considerations for time to stabilization assessment - Corrected Proof

Phillip A. Gribble, Jessica Mitterholzer, Alyse N. Myers — 2011-10-04

Abstract: Objectives: Because of the growing use of time to stabilization (TTS) and similar measures with single-limb landings in lower extremity research, it is important to determine if the task performance needs to be normalized further. The purpose of this study was to compare TTS of healthy participants using a standardized versus a normalized horizontal jumping distance. Design: Crossover study. Methods: Twenty-one healthy participants performed single landings using two horizontal jumping distances: standardized (70cm) and normalized (leg length). Resultant vector TTS (RVTTS) was calculated to represent the dynamic stability performance. Results: For RVTTS, the participants took significantly longer to stabilize when using the normalized jumping distance (1.997±0.181s) compared with the standardized jumping distance (1.921±0.126s) (t=5.134; p<0.001; power=0.65). RVTTS during the normalized jumping distance was more strongly correlated with leg length (r=0.628; p=0.002) than during the standardized jumping distance (r=0.563; p=0.008). Conclusions: Normalizing the horizontal jumping distance during the single-limb jumping task creates a performance decrement in RVTTS among healthy participants. Because dynamic stability measured with RVTTS when jumping a normalized distance is more strongly correlated with leg length than when jumping a standardized jumping distance, researchers using this task and analysis may want to consider using this additional normalizing step in future investigations.

Secular trends in fitness, moderate-to-vigorous physical activity, and TV-viewing among first grade school children of Crete, Greece between 1992/93 and 2006/07 - Corrected Proof

2011-10-03

Abstract: To assess secular changes in physical fitness (PF), moderate-to-vigorous-physical activity (MVPA) and TV-viewing in 1st-grade children from Crete, Greece. Cross sectional cohorts examined in academic years 1992/93 and 2006/07. Two representative samples of children, aged 5.9–7.8 years, were studied during 1992/93 (N=606) and 2006/07 (N=361). PF (sit-and-reach, standing-broad-jump, sit-ups and 20m-shuttle-run-test) was assessed by the European-PF test battery and MVPA by a physical activity (PA) questionnaire. Data on the frequency of TV-viewing was also collected. Between 1992/93 and 2006/07, there was a significant increase in all fitness tests in both genders (P<0.001) and in MVPA in boys (76.5min/week vs. 38.7min/week, P<0.001). Time spent watching TV on weekdays was significantly more in both genders in 2006/07, compared to 1992/93 (P<0.001). In 2006/07, active boys and active girls spent more time in MVPA than active boys and girls in 1992/93 (P<0.001). Significantly higher proportions of boys and girls engaged in vigorous activities in 2006/07, than 1992/93 (P<0.001 and P=0.027, respectively). A significant increase in physical and cardiorespiratory fitness in both genders and MVPA in boys was observed in children from Crete between 1992/93 and 2006/07. The increase in weekday TV-viewing, despite being parallel to an increase in leisure-time MVPA, could have an unfavorable effect on health and should be tackled in future interventions in this population. Dietary, anthropometric and biochemical indices should also be investigated to assess their impact on the secular changes in physical fitness and activity observed in this sample of children.

Neighborhood characteristics and TV viewing in youth: Nothing to do but watch TV? - Corrected Proof

2011-09-28

Abstract: Objectives: Neighborhoods that discourage physical activity may encourage indoor activities such as television viewing; however few studies have examined associations between neighborhood characteristics and sedentary activities. This study examined cross-sectional and longitudinal associations between perceived and objective measures of the physical and social neighborhood environment and TV viewing among children and adolescents. Design. Cross-sectional and longitudinal. Method. Parents of 190 children and 169 adolescents completed questionnaire items regarding facilities for physical activity, neighborhood safety (general and traffic), social trust/cohesion, social networks and their child's TV viewing in 2006. Adolescents self-reported their TV viewing. Objective measures of reported crime and neighborhood destinations, road connectivity and traffic exposure were also collected. Questions about TV viewing were repeated in 2008 (longitudinal sample: 157 children; 105 adolescents). Results. In children, cul-de-sac density and reported crime were positively and parental agreement that their neighborhood has good sporting facilities was negatively associated with TV viewing in cross-sectional analyses. There were no longitudinal associations among children. In adolescents, number of sports options and parental agreement that there is so much traffic that it is difficult/unpleasant for their child to walk were negatively associated with TV viewing 2 years later. Conclusions. Crime and a lack of quality sporting facilities or options may contribute to greater TV viewing among youth.

