Sodium supplementation is not required to maintain serum sodium concentrations during an Ironman triathlon

Context

Critical assessment of recommendations that athletes consume additional sodium during athletic events.

Objective

To evaluate if sodium supplementation is necessary to maintain serum sodium concentrations during prolonged endurance activity and prevent the development of hyponatraemia.

Design

Prospective randomised trial of athletes receiving sodium (620 mg table salt), placebo (596 mg starch), or no supplementation during a triathlon. The sodium and placebo tablets were taken ad libitum, with the suggested range of 1–4 per hour.

Setting

The 2001 Cape Town Ironman triathlon (3.8 km swim, 180 km cycle, 42.2 km run).

Subjects

A total of 413 triathletes completing the Ironman race.

Main outcome measures

Sodium supplementation was not necessary to maintain serum sodium concentrations in athletes completing an Ironman triathlon nor required to prevent hyponatraemia from occurring in athletes who did not ingest supplemental sodium during the race.

Results

Subjects in the sodium supplementation group ingested an additional 3.6 (2.0) g (156 (88) mmol) sodium during the race (all values are mean (SD)). There were no significant differences between the sodium, placebo, and no supplementation groups with regard to age, finishing time, serum sodium concentration before and after the race, weight before the race, weight change during the race, and rectal temperature, systolic and diastolic blood pressure after the race. The sodium supplementation group consumed 14.7 (8.3) tablets, and the placebo group took 15.8 (10.1) tablets (p  =  0.55; NS).

Conclusions

Ad libitum sodium supplementation was not necessary to preserve serum sodium concentrations in athletes competing for about 12 hours in an Ironman triathlon. The Institute of Medicine''s recommended daily adequate intake of sodium (1.5 g/65 mmol) seems sufficient for a healthy person without further need to supplement during athletic activity.     

Core temperature and hydration status during an Ironman triathlon

Background

Numerous laboratory based studies have documented that aggressive hydration strategies (∼1–2 litres/h) are required to minimise a rise in core temperature and minimise the deleterious effects of hyperthermia on performance. However, field data on the relations between hydration level, core body temperature, and performance are rare.

Objective

To measure core temperature (T_core) in triathletes during a 226 km Ironman triathlon, and to compare T_core with markers of hydration status after the event.

Method

Before and immediately after the 2004 Ironman Western Australia event (mean (SD) ambient temperature 23.3 (1.9)°C (range 19–26°C) and 60 (14)% relative humidity (44–87%)) body mass, plasma concentrations of sodium ([Na⁺]), potassium ([K⁺]), and chloride ([Cl⁻]), and urine specific gravity were measured in 10 well trained triathletes. T_core was measured intermittently during the event using an ingestible pill telemetry system, and heart rate was measured throughout.

Results

Mean (SD) performance time in the Ironman triathlon was 611 (49) minutes; heart rate was 143 (9) beats/min (83 (6)% of maximum) and T_core was 38.1 (0.3)°C. Body mass significantly declined during the race by 2.3 (1.2) kg (−3.0 (1.5)%; p<0.05), whereas urine specific gravity significantly increased (1.011 (0.005) to 1.0170 (0.008) g/ml; p<0.05) and plasma [Na⁺], [K⁺], and [Cl⁻] did not change. Changes in body mass were not related to finishing T_core (r  =  −0.16), plasma [Na⁺] (r  =  0.31), or urine specific gravity (r  =  −0.37).

Conclusion

In contrast with previous laboratory based studies examining the influence of hypohydration on performance, a body mass loss of up to 3% was found to be tolerated by well trained triathletes during an Ironman competition in warm conditions without any evidence of thermoregulatory failure.     

Raised troponin T and echocardiographic abnormalities after prolonged strenuous exercise--the Australian Ironman Triathlon

Background

There is concern about whether cardiac damage occurs as a result of prolonged strenuous exercise.

Objective

To investigate whether competing in a triathlon is associated with cardiac damage based on a sustained increase in cardiac troponin T (cTnT), and whether such an increase correlates with echocardiographic changes

Methods

cTnT and echocardiographic measurements were made in 38 participants in the 2001 Australian ironman triathlon. cTnT was measured the day before, immediately after, and the day following the race. Echocardiography was done the day before, immediately after, and two to six weeks later for measurement of ejection fraction, stroke volume, cardiac output, wall motion analysis, and global left ventricular function (LVF).

