Journal of Science and Medicine in Sport - Articles in Press

Comparison of offensive agility techniques in Australian Rules football - Corrected Proof

Ryan J. Bradshaw, Warren B. Young, Andrew Russell, Peter Burge — 2010-07-27

Abstract: Agility skill is important in Australian Rules football (ARF) as it enables an attacking player to successfully evade an opponent. To date, no research has examined offensive agility techniques in ARF. There were two purposes of this study: first, to compare the change of direction (COD) speed of three offensive agility techniques, and second, compare the reaction speed and accuracy when observing the same techniques from a defensive perspective. The techniques included the side-step, shuffle, and split-step. Seventeen players from an Australian Football League club were required to perform four trials of each technique. COD speed was expressed as a total time, and divided into entry, foot plant preparation, and exit time. In addition, nineteen players from the same club were assessed on a video-based reaction test. Players were required to respond by depressing a thumb switch to indicate whether the player on screen changed direction to the left or right. From an offensive perspective, the split-step foot plant preparation time (0.66s) was significantly slower than both the side-step (0.7s) and shuffle (0.75s) (p<0.05), but there were no significant differences in entry and exit times between techniques. From a defensive perspective, the players were significantly slower and less accurate when reacting to the player in the video performing the split-step (0.19s) and shuffle (0.15s) compared to the side-step (0.12s) (p<0.05). In a one-on-one situation in ARF, the split-step may be the most effective offensive technique. Not only was it slower and less accurate to react to, the exit speed following the change in direction was not significantly slower than the side-step. However, a performer would need to consider the cost of a slower foot plant preparation time versus the potential to deceive an opponent when under time stress.

Relationship between plantar pressures, physical activity and sedentariness among preschool children - Corrected Proof

2010-07-12

Abstract: It has been speculated that high plantar pressures might cause foot pain and discomfort which, in turn, may discourage children from being physically active and result in them spending more time in sedentary activities. The purpose of this study was to determine whether plantar pressure distributions generated by preschool children were correlated with objectively measured time spent in physical activity and sedentary behaviour. Dynamic plantar pressures were measured for 33 preschool children (age=4.3±0.6 years; height=1.06±0.1m; mass=18.4±2.9kg; 17 boys) as they walked across an emed AT-4 pressure platform. Physical activity was objectively assessed using MTI ActiGraph accelerometers. Total physical activity (counts per minute), percentage of time spent in moderate-to-vigorous physical activity (MVPA), light activity and sedentary behaviour were then calculated. Peak pressures across the heel were found to significantly correlate with total physical activity (r=−0.53; p=0.03) and time in MVPA (r=−0.47; p=0.05) in boys. Similarly, the correlation data suggested that girls who generated higher peak pressures in the toe region spent more time in sedentary behaviour (r=0.53; p=0.04). As high plantar pressures appear to be a potential negative correlate of physical activity and sedentary behaviour, it is recommended that further research be conducted to design, test and evaluate the potential of interventions to reduce plantar pressures in inactive children so they can enjoy the benefits associated with participating in a more active lifestyle.

Variation in the PPARα gene in Polish rowers - Corrected Proof

Agnieszka Maciejewska, Marek Sawczuk, Paweł Cięszczyk — 2010-07-12

Abstract: The PPARα gene code for transcriptional factor that is a central regulator of expression of genes involved in fatty acid metabolism and is believed to be a one of the genes of health-related fitness phenotype. The aim of this study was to examine the hypothesis that G allele of PPARα intron 7 G/C polymorphic site (rs4253778) is positively associated with endurance athlete status. PPARα genotypes were analyzed for 55 Polish rowers: 30 elite rowers representing the highest national competitive standard and 25 non-elite rowers representing regional standard. Control samples were prepared from 115 unrelated volunteers. The G/C polymorphic site in PPARα intron 7 was scanned by using PCR-RFLP protocol with TaqI enzyme. The allele frequency and genotype distribution was determined by gene and genotype counting. Significance was assessed by χ2 analysis. The obtained results revealed that frequency of the PPARα GG genotype (87% vs. 63%; p=0.04) and G allele (93% vs. 79%; p=0.009) were significantly higher in the elite group of the Polish rowers compared to sedentary controls. These data confirm that GG genotype is more prevalent in the group of endurance athletes therefore G allele may be considered as one of the endurance-related allele.

Measuring children's self-reported sport participation, risk perception and injury history: Development and validation of a survey instrument - Corrected Proof

Emma J. Siesmaa, Jennifer D. Blitvich, Peta E. White, Caroline F. Finch — 2010-07-12

Abstract: Despite the health benefits associated with children's sport participation, the occurrence of injury in this context is common. The extent to which sport injuries impact children's ongoing involvement in sport is largely unknown. Surveys have been shown to be useful for collecting children's injury and sport participation data; however, there are currently no published instruments which investigate the impact of injury on children's sport participation. This study describes the processes undertaken to assess the validity of two survey instruments for collecting self-reported information about child cricket and netball related participation, injury history and injury risk perceptions, as well as the reliability of the cricket-specific version. Face and content validity were assessed through expert feedback from primary and secondary level teachers and from representatives of peak sporting bodies for cricket and netball. Test–retest reliability was measured using a sample of 59 child cricketers who completed the survey on two occasions, 3–4 weeks apart. Based on expert feedback relating to face and content validity, modification and/or deletion of some survey items was undertaken. Survey items with low test–retest reliability (κ≤0.40) were modified or deleted, items with moderate reliability (κ=0.41–0.60) were modified slightly and items with higher reliability (κ≥0.61) were retained, with some undergoing minor modifications. This is the first survey of its kind which has been successfully administered to cricketers aged 10–16 years to collect information about injury risk perceptions and intentions for continued sport participation. Implications for its generalisation to other child sport participants are discussed.

Understanding perceptions of injury risk associated with playing junior cricket - Corrected Proof

Peta E. White, Caroline F. Finch, Rebecca Dennis, Emma Siesmaa — 2010-07-12

Abstract: Preventing sports injuries in children is important, but there is limited information about children's perceptions of injury risk or their injury beliefs and attitudes. This study investigated injury risk perceptions in a sample of junior sports participants across different age levels of play. Junior cricket players (n=284, aged 8–16) completed a survey about their injury risk perceptions. Survey questions asked about players’ perceived injury risk to themselves compared to cricketers in general, as well as their perceived injury risk across different playing position, ground condition, and protective equipment use scenarios. Chi-square analysis found that risk perceptions were significantly higher in U12 and U14 players for both batting and fielding compared to U16 players and that U16 players had a higher risk perception associated with bowling. Players tended to see themselves as less likely to be injured than cricketers in general and perceived there to be a high risk of injury when fielding close to the batter and a comparatively low risk of injury when fielding in the outfield. Junior players also perceived there to be a high injury risk associated with playing on hard and bumpy grounds. Despite their relatively accurate perceptions of risk and appreciation for the importance of protective equipment, junior players need continual reminding of the importance of safety strategies by coaches and others. Coaches need to inform players that fielding injuries can occur anywhere on the ground, and include skills practice accordingly.

