Journal of Science and Medicine in Sport

Editorial Board

2010-03-01

Recognising the diversity of the athletes and activity participants we work with

Gregory S. Kolt — 2010-02-15

In the Journal of Science and Medicine in Sport we publish papers from authors representing all corners of the world. For example in this issue we have contributions stemming from Australia, New Zealand, France, Spain, Italy, Japan, Portugal, Germany, and Iran. This broad coverage brings us a rich mix of viewpoints and contexts, and contributes to our understandings of sports medicine and sports science applications to a broad spectrum of the population. We often make the assumption that an athlete is an athlete, no matter where in the world they come from. While there is some element of truth to this assumption, we need to be cognisant of not only the similarities in athletes but also their differences brought about by their country, ethnicity, and culture of origin.

Normative values for three clinical measures of motor performance used in the neurological assessment of sports concussion

2009-09-30

Abstract: Postural control and motor coordination are essential components of normal athletic activity. Tasks involving balance and coordination are used to determine neurological function in sports-related concussion. Determining normative values for these tasks is therefore essential to provide sports medicine professionals with a frame of reference with which to interpret clinical measures obtained from players suspected of sustaining a concussion. One hundred and seventytwo healthy subjects (16–37 yrs) performed three timed tests: Tandem Gait (TG); Finger-to-Nose (FTN); Single-Leg-Stance (SLS) on firm and foam surfaces. Unadjusted geometric means (±SD) for each measure were averaged across three trials. Time to complete TG was 11.2±1.2s. FTN for the dominant and non-dominant arm were 2.9±1.1s and 3.0±1.2s, respectively. SLS values for dominant and non-dominant leg were 20.4±3.0s (firm), 3.4±1.6s (foam), and 21.0±2.9s (firm), 3.3±1.6s (foam), respectively. For TG, there was an order effect (P<.001) but no age, sex or BMI effects. FTN demonstrated a dominant arm preference (P<.001), sex (P=.006), BMI (P=.043) and order effects (P<.001). SLS demonstrated an order effect on the firm surface (P=.009) and an order (P<.001) and BMI (P=.001) effect on foam. Intra-rater reliability, as measured by ICC (3,3), demonstrated that TG and FTN had excellent reliability compared to SLS. FTN and TG should continue to be used in test batteries to determine neurological function in sports-related concussion.

Hip adductor muscle strength is reduced preceding and during the onset of groin pain in elite junior Australian football players

2009-09-30

Abstract: Groin pain is a condition with a high prevalence in young Australian football players. It is considered that early identification of this condition allows for optimal management. Eighty-six players from two elite under-age Australian football sides were screened weekly for hip adductor muscle strength, using a hand-held dynamometer and for the onset of groin pain. The maximum variation in the average hip adductor muscle strength values of the sample was a 2.6% decrease from baseline in week 7 of the study. Twelve players (14% of the sample studied) reported groin pain for two consecutive weeks and were considered to have an onset of groin injury. The mean hip adductor muscle strength of these players was decreased significantly from baseline by an average of 11.75±2.50% at the week of pain onset (F=264.76 (1,11), p<0.001), and 5.82±5.16% in the week preceding the onset of pain (F=14.03 (1,10), p=0.004). These results confirm that hip adductor muscle strength is decreased both preceding and during the onset of groin injury in elite under-age Australian footballers.

Searching for ski-lift injury: An uphill struggle?

Pam Smartt, David Chalmers — 2009-09-30

Abstract: Injuries arising from ski-lift malfunction are rare. Most arise from skier error when embarking or disembarking, or from improper lift operation. A search of the literature failed to uncover any studies focusing specifically on ski-lift injuries. The purpose of this study was to identify and characterise ski-lift injury resulting in hospitalisation and comment on barriers to reporting and reporting omissions. New Zealand hospitalised injury discharges 2000–2005 formed the primary dataset. To aid case identification these data were linked to ACC compensated claims for the same period and the data searched for all hospitalised cases of injury arising from ski-lifts. 44 cases were identified representing 2% of snow-skiing/snowboarding cases. 28 cases (64%) were male and 16 (36%) female, the average age was 32 yrs (range 5–73 yrs). The majority of cases were snow-skiers (35 cases, 80%). Most of the injuries were serious, or potentially so, with 1 case of traumatic pneumothorax, one of pulmonary embolism (after jumping from a ski-lift) and 28 cases sustaining fractures (six to the neck-of-femur, one to the lumbar spine and one to the pubis). ICISS scores for all cases ranged from 1.00 to 0.8182 (probability of dying in hospital 0–18.18%). Only 14 (32%) cases could be easily identified from ICD-10-AM e-codes and activity codes in the discharge summary. The ICD-10-AM external cause code for ski-lift injury V98 (“other specified transport accidents”) was only assigned to 39% of cases. The type of ski-lift could only be determined in 24 cases (55%).