Results

No subject had detectable cTnT in the pre‐race sample. Following the race, 32 subjects (86.5%) had detectable levels of cTnT (>0.01 ng/ml), with six (16.2%) having >0.10 ng/ml. The day after the race, nine subjects (23.7%) still had detectable cTnT, with two recording a level >0.10 ng/ml. Previously described echocardiographic changes of “cardiac fatigue” were observed in the whole cohort. There was a modest but significant correlation between change in ejection fraction and peak cTnT level (p = 0.02, r = 0.39). Athletes with a post‐race cTnT >0.10 ng/ml had a greater decrease in global LVF (p = 0.02) and a trend toward a greater fall in ejection fraction and stroke volume than athletes with cTnT levels <0.10 ng/ml. Cardiac output fell in the group with cTnT >0.10 ng/ml (p>0.05).

Conclusions

Participation in ironman triathlon often resulted in persistently raised cTnT levels, and the troponin rise was associated with echocardiographic evidence of abnormal left ventricular function. The clinical significance and long term sequelae of such damage remains to be determined.     

Preload maintenance protects against a depression in left ventricular systolic, but not diastolic, function immediately after ultraendurance exercise

Objective

To investigate indices of left ventricular (LV) function before and after a 224 km Ironman triathlon, specifically in the presence of unaltered haemodynamic loading.

Method

LV loading and function were assessed before and after the race using M mode and Doppler echocardiography in 39 (mean (SD) age 33 (8) years, body mass 77.6 (8.6) kg; 36 male) triathletes in the Trendelenburg position. Specifically left ventricular end diastolic volume (LVEDV) was assessed to estimate preload, and systolic blood pressure to estimate afterload as well as heart rate (HR). Systolic functional indices included ejection fraction (EF) and the end systolic pressure/volume ratio (ESPV), and diastolic functional indices included peak mitral flow velocity in early (E) and atrial (A) filling as well as the ratio E/A. Data obtained before and after the race were compared by t tests, and delta LV functional indices were correlated with delta heart rate.

Results

Preload (LVEDV: 143 (34) ml before v 147 (34) ml after) and afterload (systolic blood pressure 121 (13) v 115 (20) mm Hg) were not significantly altered after the race (p>0.05), nor were EF (61 (8)% v 58 (10)%) and ESPV (2.4 (0.9) v 2.1 (0.8) mm Hg/cm³). The diastolic filling ratio E/A was significantly reduced after the race (1.73 (0.25) v 1.54 (0.23); p<0.05) due primarily to a reduction in E. HR was significantly higher after the race (57 (9) v 75 (8) beats/min; p<0.05), but delta HR was not related to delta E/A (p>0.05).

Conclusion

When preload and afterload are unaltered after the race, because of the adoption of a unique assessment posture, LV systolic function is not depressed. A depression in LV diastolic function persists which is not explained by an increase in heart rate after the race.     

Nitric oxide synthase-derived plasma nitrite predicts exercise capacity

Background

Nitrite is the main oxidation product of nitric oxide (NO) in plasma. It sensitively reflects changes in endothelial NO synthase (eNOS) activity under fasting conditions and serves as an endocrine NO donor, contributing to the regulation of blood flow through reaction with haemoglobin. As NO is necessary to maintain an adequate vascular response to the increased demands of blood flow, it is believed to be important for vasodilation induced by exercise.

Objective

To investigate whether the capacity of the vasculature to produce nitrite is associated with exercise performance.

Design

With the use of chemiluminescence detection, nitrite concentrations in 55 healthy subjects (mean (SEM) age 40 (2) years; 22 men) were studied before and after an exercise test, and endothelial function was determined by measuring flow‐mediated dilation of the brachial artery using high‐resolution ultrasound. In a subset of subjects, the NOS inhibitor, N^G‐monomethyl‐l‐arginine, was applied to elucidate the effect of eNOS on changes in nitrite.