Health promotion in sport: An analysis of peak sporting organisations’ health policies - Corrected Proof

2010-07-12

Community settings have been identified as a key context for achieving health promotion objectives. In particular, the Ottawa Charter highlights the importance of settings in health promotion, whereby “health is created and lived by people within the settings of their everyday life; where they learn, work, play and love”. Sports clubs have been proposed as providing an opportunity to embed health promotion into everyday activities.

Comparison of body composition with bioelectric impedance (BIA) and dual energy X-ray absorptiometry (DEXA) among Singapore Chinese - Corrected Proof

2010-07-09

Abstract: The purpose of the study was to determine the agreement of bioelectric impedance (BIA) with dual energy X-ray absorptiometry (DEXA) among Singapore Chinese adults. Hundred subjects [63 healthy males (age: 25.2±0.5 yrs; weight: 69.7±1.9kg; BMI: 22.8±0.4kgm−2) and 37 females (age: 22.9±0.3 yrs; weight: 51.8±0.8kg; BMI: 20.2±0.4kgm−2)] were selected and body fat percentage (%BF) was measured by DEXA and BIA. Paired t test and coefficient of correlation statistics were utilized to compare the relationship between %BFBIA and %BFDEXA. Bland and Altman plot was employed to investigate the agreement of %BFBIA with %BFDEXA. The limits of agreement between different methods were defined as mean (M; bias)±1.96SD of the difference between the methods (95% confidence interval; CI). %BFBIA, when compared to %BFDEXA, revealed non-significant underestimation of %BF in females (24.1%<24.4%, p>0.05) and significant overestimation in males (15.5%<17.7%, p<0.01). There was good absolute agreement between %BFBIA and %BFDEXA among the whole cohort (1.3±6.9%) as well as among both genders (male: 2.2±6.7%, female: −0.3±6.1%) due to small mean differences between both methods. However, wider limits of agreement were revealed for %BFBIA among whole cohort and as well as on gender basis. The results indicate a good agreement between BIA and DEXA in measuring %BF among Singapore Chinese adults, but may not be a suitable method of measuring %BF for clinical purposes among this population due to wider limits of agreement.

The epidemiology of anabolic–androgenic steroid use among Australian secondary school students - Corrected Proof

Matthew Dunn, Victoria White — 2010-07-09

Abstract: There is evidence to suggest that the prevalence of anabolic–androgenic steroids (AAS) is higher among young people than the general population. The purpose of the current study was to examine the proportion of students who reported lifetime and past-year AAS use, explore other drug use among those who reported AAS use, and investigate demographic correlates of AAS use. Data was taken from a cross-sectional survey of a representative sample of Australian secondary students. A stratified two-stage probability sampling methodology was employed and schools were randomly sampled from each Australian State and Territory. A total of 376 schools participated in the survey. Lifetime AAS use was reported by 2.4% of 12–17-year-old students; use was more common among 12–15-year olds then 16–17-year olds. Regardless of age, being male, speaking a language other than English at home, not be at school on the previous school day, and rating own scholastic ability as below average were all associated with a greater likelihood of using AAS in their lifetime and in the past year. Those who reported AAS use also reported the use of a range of other substances, suggesting that AAS use may be part of a broader experimentation with substances. Interventions towards these groups regarding AAS may best be placed within a larger substance use intervention rather than being AAS-specific. In light of the low levels of AAS use among this group, more detailed research into AAS use among adolescent sporting groups may be warranted.

Trends in hospitalised sport/leisure injuries in New South Wales, Australia—Implications for the targetting of population-focussed preventive sports medicine efforts - Corrected Proof

Caroline F. Finch, Rebecca Mitchell, Soufiane Boufous — 2010-07-09

Abstract: Sport/leisure injuries are a population health issue in Australia. Over 2003–2004 to 2007–2008, the rate of sport/leisure injury NSW hospitalisations was 195.5/100,000 residents. Males and children/young people had consistently highest rates of hospitalisation. There was no significant decline in rates over this period and no change in the profiles of the types of sport/leisure injuries. The extent to which effective preventive programs have been developed and implemented needs to be determined as current programs do not seem to be impacting on hospitalisation rates. Medical/health promotion agencies and sports bodies need to jointly formulate and implement policies to reduce sport/leisure injuries. This is one of the most significant challenges facing sports medicine professionals today.

Impact of scoring algorithm on physical activity prevalence estimates in Australian adults - Corrected Proof

Nicole M. Mealing, Heather R. Bowles, Dafna Merom, Adrian Bauman — 2010-07-01

Abstract: Public health recommendations for physical activity are operationalised by defining thresholds for frequency (sessions/week), duration (min/week), or volume (MET-min/week). This study compared estimates of meeting physical activity recommendations when scoring algorithms varied in specifications for frequency and duration but were comparable in volume. Data were obtained from 13,105 Australian adult respondents to the 2006 Exercise, Recreation and Sport Survey (ERASS). Prevalence estimates were calculated using algorithms defined by (i) frequency only (≥5 sessions/week); (ii) duration only (≥150min/week); (iii) duration only when minutes of vigorous activity were weighted by 2 (≥150weighted-min/week); (iv) frequency and duration (≥5 sessions/week, ≥150min/week); (v) volume only (≥600MET-min/week); and (vi) volume and frequency (≥600MET-min/week, ≥5 sessions/week). The proportion of adults who met recommendations operationalised without a frequency requirement was twice the proportions obtained for algorithms with frequency requirements. Volume or duration-based algorithms yielded higher estimates for men than women, and for the younger age groups (<35 years) than the older groups, with the opposite observation for frequency-based algorithms. Consistent for all algorithms, people classified at the highest educational attainment had the highest prevalence of meeting recommendations. Agreement in achieving 600MET-min/week when activities were categorised using activity-specific MET values versus median MET values was 98.3%. Prevalence rates based on 600MET-min/week were similar to 150weighted-min/week. In conclusion, varying frequency and duration requirements of scoring algorithms can yield different population estimates and patterns by population subgroup of physical activity for a health benefit.

Soccer-specific accuracy and validity of the local position measurement (LPM) system - Corrected Proof

Wouter G.P. Frencken, Koen A.P.M. Lemmink, Nico J. Delleman — 2010-07-01

Abstract: Limited data is available on accuracy and validity of video-based, GPS and electronic tracking systems, particularly with reference to curved courses and short high intensity running activities. The main goal of this study was to assess soccer-specific accuracy and validity of the radio-frequency based local position measurement (LPM) system (1000Hz) for measuring distance and speed during walking and sprinting. Three males walked and sprinted 4 soccer-specific courses 10 times each. Distance and speed recorded by LPM were compared to actual distance and speed measured by measuring tape and timing gates. In addition, accuracy was assessed. The static accuracy (SD of the mean) is 1cm for devices put on the pitch and 2–3cm when worn by participants. LPM underestimates actual distance (mean difference at most −1.6%). Coefficient of variation becomes larger at higher speed and increased turning angle. With regard to speed, validity correlations are high (range: 0.71–0.97). The LPM speed is significantly and systematically lower, although absolute and relative differences are small, between −0.1kmh−1 (−1.3%) and −0.6kmh−1 (−3.9%). The typical error of the estimate increases with increased speed, but does not increase with increased turning angle. Because the reported differences are small, we conclude that the LPM-system produces highly accurate position and speed data in static and dynamic conditions and is a valid tool for player tracking in soccer and ball team sports in general.

