Journal of Science and Medicine in Sport - Articles in Press

The use of the dual-task paradigm in detecting gait performance deficits following a sports-related concussion: A systematic review and meta-analysis - Corrected Proof

Hopin Lee, S. John Sullivan, Anthony G. Schneiders — 2012-05-21

Abstract: Objectives: The purpose of this systematic review was to determine the viability of the dual-task paradigm in the evaluation of a sports-related concussion.Design: Systematic review and meta-analysis.Methods: Eight electronic databases were searched from their inception until the 11th of April 2011. Studies were grouped according to their reported gait performance variables and their time(s) of assessment(s). Raw mean differences (MD) and 95% confidence intervals (CI) were calculated based on raw means and standard deviations for gait performance measures in both single- and dual-task conditions. Dual-task deficits were pooled using a random effects model and heterogeneity (I2) between studies was assessed.Results: Ten studies representing a total sample of 168 concussed and 167 matched (age and gender) non-concussed participants met the inclusion criteria. Meta-analysis demonstrated that dual-task performance deficits were detected (p<0.05) in the concussed group for gait velocity (GV) (MD=−0.133; 95% CI −0.197, −0.069) and range of motion of the centre of mass in the coronal plane (ML-ROM) (MD=0.007; 95% CI 0.002, 0.011), but not in the non-concussed group; GV (MD=−0.048; 95% CI −0.101, 0.006), ML-ROM (MD=0.002; 95% CI −0.001, 0.005).Conclusions: The results of this study indicate that GV and ML-ROM are sensitive measures of dual-task related changes in concussed patients and should be considered as part of a comprehensive assessment for a sports-related concussion.

Contribution of autonomic dysfunction to abnormal exercise blood pressure in type 2 diabetes mellitus - Corrected Proof

Kassia S. Weston, Julian W. Sacre, Christine L. Jellis, Jeff S. Coombes — 2012-05-18

Abstract: Objectives: The purpose of this study was to compare the presence and severity of autonomic dysfunction in type 2 diabetes mellitus patients, with and without exaggerated blood pressure responses to exercise.Design: We performed a cross-sectional analysis of 98 patients with type 2 diabetes mellitus (aged 59±9).Method: Both time (standard deviation of RR intervals, root-mean-square of successive RR interval differences) and frequency (total spectral power, high frequency, low frequency, very low frequency) domains of heart rate variability were analysed in a 5min recording at rest and 20min after a maximal treadmill test. An exaggerated blood pressure response to exercise was identified by peak blood pressure ≥190/105mmHg (women) or ≥210/105mmHg (men).Results: Each group of either exaggerated exercise blood pressure response or normal blood pressure response consisted of 49 patients. At rest there were no significant differences between groups for all time and frequency domain parameters of heart rate variability. Post-exercise, there was a significant (p<0.05) reduction in the SDNN, RMSSD and TP in the exaggerated exercise blood pressure group. Independent correlates (p<0.01) of exercise systolic blood pressure included post-exercise TP, resting systolic blood pressure, cardiac autonomic neuropathy and beta-blockers (beta=−0.28, adj. R2=0.32, p<0.001).Conclusions: Reduced post-exercise heart rate variability in patients with type 2 diabetes mellitus, with an exaggerated exercise blood pressure response suggests preclinical autonomic dysfunction characterized by impaired vagal modulation.

The effect of estimation and production procedures on running economy in recreational athletes - Corrected Proof

James A. Faulkner, Brandon P. Woolley, Danielle M. Lambrick — 2012-05-14

Abstract: Objectives: Running economy is an important component in any endurance event. However, the influence of effort perception on running economy has yet to be examined.Design: The purpose of this study was to assess the oxygen cost of running (running economy) at identical ratings of perceived exertion (RPE) during estimation (EST) and production (PR) procedures, during treadmill exercise.Methods: Fourteen, well-trained male participants actively produced (self-regulated) a range of submaximal exercise intensities equating to RPE values 9, 11, 13, 15 and 17, and passively estimated their perception of exertion during an incremental graded-exercise test (GXT). Allometric scaling was used to ensure an appropriate comparison in running economy between conditions.Results: The present study demonstrated that the overall running economy between conditions was statistically similar (p>0.05). A significant interaction was however identified between Conditions and RPE (p<0.001). The interaction revealed that running economy significantly improved during PR but remained fairly consistent during EST between moderate and high perceptions of exertion (RPE 11–17). Despite similarities in running economy between conditions, physiological (oxygen uptake, heart rate, minute ventilation and blood lactate) and physical (running velocity) markers of exercise intensity were significantly higher during EST for equivalent perceptions of exertion (all p<0.05).Conclusions: Passive estimation procedures may improve running economy and enhance athletic performance when compared to identical perceptions of exertion elicited during active production procedures. Athletes, coaches and physical trainers should consider the perceptual procedures utilised during training to ensure that an athlete trains at the most effective training intensity.

Tibiofemoral and patellofemoral mechanics are altered at small knee flexion angles in people with patellofemoral pain - Corrected Proof