Increasing school playground physical activity: A mixed methods study combining environmental measures and children's perspectives

2009-09-30

Abstract: Schools are integral settings in which children can participate in moderate and vigorous physical activity. This study reports on the relationship between playground characteristics and child activity levels using a combination of quantitative and qualitative methods. The aim of the study is to increase understanding of how children respond to their school playground environments. Twenty-three primary schools located in a predominantly low socio-economic area of Melbourne, Australia were involved. SOPLAY (System for Observing Play and Leisure Activity in Youth) was administered in all 23 schools to measure the levels of student physical activity and playground environmental factors such as equipment provision. In 12 of the 23 schools, a sample of 9–11-year-old students participated in focus group discussions exploring perceptions of their school playgrounds using a photo ordering technique. A larger proportion of students participated in VPA when loose equipment (60% vs. 52%; p<0.001) and teacher supervision (62% vs. 52%; p<0.001) were present in activity settings, compared to when they were unavailable. Fixed play equipment and bitumen with court/play-line markings were seen by children as settings inviting active play but only had the greatest impact on moderate activity (fixed play equipment: 35% vs. 20%, p<0.001; court markings/goals: 62% vs. 52%, p<0.001; play-line markings: 25% vs. 20%, p=0.04). The mixed method design provided a greater understanding of the potential influence of environmental characteristics on children's lunch time activity levels and their perceptions of play areas. The findings indicate that relatively simple changes such as the provision of loose equipment, painting of court and play-line markings, and increased teacher presence on the playground, are likely to provide opportunities for increased physical activity.

Engaging adolescent girls from linguistically diverse and low income backgrounds in school sport: A pilot randomised controlled trial

Dean A. Dudley, Anthony D. Okely, Philip Pearson, Jennifer Peat — 2009-09-30

Abstract: The purpose of this study was to determine the feasibility, acceptability, and potential efficacy of a school-based physical activity program delivered during school sport time among adolescent girls from low income predominately linguistically diverse backgrounds in New South Wales, Australia. Using a 3-month, 2-arm, parallel-group pilot RCT design, 38 adolescent girls (Year 11) were recruited to participate in the program and randomised into intervention (n=17) or control groups (n=21). The intervention program aimed to increase physical activity by improving enjoyment, physical self-perception and perceived competence. Baseline and follow-up (12 weeks) assessments included enjoyment of physical activity, physical self-perception, and objectively measured physical activity during school sport sessions. Process data were collected through observations of lessons, attendance records, and interviews with participants and staff. Recruitment (63%) and retention (68%) goals were less than anticipated but similar to other studies. Participation was higher for the intervention (72%) than the control (60%) group and the intervention group reported high levels of satisfaction with the program. At follow-up, girls in the intervention group, compared with the control group, showed greater improvement in their enjoyment of physical activity during school sport (adjusted mean difference=3.8, 95% Confidence Interval [CI] −2.4, 10.1; Cohen's d=0.42 standard deviation units) and body image (adjusted difference mean=1.0, 95% CI −0.4, 2.3; d=0.50). There was a smaller decline in participation in physical activity during school sport (adjusted mean=13.6, 95% CI −21.8, 48.9; d=0.24). This study highlights major barriers confronting adolescent girls’ participation in school sport. Some of these include teacher attitudes and support, activities and programming, purpose and distinction, and student input. Negotiating these barriers and overcoming them in a school setting appears feasible with support from the entire school community.

Which factors determine the freely chosen cadence during submaximal cycling?

Fabrice Vercruyssen, Jeanick Brisswalter — 2009-09-30

Abstract: The present review of cycling science focuses on the identification of criteria that affect the freely chosen cadence (FCC) during submaximal exercise of short and prolonged durations. Cadence selection during submaximal cycling constitutes a potential parameter affecting the endurance performance in subjects of varying aerobic fitness level and experience. The activity constraints such as specificity (e.g. cycle bout of triathlon) and exercise duration may play an important role in the selection of cadence and must be taken into consideration in the task description. The ‘holistic’ approach of this review is based on a multifactorial analysis considering the cycling constraints, and the physiological and biomechanical factors of cadence selection so as to establish any interrelationships between these factors. During cycle bouts of short duration (<15min), it has been well argued that experienced cyclists, trained runners and triathletes adopt high cadences (80–100rpm) systematically above the energetically optimal cadence (EOC) at which the oxygen uptake is minimal (55–65rpm). The choice of a high cadence has been shown to be dependent upon several factors, such as the aerobic fitness level, the reduction in forces applied to the cranks, the lower extremity net joint moments and minimal neuromuscular fatigue. However, with increasing exercise duration the FCC has been reported to be close to the EOC exclusively in endurance athletes practising a variety of activities, suggesting an impact of training mode on the muscular adaptations and the organisation of the movement pattern.