Gender differences in personal, social and environmental influences on active travel to and from school for Australian adolescents - Corrected Proof

Eva Leslie, Peter Kremer, John W. Toumbourou, Joanne W. Williams — 2010-07-01

Abstract: Active travel (walking or cycling for transport) is an important contributor to adolescents overall physical activity (PA). This study examines associations between personal, social and environmental variables and active travel to and from school using data from a large observational study to examine active travel in 2961 year 6 and 8 students (48.7% male), aged 10–14 years (M=11.4, SD=0.8yrs) from 231 schools. Participants completed an on-line survey and all reported living within 2km of school. Data collected included mode of travel to and from school, self-reported health, and PA variables. Social environmental variables included having playgrounds, parks or gyms close by, feeling safe to walk alone, barriers to walking in the neighbourhood (e.g. traffic, no footpaths), peer and family support for PA, existence of sports teams/scout groups, community disorder and perceived neighbourhood safety. Results showed that while more girls (44.3%) than boys (37.4%) walked to school, lower proportions rode bikes (8.3% vs 22.4%) and hence fewer were active travellers overall. Logistic regression models, adjusted for age, location and socio-economic status were conducted for active travel to/from school, separately for boys and girls. Predictors for boys and girls being ‘active travellers’ to/from school included recreational facilities close to home, higher perceived safety of the neighbourhood and higher community disorder. For boys, social support from friends, scout groups available and higher enjoyment of physical activity was also important. These findings suggest areas for future research and may be used to guide strategies to increase active travel to and from school.

Perceived and actual competence among overweight and non-overweight children - Corrected Proof

Rachel A. Jones, Anthony D. Okely, Peter Caputi, Dylan P. Cliff — 2010-06-28

Abstract: Child overweight and obesity continues to be a global public health concern. The aim of this study was to investigate whether children's actual and perceived physical competence and parental perception's of their child's competence differ by weight status. Understanding these differences is important because physical activity levels are significantly lower among overweight children than their lean counterparts and children's motivation to participate in physical activity is influenced by their perceived and actual competence and their parents perceptions of their competence. Cross-sectional data were collected from 1414 9- and 11-year-old children and their parents from 20 primary schools in New South Wales, Australia. Outcomes measured included child and parental perceptions of physical competence and children's actual physical competence. Parents of overweight boys perceived them to be significantly less competent than parents of non-overweight boys. For 11-year-old girls, parent's perception of their daughter's ability to run (mean diff=1.06 [95% CI 0.73, 1.40]), jump (mean diff=0.54 [95% CI 0.15, 0.93]) and leap (mean diff=0.78 [95% CI 0.41, 1.17]) was lower among parents of overweight children. Overweight children also reported lower perceived physical competence than non-overweight children. 9- and 11-year-old overweight boys had lower actual physical competence than non-overweight boys (mean diff=1.32 [95% CI 0.29, 2.35]; mean diff=1.26 [95% CI 0.37, 2.15], respectively). Overweight 11-year-old girls had lower actual competence than non-overweight 11-year-old girls (mean diff=1.14 [95% CI 0.70, 2.12]). This study highlighted several differences between overweight and non-overweight children. Better understanding these differences at different stages of development may lead to identifying more specific and appropriate intervention points to promote physical activity in overweight children.

The concept of ‘Organismic Asymmetry’ in sport science - Corrected Proof

Keith Davids, Duarte Araújo — 2010-06-28

Abstract: The concept of organismic asymmetry refers to an inherent bias for seeking explanations of human performance and behaviour based on internal mechanisms and referents. A weakness in this tendency is a failure to consider the performer–environment relationship as the relevant scale of analysis. In this paper we elucidate the philosophical roots of the bias and discuss implications of organismic asymmetry for sport science and performance analysis, highlighting examples in psychology, sports medicine and biomechanics.

Physical collisions and injury during professional rugby league skills training - Corrected Proof

Tim Gabbett, David Jenkins, Bruce Abernethy — 2010-05-19

Abstract: This study described the number and intensity of collisions experienced by professional rugby league players during pre-season and in-season skills training sessions using microtechnology (e.g. accelerometers, gyroscopes). Short, medium, and long recovery periods between matches were accounted for and the incidence of collision injuries sustained in the training environment was also assessed. Thirty professional rugby league players (mean±SD age, 23.6±3.8yr) participated in this study. The number and intensity of collisions and the incidence of collision injuries were monitored during 117 skills training sessions. Over the course of the season, an average of 77 collisions occurred per player, per session. The average number of mild, moderate, and heavy collisions performed by each member of the squad per session was 24, 46, and 7, respectively. A total of 37 collision injuries were recorded during training over the season, equating to an injury incidence of 6.4 per 10,000 collisions. Over half (54.1%) of all collision injuries resulted in no loss of training time, and less than 14% of collision injuries resulted in a missed match. The greatest number of collisions occurred during training sessions in the weeks with the longest recovery between matches (10 days). The incidence of collision injuries also peaked during the 10 day between match recovery cycle. These findings demonstrate that while significant physiological demands are placed on rugby league players as a result of the large number and intensity of physical collisions performed in training, these collisions are associated with minimal injury risk.

Comparison of methods for kinematic identification of footstrike and toe-off during overground and treadmill running - Corrected Proof

Rebecca E. Fellin, William C. Rose, Todd D. Royer, Irene S. Davis — 2010-05-18

Abstract: When analysing gait, the identification of the period of stance is often needed. Forceplates are typically used, but in their absence kinematic data can be employed. Five kinematic methods have been previously described in the literature. However, these methods have not been compared to each other for overground or treadmill running. Therefore, the purpose of this study was to compare these five kinematic methods of identifying the stance phase with vertical ground reaction force data both during overground and treadmill running. We recruited forty recreational runners (20 males) for this study. Twenty runners underwent an instrumented gait analysis during overground running, and twenty were tested during instrumented treadmill running. All runners ran at 3.35m/s. Each kinematic method was compared with stance identified from the vertical ground reaction force (gold standard) for overground running. This method was then repeated for treadmill running. Two methods were found to be valid and reliable for determining footstrike. These were the time when the distal heel marker reached a minimum vertical position, and when the vertical velocity of this same marker changed from negative to positive. These methods had absolute errors that ranged from 22.4ms to 24.6ms for both modes of running. Toe-off was best identified using peak knee extension, with absolute errors of 4.9ms for overground running and 5.2ms for treadmill running. Utilising automated kinematic methods of determining stance will aid researchers studying running when forceplates are unavailable.