Gretchen B. Salsich, William H. Perman — 2012-05-14

Abstract: Objectives: To test the hypothesis that, at 0° and 20° of knee flexion, patellofemoral contact area would be lower, while tibiofemoral rotation and patellofemoral malalignment would be higher in participants with patellofemoral pain (PFP) compared to pain-free participants. We hypothesized that no differences would be detected at 40° due to increasing patellar stability.Design: Cross-sectional, descriptive study.Method: Twenty-seven people with PFP and 29 pain-free people participated. Participants underwent magnetic resonance imaging at 0°, 20°, and 40° knee flexion with the limb in a simulated weight-bearing position. Patellofemoral contact area, tibiofemoral rotation angle, patellofemoral alignment (bisect offset index and patellar tilt angle) were quantified and compared between groups at each angle using Student's t-tests. An a-posteriori comparison was made between the pain-free group and a subgroup of 15 participants with patellofemoral pain who demonstrated a faulty lower limb movement pattern (“medial collapse”).Results: In the patellofemoral pain group, contact area was lower at 0° (203.8±45.5mm2 vs. 224.1±46.6mm2, p=0.05) and 20° (276.8±56.2mm2 vs. 316.7±82.8mm2, p=0.02), bisect offset index (BOS) and patellar tilt angle (PTA) were higher at 0° (bisect offset index: 0.69±0.13 vs. 0.64±0.09, p=0.04; patellar tilt angle: 12.5±7.6° vs. 9.2±5.8°, p=0.04). In the patellofemoral pain subgroup, tibiofemoral rotation was higher at 0° compared to pain-free participants (6.4±5.9° vs. 4.0±4.6°, p=0.07).Conclusions: While contact area and patellofemoral alignment were altered in people with patellofemoral pain, tibiofemoral rotation was altered in a subgroup of people who demonstrated medial collapse. Subgroup classification may help identify mechanisms of pain and assist in developing targeted interventions.

Quadratus lumborum asymmetry and lumbar spine injury in cricket fast bowlers - Corrected Proof

Alex Kountouris, Marc Portus, Jill Cook — 2012-05-11

Abstract: Objective: Previous studies have demonstrated quadratus lumborum asymmetry in cricket fast bowlers, but there has been conflicting evidence regarding the relationship to lumbar spine injury, particularly vertebral bone stress injuries. This study investigated the relationship between quadratus lumborum asymmetry and lumbar spine injury in adolescent cricket fast bowlers.Design: The study was a prospective cohort design.Method: Magnetic resonance imaging of 38 adolescent cricket fast bowlers was completed prior to a cricket season, and the cross sectional area of the quadratus lumborum muscle was measured at each lumbar spinal level. The bowlers were followed through the cricket season and those that reported lumbar spine injuries were investigated and classified as either having a soft tissue injury or a bone stress injury. The pre-season cross sectional area of quadratus lumborum was associated with injury status at the conclusion of the cricket season.Results: Twenty-one percent of the cohort developed lumbar bone stress injuries during the cricket season. There was no significant relationship between lumbar spine injury and quadratus lumborum cross sectional area.Conclusions: A high incidence of lumbar bone stress injuries was demonstrated in adolescent fast bowlers. Unlike previous research that demonstrated a link between lumbar spine bone stress injuries and quadratus lumborum cross-sectional area, no such relationship was found.

Potential moderators and mediators of intervention effects in an obesity prevention program for adolescent boys from disadvantaged schools - Corrected Proof

David R. Lubans, Philip J. Morgan, Robin Callister — 2012-05-10

Abstract: Objectives: The purpose of this study was to explore potential moderators and mediators of intervention effects in the Physical Activity Leaders (PALs) obesity prevention program for adolescent boys from disadvantaged secondary schools.Design: Group randomized controlled trial.Methods: One hundred adolescent boys (mean age=14.3 (0.6) years) from four schools were randomized to the PALs intervention or a control group for the 6-month study period. The primary outcome was change in BMI and secondary outcomes were physical activity assessed using pedometers and constructs from Social Cognitive Theory (SCT) assessed using a questionnaire.Results: Moderation analyses revealed a significant weight status interaction for BMI (p=0.04), indicating stronger intervention effects for youth classified as overweight/obese at baseline. The intervention had a significant effect on resistance training self-efficacy (p<0.001), but none of the SCT constructs satisfied the criteria for mediation. The number of intervention sessions attended was associated with changes in BMI (r=−0.38, p=0.001), resistance training self-efficacy (r=0.42, p<0.001) and physical activity behavioral strategies (r=0.26, p=0.018). Changes in BMI were also associated with changes in resistance training self-efficacy (r=−0.21, p=0.06) and physical activity behavioral strategies (r=−0.29, p=0.009).Conclusions: A school-based intervention incorporating student leadership increased adolescent boys’ resistance training self-efficacy, but changes in physical activity were not detected and none of the SCT constructs satisfied the criteria for mediation. Baseline weight status was a moderator of intervention effect with the strongest intervention effects observed among overweight and obese adolescent boys.

Knee and ankle osteoarthritis in former elite soccer players: A systematic review of the recent literature - Corrected Proof

2012-05-10

Abstract: Objectives: To investigate the prevalence of knee and/or ankle osteoarthritis in former elite soccer player.Design: Systematic review.Methods: Medline, Embase and SPORTDiscus (2000 to January 2012) were used. To be included, studies were required to be a primary study, written in English, Dutch, French or German, former elite soccer players had to be the study population, and presenting knee or ankle OA had to be the outcome measure.Results: The search strategy resulted in four studies. Two studies, evaluated as having a high methodological quality, found a prevalence rate of knee OA between 60 and 80%. Both studies used radiographic examination as their measurement instrument to diagnose OA; the presence of ankle OA was not determined. The other two studies, evaluated as having a moderate methodological quality, found a prevalence rate of knee OA between 40 and 46% and a prevalence rate of ankle OA between 12 and 17%. These studies used a questionnaire as their measurement instrument wherein players were asked if they had ever been diagnosed with OA by a medical specialist.Conclusions: The prevalence of knee and ankle OA in former elite soccer players can be considered high compared to the general population and to other occupations. To identify players at risk for OA, a health surveillance program should be implemented in elite soccer as a preventive measure. Further research should be conducted to determine if the risk of developing OA varies among different subgroups of elite soccer players and what the consequences of this high OA prevalence are.