Results

Exercise significantly (p<0.001) increased plasma nitrite from 97 (6) to 125 (8) nM. The relative increase in plasma nitrite was related to flow‐mediated dilation (6.1 (0.3)%; r = 0.36; p = 0.01). N^G‐Monomethyl‐l‐arginine blocked increases in nitrite. Post‐exercise nitrite concentration correlated with exercise performance, as determined by maximally reached stress power (r = 0.37; p<0.007), and inversely with age. Multivariate analysis showed that both age and post‐exercise nitrite concentration were independent predictors of stress endurance and power.

Conclusion

The results suggest a role for plasma nitrite in the adaptation of haemodynamics during exercise. An impaired increase in plasma nitrite may limit exercise capacity.     

Maximal lipidic power in high competitive level triathletes and cyclists

Objective

To describe the fat‐oxidation rate in triathlon and different modalities of endurance cycling.

Methods

34 endurance athletes (15 male triathletes, 4 female triathletes, 11 road cyclists and 4 male mountain bikers) underwent a progressive cycloergometer test until exhaustion. Relative work intensity (VO_2max), minimal lactate concentration (La⁻_min), lactic threshold, individual lactic threshold (ILT), maximal fat‐oxidation rate (Fat_max, Fat_max zone) and minimal fat‐oxidation rate (Fat_min) were determined in each of the groups and were compared by means of one‐way analysis of variance.

Results

No significant differences were found for Fat_max, Fat_min or for the Fat_max zone expressed as fat oxidation rate (g/min). Intensities −20%, −10% and −5% Fat_max were significantly lower for mountain bikers with respect to road cyclists and female triathletes, expressed as % VO_2max. Intensities 20%, 10% and 5% Fat_max were significantly lower for mountain bikers with respect to male triathletes and female triathletes, and for male triathletes in comparison with female triathletes, expressed as % VO_2max. Lactic threshold and La⁻_min did not show significant differences with respect to Fat_max. Lactic threshold was found at the same VO_2max with respect to the higher part of the Fat_max zone, and La⁻_min at the same VO_2max with respect to the lower part of the Fat_max zone.

Conclusions

The VO_2max of Fat_max and the Fat_max zone may explain the different endurance adaptations of the athletes according to their sporting discipline. Lactic threshold and La⁻_min were found at different relative work intensities with respect to those of Fat_max even though they belonged to the Fat_max zone.Fat and carbohydrates (CHO) are the main energetic substrates of aerobic metabolism that resynthesise the ATP in the skeletal muscle. The relative use of fat and CHO during exercise may vary in an important way and depends fundamentally on the maximal oxygen uptake VO_2max.¹ Moreover, it should be taken into account that, during exercise, women oxidise more intramuscular triglycerides than men,² and use less muscle glycogen.³In endurance specialities, having a large capacity to metabolise CHO is a determining factor for performance, but so is the ability to economise this substrate as an effect of a greater capacity to use fat.⁴ It has been observed that athletes have a lower fat‐oxidation rate at low and high intensities compared with moderate intensities.^1,5 Also, there is a relative individual intensity at which the maximal fat‐oxidation rate is produced.Until recently, the methods followed by some authors only measured the athletes fat‐oxidation rate in a reduced number of work intensities: two,^5,6,7 three^1,8,9 or four.¹⁰ Now there is a method to measure the fat‐oxidation rate for each of the relative work intensities, by means of indirect calorimetry and using stoichiometric equations.¹¹ However, this method has only been applied in a few studies carried out with cyclists.^11,12,13Some authors have observed that cycling endurance performance at a concrete work intensity improves with a training focused on this intensity.¹⁴ After this principle (training specificity), other authors have observed that the fat‐oxidation rate increases specifically for the concrete intensity that has been trained.⁷ Thus, differences in the training of triathlon and cycling endurance modalities may produce different adaptations of the fat‐oxidation rate at each of the aerobic work intensities.The aim of this study was to use a cross‐sectional design to describe the fat‐oxidation rate in different modalities of endurance cycling and triathlon (mountain biking and road cycling in men, and short distance men''s and women''s triathlon), where the pace of the race is developed at different relative work intensities.     