Optimising breast support in female patients through correct bra fit. A cross-sectional study - Corrected Proof

Deirdre E. McGhee, Julie R. Steele — 2010-05-10

Abstract: Ill-fitting bras and insufficient breast support can lead to the development of musculoskeletal pain and inhibit women participating in physical activity. This study aimed to systematically determine the best method for women to independently choose a well-fitted bra. The bra size of 104 women (mean age=43.5±13.2 years; average bra size=12B; band size range=10–14, cup size range=A–DD cup; Australian sizes) was determined through self-selection and bra size measurements. This was compared to the “correct bra size” as determined by professional bra fitting criteria, which were also used to assess the bra fit of each participant's own bra. Eighty-five percent of the participants were found to be wearing ill-fitting bras and the bra sizes determined by self-selection or using bra-sizing measurement systems were significantly different to the correct bra size (p<0.001). Therefore, women were found to have a poor ability to independently choose a well-fitted bra, which was not improved by trying on several bras or using bra-sizing measurements. Education of professional bra fitting criteria may offer medical practitioners and allied health professionals a simple strategy to improve the ability of their female patients to independently choose a well-fitted bra.

Secular trends in health-related physical fitness in Spanish adolescents: The AVENA and HELENA Studies - Corrected Proof

2010-05-10

Abstract: We analysed the secular trends in health-related physical fitness in Spanish adolescents between 2001–2002 and 2006–2007. Two representative population studies were conducted 5 years apart in adolescents (12.5–17.5 years) from Zaragoza (Spain) that participated in the AVENA study in 2001–2002 and in the HELENA-CSS study in 2006–2007. Both studies used the same tests to assess physical fitness: the handgrip strength, bent arm hang, standing broad jump, 4×10m shuttle run and 20m shuttle run tests. Performance in 4×10m shuttle run and 20m shuttle run tests was higher in 2006–2007 (Cohen's d ranging from 0.2 to 0.4, p<0.05), whereas performance in handgrip strength and standing broad jump tests was lower in 2006–2007 (Cohen's d ranging from 0.3 to 1.1, p<0.001). Adjustment for age, pubertal status, fat mass, fat free mass and parental education did not alter the results. The odds ratio (OR) of meeting the FITNESSGRAM Standards for healthy cardiorespiratory fitness was higher in 2006–2007 in both boys (OR, 95% CI: 2.123, 1.157–3.908) and girls (OR, 95% CI: 2.420, 1.377–4.255). The results indicate that levels of both speed/agility and cardiorespiratory fitness were higher in 2006–2007 than in 2001–2002, whereas muscular strength components were lower in 2006–2007.

Echocardiographic study of early left ventricular remodeling in highly trained preadolescent footballers - Corrected Proof

2010-05-10

Abstract: Almost all the studies of athlete's heart have been carried out on adult and older adolescent players; hence the limited data on the cardiac response to exercise in the beginning of the active sports career in the youngest athletes. The study was designed to examine the physiological limits of left ventricle (LV) cavity size and wall thickness in elite footballers at the preadolescent age, it the beginning of the active sports career. Ninety-four highly trained male footballers (mean aged 12.85±0.84) competing in the Serbian Football League and 47 age-matched healthy male controls, aged 12–14, were enrolled in the study. All the echocardiographic findings were adjusted to BSA−0.5, while left ventricle mass (LVM) was additionally adjusted to BSA−1.5. Reference ranges were defined as values of 5–95th centile according to the mean values in both groups. The proportions of the footballers with LV dimensions outside expected ranges were additionally noted. The data indicate significant increases in absolute values of LV dimensions, aortic root size and left atrium (p<0.001) in preadolescent professional footballers compared with the values expected for age-matched controls, whereas there are no differences in absolute values of ventricular septal and posterior wall thickness, LV wall thickness and LVM (p>0.05). Upon body-size adjustments, significant increases were observed in all echocardiographic parameters (p<0.001). Our data indicate an early cardiac remodeling, already apparent in preadolescence, even after a short period of training.

The role of shoulder muscles is task specific - Corrected Proof

Craig E. Boettcher, Ian Cathers, Karen A. Ginn — 2010-05-10

Abstract: The aim of this study was to compare activity in shoulder muscles during unsupported internal and external rotation to examine their functional roles, and determine whether they retain their ‘stabiliser’ or ‘mover’ role regardless of the shoulder task. Electromyographic recordings in the dominant shoulder of 15 normal subjects were taken from 13 shoulder muscle sites using a combination of surface and intramuscular electrodes during isometric shoulder internal and external rotation in an unsupported abducted position under conditions of increasing load. During internal rotation significantly higher activity levels were found in subscapularis (p<0.001). During external rotation significantly higher activity levels were demonstrated in supraspinatus, infraspinatus, trapezius and serratus anterior (p<0.05). There were no significant differences in activity levels in deltoid, pectoralis major and latissimus dorsi during internal and external rotation. As rotational forces increased there was a significant increase in activity in all muscle sites activated above low levels (r2=0.93±0.07; mean±s.d.). This study has shown that shoulder muscle function is task specific and that shoulder muscle motor strategy for a particular task does not change with increasing torque. As the only shoulder rotators that demonstrated direction specificity the rotator cuff muscles are likely to be functioning to provide rotation torque while the deltoid is likely to be providing dynamic shoulder stability during the task examined. Higher scapulothoracic muscle activity during external rotation indicated the need for greater dynamic scapular stability as a result of higher rotator cuff activity during external than internal rotation.

Movement pattern comparisons in elite (AFL) and sub-elite (WAFL) Australian football games using GPS - Corrected Proof

Cameron Brewer, Brian Dawson, Jarryd Heasman, Glenn Stewart, Stuart Cormack — 2010-05-03

Abstract: This study examined differences in movement patterns between AFL (elite) and WAFL (sub-elite) players using Global Positioning System (GPS) devices. Maximum speed data and totals of high intensity efforts (>15kmh−1), sprint efforts (>20kmh−1) and distance covered were collected on 41 players during the 2008 season. Data were expressed per min of game time played, separated into first and second halves, and also into positions, for both elite and sub-elite players. Overall, elite players had higher movement demands, including 9% more distance covered/min (128±12mmin−1 vs. 117±15mmin−1; p<0.01, ES=0.84), and 21% more high intensity efforts/min (2.9±0.6 vs. 2.4±0.6; p<0.01, ES=0.83). Movement demands significantly declined (p<0.05–0.01) from first to second half, in both competition levels. For both leagues, Small Forwards/Small Backs and Midfield players covered significantly greater (p<0.05–0.01) total distances and completed more high intensity efforts than other positions. Ruckmen recorded significantly lower (p<0.05–0.01) movement demands than Small Forwards/Small Backs, Midfielders and Centre Half-Forwards/Centre Half-Backs over most variables. In conclusion, elite players recorded higher overall movement demands than sub-elite players. This information may be useful for coaches and conditioning staff in designing appropriate training drills for specific role requirements of individual players and assist in the progression of players from sub-elite to elite levels of competition.

Alternate methods to prevent protease use as a masking agent in sport - Corrected Proof

2010-04-12

Abstract: Manipulation of urinary samples in sports drug testing with proteases is being used by athletes as masking agents to complicate or inhibit the detection of peptide hormones and proteins such as erythropoietin, human growth hormones or insulin. A great number of strategies have been suggested to prevent the use of proteases. The main problem in the use of proteases is that athletes have usually introduced proteases into the urethra before delivering a doping control urine sample. We propose a viable, relatively simple, and inexpensive solution to prevent the use of proteases in sports.

