Journal of Science and Medicine in Sport

Editorial Board

2010-07-01

Take what happens on the field seriously

Gregory S. Kolt — 2010-06-04

Playing sport, although fun, can have significant consequences in terms of injury. It is the clear identification of such injury, and its appropriate immediate management, that continues to allow us to have fun and success on the field. I was reminded of this recently when my 11-year-old son ran out onto the field for his first ever game of Australian football. All went well for the first 10min until he found himself in an unfortunate and accidental collision with another player that led him to a state of unconsciousness on the ground. To my surprise from the sideline, play continued around him, no-one really seemed concerned (except of course me), and his team proceeded to score a goal and celebrate. On recognising what had happened, I raced out onto the ground and within 5s he had gained consciousness but clearly had no idea where he was or how he got there. On recognising the symptoms and significance of the event, I removed him from the field and ran through a series of tests and confirmed concussion. What surprised me further was the encouragement of many around him (mainly adults) to simply give him a rest and get him back on the field after half-time. Needless to say, I did not follow this advice but rather went down the path of appropriate medical management – he thankfully recovered in a very textbook like manner. By the time his next game came around several weeks later he played a brilliant game and received the best-on-ground award.

Stop injecting corticosteroid into patients with tennis elbow, they are much more likely to get better by themselves!

Hamish Osborne — 2009-11-30

Tennis elbow is a common presentation to family practitioners and various medical specialists. Injectable corticosteroids have been used and continue to be used as one of the mainstays of treatment for tennis elbow. This is in spite of the fact that shortcomings have existed regarding its use since one of the earliest published clinical trials. Seven of thirteen patients injected had recurrence of symptoms during follow-up studies of at least 6 months with only 38% obtaining permanent relief.

The effect of footwear and sports-surface on dynamic neurological screening for sport-related concussion

2010-03-15

Abstract: The Sport Concussion Assessment Tool (SCAT) is a standardised global assessment for the identification of sport-related concussion (SRC). An integral component of the SCAT is the neurological screen, which contains the assessment of motor performance including gait evaluation. However, it is not known how performance of gait is affected by the surface/footwear interactions encountered in various sporting environments. The purpose of this study was to investigate the effect of footwear and sporting surface on the time to perform a standardised Tandem Gait (TG) task. One hundred and eight amateur athletes were recruited, and three common sports-surfaces (grass, hardwood court, artificial turf) were compared. All groups were tested barefoot and with sports-surface specific footwear. Mixed model ANOVA, controlling for covariates and including a post hoc Bonferroni procedure, was used to investigate the influence of footwear and sports-surface on TG time. The study demonstrated that times for a defined TG task in healthy athletes depended on footwear, sports-surface, and the specific athletic population. The study demonstrated a significant interaction (F2,104=3.35, p=0.039) between groups (grass, hardwood court and artificial turf), and times were faster wearing footwear compared to barefoot (F2,138=26.31, p=0.001). In contrast to the footwear conditions, there was no statistical difference between the barefoot conditions on any of the sport-surfaces. These findings suggest that clinicians should standardise footwear and the testing surface at baseline in order to accurately assess motor performance tests when SRC is suspected.

Bone properties in child and adolescent male hockey and soccer players

2009-09-30

Abstract: Children and adolescents who train extensively in high-impact, weight-bearing activities have enhanced bone mineral density. The purpose of this study was to evaluate bone strength, as reflected by quantitative ultrasound (QUS, Sunlight Omniscence), of child (10–12 yrs old) and adolescent (14–16 yrs old) male soccer and hockey players in comparison with age-matched controls. The groups included 30 child (CH) and 31 adolescent (AH) hockey players, 26 child (CS) and 30 adolescent (AS) soccer players, as well as 34 child (CC) and 31 adolescent (AC) healthy, non-athletic, age-matched controls. All athletes trained at an elite level year-round, with no difference in training volume between groups. Ultrasound speed of sound (SOS) was measured at the distal-radius and mid-tibia. In both age groups, hockey players were the heaviest and had the highest fat-free mass. No differences were found among groups in total energy intake, calcium or vitamin D intake. Radial and tibial SOS increased with age. Hockey players had higher radial SOS in both age groups (children: CH:3763±74, CS:3736±77, CC:3721±88m/s; adolescents: AH:3809±105, AS:3767±85, AC:3760±94m/s). Tibial SOS was higher in soccer players compared with controls. In spite of the higher body mass and fat-free mass in hockey players, their tibial SOS was similar to the non-athletes in both age groups. These findings support previous suggestions of sport-specific effects on bone strength. However, they need to be corroborated with longitudinal or prospective intervention studies.