Rating of perceived exertion during cycling is associated with subsequent running economy in triathletes - Corrected Proof

Jason Bonacci, Veronica Vleck, Philo U. Saunders, Peter Blanch, Bill Vicenzino — 2012-05-10

Abstract: Objectives: To determine which commonly measured variables of cycling intensity are related to subsequent running economy in triathletes.Design: Cross-sectional laboratory study.Methods: Running economy was compared between a control run (no preceding cycle) and a run performed after a 45min high-intensity cycle in eighteen triathletes. Power output, heart rate, rating of perceived exertion (RPE) and blood lactate concentration were monitored throughout the cycle. The relationship between measures of cycle intensity and the change in running economy was evaluated using Pearson's product moment correlation. Changes in running economy were also interpreted using the smallest worthwhile change (>2.4%) and grouped accordingly (i.e. impaired, no change, or improved running economy).Results: Triathletes’ RPE at the end of the cycling bout was significantly associated with the change in running economy after cycling (r=0.57, p=0.01). Average RPE of the cycle bout and RPE at the end of the cycling bout were significantly different between groups, with higher RPE scores being related to impairments in running economy (p=0.04 and p=0.02 respectively).Conclusions: RPE during cycling is associated with subsequent running economy in triathletes. RPE is a simple, cost-effective measure that triathletes and their coaches can use in competition and training to control cycling intensity without the need for specialist equipment such as crank systems or blood analysers.

Dorsiflexion and dynamic postural control deficits are present in those with chronic ankle instability - Corrected Proof

2012-05-10

Abstract: Objectives: To determine if differences in weight-bearing ankle dorsiflexion range of motion (DFROM) and Star Excursion Balance Test (SEBT) reach distances were present between participants with chronic ankle instability (CAI) and healthy individuals. A secondary objective was to re-examine the relationship between these measures in participants with and without CAI.Design: Case–control.Methods: Thirty participants with CAI were matched to 30 healthy participants. All participants performed maximum reach in the anterior, posteromedial and posterolateral directions of the SEBT; as well as, the Weight-Bearing Lunge Test (WBLT) to measure DFROM. Dependent variables included maximal DFROM (cm) and normalized SEBT reach distances (%). Independent t-tests were used for group comparisons (a priori p≤0.05). Simple-linear regression examined the relationship between the WBLT and each SEBT direction.Results: Significant differences were detected between groups for the WBLT (CAI: 10.73±3.44cm, healthy: 12.47±2.51cm; p=0.03) and anterior reach distance (CAI: 76.05±6.25%, healthy: 80.12±5.88%; p=0.01). No differences were identified in posteromedial or posterolateral (ps>0.70) reach. The WBLT had a significant moderate correlation to anterior reach in both groups (ps<0.05) but was not significantly correlated to posteromedial or posterolateral reach distance (ps>0.70).Conclusions: The results indicate that participants with CAI demonstrated less DFROM and anterior SEBT reach distance compared to health controls. Additionally, both groups demonstrated similar correlations between WBLT and SEBT performance. These findings suggest that participants with CAI have alterations in ankle motion which may negatively influence dynamic postural control; however, the relationship between WBLT and SEBT performance is consistent in those with and without CAI.

Resistance training to improve power and sports performance in adolescent athletes: A systematic review and meta-analysis - Corrected Proof

Simon K. Harries, David R. Lubans, Robin Callister — 2012-04-27

Abstract: Objective: Resistance training in untrained adolescents can positively effect health-related fitness as well as improve muscular power and sports performance. The impact of resistance training on adolescent athletes is less clear. The purpose of this review is to determine the effectiveness of resistance training programs on muscular power and sports performance in adolescent athletes.Design: Systematic review and meta-analysis of previously published studies investigating resistance training in adolescent athlete populations.Methods: A systematic search of Medline, Embase, and SPORTDiscus databases was conducted on 21st March 2011 to identify studies evaluating resistance training programs on power and sports performance in adolescent athletes.Results: Thirty-four studies were identified. All but two of the studies reported at least one statistically significant improvement in an alactic muscular power outcome. The most common indicators of alactic power were vertical jump (25 studies) and sprint running (13 studies) performance. Fourteen studies provided data to allow for pooling of results in a meta-analysis. A positive effect was detected for resistance training programs on vertical jump performance (mean difference 3.08 [95% CI 1.65, 4.51], Z=4.23 [P<0.0001]).Conclusion: There is sufficient evidence to conclude that resistance-training interventions can improve muscular power in adolescent athletes. A positive effect on sports performance attributable to participation in resistance training was reported by almost half the included studies, however limited objective evidence to support these claims was found. Improvements in motor performance skills, such as jumping, are widely stated as indicators of improvements in sporting performance.

An integrative test of agility, speed and skill in soccer: Effects of exercise - Corrected Proof

William Bullock, Derek Panchuk, James Broatch, Ryan Christian, Nigel K. Stepto — 2012-04-23

Abstract: Objectives: The aim of this study was to evaluate the effect of 45min of soccer-specific exercise in the reactive motor skills test (RMST); a novel test which measures sprint, passing and reactive agility (RAT) performance.Design: A repeated-measures design was used to collect performance data.Method: Forty-two high-level amateur male soccer players (age 18.5±3.5years) were recruited. Participants were familiarised with the RMST prior to initial testing. Participants undertook 10 repetitions of the RMST before and after 45min of soccer-specific exercise using the Loughborough Intermittent Shuttle Test. Eighteen of these participants repeated the RMST for test re-test reliability determination. Paired t-tests and effect size statistics were used to determine the effect of 45min of intermittent exercise on RMST performance. Reliability was assessed using the standard error of measurement.Results: The exercise protocol resulted in moderate decreases of sprint (3.0±0.9%, mean±SD; 1.030±0.09 ES±90% Confidence Intervals; p<0.00001) and RAT performance (1.5±1.1%; 1.015±0.011; p<0.05), but improved passing task time (−2.7±1.2%; 0.973±0.012; p<0.001) and passing accuracy (3.6±3.3%; 1.036±0.33). Change in total test time was trivial. The test-retest coefficient of variation for the test was 2.4±0.8%.Conclusions: Soccer-specific exercise decreased sprint and reactive agility performance but improved technical skill performance on a novel, integrative and reliable test of soccer skill performance. Overall RMST performance time was largely unchanged.