Epo production at altitude in elite endurance athletes is not associated with the sea level hypoxic ventilatory response - Corrected Proof

Robert F. Chapman, James Stray-Gundersen, Benjamin D. Levine — 2010-04-02

Abstract: The level of circulating erythropoietin (EPO) in response to a fixed level of hypoxia shows substantial inter-individual variability, the source of which is undetermined. Arterial PO2 at altitude is regulated in part by the hypoxic ventilatory response, which also shows a wide inter-individual variability. We asked if the ventilatory response to hypoxia is related to the magnitude of EPO release at moderate altitude. Twenty-six national class US distance runners (17 M, 9 F) participated in a test of isocapnic hypoxic ventilatory response (HVR) at sea level, 2–7 days prior to departure to altitude. EPO measures were obtained at sea level and after 20h at 2500m. HVR for all subjects was 0.21±0.16Lmin−1%SaO2−1 (range 0.01–0.61Lmin−1%SaO2−1), with no significant difference between men and women. EPO was significantly increased from pre-altitude (8.6±2.6ngml−1, range 4.0–14.6ngml−1) to acute altitude (16.6±4.4ngml−1, range 5.0–27.0ngml−1), an increase of 92.2±70.1%. There was no significant sex difference in the EPO increase. ΔEPO for all subjects was not correlated with HVR (r=−0.17). Similarly, a statistically or physiologically significant correlation was not present between ΔEPO and HVR within the group of men (r=−0.22) or women (r=−0.19). The variability in the acute EPO response to moderate altitude is not explained by differences in peripheral chemoresponsiveness in elite distance runners. These results suggest that factors acting downstream from the lung influence the magnitude of the acute EPO response to altitude.

A functional variant within the MMP3 gene does not associate with human range of motion - Corrected Proof

2010-04-01

Abstract: A recent heritability study has demonstrated that human range of motion (ROM) has a substantial genetic component. Furthermore, the COL5A1 BstUI RFLP has now been identified as the first gene variant to be associated with human ROM. Interestingly, this variant is known to interact with a functional variant within the MMP3 gene (rs679620) to increase risk of Achilles tendinopathy. We sought to determine whether the MMP3 rs679620 variant was associated with ROM both as a single marker and as an interacting marker with the COL5A1 BstUI RFLP. One hundred and twenty one participants were included in this study. All participants were genotyped for the MMP3 rs679620 variant, and performed passive straight leg raise (SLR) and sit and reach (SR) measurements. There were no significant differences in left leg SLR (L-SLR), right leg SLR (R-SLR), or SR measurements between the genotype groups (L-SLR, P=0.494; R-SLR, P=0.435; SR, P=0.266). Furthermore, there was no evidence of an interaction between the COL5A1 BstUI RFLP and the MMP3 rs679620 variant. Our study suggests that the MMP3 rs679620 variant does not associate with passive ROM.

Effort regulation in rowing races depends on performance level and exercise mode - Corrected Proof

Morgan R. Brown, Simon Delau, François D. Desgorces — 2010-03-15

Abstract: This study investigated the influence of performance level and exercise mode on the rowers’ pacing strategies. On-water and indoor split times and placements (every 500-m) were obtained from individual 2000-m performances set at the elite, national and sub-elite competitive levels. The data was sorted into indoor (n=580) and on-water exercises (n=507). Indoor and on-water strategies statistically differed, whatever the competition level (p<0.001). Analysis of absolute and normalised velocities demonstrated higher and steadier paces in elite races compared to national and sub-elite races (p<0.001). On water, intermediate placements highlighted the great influence of taking the front of the race particularly at the elite level (at the elite level 78% of the winners were first at the middle of the race and 100% were in the first three). A “parabolic-shaped” profile could describe all races but performance level and exercise mode may alter this effort regulation to even (elite races) or positive paces (national and sub-elite indoor races). The even paces reported as the optimal strategy were not observed in lower performance levels probably because of rowers’ inability to combine higher physiological effort and technical requirements of on-water rowing. Training exercise may account for these paces differences, according to the athletes’ competitive level and to exercise mode.

ACL reconstructed patients with a BPTB graft present an impaired vastus lateralis neuromuscular response during high intensity running - Corrected Proof

2010-03-15

Abstract: The purpose of the present study was to investigate whether the electromyographic response of the vastus lateralis (VL) muscle in the anterior cruciate ligament (ACL) reconstructed leg is similar to that of the intact contralateral leg and healthy controls, during moderate and high intensity running. Fourteen bone–patellar tendon–bone (BPTB) ACL reconstructed amateur soccer players and fourteen healthy control amateur soccer players volunteered to participate in the study. Electromyographic (EMG) traces from the vastus lateralis (VL) muscle were collected bilaterally, as athletes ran on a treadmill for 10min on separate occasions, at moderate and high intensity. The dependent variable examined was the EMG amplitude during stance. During the moderate intensity running, EMG amplitude of the VL did not increase with time for any of the tested legs. During the high intensity running, the EMG amplitude of the VL increased significantly with time for the intact (F=6.747, p=0.001) and the control leg (F=4.258, p=0.008), but remained unchanged for the ACL reconstructed leg. During moderate intensity running, there was no difference in the neuromuscular response of the VL in the reconstructed leg compared to the intact and control leg. High intensity running resulted in an impaired neuromuscular response of the VL in the reconstructed leg compared to the intact and control leg. It seems that potential impairments of the neuromuscular response after ACL reconstruction should be tested under high rather than moderate intensity efforts.

Hypoleptinaemia in extreme body mass models: The case of international rugby players - Corrected Proof

S. Bréban, C. Chappard, C. Jaffré, C.L. Benhamou — 2010-01-25

Abstract: Leptinaemia has been poorly studied in athlete populations with the consequences of athletic hypoleptinaemia yet to be examined. Our aim was to determine if systemic leptinaemia is influenced in high body mass athletes. We recruited 24 rugby players (21.5±4.7 years; 11.8±2.9h/week) and 26 controls (22.3±3.1 years; 1.9±1.4h/week). BMD (whole body (WB), limbs, lumbar spine and non-dominant femur) and body composition (WB Lean Mass (LM) and FM) were measured by Dual X-ray Absorptiometry. Circulating levels of serum leptin (ng/ml), adiponectin (μg/ml), insulin (ng/ml), osteocalcin (ng/ml) and CTx (ng/ml) were assessed by ELISA assays. BMD were significantly higher in rugby players vs controls, at all bone sites, yet after adjustments for body mass index. They had significantly higher LM and FM but no differences in %FM. They had significantly higher osteocalcin but lower CTx, insulin and leptin concentrations. Leptin levels were strongly correlated to %FM (r=0.85, p<0.0001), as well as to absolute FM (r=0.77, p=0.0002), in the rugbymen group. Rugby practice was associated to a bone remodelling process in favour of bone formation. There was a significant hypoleptinaemia in our rugby players, while their percent FM was equivalent and absolute FM significantly higher than the control levels. These data suggest that leptin is under control of physical activity and not just fat mass.