Reduced humeral torsion predicts throwing-related injury in adolescent baseballers

Rod J. Whiteley, Roger D. Adams, Leslie L. Nicholson, Karen A. Ginn — 2009-09-30

Abstract: The amount of torsion in the humerus is determined by both genetic and activity-related factors, and affects the external rotation range of motion available at the shoulder. Previous research has shown athletes participating in throwing sports to have a greater amount of humeral retrotorsion in their dominant arm. The purpose of this study was to investigate the predictive ability of both the genetic and activity-related aspects of humeral torsion regarding throwing-related injury. The amount of humeral torsion in both arms of 35 high level adolescent male baseballers (mean age 16.6 years±0.6 years) was measured at study commencement. Significantly increased humeral retrotorsion in the dominant arm compared to the non-dominant arm was found (p=0.04). These athletes were followed for a period of 30 months, and any injury to their throwing arm which resulted in missing either a game or practice was recorded. ROC curve analysis was used to determine the predictive ability of humeral torsion with respect to the occurrence of injury to the throwing arm. Of the 35 athletes, 19 suffered a throwing arm injury. AUC values derived from ROC analysis showed humeral torsion in the non-dominant arm (AUC: 0.679, 95% CI: 0.502–0.857), as well as the average of the humeral torsion in both arms (0.692, 0.512–0.873), to be predictive of injury. Torsion in the dominant arm was not a significant throwing arm injury predictor. Thus non-dominant arm humeral torsion (the genetic contribution) was found to be the predictor of throwing arm injury.

Factors associated with increased propensity for hamstring injury in English Premier League soccer players

Gary Henderson, Christopher A. Barnes, Matthew D. Portas — 2009-10-05

Abstract: The aim of this study was to concurrently model the influence of a number of physical and performance parameters on subsequent incidence of hamstring injury in a squad of English Premier League soccer players. Thirty six healthy, male, elite, professional soccer players (age 22.6±5.2 years, height 1.81±0.08m, mass 75.8±9.4kg, lean mass 69.0±8.0kg) were assessed during the first week of pre-season training for anthropometry, flexibility, lower limb strength and power, speed and agility. Over the subsequent 45 week competitive season all hamstring injuries were diagnosed and recorded. Multiple logistic regression analysis was performed to link individual physical and performance capabilities with propensity to sustain a hamstring injury. A model containing age, lean mass, non-counter movement jump (NCM) performance and active hip flexion range of movement (ROM) was significantly (p<0.05) associated with increased propensity for hamstring injury. Odds for sustaining an injury increased ×1.78 for each 1 year increase in age, ×1.47 for each 1cm increase in NCM and ×1.29 for each 1° decrease in active range of hip flexion. Older, more powerful and less flexible soccer players are at greater risk of sustaining a hamstring injury. Support staff should identify such individuals and make appropriate interventions to minimise risk without compromising performance capabilities.