Effects of passive ankle dorsiflexion stiffness on ankle mechanics during drop landings - Corrected Proof

J.W. Whitting, J.R. Steele, D.E. McGhee, B.J. Munro — 2012-04-23

Abstract: Objectives: Vertical landing tasks strain the Achilles tendon and plantar-flexors, increasing acute and overuse strain injury risk. This study aimed to determine how passive ankle dorsiflexion stiffness affected ankle mechanics during single limb drop landings at different vertical descent velocities. Design: Cross-sectional study. Methods: Passive ankle dorsiflexion stiffness and passive weight-bearing dorsiflexion range of motion (DROM) were quantified for 42 men. Participants were then grouped as having low (LPS: 0.94±0.15Nm°−1; n=16) or high (HPS: 2.05±0.36Nm°−1; n=16; p<0.001) passive ankle dorsiflexion stiffness. Three-dimensional ankle joint kinematics was quantified while participants performed drop landings onto a force platform at two vertical descent velocities (slow: 2.25±0.16ms−1; fast: 3.21±0.17ms−1). Results: Although affected by landing velocity, there were no significant effects of passive ankle dorsiflexion stiffness, nor any significant ankle dorsiflexion stiffness×vertical descent velocity interactions on any outcome variables characterising ankle mechanics during drop landings. Furthermore, there was no significant difference between the groups for passive weight-bearing DROM (LPS: 43.9±4.1°; HPS: 42.5±5.7°), indicating that the results were not confounded by between-group differences in ankle range of motion. Conclusions: Neither high nor low passive ankle dorsiflexion stiffness was found to influence ankle biomechanics during drop landings at different descent velocities. Landing strategies were moderated more by the demands of the task than by passive ankle dorsiflexion stiffness, indicating that passive ankle dorsiflexion stiffness may not affect plantar-flexor strain during a drop landing.

Assessment of leisure-time physical activity for the prediction of inflammatory status and cardiometabolic profile - Corrected Proof

2012-04-23

Abstract: Objectives: Associations of leisure-time physical activity (LTPA), commuting and total physical activity with inflammatory markers, insulin resistance and metabolic profile in individuals at high cardiometabolic risk were investigated.Design: This was a cross-sectional study.Methods: A total of 193 prediabetic adults were compared according to physical activity levels measured by the international physical activity questionnaire; p for trend and logistic regression was employed.Results: The most active subset showed lower BMI and abdominal circumference, reaching significance only for LTPA (p for trend=0.02). Lipid profile improved with increased physical activity levels. Interleukin-6 decreased with increased total physical activity and LTPA (p for trend=0.02 and 0.03, respectively), while adiponectin increased in more active subsets for LTPA (p for trend=0.03). Elevation in adjusted OR for hypercholesterolemia was significant for lower LTPA durations (p for trend=0.04). High apolipoprotein B/apolipoprotein A ratio was inversely associated with LTPA, commuting and total physical activity. Increase in adjusted OR for insulin resistance was found from the highest to the lowest category of LTPA (p for trend=0.04) but significance disappeared after adjustments for BMI and energy intake. No association of increased C-reactive protein with physical activity domains was observed.Conclusion: In general, the associations of LTPA, but not commuting or total physical activity, with markers of cardiometabolic risk reinforces the importance of initiatives to increase this domain in programs for the prevention of lifestyle-related diseases.

Sprint speed characteristics of high-level American female soccer players: Female Athletes in Motion (FAiM) Study - Corrected Proof

Jason D. Vescovi — 2012-04-19

Abstract: Objectives: Sprint speed is important in soccer and while descriptions of male players are plentiful relatively few data exist for high-level female players. The aim of this study was to determine speed characteristics of high-level American female soccer players and evaluate if speed could distinguish between players selected (n=56) and those not selected (n=84) in a professional draft.Design: A cross-sectional study design.Method: One hundred and forty women participating in a try-out for a professional soccer league had speed assessed over 35m with splits at 5, 10 and 20m. Speeds for the static start distances (5, 10, 20 and 35m) as well as for ‘flying’ splits (flying 5, 10, 25 and 30m; also first 15 and final 15m) were determined.Results: Mean speed over 5, 10, 20 and 35m was 15.1±1.1, 18.0±0.9, 21.2±0.9 and 23.4±0.9kmh−1, respectively. Mean peak speed was 27.3±1.4kmh−1 and occurred during the final 15m of the sprint (20–35m). Speed for all flying splits exceeded 21.0kmh−1, with maximum values observed in excess of 30.0kmh−1. All speeds, except for the flying 5m split, were faster in the drafted players compared to non-drafted players.Conclusions: These data indicate that elite female soccer players achieve speeds ranging between 22 and 26kmh−1 over distances of 15–20m and can reach 27kmh−1 when evaluated over 35m. Sprint speed was able to distinguish between drafted and non-drafted players.

Influence of the MCT1-T1470A polymorphism (rs1049434) on blood lactate accumulation during different circuit weight trainings in men and women - Corrected Proof

2012-04-19

Abstract: Objective: To analyze the effect of the MCT1 T1470A polymorphism (rs1049434) on venous blood lactate levels in men and women, during three different circuit weight training protocols.Design: Cross-sectional laboratory study.Methods: 14 women and 15 men, all caucasian and moderately active, performed three circuit training sessions (Weight Machine Protocol, Free Weight Protocol and Combined Protocol) at 70% of the 15 repetition maximum and 70% of the heart rate reserve, in non-consecutive days. The sessions included three sets of a circuit of eight exercises. Venous lactate measurements were obtained after each set and during the recoveries between sets (i.e. in min 3, 5, 7 and 9). One-way analysis of covariance and one-way analysis of covariance with repeated measures were used to determine differences among genotypes (AA, TA and TT) in lactate levels.Results: In men, the AA group had higher lactate values than the TT group in all the measures (p≤0.03) except for the average lactate during the Weight Machine Protocol, in which a borderline significant difference was found (p=0.07). We did not observe differences across genotypes in females.Conclusion: Our data suggest an influence of the MCT1 polymorphism on lactate transport across sarcolemma in males. Future studies on lactate transport and metabolism should take into account the gender-specific results.