Injury risk associated with ground hardness in junior cricket - Corrected Proof

Dara M. Twomey, Peta E. White, Caroline F. Finch — 2011-09-28

Abstract: To establish if there is an association between ground hardness and injury risk in junior cricket. Nested case-series of players who played matches on specific grounds with objective ground hardness measures, within a prospective cohort study of junior community club cricket players. Monitoring of injuries and playing exposure occurred during 434 matches over the 2007/2008 playing season. Objective assessment of the hardness of 38 grounds was undertaken using a Clegg hammer at 13 sites on 19 different junior cricket grounds on the match eve across the season. Hardness readings were classified from unacceptably low (<30g) to unacceptably high (>120g) and two independent raters assessed the likelihood of each injury being related to ground hardness. Injuries sustained on tested grounds were related to the ground hardness measures. Overall, 31 match injuries were reported; 6.5% were rated as likely to be related to ground hardness, 16.1% as possibly related and 74.2% as unlikely to be related and 3.2% unknown. The two injuries likely to be related to ground hardness were sustained while diving to catch a ball resulting, in a graze/laceration from contact with hard ground. Overall, 31/38 (82%) ground assessments were rated as having ‘unacceptably high’ hardness and all others as ‘high/normal’ hardness. Only one injury occurred on an objectively tested ground. It remains unclear if ground hardness is a contributing factor to the most common injury mechanism of being struck by the ball, and needs to be confirmed in future larger-scale studies.

Hot ambient conditions do not alter intermittent cycling sprint performance - Corrected Proof

Fuad Almudehki, Olivier Girard, Justin Grantham, Sebastien Racinais — 2011-09-22

Abstract: To investigate the effect of hot exposure on the ability to perform intermittent cycling sprints. Ten male volunteers performed 35min of intermittent cycling comprising of 8 maximal 6-s sprints interspersed by 1min of passive recovery followed by 4min of constant-load pedaling (1Wkg−1 of body weight) on a cycle ergometer in control (24°C, 24% rH) and hot (40°C, 40% rH) environments. Peak power output did not decrease during the exercise and was not dependent on the environmental temperature (average of 767±120W in control and 767±119W in hot, NS). Skin temperatures (e.g., chest: 36.8±0.8 vs. 32.7±0.6°C), heart rate (132±13 vs. 118±13bpm) and rating of perceived exertion (13±3 vs. 11±3) were higher (all p<0.05) in hot than control environment. However, EMG activity (RMS, vastus lateralis) and neuromuscular efficiency (power/RMS ratio) were similar at the two environmental conditions. Despite higher cardiovascular and perceptual strain in the hot trial, heat exposure did not alter neither peak power output nor related muscle activation and neuromuscular efficiency in the absence of hyperthermia (average core temperature of 37.6±0.3°C in control vs. 37.7±0.4°C in hot, NS).