Parent influences on preschoolers’ objectively assessed physical activity

Melody Oliver, Grant M. Schofield, Philip J. Schluter — 2009-09-30

Abstract: The purposes of this study were to examine the relationship between accelerometer-derived physical activity (PA) in preschoolers and their parents, and to investigate other potential child and parental associates of child PA. Families of children aged 2–5 yrs were recruited in Auckland, New Zealand, from October 2006 to July 2007. Consenting children and parents had their height, weight, and waist circumference measured and were asked to wear accelerometers over 7 consecutive days, measuring PA in 15s epochs. Accelerometer data were gathered from 78 children, 62 mothers and 20 fathers over a median of 6.5–7 days, and converted to estimated daily PA rates for each individual using negative binomial generalised estimating equation (GEE) modelling. Potential associates of children's daily PA rates were then assessed using normal GEE models with exchangeable correlation structures. After taking account of all factors in the final multivariable model, parental PA rates (coefficient 0.09, 95% CI 0.03, 0.16, P=0.01) and child age (coefficient 0.11, 95% CI 0.01, 0.21, P=0.03) were the only factors significantly associated with child PA rates. Younger children may stand to benefit from PA intervention, and encouraging parental involvement in preschool PA interventions may be useful for increasing PA levels in young children. More work in this field is needed to corroborate these findings, improve generalisability, and determine causality.

Mortality and longevity of elite athletes

Masaru Teramoto, Timothy J. Bungum — 2009-09-30

Abstract: The health benefits of leisure-time physical activity are well known, however the effects of engaging in competitive sports on health are uncertain. This literature review examines mortality and longevity of elite athletes and attempts to understand the association between long-term vigorous exercise training and survival rates. Fourteen articles of epidemiological studies were identified and classified by type of sport. Life expectancy, standardised mortality ratio, standardised proportionate mortality ratio, mortality rate, and mortality odds ratio for all causes of death were used to analyse mortality and longevity of elite athletes. It appears that elite endurance (aerobic) athletes and mixed-sports (aerobic and anaerobic) athletes survive longer than the general population, as indicated by lower mortality and higher longevity. Lower cardiovascular disease mortality is likely the primary reason for their better survival rates. On the other hand, there are inconsistent results among studies of power (anaerobic) athletes. When elite athletes engaging in various sports are analysed together, their mortality is lower than that of the general population. In conclusion, long-term vigorous exercise training is associated with increased survival rates of specific groups of athletes.

Factors affecting walking activity of older people from culturally diverse groups: An Australian experience

2009-10-15

Abstract: This study sought to investigate the walking habits of older people from diverse cultural backgrounds, and to identify the factors associated with their walking. Three hundred and thirty three people over the age of 60 years were recruited from seven culturally diverse groups from the Western suburbs of Melbourne, Australia. A survey questionnaire recording physical activity, and various factors related to activity, was interviewer-administered in the participants’ preferred language. Data were analysed using Kruskal–Wallis, χ2 and Mann–Whitney tests. Forty-seven percent of the participants walked at least 150min per week, with no significant difference in prevalence between genders or cultural groups. Some cultural differences were found in relation to reasons and locations for walking, and women were more likely than men to report walking in the shopping mall, whilst men were more likely than women to report walking in the park and along walking trails. Those who attained >150min of walking were more likely to report health and fitness as reasons for walking, to perceive their walking environment as more pleasurable, to use walking trails, and to consider their environment safe and to facilitate social interaction. This study indicates that the continued advocating of walking as a health promoting activity should be central to future campaigns to increase physical activity in this age group. The provision of locations that are accessible, safe, aesthetically pleasing, and encourage social engagement are likely to facilitate older people's participation in walking. For maximum effectiveness, however, strategies may benefit from being tailored to meet specific gender and cultural preferences.

Serum collagen-derived peptides are unaffected by physical training in older sedentary subjects