The effect of ankle taping or bracing on proprioception in functional ankle instability: A systematic review and meta-analysis - Corrected Proof

Jacqueline Raymond, Leslie L. Nicholson, Claire E. Hiller, Kathryn M. Refshauge — 2012-04-18

Abstract: Objective: To determine if wearing an ankle brace or taping the ankle, compared to no brace or tape, improves proprioceptive acuity in people with a history of ankle sprain or functional ankle instability.Design: Systematic review and meta-analysis.Method: Studies using controlled, cross-over designs whereby participants who had sprained their ankle at least once or had functional ankle instability, underwent some form of proprioceptive sensation testing with and without ankle brace or tape, were included. Proprioceptive acuity was reported for the ankle tape/brace condition and the condition where no tape or brace was worn. Meta-analysis was employed to compare proprioceptive acuity with and without ankle tape/brace.Results: Eight studies were included in the review. Studies measured either sense of movement or sense of joint position. The mean differences in 19 of 32 comparisons were not significant. Of the remaining mean differences, 10 were positive, indicating better proprioceptive acuity in the taped/braced condition and 3 were negative, indicating poorer proprioceptive acuity. Overall, there was no significant effect with ankle tape/brace compared to the no tape/brace condition (mean difference: 0.08°, 95% CI: −0.39 to 0.55). This finding was consistent when the two aspects of proprioception (sense of movement or joint position) were considered separately.Conclusions: The pooled evidence suggests that using an ankle brace or ankle tape has no effect on proprioceptive acuity in participants with recurrent ankle sprain or who have functional ankle instability.

The effect of warm-up on intermittent sprint performance and selected thermoregulatory parameters - Corrected Proof

Pongson Yaicharoen, Karen Wallman, Alan Morton, David Bishop — 2012-04-13

Abstract: Objectives: To investigate the effect of various warm-up intensities based upon individual lactate thresholds on subsequent intermittent sprint performance, as well as to determine which temperature (muscle; Tmu, rectal; Tre or body; Tb) best correlated with performance (total work, work and power output of the first sprint, and % work decrement).Design: Nine male team-sport participants performed five 10-min warm-up protocols consisting of different exercise intensities on five separate occasions, separated by a week.Methods: Each warm-up protocol was followed by a 6×4-s intermittent sprint test performed on a cycle ergometer with 21-s of recovery between sprints. Tmu, Tre and Tb were monitored throughout the test.Results: There were no differences between warm-up conditions for total work (Jkg−1; P=0.442), first sprint work (Jkg−1; P=0.769), power output of the first sprint (Wkg−1; P=0.189), or % work decrement (P=0.136), respectively. Moderate to large effect sizes (>0.5; Cohen's d) suggested a tendency for improvement in every performance variable assessed following a warm-up performed at an intensity midway between lactate inflection and lactate threshold. While Tmu, Tre, Tb, heart rate, ratings of perceived exertion and plasma lactate increased significantly during the exercise protocols (P<0.05), there were no significant correlations between Tmu, Tre, and Tb assessed immediately after each warm-up condition and any performance variable assessed.Conclusions: Warm-up performed at an intensity midway between lactate inflection and lactate threshold resulted in optimal intermittent sprint performance. Significant increases in Tmu, Tre and Tb during the sprint test did not affect exercise performance between warm-up conditions.

Young and free? A study of independent mobility among urban and rural dwelling Australian children - Corrected Proof

Alison Carver, Anna F. Timperio, David A. Crawford — 2012-04-13

Abstract: Objectives: To examine urban/rural differences in children's independent mobility; associations between mobility licences and children's independent mobility; and potential correlates of mobility licences.Design: Cross-sectional study of 430 primary (48% boys; 72% urban) and 258 secondary schoolchildren (52% boys; 51.6% urban) and their parents.Methods: Parents survey reported the mobility licences they granted to their children (e.g. allowing them to cross main roads on their own), access to outdoor playspaces and mobile phone ownership. Children survey reported their independent mobility on school journeys and on weekends. Differences were examined in mobility licences and independent mobility by sex, urban/rural setting and age-group. Regression analyses examined associations between mobility licences and independent mobility; and how access to playspaces, and mobile phone ownership, were associated with mobility licences.Results: Overall, on average, boys were granted more mobility licences, than were girls, but there were no significant differences by urban/rural location. Variations in independent mobility by urban/rural locality were identified on the school journey but not on weekends. Boys attending urban primary schools had highest rates (44%) of walking/cycling independently to school; those attending rural secondary schools had the lowest (14%). Among urban boys and rural primary school-aged girls access to outdoor playspaces was associated with mobility licences. Mobile phone ownership was associated with mobility licences only among boys attending urban primary schools.Conclusions: Many Australian children in urban and rural areas lack independent mobility. Further research should examine social/physical environmental influences on parental restrictions, to inform interventions that aim to promote children's independent mobility.