Acute neuromuscular and fatigue responses to the rest-pause method - Corrected Proof

Paul W.M. Marshall, Daniel A. Robbins, Anthony W. Wrightson, Jason C. Siegler — 2011-09-22

Abstract: Objectives. To compare muscle recruitment, maximal force, and rate of force development changes following different resistance exercise protocols with a constant volume-load. Design. Within-subjects randomized crossover trial. Methods. Fourteen (n=14) resistance trained male participants completed three different resistance exercise protocols involving 20 squat repetitions, prescribed at 80% of 1-repetition-maximum. Protocol A consisted of 5 sets of 4 repetitions with 3min inter-set rest intervals, protocol B was 5 sets of 4 repetitions with 20s inter-set rest intervals, and the rest-pause method was an initial set to failure with subsequent sets performed with a 20s inter-set rest interval. Maximal squat isometric force output and rate of force development (RFD) were measured before, immediately upon completion (IP), and 5min (5P) following each protocol. Muscle activity from 6 different thigh and hip muscles was measured with surface electromyography (EMG) at each time point, and during every squat repetition. Results. Participants completed the rest-pause method in 2.1±0.4 sets, with a total protocol duration of 103s compared to 140s and 780s for protocols B and A, respectively. All protocols elicited similar decreases (p<0.05) in maximal force and RFD at IP, with full recovery at 5P. Increased motor unit recruitment was observed during the rest-pause method compared to both protocols A and B for all muscles measured (p<0.05). Conclusions. As a result of the increased EMG during exercise and no greater post-exercise fatigue, it was concluded that the rest-pause method may be an efficacious training method for resistance-trained individuals.

Cross education and immobilisation: Mechanisms and implications for injury rehabilitation - Corrected Proof

Ashlee M. Hendy, Michael Spittle, Dawson J. Kidgell — 2011-09-19

Abstract: Unilateral strength training produces an increase in the strength of the contralateral homologous muscle group. This process of strength transfer, commonly known as cross education, is generally attributed to neural adaptations. It has been suggested that unilateral strength training of the free limb may assist in maintaining the functional capacity of an immobilised limb via cross education of strength, potentially enhancing recovery outcomes following injury. This review will examine the impact of immobilisation on muscle tissue and the central nervous system, the possible mechanisms that may contribute to cross education strength transfer, and possible implications for the practical application of unilateral training to maintain strength during immobilisation. Immobilisation is well known for its detrimental effects on muscular strength and cross sectional area. Early reductions in strength appear to outweigh atrophy, suggesting a neural contribution to strength loss, however direct evidence for the role of the central nervous system in this process is limited and inconsistent. Similarly, the precise neural mechanisms responsible for cross education strength transfer remain somewhat unknown. Two recent studies demonstrated that unilateral training of the free limb successfully maintained strength in the contralateral immobilised limb, although the role of the nervous system in this process was not quantified by either study. Cross education provides a unique opportunity for enhancing rehabilitation following injury. By gaining a deeper understanding of the neural adaptations occurring during immobilisation and cross education, future research can look towards the application of unilateral training in a clinical musculoskeletal injury setting.

Performance accuracy and functional variability in elite and developing fast bowlers - Corrected Proof

Elissa Phillips, Marc Portus, Keith Davids, Ian Renshaw — 2011-09-12

Abstract: Objectives: The relationship between performance variability and accuracy in cricket fast bowlers of different skill levels under three different task conditions was investigated. Bowlers of different skill levels were examined to observe if they could adapt movement patterns to maintain performance accuracy on a bowling skills test. Design: 8 national, 12 emerging and 12 junior pace bowlers completed an adapted version of the Cricket Australia bowling skills test, in which they performed 30 trials involving short (n=10), good (n=10), and full (n=10) length deliveries. Methods: Bowling accuracy was recorded by digitising ball position relative to the centre of a target. Performance measures were mean radial error (accuracy), variable error (consistency), centroid error (bias), bowling score and ball speed. Radial error changes across the duration of the skills test were used to record accuracy adjustment in subsequent deliveries. Results: Elite fast bowlers performed better in speed, accuracy, and test scores than developing athletes. Bowlers who were less variable were also more accurate across all delivery lengths. National and emerging bowlers were able to adapt subsequent performance trials within the same bowling session for short length deliveries. Conclusions: Accuracy and adaptive variability were key components of elite performance in fast bowling which improved with skill level. In this study, only national elite bowlers showed requisite levels of adaptive variability to bowl a range of lengths to different pitch locations.