Véronique A. Cornelissen, Robert H. Fagard, Paul J. Lijnen — 2009-10-08

Abstract: Cardiac fibrosis occurs with normal aging and may have important pathological consequences. Accumulating evidence shows that biochemical assessment of fibrosis using collagen markers such as serum levels of the aminoterminal propeptide of types I and III collagen (PINP, PIIINP) and the carboxyterminal telopeptide of type I collagen (ICTP) represents a practical, validated and non-invasive method to assess myocardial collagen turnover. It is generally accepted that a sedentary lifestyle may be at least partly responsible for the age-related changes in the cardiovascular system. We aimed to investigate whether dynamic aerobic endurance training at lower or higher intensity (33% and 66% of heart rate reserve) may influence markers of collagen synthesis (PINP, PIIINP) and degradation (ICTP) in at least 55-year-old healthy sedentary men and women. A randomised crossover study comprising three 10-week periods was performed. In the first and third period, participants exercised at, respectively, lower or higher intensity in random order, with a sedentary period in between. Training programs were identical except for intensity and were performed three times 50min/week. 39 (18 men) out of 48 randomised participants completed the study; age averaged 59 years. Serum concentrations of PINP, PIIINP and ICTP were determined at baseline and at the end of each 10-week period. Our results showed that 10 weeks of endurance training at lower or higher intensity did not significantly alter serum markers of collagen synthesis and degradation in healthy older men and women.

Strength increases in upper and lower body are larger with longer inter-set rest intervals in trained men

2009-10-08

Abstract: The purpose of the current study was to compare different rest interval durations on upper and lower body strength. Thirty-six recreationally trained men were randomly assigned to 1min (G1; n=12), 3min (G3; n=12) or 5min (G5; n=12) rest interval groups. Each group performed the same resistance training program. Maximal strength was assessed at baseline, mid-point (8 weeks) and post-training (16 weeks) for the bench press and leg press exercises. For the bench press, significant increases were demonstrated within G3 and G5 at 8 weeks and at 16 weeks versus baseline (p<0.05). Additionally, for the bench press, G5 (98.2±3.7kg) was significantly stronger than G1 (92.5±3.8kg) at 16 weeks (p<0.05). For the leg press, significant increases were demonstrated within all groups at 8 weeks and at 16 weeks versus baseline (p<0.05). Additionally, for the leg press, G5 (290.8±23.5kg) was significantly stronger than G1 (251.0±15.8kg) at 8 weeks (p<0.01) and G3 (305.0±23.9kg) and G5 (321.7±21.7kg) were significantly stronger than G1 (276.7±10.7kg) at 16 weeks (p<0.05). The findings of the current study indicate that utilising 3 or 5min rest intervals between sets may result in significantly greater increases in upper and lower body strength beyond the initial weeks of training versus utilising 1-min rest intervals between sets.

Relationship between rowing ergometer performance and physiological responses to upper and lower body exercises in rowers

2009-10-19

Abstract: The aim of this investigation was to compare the physiological responses of 2000m rowing ergometer test with 7-min bench pull and leg press tests. We hypothesised that leg press exercise contributes to 2000m rowing ergometer test results, rather than bench pull performed by arms. College level rowers (n=12) performed 2000m rowing test and after one day 7-min bench pull and leg press (50% from the 1 RM). Stroke rate, heart rate (HR), blood lactate (LA) and ratings of perceived exertion (RPE) were measured during all tests. The number of repetitions was highest during 2000m rowing test (194.2±19.5) and lowest during bench pull (122.6±17.7) (during leg press 173.5±11.8). Differences between 2000m rowing test, leg press and bench pull tests were significant in mean and maximal HR. In LA concentration, the highest values were at 3rd min of recovery after rowing test (14.8±1.7mmoll−1). Between bench pull (8.8±1.9 and 8.5±2.7mmoll−1) and leg press (11.8±2.5 and 11.2±2.3mmoll−1) tests, the difference in LA concentration was not significant (p>0.05). Ratings of perceived exertion were highest in 2000m rowing test (19.3±0.9), difference with leg press and bench pull tests was not significant. There were significant relationships in mean and maximal HR (r=0.713–0.767) and Borg scale (r=0.764) during rowing test and leg press. The number of repetitions during leg press exercise correlated significantly with rowing test time (r=−0.677). In conclusion, this study suggests that in rowers there are major differences in the physiological adaptation to upper body and leg exercise, performed at similar intensities. Leg press exercise could be used to measure sport-specific strength endurance in rowers.