Ibuprofen does not affect serum electrolyte concentrations after an ultradistance run

Objective

To determine the effects of ibuprofen on serum electrolyte concentrations after a 160 km running race.

Methods

Twenty nine subjects (mean (SD) age 47.9 (7.4) years) ingested 600 mg ibuprofen the day before, and 1200 mg ibuprofen during, a 160 km competitive trail running race (approximately every 4 h in 200 mg doses). Twenty five control subjects (mean (SD) age 46.8 (10.3) years) avoided ingestion of ibuprofen before or during the race. Blood was drawn on the day before the race and immediately after the race. Serum biochemical profiles were analysed by a clinical laboratory. Significant effects of treatment and time were determined with a general linear model with repeated measures.

Results

Subjects in the two groups did not differ by age, training volume, race experience, body mass index, body fat, or finishing time (25.8 (3.3) vs 25.6 (3.9) h). Body weight did not change significantly over the race (measured before, mid‐race (90 km), and after). Ibuprofen ingestion did not significantly affect any of the serum markers including creatine kinase (p = 0.16). A significant decrease in serum sodium (p = 0.006), potassium (p = 0.001), chloride (p<0.001), calcium (p<0.001), albumin (p<0.001) and globulin (p<0.001) was observed after the race. Increases were seen in creatine kinase (p<0.001), creatinine (p<0.001), blood urea nitrogen (p<0.001), uric acid (p<0.001) and glucose (p<0.001) as the result of the race.

Conclusions

These data suggest that the non‐specific cyclo‐oxygenase inhibitor, ibuprofen, does not alter serum electrolyte concentrations during ultradistance running. However, the stress of ultradistance running appears to be related to significant changes in certain serum markers.     

Regional bone mineral density in male athletes: a comparison of soccer players, runners and controls

Objectives

To investigate the association of soccer playing and long‐distance running with total and regional bone mineral density (BMD).

Design

Cross‐sectional study.

Setting

Academic medical centre.

Participants

Elite male soccer players (n = 15), elite male long‐distance runners (n = 15) and sedentary male controls (n = 15) aged 20–30 years.

Main outcome measurements

BMD (g/cm²) of the lumbar spine (L1–L4), right hip, right leg and total body were assessed by dual‐energy x‐ray absorptiometry, and a scan of the right calcaneus was performed with a peripheral instantaneous x‐ray imaging bone densitometer.

Results

After adjustment for age, weight and percentage body fat, soccer players had significantly higher whole body, spine, right hip, right leg and calcaneal BMD than controls (p = 0.008, p = 0.041, p<0.001, p = 0.019, p<0.001, respectively) and significantly higher right hip and spine BMD than runners (p = 0.012 and p = 0.009, respectively). Runners had higher calcaneal BMD than controls (p = 0.002). Forty percent of the runners had T‐scores of the lumbar spine between −1 and −2.5. Controls were similar: 34% had T‐scores below −1 (including 7% with T‐scores lower than −2.5).

Conclusions

Playing soccer is associated with higher BMD of the skeleton at all sites measured. Running is associated with higher BMD at directly loaded sites (the calcaneus) but not at relatively unloaded sites (the spine). Specific loading conditions, seen in ball sports or in running, play a pivotal role in skeletal adaptation. The importance of including an appropriate control group in clinical studies is underlined.     

Serum concentrations of two biochemical markers of brain tissue damage S-100B and neurone specific enolase are increased in elite female soccer players after a competitive game

Background

It is a matter of debate whether or not ordinary heading of the ball in soccer causes injury to brain tissue.

Objective

To analyse concentrations of the biochemical markers of brain tissue damage S‐100B and neurone specific enolase (NSE) in serum of female elite soccer players in association with a competitive game.

Methods

Venous blood samples were obtained from 44 female soccer players before and after a competitive game for analysis. The number of headers and trauma events (falls, collisions, etc) was assessed from videotape recordings for each player.

Results

Concentrations of both brain damage markers were increased after the game (S‐100B, 0.18 (0.11) v 0.11 (0.05) μg/l (p  =  0.000); NSE, 10.14 (1.74) v 9.05 (1.59) μg/l (p  =  0.001)). There was a significant correlation between changes in S‐100B concentrations and both the number of headers (r  =  0.430, p  =  0.004) and the number of other trauma events (r  =  0.517, p<0.001).