The validity and reliability of a global positioning satellite system device to assess speed and repeated sprint ability (RSA) in athletes

2009-09-30

Abstract: There is a limited understanding of the validity and reliability of commercially available global positioning satellite (GPS) devices for assessing repeated sprint performance in athletes. The aims of this study were to assess the convergent validity and the test–retest reliability of a GPS device for measuring repeated sprint ability test (RSAT) variables. Two groups participated in this study, a group of 21 physical education students (age: 20.2±2.3 years, stature: 1.75±0.42m, body mass: 68.0±6.8kg) and a second group 14 elite junior soccer players (age: 14.5±1.2 years, stature: 1.60±0.09m, body mass: 57.7±3.8kg) volunteered to participate in this study. Convergent validity was assessed as the correlation between sprint performance (15 and 30-m) using both timing lights and a portable GPS device during a RSAT (7×30-m sprints with 30-s of active recovery). The 7×30-m RSAT test–retest reliability using GPS device was assessed in elite junior soccer players repeating the test 1 week apart and expressing reliability as a coefficient of variation. Results showed a strong correlation between peak speed measures with the GPS device and RSAT performance measured with timing lights for the 15-m (r2=0.87, p<0.001, N=147) and 30-m (r2=0.94, p<0.001, N=147) splits, respectively. There was a low coefficient of variation for summated maximal speed (1.7%) and peak speed (1.2%) during the 7×30-m RSAT, but high variation for the percentage decrement score (36.2%). These results provide evidence to support the use of the GPS device as an alternative measure to assess repeated sprint performance but suggest a percentage decrement score is not a reliable measure of RSAT performance.

Throwing velocity and jump height in female water polo players: Performance predictors

2009-09-30

Abstract: Throwing velocity and vertical jumping ability are essential components for shooting and passing in water polo. The purpose of this study was to determine whether there is a relationship between throwing velocity and water jump height in highly skilled female water polo players. Throwing velocity and head height at ball release were measured in twenty-two female players (age 20.41 years (6.16); weight 68.28kg (8.87)) with two 50 frames per second cameras while shooting at goal. Water jump height was also measured with a modified Yardstick® device. Multiple regression analyses showed that peak lower limb power was the most significant predictor of maximal velocity. Power alone accounted for 62% of the variance in maximum velocity (p<0.001). Once power was entered into the model none of the other physical characteristics (lean mass, fat mass, land jump height and anthropometry) made a significant contribution to throwing velocity. After controlling for the effect of power, head height at ball release accounted for an additional significant proportion of the variance in maximal velocity (R2 change 7%; p=0.049). Lower body power was a significant predictor of higher throwing velocity in highly skilled female water polo players. Players with relatively higher underlying levels of lower limb power who are able to generate greater elevation out of the water are able to throw the ball faster.

Identification and reliability of pacing strategies in outrigger canoeing ergometry

Rebecca M. Sealey, Warwick L. Spinks, Anthony S. Leicht, Wade H. Sinclair — 2009-09-30

Abstract: This study examined the pacing strategies utilised; and the performance reproducibility during repeated outrigger canoeing ergometer time trials. Trained female outrigger canoeists (N=11) completed four 1000m outrigger canoe ergometer time trials. There was a significant 1.5% improvement in 1000m time in trial four compared to trial one. A fast start strategy was adopted in 36 of the 44 trials (82%) followed by a deceleration during the mid stages. As trials progressed there was an increased adoption of negative pacing (fast finish) between the last two splits, indicating a learning effect of pacing strategy across repeated trials. These results demonstrate that although some performance improvement was evident between the first and fourth time trials, the 1000m outrigger ergometer time trial is a reliable test that may be used as a tool to assist with crew selection and performance monitoring. Further, on account of the variation in pacing strategy noted in the fourth trial, the authors recommend utilising one familiarisation session and one test session when assessing performance such that learning or training adaptations resulting from multiple trials do not impact on results.