Step-rate thresholds for moderate and vigorous-intensity activity in persons with Down syndrome - Corrected Proof

Stamatis Agiovlasitis, Michael W. Beets, Robert W. Motl, Bo Fernhall — 2012-04-12

Abstract: Objective: Monitoring physical activity intensity in persons with Down syndrome (DS) may be affected by an altered relationship between metabolic equivalent units (METs) and step-rate. This study examined whether the relationship between METs and step-rate is altered in persons with DS and developed step-rate thresholds for activity intensity for these persons.Design: Cross-sectional.Methods: Eighteen persons with DS (25±7years; 8 women) and 22 persons without DS (26±5years; 9 women) completed six over-ground walking trials each lasting 6min at their preferred speed and at 0.5, 0.75, 1.0, 1.25, and 1.5ms−1. METs were measured with portable spirometry and step-rate with hand-tally. Random effects models were used to predict METs from step-rate, squared step-rate, height, presence of DS, sex, and body mass index (BMI).Results: Step-rate, squared step-rate, height, and presence of DS contributed significantly to the model (SE=0.20 METs; R2=0.63); sex and BMI did not contribute. As height increased, step-rate thresholds for moderate and vigorous-intensity activity decreased. For a given height, participants with DS had lower step-rate at the moderate-intensity threshold than participants without DS. Across participant heights, the moderate-intensity cut-off ranged between 101 and 76stepsmin−1 in persons with DS and between 103 and 80stepsmin−1 in persons without DS. For persons with DS, step-rate at the vigorous-intensity threshold ranged between 136 and 126stepsmin−1.Conclusions: Persons with DS showed altered relationship between METs and step-rate and had lower step-rate thresholds for moderate-intensity activity than persons without DS.

The incidence of behaviours associated with body checking among youth ice hockey players - Corrected Proof

Simon Malenfant, Claude Goulet, Luc Nadeau, Denis Hamel, Carolyn A. Emery — 2012-04-12

Abstract: Objectives: To determine if a difference exists between the incidence and intensity of the physical contacts of Pee Wee (aged 11–12 years) ice hockey players according to whether the players participate in a league in which body checking is permitted (Calgary, Canada) compared to a league in which body checking is not permitted (Québec City, Canada).Design: Cohort study conducted in Québec City and Calgary during the 2007–2008 Pee Wee ice hockey season.Methods: Ten games were randomly selected for each city (n=20) and analysed. Games were videotaped and subsequently analysed with a validated observation system allowing quantification of the intensity of the various physical contacts. Incidence rate ratios (RR) based on multivariate Poisson regression were used to compare the physical contacts between provinces. All analyses were controlling for game period, score difference, and zone on the playing surface.Results: A total of 2418 physical contacts with the trunk and 757 other physical contacts were observed. Very light intensity trunk physical contacts were more frequent in Québec City (adjusted incidence RR [ARR]: 0.68; 95% CI: 0.48–0.97). Very high intensity trunk physical contacts were more frequent in Calgary (ARR: 12.72; 95% CI: 4.48–36.14). Hooking (ARR: 0.89; 95% CI: 0.84–0.95) and slashing (ARR: 0.91; 95% CI: 0.85–0.97) were more frequent in Québec City.Conclusion: Results suggest that players’ behaviours are different in leagues where body checking is permitted compared to leagues where it is not permitted. Policy allowing body checking in Pee Wee ice hockey increases the frequency and intensity of physical contacts.

Non-traditional wearing positions of pedometers: Validity and reliability of the Omron HJ-203-ED pedometer under controlled and free-living conditions - Corrected Proof

Katrien A. De Cocker, Jotie De Meyer, Ilse M. De Bourdeaudhuij, Greet M. Cardon — 2012-04-09

Abstract: Objectives: To test the validity and intra-instrument reliability of the HJ-203 Omron pedometer when worn in different positions, under controlled and free-living conditions.Design: Cross-sectional.Methods: Forty healthy adults (20 men, 29.5±7.7 years) participated in three controlled tests, i.e. 20 step test, stair climbing (up and down), and treadmill walking (five bouts at different speeds). All participants wore a HJ-203 pedometer in the pants pocket, in a carrier bag, and around the neck. Fifty-four adults (23 men, 33.9±11.1 years) participated in a free-living conditions test, wearing a HJ-203 in the pants pocket and around the neck during one day.Results: During controlled tests, absolute percentage error ranged between 0.1% and 14.0%. Accuracy was influenced by wearing position (p<0.001), walking speed (p<0.001), and wearing position×walking speed (p=0.001). Accuracy was poor for pedometers worn in the pants pocket, especially at slower speeds; and best when worn around the neck. During free-living conditions, APE ranged between 30.7% and 36.9% and did not differ statistically between pants pocket and neck position. Intra-instrument reliability varied for controlled tests (ICC=0.14–0.96) and was acceptable during free-living conditions (ICC=0.94).Conclusion: The HJ-203 Omron pedometer showed acceptable accuracy for all wearing positions during stairs walking and treadmill walking at higher speeds; but limited accuracy during free-living conditions when worn at non-traditional wearing positions (necklace and pants pocket). Reliability was acceptable during treadmill walking at higher speeds and free-living conditions.

Promoting lower extremity strength in elite volleyball players: Effects of two combined training methods - Corrected Proof

Mathias Voelzke, Norman Stutzig, Hans-Alexander Thorhauer, Urs Granacher — 2012-04-09

Abstract: Objectives: To compare the impact of short term training with resistance plus plyometric training (RT+P) or electromyostimulation plus plyometric training (EMS+P) on explosive force production in elite volleyball players.Design: Sixteen elite volleyball players of the first German division participated in a training study.Methods: The participants were randomly assigned to either the RT+P training group (n=8) or the EMS+P training group (n=8). Both groups participated in a 5-week lower extremity exercise program. Pre and post tests included squat jumps (SJ), countermovement jumps (CMJ), and drop jumps (DJ) on a force plate. The three-step reach height (RH) was assessed using a custom-made vertec apparatus. Fifteen m straight and lateral sprint (S15s and S15l) were assessed using photoelectric cells with interims at 5m and 10m.Results: RT+P training resulted in significant improvements in SJ (+2.3%) and RH (+0.4%) performance. The EMS+P training group showed significant increases in performance of CMJ (+3.8%), DJ (+6.4%), RH (+1.6%), S15l (−3.8%) and after 5m and 10m of the S15s (−2.6%; −0.5%). The comparison of training-induced changes between the two intervention groups revealed significant differences for the SJ (p=0.023) in favor of RT+P and for the S15s after 5m (p=0.006) in favor of EMS+P.Conclusions: The results indicate that RT+P training is effective in promoting jump performances and EMS+P training increases jump, speed and agility performances of elite volleyball players.