Adjusting step count recommendations for anthropometric variations in leg length - Corrected Proof

2010-01-22

Abstract: Recent public health recommendations for step frequency over a given timeframe (stepsmin−1) associated with moderate-intensity physical activity (MPA) have been developed. The recommendation suggests 100 stepsmin−1. This estimate overlooks the impact of anthropometric differences between individuals, notably leg length, which is related to step frequency. Therefore this study examined the impact of leg length on stepsmin−1 associated with MPA. Twenty adults age 20–40 years (age 26.4±4.6 years, 9 males) walked over-ground at five walking speeds (0.5ms−1, 0.75ms−1, 1.0ms−1, 1.25ms−1, and 1.5ms−1), lasting 6min each, while wearing a portable gas analyser. Participants’ step frequency (stepsmin−1) for each walking speed was determined using a hand-tally counter. Random effects models were used to predict stepsmin−1 from METs and participant anthropometric measures (body mass index and leg length [cm]). Model estimates were used to predict stepsmin−1 corresponding to heights ranging from 5ft. to 6ft. 6in. (6 in increments). Overall, 100 stepsmin−1 corresponded to expending 3 METs (SEE 3.49 stepsmin−1, R2=0.68). As leg length increased estimated stepsmin−1 decreased by −1.15stepsmin−1 (95CI −2.19 to −0.10 stepsmin−1). Based on leg length for individuals 5ft to 6ft 6in., stepsmin−1 ranged from 111 to 85, respectively. Established stepsmin−1 cutpoints associated with MPA are general public health guidelines and anthropometric differences in leg length should be accounted for when developing step frequency recommendations for physical activity or weight loss studies that include individuals of varying height.

Maximal oxygen uptake, ventilatory thresholds and mechanical power during cycling in Tropical climate in Guadeloupean elite cyclists - Corrected Proof

O. Hue, S. Antoine-Jonville, O. Galy, S. Blonc — 2010-01-22

Abstract: The Tropical climate imposes a high level of physiological stress, which could modify the target heart rate in training load prescription, as the recommendations are often determined by maximal oxygen uptake testing in temperature-neutral laboratories. To test this hypothesis, 7 high-level cyclists performed two randomised maximal tests in neutral (19.2±0.9°C; 51.7±1.3% RH) and Tropical environment (25.8±1.1°C; 63.7±2.3% RH). Neither maximal oxygen uptake nor ventilatory threshold was influenced by the environmental conditions. However, ventilation (p<0.005) and the respiratory equivalent in O2 (p<0.05) were significantly higher in the Tropical environment, whereas maximal power output and the time to attain maximal oxygen uptake were significantly lower (p<0.05 for both). Moreover, the ventilatory cost of cycling (expressed in LW−1) was significantly greater in the Tropical condition (0.40±0.03LW−1 vs. 0.32±0.05LW−1, in Tropical vs. Neutral; condition effect: p<0.005; condition×time: p<0.001). Rectal temperature was influenced by neither the environmental conditions nor exercise (36.7±0.1 and 37.0±0.1°C vs. 36.8±0.1 and 37.1±0.2°C, in Tropical vs. Neutral, before and after exercise) but was influenced by condition×time (p<0.05). The heart rate (HR) values usually used for training prescription were not significantly different (154±5bpm vs. 156±4bpm and 172±4bpm vs. 167±4bpm in Tropical vs. Neutral climate, for the first and second thresholds, respectively). We concluded that the usual parameters measured during maximal exercise to establish training programs are not impaired in moderate Tropical environment. Nevertheless, the thermal stress attested by the increased ventilatory cost of cycling could have prevented the cyclists from performing a true maximal test in Tropical conditions.

Fielders and batters are injured too: A prospective cohort study of injuries in junior club cricket - Corrected Proof

Caroline F. Finch, Peta White, Rebecca Dennis, Dara Twomey, Andrew Hayen — 2009-12-25

Abstract: Internationally, there is a lack of good quality, prospectively collected injury data reported for junior club cricketers. This study describes injury rates according to age level of play and playing positions in junior community-level club cricketers to identify priorities for prevention. A prospective cohort study was used to monitor injuries in 88 under 12 years (U12), 203 U14 and 120 U16 players from the Ballarat Junior Cricket Association, Australia over the 2007/2008 playing season. Injury rates were calculated per 1000 participations when batting, bowling or fielding in matches and training sessions. Injury rate ratios were used to compare rates across age levels of play and position of play. Overall, 47 injuries were reported. Injury rates increased with age level of play with only one U12 player injured. Match injury rates were 3.57 per 1000 U14 participations versus 4.80 per 1000 U16 participations. Training injury rates were 4.20 per 1000 U14 participations versus 5.11 per 1000 U16 participations. On a proportionate basis, injuries occurred equally to fielders, batters and bowlers. There was a trend towards more injuries occurring while batting and fielding in matches, and more injuries occurring while bowling and batting during training sessions. In conclusion, injury rates in junior cricket players are low, but increase with age level of play. Unlike adult forms of the game, injuries occur to fielders and batters at least as frequently as to bowlers, indicating that preventive strategies need to be developed for all junior players and not just bowlers, as has been the focus previously.

Influence of posture and body type on the experience of exercise-related transient abdominal pain - Corrected Proof

Darren P. Morton, Robin Callister — 2009-12-18

Abstract: The aim of this study was to evaluate the influence of posture and body type on the experience of exercise-related transient abdominal pain (ETAP). Postural and somatotype assessments were performed on 104 active males and 55 active females aged 18.6±0.4 years (mean±SD) and were correlated against their self-reported experience of ETAP. Individuals demonstrating kyphosis were more likely to be susceptible to ETAP (p<0.01). Among the individuals susceptible to ETAP, the extent of kyphosis and lordosis influenced the pain severity (p<0.05). There was no relationship between any measure of body type and ETAP. The findings indicate that postural abnormality, particularly in the thoracic region, influences the experience of ETAP.

Influence of sex on the “Athlete's Heart” in trained cyclists - Corrected Proof

Thomas Rowland, Melissa Roti — 2009-12-18

Abstract: Compared to females, male endurance athletes have generally been considered to demonstrate greater values of cardiac mass and volume (the “athlete's heart”). However, studies addressing this issue have frequently failed to match training volumes between groups or provided inadequate adjustment of variables for body size and composition. This study compared echocardiographic anatomic features in 8 female and 8 male competitive cyclists with a similar training history. Conforming to most previous reports, left ventricular mass and end diastolic dimension, adjusted for fat free body mass and body surface area, respectively, were greater in the males (3.56±0.83gkg−1 versus 2.50±0.38gkg−1; 41.7±2.2mm and 37.4±2.5mm per BSA0.5). This study indicated that when training volume as well as body size and composition are considered, male endurance athletes exhibit greater cardiac dimensions and mass compared to their female counterparts.