Acute effects of 15min static or contract-relax stretching modalities on plantar flexors neuromuscular properties

Nicolas Babault, Blah Y.L. Kouassi, Kevin Desbrosses — 2009-09-30

Abstract: The present study aimed to investigate the immediate effects of 15min static or sub-maximal contract-relax stretching modalities on the neuromuscular properties of plantar flexor muscles. Ten male volunteers were tested before and immediately after 15min static or contract-relax stretching programs of plantar flexor muscles (20 stretches). Static stretching consisted in 30s stretches to the point of discomfort. For the contract-relax stretching modality, subjects performed 6s sub-maximal isometric plantar flexion before 24s static stretches. Measurements included maximal voluntary isometric torque (MVT) and the corresponding electromyographic activity of soleus (SOL) and medial gastrocnemius (MG) muscles (RMS values), as well as maximal peak torque (Pt) elicited at rest by single supramaximal electrical stimulation of the tibial nerve. After 15min stretching, significant MVT and SOL RMS decreases were obtained (−6.9±11.6% and −6.5±15.4%, respectively). No difference was obtained between stretching modalities. Pt remained unchanged after stretching. MG RMS changes were significantly different between stretching modalities (−9.4±18.3% and +3.5±11.6% after static and contract-relax stretching modalities, respectively). These findings indicated that performing 15min static or contract-relax stretching had detrimental effects on the torque production capacity of plantar flexor muscles and should be precluded before competition. Mechanisms explaining this alteration seemed to be stretch modality dependent.

Work-rate of substitutes in elite soccer: A preliminary study

2009-09-30

Abstract: The aim of this study was to investigate the work-rate of substitutes in professional soccer. A computerised player tracking system was used to assess the work-rates of second-half substitutes (11 midfielders and 14 forwards) in a French Ligue 1 club. Total distance, distance covered in five categories of movement intensity and recovery time between high-intensity efforts were evaluated. First- and second-half work-rates of the replaced players were compared. The performance of substitutes was compared to that of the players they replaced, to team-mates in the same position who remained on the pitch after the substitution and in relation to their habitual performances when starting games. No differences in work-rate between first- and second-halves were observed in all players who were substituted. In the second-half, a non-significant trend was observed in midfield substitutes who covered greater distances than the player they replaced whereas no differences were observed in forwards. Midfield substitutes covered a greater overall distance and distance at high-intensities (p<0.01) and had a lower recovery time between high-intensity efforts (p<0.01) compared to other midfield team-mates who remained on the pitch. Forwards covered less distance (p<0.01) in their first 10-min as a substitute compared to their habitual work-rate profile in the opening 10-min when starting matches while this finding was not observed in midfielders. These findings suggest that compared to midfield substitutes, forward substitutes did not utilise their full physical potential. Further investigation is warranted into the reasons behind this finding in order to optimise the work-rate contributions of forward substitutes.

Continuous change in spring-mass characteristics during a 400m sprint

2009-09-30

Abstract: The purpose of the present study was to utilise a spring-mass model to (1) continuously measure vertical stiffness (Kvert) and leg stiffness (Kleg) over an entire 400m sprint, and (2) investigate the relationship between leg spring stiffness (Kvert and Kvert) and the performance characteristics of mean forward running velocity (Vforwad), mean stride frequency (fstride), and mean stride length (Lstride). Eight well-trained male athletes performed a 400m sprint with maximal effort on an outdoor field track. Kvert was calculated from the subjects’ body mass, ground contact time and flight time at each step. Vforwad, fstride and Lstride were determined from video images. Kvert and Vforwad peaked at the 50–100m interval, and consistently decreased from the middle to the later part of the sprint. Kleg peaked at first 50m interval, and remained constant from next 50m interval to finish. As compared with peak values, Kvert and Vforward in the last 50m decreased by about 40% and 25%, respectively. A significant positive linear relationship existed between the Kvert and Vforward. While Kvert was significantly correlated with fstride, it had no correlation with Lstride. Further, no significant positive linear relationship was found between Kleg and Vforward, fstride, or Lstride. This result indicates that in order to keep Vforward at later stage of a 400m sprint, maintaining the higher fstride through retaining a higher Kvert would be necessary.

Energetics and biomechanics as determining factors of swimming performance: Updating the state of the art

2009-09-30

Abstract: The biophysical determinants related to swimming performance are one of the most attractive topics within swimming science. The aim of this paper was to do an update of the “state of art” about the interplay between performance, energetic and biomechanics in competitive swimming. Throughout the manuscript some recent highlights are described: (i) the relationship between swimmer's segmental kinematics (segmental velocities, stroke length, stroke frequency, stroke index and coordination index) and his center of mass kinematics (swimming velocity and speed fluctuation); (ii) the relationships between energetic (energy expenditure and energy cost) and swimmer's kinematics; and (iii) the prediction of swimming performance derived from above mentioned parameters.