The HAPPY Study: Development and reliability of a parent survey to assess correlates of preschool children's physical activity - Corrected Proof

Trina Hinkley, Jo Salmon, Anthony D. Okely, David Crawford, Kylie Hesketh — 2012-04-05

Abstract: Correlates of preschool children's physical activity across all domains of the social ecological model have previously been reported in the literature. However, there is a scarcity of reliable instruments designed to capture such correlates in preschool-aged children.Objective: This study reports the development, and assessment of the test–retest and internal reliability of a comprehensive proxy survey instrument designed to measure correlates of preschool children's physical activity across the three domains of the social ecological model.Design: Study one included data from 47 parents of preschool aged (3–5 years) children who completed the survey on two occasions. Study two included data from 943 participants who completed the survey as part of the larger Healthy Active Preschool Years Study.Methods: A comprehensive search of the literature and a series of focus groups were used to identify potential correlates for inclusion in the survey. Study one investigated the test–retest reliability of the survey; study two investigated internal reliability. Test–retest reliability was assessed using Kappa statistics and percent agreement for categorical variables, and intraclass correlation for continuous variables. Internal reliability was assessed using Cronbach's alpha.Results: In total, 230 items, summed and composite scores were assessed. Of those items, 190 (83%) showed acceptable reliability. The majority of items in each domain of the social ecological model – individual (75%), social (81%) and physical environment (90%) – showed acceptable reliability.Conclusion: The Healthy Active Preschool Years parent proxy survey shows good reliability and is appropriate for use with the target population. Future studies should investigate validity of the constructs in the survey.

Correlation of isokinetic and novel hand-held dynamometry measures of knee flexion and extension strength testing - Corrected Proof

2012-03-16

Abstract: Objectives: Describe inter-rater reliability of, and correlations between a novel method of isometric knee extension and flexion and eccentric knee flexion strength using hand-held dynamometry and isokinetic testing for flexion/extension in the knees of athletic participants. Document strength data normalized to the individual's limb muscle mass.Design: Observational and reliability study.Methods: Inter-rater reliability for each of the hand-held dynamometry measures was established in both legs of 10 volunteers (6 male). During routine annual screening, 216 male professional football (soccer) players were examined using these same measures in addition to performing an isokinetic evaluation of knee flexion and extension strength. Intra-class correlation coefficients for inter-rater reliability, Pearson r correlations between hand-held dynamometry and isokinetic dynamometry were calculated. Peak torque, peak torque normalized to: body weight; lean body mass; and lean limb mass were documented.Results: Excellent inter-rater reliability was demonstrated with intra-class correlation(2,1) values of 0.90, 0.91, and 0.96, for the eccentric hamstrings, isometric hamstrings, and isometric quadriceps measures respectively. Medium to high correlations (r=0.322–0.617) which were all significant (p<0.001) were found for the comparisons between the hand-held dynamometry and isokinetic measures.Conclusions: We present 3 novel and reliable methods of examining knee flexion and extension strength using hand-held dynamometry which require less skill and strength on the part of the examiner than previous measures. Correlations between these measures and isokinetic dynamometry are documented. The hand-held dynamometry examinations took less than 4min per player to conduct and may be useful in clinical practice where isokinetic examination can be difficult to implement.

The contribution of situational probability information to anticipatory skill - Corrected Proof

Damian Farrow, Machar Reid — 2012-03-14

Abstract: Objectives: To determine the contribution of situational probability information to the anticipatory responses of skilled tennis players representative of two different stages of development.Design: Participants were required to predict the location of tennis serves presented to them on a plasma touchscreen from the perspective of the receiver.Methods: Serves were sequenced into a series of games and sets with a score presented before each point, typical of a game of tennis. The game score was manipulated to provide advance probability information. The location of the serve for the first point of each game was always directed to the same location. A total of 12 service games consisting of 96 points were presented with interest in whether players would detect the relationship between the game score and resultant serve location.Results: A 2×12 (age×service game) ANOVA with repeated measures on the second factor revealed a significant age by service game interaction for response time (F11,297=3.86, p<0.05, ηp2=.12). The older players picked up the occurrence of the first point service pattern after the ninth service game whereas the younger, players did not. There were no significant response accuracy differences between the groups in relation to the first point.Conclusions: The findings highlight the important role of situational probability information, in addition to movement kinematics, for successful anticipatory performance and suggest that the pick-up of such information is not utilised by younger players.

Influence of training years on upper-body strength and power changes during the competitive season for professional Australian rules football players - Corrected Proof

Con Hrysomallis, David Buttifant — 2012-03-07

Abstract: Objectives: To determine if upper-body strength or power changes during the competitive season for elite Australian rules footballers and what influence the number of training years has on any changes.Design: Repeated measures.Methods: Twenty elite Australian rules footballers were assessed at preseason, in-season and postseason. Strength was assessed by the 1 Repetition Maximum bench press and power was assessed by bench press throws. Athletes’ results were analysed as a whole group as well as being divided into two groups according to training years: less than 3 years training and greater than 3 years training. All athletes performed the same resistance training program.Results: There were no significant differences in height, body mass, or skinfold measurements between the two age groups. As a whole group, there was no significant change in 1RM bench press. There was a small but significant decrease in mean bench throw power in-season (525W) compared to preseason (542W) and it then increased at postseason (541W). Within group analysis revealed the in-season decrease in upper-body power was largely pertaining to the younger athletes. The older group maintained their upper body power levels while the younger group decreased power in-season (4%) before regaining it at season's end.Conclusion: Older footballers were able to maintain their upper body power while the younger footballers had a small but significant decrease in-season before regaining it by season's end. The overall volume of training and playing appears to have affected the younger athletes’ power more than older athletes. Both age groups maintained upper body strength.