Position statement on physical activity and exercise intensity terminology - Corrected Proof

Kevin Norton, Lynda Norton, Daryl Sadgrove — 2009-12-11

Abstract: The terminology used for monitoring and promoting physical activity and exercise among health and fitness professionals varies considerably. There is a large array of descriptor terms reported in the literature and used in day-to-day practice and this inconsistency can be confusing for clients and practitioners alike. The variation in terminology also makes it difficult to track changes in activity patterns over time and across studies. There are also a range of objective and relative intensity cut-offs used to describe the same intensity descriptors. This position statement addresses the question of standardisation of physical activity and exercise intensity terminology and makes recommendations that should assist those undertaking research and prescribing physical activity/exercise as well as those clients who are receiving professional guidance.

Quantifying movement demands of AFL football using GPS tracking - Corrected Proof

Ben Wisbey, Paul G. Montgomery, David B. Pyne, Ben Rattray — 2009-11-09

Abstract: Global positioning system (GPS) monitoring of movement patterns is widespread in elite football including the Australian Football League (AFL). However documented analysis of this activity is lacking. We quantified the movement patterns of AFL football and differences between nomadic (midfield), forward and defender playing positions, and determined whether the physical demands have increased over a four season period. Selected premiership games were monitored during the 2005 (n=80 game files), 2006 (n=244), 2007 (n=632) and 2008 (n=793) AFL seasons. Players were fitted with a shoulder harness containing a GPS unit. GPS data were downloaded after games and the following measures extracted: total distance (km), time in various speed zones, maximum speed, number of surges, accelerations, longest continuous efforts and a derived exertion index representing playing intensity. In 2008 nomadic players covered per game 3.4% more total distance (km), had 4.8% less playing time (min), a 17% higher exertion index (per min), and 23% more time running >18kmh−1 than forwards and defenders (all p<0.05). Physical demands were substantially higher in the 2008 season compared with 2005: an 8.4% increase in mean speed, a 14% increase in intensity (exertion index) and a 9.0% decrease in playing time (all p<0.05). Nomadic players in AFL work substantially harder than forwards and defenders in covering more ground and at higher running intensities. Increases in the physical demands of AFL football were evident between 2005 and 2008. The increasing speed of the game has implications for game authorities, players and coaching staff.

The relationship between joint range of motion, muscular strength, and race time for sub-elite flat water kayakers - Corrected Proof

Mark R. McKean, Brendan Burkett — 2009-11-09

Abstract: Upper body strength and flexibility are common training activities in elite flat water kayaking yet the relationship between joint range of motion, muscular strength, and race time is unclear. The aim of this research was to firstly quantify the flexibility and strength of sub-elite kayakers and then determine the relationship of this data to performance race times. Twenty-nine national standard kayak paddlers were assessed for shoulder and pelvic flexibility, upper body strength, and performance time. The shoulder internal and external rotation range of movement for kayak paddlers was reduced in comparison to other populations. For the female paddlers significant (p<0.01) and strong correlations (r>0.70) were found between shoulder flexion range of movement, shoulder strength, and strength endurance. Strength scores for kayak paddlers are reported for the first time showing the Pull:Push strength ratio for male kayak paddlers was 129%, and for females 147%. The strength ratio was significantly different (p<0.01) across gender and also different to published ratios from other sports. Several other measures were also significantly different across gender. All paddlers showed significant and strong correlations between the three 8RM shoulder strength exercises, highlighting the importance of maintaining balance of strength for the muscles acting on the shoulder. There was only one measure, the strength endurance Bench-Pull-Max-Power for females that significantly and strongly correlated to the on-water performances; identifying the poor relationship between current dry land training activities and race performance. No single strength or ROM measure correlated strongly with on-water performances for either sex, as a sport kayaking appears to reduce the ROM about the shoulder joint.

Does plyometric training improve strength performance? A meta-analysis - Corrected Proof

Eduardo Sáez-Sáez de Villarreal, Bernardo Requena, Robert U. Newton — 2009-11-09

Abstract: Majority of the research suggests plyometric training (PT) improves maximal strength performance as measured by 1RM, isometric MVC or slow velocity isokinetic testing. However, the effectiveness of PT depends upon various factors. A meta-analysis of 15 studies with a total of 31 effect sizes (ES) was carried out to analyse the role of various factors on the effects of PT on strength performance. The inclusion criteria for the analysis were: (a) studies using PT programs for lower limb muscles; (b) studies employing true experimental design and valid and reliable measurements; (c) studies including sufficient data to calculate ES. When subjects can adequately follow plyometric exercises, the training gains are independent of fitness level. Subjects in either good or poor physical condition, benefit equally from plyometric work, also men obtain similar strength results to women following PT. In relation to the variables of program design, training volume of less than 10 weeks and with more than 15 sessions, as well as the implementation of high-intensity programs, with more than 40 jumps per session, were the strategies that seem to maximize the probability to obtain significantly greater improvements in performance (p<0.05). In order to optimise strength enhancement, the combination of different types of plyometrics with weight-training would be recommended, rather than utilizing only one form (p<0.05). The responses identified in this analysis are essential and should be considered by the strength and conditioning professional with regard to the most appropriate dose–response trends for PT to optimise strength gains.

The −174 G/C polymorphism of the IL6 gene is associated with elite power performance - Corrected Proof

2009-10-26

Abstract: The −174 G/C polymorphism [rs1800795] of the IL6 gene is a candidate to explain individual variations in health and exercise related phenotypes. We compared −174 G/C genotypic and allelic frequencies in three groups of men of the same Caucasian (Spanish) descent: elite endurance athletes (cyclists, runners; n=100); elite power athletes (jumpers, throwers, sprinters; n=53) and non-athletic controls (n=100). The frequency of the GG genotype (P=0.030) and G allele (P=0.026) was higher in the power athletes group compared with the control group. The frequency of the GG genotype (P=0.033) and G allele (P=0.013) was also higher in the power athletes group compared with the endurance athletes group. The odds ratio of being a power athlete if the subject had the GG genotype (dominant model) was 2.471 (95% confidence interval: 1.242–4.915) compared to the control group or the endurance athlete group. We did not find differences between the control and endurance athlete groups. In summary, our findings suggest that the G allele of the IL6 −174 G/C polymorphism might favour sprint/power sports performance.

Fundamental movement skills among Australian preschool children - Corrected Proof

Louise L. Hardy, Lesley King, Louise Farrell, Rona Macniven, Sarah Howlett — 2009-10-23

Abstract: Early childhood is a critical period for the development of fundamental movement skills (FMS). Children who do not master FMS are more likely to experience failure in the motor domain and less likely to participate in sport and games during childhood and adolescence. Studies among primary school aged children report low levels of FMS mastery indicating the need to implement FMS programs during the preschool years. Cross-sectional study of 425 children attending preschools in the Sydney, Australia in 2008. FMS were assessed using the Test of Gross Motor Development-2 including locomotor (run, gallop, hop, horizontal jump) and object control (strike, catch, kick overhand throw) skills. Data were analysed using linear regression and chi-squared analyses. Total locomotor score was higher among girls compared with boys (p<0.00); however only the hop was significantly different (p=0.01). Boys had higher total (p<0.00) and individual object control scores compared with girls, except the catch (p=0.6). The prevalence of mastery differed across each FMS. Girls generally had higher mastery of locomotor skills and boys had higher mastery of object control skills. These findings highlight the need to provide structured opportunities which facilitate children's acquisition of FMS, which may include providing gender separated games, equipment and spaces. That mastery of FMS is low in primary school children indicates the importance of early intervention programs in preschools. Preschools and child care centers hold promise as a key setting for implementing FMS programs.