The use of a single inertial sensor to identify stride, step, and stance durations of running gait

James B. Lee, Rebecca B. Mellifont, Brendan J. Burkett — 2009-09-30

Abstract: Current developments in inertial sensor technology could enable the measurement of running gait outside of the traditional laboratory environment. The purpose of this research was to determine the level of agreement between an inertial sensor and infrared camera based estimates of stride, step, and stance durations across a range of running speeds. An inertial sensor was placed on the sacrum of 10 elite national standard runners, and the stride, step, and stance of running gait were compared. A total of 504 samples were collected and the running velocities stratified into three equal groups of low (10–12km/h), medium (13–15km/h), and high (16–19km/h). A single inertial sensor was found to be suitable for identifying stride duration with Bland–Altman limits of agreement of 95%. The stride data showed agreement at less than 0.02s for most limits. Agreement for step showed five of the eight upper and lower limits below 0.02s. The largest differences between both capture methods were for stance. An average bias of 0.0008s was found and standard error ranged between 0.0004s and 0.0009s across all variables. The results from this research found that inertial sensors are suitable to measure stride, step, and stance duration, and provide the opportunity to measure running gait outside of the traditional laboratory.

Nutritional supplementation habits and perceptions of elite athletes within a state-based sporting institute

B.J. Dascombe, M. Karunaratna, J. Cartoon, B. Fergie, C. Goodman — 2009-09-30

Abstract: The purpose of this investigation was to examine the nutritional supplement intake of athletes from a state-based sports institute. Athletes (n=72) from seven sports (kayaking, field hockey, rowing, waterpolo, swimming, athletics and netball) completed a questionnaire detailing their daily usage and rationale therefore. The large majority (63/72; 87.5±12.5%) of surveyed athletes reported using nutritional supplements, with no difference between female (31/36; 86.1±13.9%) and male (32/36; 88.9±11.1%) athletes. Kayakers (6.0±2.9) consumed a higher number of nutritional supplements than swimmers (4±2.2), field hockey (1.5±1.0), rowing (2.4±1.4), waterpolo (2.3±2.4), athletics (2.5±1.9) and netball (1.7±1.0) athletes. The athletes believed that nutritional supplements are related to performance enhancements (47/72; 65.3%), positive doping results (45/72; 62.5%), and that heavy training increases supplement requirements (47/72; 65.3%). The cohort was equivocal as to their health risks (40/72; 55.6%) or their need with a balanced diet (38/72; 52.8%). The most popular supplements were minerals (33/72; 45.8%), vitamins (31/72; 43.1%), other (23/72; 31.9%), iron (22/72; 30.6%), caffeine (16/72; 22.2%), protein (12/72; 16.7%), protein–carbohydrate mix (10/72; 13.9%), creatine (9/72; 12.5%) and glucosamine (3/72; 4.2%). The majority of supplementing athletes (n=63) did not know their supplements active ingredient (39/63; 61.9%), side effects (36/63; 57.1%) or mechanism of action (34/63; 54.0%) and admitted to wanting additional information (36/63; 57.0%). Only half of the athletes knew the recommended supplement dosages (33/63; 52.4%). The performance enhancing perception may explain the large proportion of athletes that reported using nutritional supplements, despite over half of the athletes believing that supplements are not required with a balanced diet and can cause positive doping violations.

The effects of omega-3 supplementation on pulmonary function of young wrestlers during intensive training

Bakhtiar Tartibian, Behzad Hajizadeh Maleki, Asghar Abbasi — 2009-09-30

Abstract: The purpose of this study was to examine the effects of omega-3 supplementation on young wrestler's pulmonary function during intensive wrestling training. Forty healthy young male wrestlers participated in this study. The subjects were randomly divided into experimental (n=10), placebo (n=10), active control (n=10) and inactive control (n=10) groups. Participants in experimental, placebo and active control groups performed wrestling incremental training up to 95% of exercise MHR, three times a week, for 12 weeks. The inactive control group did not participate in any exercise training. Subjects in the experimental group were asked to consume omega-3 (1000mg/day for 12 weeks), while those in placebo were refused any doses of omega-3. The pulmonary variables were measured at baseline and at the end of 12 weeks of training program. Results indicated that consuming omega-3 during 12 weeks training had a significantly positive effect on pulmonary variables such as FEV1, FVC, VC, MVV, FEF25–75, FIV1 (p=0.001), but no significant changes were observed in FEV1% (p=0.141) and FIV1% (p=0.117). The results of the present study suggest that consuming omega-3 during intensive wrestling training can improve pulmonary function of athletes during and in post-exercise.