Can we teach moderate intensity activity? Adult perception of moderate intensity walking - Corrected Proof

Rebecca Braham, Michael Rosenberg, Brianna Begley — 2012-03-02

Abstract: Objective: To investigate how people determine the intensity of their physical activity, respond to instruction, and their understanding of moderate intensity walking.Design: Experimental.Methods: Forty nine regular walkers had their walking speed, heart rate and rate of perceived exertion measured during their normal walking behaviour, when instructed to walk at a moderate intensity, and after provision of feedback on how to meet moderate intensity walking.Results: Although moderate intensity walking was generally perceived as too low to be beneficial, walking speed was the best variable matched across all experiments for moderate intensity (83.7%, 67.3% and 93.9%), followed by heart rate, with a large proportion of participants responding favourably to instruction relating to heart rate and speed to meet moderate intensity walking. Rate of perceived exertion was a poor reflector of walking intensity.Conclusion: Most participants naturally selected a walking intensity that elicits moderate intensity and when instructed to walk at moderate intensity, the intensity is more vigorous. Attempting to match speed and heart rate limits for moderate intensity reduced the intensity perceived by participants.

Effect of increasing the choice of active options on children's physically active play - Corrected Proof

2012-02-20

Abstract: Objectives: To determine whether increasing the choice of physical activity options increases the duration and intensity of children's physically active play.Design: This cross-sectional laboratory study included gender (male and female) and choice group [single toy (no choice), three toys (low choice), five toys (high choice)] as between participant factors.Methods: Boys and girls (n=36, 8–12y) were stratified, randomly assigned to a choice group that always provided access to each participant's most liked active toy(s), and allowed 60min of free time. The same sedentary alternatives were freely available to all participants. Physical activity outcomes were measured by accelerometry, heart rate, and direct observation.Results: The number of active toys the children played with increased (p<0.001) across each choice group. Minutes spent in MPA were greater in the low choice (p<0.05) and high choice (p<0.02) groups than the no choice group. Active playtime was greater (p<0.01) in the low choice (79%) and high choice (95%) groups compared to the no choice group. Girls in the low and high choice groups had greater (p<0.05) percent heart rate reserve when compared to girls in the no choice group. There was no difference in the boys’ percent heart rate reserve between the no choice, low choice and high choice groups.Conclusions: Increasing the choice of active toys increases both the duration and intensity of physically active play, especially in girls.

Metastability and emergent performance of dynamic interceptive actions - Corrected Proof

Ross A. Pinder, Keith Davids, Ian Renshaw — 2012-02-13

Abstract: Objectives: Adaptive patterning of human movement is context specific and dependent on interacting constraints of the performer–environment relationship. Flexibility of skilled behaviour is predicated on the capacity of performers to move between different states of movement organisation to satisfy dynamic task constraints, previously demonstrated in studies of visual perception, bimanual coordination, and an interceptive combat task. Metastability is a movement system property that helps performers to remain in a state of relative coordination with their performance environments, poised between multiple co-existing states (stable and distinct movement patterns or responses). The aim of this study was to examine whether metastability could be exploited in externally paced interceptive actions in fast ball sports, such as cricket.Design: Here we report data on metastability in performance of multi-articular hitting actions by skilled junior cricket batters (n=5).Methods: Participants’ batting actions (key movement timings and performance outcomes) were analysed in four distinct performance regions varied by ball pitching (bounce) location.Results: Results demonstrated that, at a pre-determined distance to the ball, participants were forced into a meta-stable region of performance where rich and varied patterns of functional movement behaviours emerged. Participants adapted the organisation of responses, resulting in higher levels of variability in movement timing in this performance region, without detrimental effects on the quality of interceptive performance outcomes.Conclusions: Findings provide evidence for the emergence of metastability in a dynamic interceptive action in cricket batting. Flexibility and diversity of movement responses were optimised using experiential knowledge and careful manipulation of key task constraints of the specific sport context.

Everything you wanted to know about selecting the “right” Actigraph accelerometer cut-points for youth, but…: A systematic review - Corrected Proof

Youngwon Kim, Michael W. Beets, Gregory J. Welk — 2012-02-06

Abstract: Objectives: The purpose of this study is to provide an overview of the evidence on the calibration of ActiGraph accelerometers to quantify moderate-to-vigorous physical activity (MVPA) for youth through the use of cut-points and describe the independent validation studies comparing the accuracy of the developed cut-points to a criterion measure.Design: A systematic review.Method: Studies were identified that: (a) developed ActiGraph accelerometer cut-points for children and youth (calibration study); or (b) performed an independent validation of already established cut-points (validation study). Both calibration studies and independent validation studies were retrieved through a systematic search of online databases. According to proposed guidelines for designing accelerometer calibration studies, each calibration study was evaluated on the following criteria: quality of a criterion measure employed; epoch length; inclusion of a variety of activities; and sample size.Results: A total of 11 calibration studies were identified. Two studies met all four criteria for a calibration study. A total of 4 independent validation studies were identified. Three of them reported that no cut-points accurately classified moderate-to-vigorous physical activity (MVPA) across all ranges of physical activity intensity levels in comparison to a criterion measure. The fourth study reported two sets of cut-points that under laboratory conditions, accurately classified moderate-to-vigorous physical activity (MVPA) compared to indirect calorimetry.Conclusions: Limited evidence suggests that two sets of cut-points correctly classify ActiGraph counts into moderate-to-vigorous physical activity (MVPA). However, limitations with calibration and validation studies indicate greater efforts aimed at designing high quality studies are needed to confirm these findings.

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.

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.

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.

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.