Identifying symmetry in running gait, using a single inertial sensor - Corrected Proof

James B. Lee, Kattie J. Sutter, Christopher D. Askew, Brendan J. Burkett — 2009-10-23

Abstract: Running gait has been shown to alter due to changes in intensity. It was hypothesised that a sacral mounted single inertial sensor could identify the centre of mass (COM) vertical accelerations. This study aimed to validate this new technique against a criterion measure and to determine the influence of changes in running intensity on COM vertical acceleration and the symmetry of COM vertical acceleration between left and right steps. Ten athletes ran for 5min at their self-selected pace, plus 1km/h above and below this velocity. Validity of the single inertial sensor was determined by comparing COM vertical acceleration against that measured with a six-camera infrared system. Large correlation (r=0.96), a small typical error of estimate (1.84), and mean bias (0.02) were found between the two systems. The greatest magnitude in COM vertical acceleration occurred at the slowest running pace and decreased as pace increased. Sixty percent of the athletes exhibited asymmetry during at least one running pace; 30% were asymmetrical across all three velocities. While significant changes in COM vertical acceleration occurred between the different running velocities, this did not always result in a change in symmetry. This study found that a single inertial sensor can be used as a valid means of measuring COM vertical acceleration. This technique can detect changes in the COM vertical acceleration that may change with running velocity. Gait symmetry (using COM vertical acceleration) during running was also quantified using the inertial sensor.

Accuracy and reliability of GPS devices for measurement of movement patterns in confined spaces for court-based sports - Corrected Proof

Rob Duffield, Machar Reid, John Baker, Wayne Spratford — 2009-10-23

Abstract: The aim of this study was to assess the accuracy and reliability of global positioning system (GPS) measures of distance and speed, compared to a high-resolution motion analysis system, for confined movement patterns used in many court-based sports. A single male participant performed 10 repetitions of four respective drills replicating court-based movement patterns and six repetitions of a random movement drill that replicated tennis match-play movement patterns. Two 1Hz and two 5Hz GPS devices concurrently measured distance covered and speed of all court-based drills. A 22 camera VICON motion analysis system, operating at 100Hz, tracked the position of an 18mm reflective marker affixed to one of the GPS devices to provide the criterion movement data. Results indicated that both 1 and 5Hz GPS devices under reported distance covered as well as both mean and peak speed compared to the VICON system (P<0.05). The coefficient of variation for both GPS devices for distance and speed measures ranged between 4 and 25%. Further, the faster the speed and more repetitive the movement pattern (over a similar location), the greater the measurement error. The inter-unit reliability for distance and speed measures of both 1 and 5Hz systems for movements in confined spaces was generally low to moderate (r=0.10–0.70). In conclusion, for court-based sports or movements in confined spaces, GPS technology under reports distance covered and both mean and peak speed of movement.

MCT1 genetic polymorphism influence in high intensity circuit training: A pilot study - Corrected Proof

2009-10-23

Abstract: Monocarboxylate Transporter 1 (MCT1) mediates the transport of the main fraction of lactate across the sarcolemma. A common polymorphic MCT1 variant has been identified, but its role in high intensity exercise performance has not been defined. We investigated the influence of MCT1 A1470T polymorphism (rs1049434) on lactate accumulation after high intensity circuit training. Ten men aged 20–26 performed three controlled circuit training (CWT) sessions at 60%, 70%, and 80% of the 15 repetition maximum (15RM), in non-consecutive days. CWT included three sets of a circuit of eight exercises, obtaining lactate measurements immediately after each set had been completed. Two independent variables were analysed: MTC1 genotypes according to the presence or absence of the A1470T polymorphism, and the intensity of circuit training. Genotype distributions were in Hardy–Weinberg equilibrium, being 30% wild-type, 50% heterozygotes, and 20% mutated homozygotes. Mean lactate concentration at 80% of 15RM were significantly higher than the mean lactate values at the other intensities (p<0.01). Significant differences between genetic groups were found in the lactate accumulation slope at 80% of 15RM (p=0.02) and in the maximal lactate concentration reached by all subjects in the study (Lmax) (p=0.03). The carriers of the A1470T polymorphism in the MTC1 gene seem to exhibit a worse lactate transport capability into the less active muscle cells for oxidation.

Match running performance in elite Australian Rules Football - Corrected Proof

Aaron J. Coutts, John Quinn, Joel Hocking, Carlo Castagna, Ermanno Rampinini — 2009-10-23

Abstract: There is little information describing the match running demands of elite-level Australian Rules Football (AF). The aims of this study were to examine: (1) match running demands; and (2) the influence of periods of increased physical activity on subsequent running performance in the Australian Football League. Time-motion analyses were performed 1–9 times per player from 16 professional AF players from the same club during games in 2005–2007, using portable global positioning systems during 65 matches. Game movements (standing, walking, jogging, running, higher-speed running, and sprinting) and distances (total distance covered [TD]; low-intensity activity [LIA, distance <14.4kmh−1]; and, high-intensity running distance [HIR, distance>14.4kmh−1]) were collected. The influence of the first half physical activities on second half activities, and each quarter on the subsequent quarter were analysed. The mean (±SD) TD and HIR distance covered during the games were 12,939±1145m and 3880±663m respectively. There were reductions in TD in the second (−7.3%), third (−5.5%) and fourth (−10.7%) quarters compared to the first quarter (p<0.01). The HIR was reduced after the first quarter (p<0.001). Players that covered larger TD or HIR during the first half or quarter decreased distance in the next half and quarter, respectively (p<0.001). These results show that a reduction in exercise intensity is inevitable during an AF match and that higher intensity activities reduce towards the end of games. High average speed during each half or quarter also affects subsequent running performance in elite-level AF.

Using EMGs and kinematics data to study the take-off technique of experts and novices for a pole vaulting short run-up educational exercise - Corrected Proof

2009-10-08

Abstract: This study attempts to characterise the electromyographic activity and kinematics exhibited during the performance of take-off for a pole vaulting short run-up educational exercise, for different expertise levels. Two groups (experts and novices) participated in this study. Both groups were asked to execute their take-off technique for that specific exercise. Among the kinematics variables studied, the knee, hip and ankle angles and the hip and knee angular velocities were significantly different. There were also significant differences in the EMG variables, especially in terms of (i) biceps femoris and gastrocnemius lateralis activity at touchdown and (ii) vastus lateralis and gastrocnemius lateralis activity during take-off. During touchdown, the experts tended to increase the stiffness of the take-off leg to decrease braking. Novices exhibited less stiffness in the take-off leg due to their tendency to maintain a tighter knee angle. Novices also transferred less energy forward during take-off due to lack of contraction in the vastus lateralis, which is known to contribute to forward energy transfers. This study highlights the differences in both groups in terms of muscular and angular control according to the studied variables. Such studies of pole vaulting could be useful to help novices to learn expert's technique.