The acute effects of different whole-body vibration amplitudes and frequencies on flexibility and vertical jumping performance

2009-10-23

Abstract: Frequency and amplitude determine the training load of whole-body vibration (WBV) exercise and thereby possible neuromuscular adaptations. We investigated the effects of amplitude and frequency of a single bout of WBV on flexibility and squat jump performance (SJ) and the time-course of these effects. In the amplitude study, twenty-five females performed three vibration protocols (VPs) for 6min at frequency of 25Hz and amplitudes of 4mm, 6mm, and 8mm and one control protocol (CP). In the frequency study, eighteen females performed three VPs at 6mm amplitude and frequencies of 15Hz, 20Hz, and 30Hz and one CP. Flexibility and SJ were measured before, immediately-post and 15min recovery. All protocols were performed on a side-to-side alternating vibration plate. In the amplitude study, flexibility was improved (p<0.01) immediately-post in VP4, VP6, VP8 (31.8±8.2, 31.9±7.6, 31.5±7.9, respectively) and at 15min recovery (31.6±8.1, 31.5±7.9, 31.0±8.2, respectively) vs. pre-vibration (30.2±8.6, 30.3±8.1, 30.2±8.3, respectively), but remained unchanged in CP (30.6±8.3 immediately-post, 30.7±8.2 at 15min vs. 30.4±8.2 pre-vibration). In the frequency study, flexibility was improved (p<0.01) immediately-post in VP15, VP20, VP30 (31.5±5.2, 31.3±5, 31.7±5.3, respectively) and at 15min recovery (31.3±5.4, 31.3±5.0, 31.3±5.3, respectively) vs. pre-vibration (30.6±5.4, 30.2±5.7, 30.3±5.9, respectively), but not in CP (30.7±5.1 immediately-post, 30.6±5 at 15min vs. pre-vibration 30.5±5.7). There were no significant effects of amplitude or frequency on SJ. In conclusion, a single WBV bout using a side-to-side alternating vibration plate may increase flexibility which persists for at least 15min, without altering jumping performance. These effects were observed irrespective of frequency and amplitude.

Hydrodynamic glide efficiency in swimming

Roozbeh Naemi, William J Easson, Ross H Sanders — 2009-09-30

Abstract: The glide is a major part of starts, turns and the stroke cycle in breaststroke. Glide performance, indicated by the average velocity, can be improved by increasing the glide efficiency, that is, the ability of the body to minimise deceleration. This paper reviews the factors that affect glide efficiency. In the first part of the review the sources of resistive force are reviewed including surface friction (skin drag), pressure (form) drag and resistance due to making waves (wave drag). The effect of body surface characteristics on the skin drag, the effect of the depth of the swimmer on wave drag, and the effects of posture and alignment, body size and shape on the form drag are reviewed. The effects of these variables on the added mass, that is, the mass of water entrained with the body are explained. The ‘glide factor’ as a measure of glide efficiency that takes into account the combined effect of the resistive force and the added mass is described. In the second part methods of quantifying the resistive force are reviewed. Finally, the ‘hydro-kinematic method’ of measuring glide efficiency is evaluated.

Comparison of segmental linear and angular momentum transfers in two-handed backhand stroke stances for different skill level tennis players

Lin-Hwa Wang, Hwai-Ting Lin, Kuo-Cheng Lo, Yung-Chun Hsieh, Fong-Chin Su — 2009-10-19

Abstract: The purpose of this study was to investigate the differences of momentum transfer from the trunk and upper extremities to the racket between open and square stances for different skill levels players in the two-handed backhand stroke. The motion capture system with twenty-one reflective markers attached on anatomic landmarks of the subject was used for two-handed backhand stroke motion data collection. Twelve subjects were divided into an advanced group and an intermediate group based on skill level. The three-dimensional linear and angular momentums of the trunk, upper arm, forearm, hand and racket were used for kinetic chain analysis. Results showed that all players with the square stance had significantly larger backward linear momentum contribution in trunk and upper arm than with the open stance (p<.05) irrespective of playing level. However, the external rotation angular momentum of the shoulder joint was significantly larger with an open stance than with a square stance (p=.047). Comparison of playing levels showed that the intermediate group performed higher linear momentum in three components of the trunk, upper arm backward linear momentum, and trunk right bending angular momentum than the advanced group significantly (p<.05). The advanced group reduces trunk linear movement to keep stability and applies trunk and linkage segment rotation to generate backhand stroke power. The advanced group also has a quick backswing for increasing acceleration and maintains longer in the follow-through phase for shock energy absorption. This information could improve training protocol design for teaching the two-handed backhand stroke and teaching players, especially beginners, how to make an effective stroke.

Change in running kinematics after cycling are related to alterations in running economy in triathletes

2010-04-01

Abstract: Emerging evidence suggests that cycling may influence neuromuscular control during subsequent running but the relationship between altered neuromuscular control and run performance in triathletes is not well understood. The aim of this study was to determine if a 45min high-intensity cycle influences lower limb movement and muscle recruitment during running and whether changes in limb movement or muscle recruitment are associated with changes in running economy (RE) after cycling. RE, muscle activity (surface electromyography) and limb movement (sagittal plane kinematics) were compared between a control run (no preceding cycle) and a run performed after a 45min high-intensity cycle in 15 moderately trained triathletes. Muscle recruitment and kinematics during running after cycling were altered in 7 of 15 (46%) triathletes. Changes in kinematics at the knee and ankle were significantly associated with the change in VO2 after cycling (p<0.05). The change in ankle angle at foot contact alone explained 67.1% of the variance in VO2. These findings suggest that cycling does influence limb movement and muscle recruitment in some triathletes and that changes in kinematics, especially at the ankle, are closely related to alterations in running economy after cycling.

Adaptations to skeletal muscle with endurance exercise training in the acutely fed versus overnight-fasted state

Stephen R. Stannard, Alex J. Buckley, Johann A. Edge, Martin W. Thompson — 2010-05-10

Abstract: Minimising carbohydrate (CHO) status in the peri-training period may accelerate the training adaptations normally observed. The aim of this study was to compare adaptations to endurance training undertaken in the acutely CHO fed and overnight-fasted states. Eight female and six male untrained, healthy participants: aged 26.6±5.8 years (mean±SD); height 174.7±7.6cm; weight 75.3±11.4kg; VO2max 3.48±0.67l/min; were randomly divided into two training groups and undertook four weeks of five days per week endurance cycle ergometer training in either the overnight-fasted (FAST) or acutely fed (FED) state. FAST training had no effect on RER or plasma glucose, lactate and FFA concentrations during subsequent submaximal exercise. Training-induced changes in Vastus lateralis citrate synthase (CS) and 3-hydroxy-CoA dehydrogenase (HAD) activities were not different between training groups (P=0.655 and 0.549, respectively), but when the effect of gender was considered, men responded better to FAST and women responded better to FED. The FAST group showed a significantly greater training-induced increase in VO2max and resting muscle glycogen concentration than FED (P=0.014 and P=0.047 respectively), but there was no gender interaction. In conclusion, these results suggest that (a) meal ingestion prior to daily exercise can modify some of the exercise training-induced adaptations normally seen with endurance training compared to when daily exercise is undertaken in the overnight-fasted state; and (b) the extent of these adaptations in skeletal muscle differ slightly between men and women.

Johann (Hans) A. Edge, PhD (1973–2010)

Stephen R. Stannard — 2010-05-17

It is with great regret that we report the untimely and premature death of our friend, colleague, and Editorial Board member Dr. Johann (Hans) Edge. Hans was tragically killed in March this year when riding his bicycle home from work at the University of Auckland in New Zealand. Hans was widely recognised as an up-and-coming ‘star’ in his chosen research area of skeletal muscle metabolism, specifically the effects of acidosis and training on skeletal muscle buffer capacity, and more recently, the biochemical and mechanisms behind adaptations to training in muscle.