Conclusion

The concentrations of both S‐100B and NSE were increased by game associated activities and events. The increases in S‐100B concentration were significantly related to the number of headers and other trauma events, which indicates that both these factors may have contributed to these increases.     

The validity and reliability of a novel activity monitor as a measure of walking

Background

The accurate measurement of physical activity is crucial to understanding the relationship between physical activity and disease prevention and treatment.

Objective

The primary purpose of this study was to investigate the validity and reliability of the activPAL physical activity monitor in measuring step number and cadence.

Methods

The ability of the activPAL monitor to measure step number and cadence in 20 healthy adults (age 34.5±6.9 years; BMI 26.8±4.8 (mean±SD)) was evaluated against video observation. Concurrently, the accuracy of two commonly used pedometers, the Yamax Digi‐Walker SW‐200 and the Omron HJ‐109‐E, was compared to observation for measuring step number. Participants walked on a treadmill at five different speeds (0.90, 1.12, 1.33, 1.56, and 1.78 m/s) and outdoors at three self selected speeds (slow, normal, and fast).

Results

At all speeds, inter device reliability was excellent for the activPAL (ICC (2,1)⩾0.99) for both step number and cadence. The absolute percentage error for the activPAL was <1.11% for step number and cadence regardless of walking speed. The accuracy of the pedometers was adversely affected by slow walking speeds.

Conclusion

The activPAL monitor is a valid and reliable measure of walking in healthy adults. Its accuracy is not influenced by walking speed. The activPAL may be a useful device in sports medicine.     

The validation of a novel activity monitor in the measurement of posture and motion during everyday activities

Background

Accurate measurement of physical activity patterns can be used to identify sedentary behaviour and may facilitate interventions aimed at reducing inactivity.

Objective

To evaluate the activPAL physical activity monitor as a measure of posture and motion in everyday activities using observational analysis as the criterion standard.

Methods

Wearing three activPAL monitors, 10 healthy participants performed a range of randomly assigned everyday tasks incorporating walking, standing and sitting. Each trial was captured on a digital camera and the recordings were synchronised with the activPAL. The time spent in different postures was visually classified and this was compared with the activPAL output.

Results

Intraclass correlation coefficients (ICC 2,1) for interdevice reliability ranged from 0.79 to 0.99. Using the Bland and Altman method, the mean percentage difference between the activPAL monitor and observation for total time spent sitting was 0.19% (limits of agreement −0.68% to 1.06%) and for total time spent upright was −0.27% (limits of agreement −1.38% to 0.84%). The mean difference for total time spent standing was 1.4% (limits of agreement −6.2% to 9.1%) and for total time spent walking was −2.0% (limits of agreement −16.1% to 12.1%). A second‐by‐second analysis between observer and monitor found an overall agreement of 95.9%.

Conclusion

The activPAL activity monitor is a valid and reliable measure of posture and motion during everyday physical activities.     

Serum concentrations of C reactive protein, alpha1 antitrypsin, and complement (C3, C4, C1 esterase inhibitor) before and during the Vuelta a Espańa

Objectives

To determine serum concentrations of proinflammatory (C reactive protein, complement C3 and C4) and anti‐inflammatory (α₁ antitrypsin, C1 esterase inhibitor (C1‐INH)) acute phase proteins in elite cyclists before and during a three week cycle tour.

Methods

Seventeen professional cyclists participating in the Vuelta a Espańa volunteered for the study. Their mean (SD) physical characteristics were: age 28 (1) years; height 1.7 (0.06) m; weight 65 (7) kg; body fat 7.6 (0.8)%; Vo₂max 75.3 (2.3) ml/kg/min. Venepuncture was performed on each subject 24 hours before the tour began (T0), on day 11 (the first rest day; T1) and day 21 (the second to last stage of the tour; T2). Samples at T1 and T2 were taken about 17 hours after the previous stage. Analysis of variance was used to determine changes over time. Where significance was found, a Tukey post hoc test was performed.

Results

C reactive protein concentrations were consistently within the normal range, although there was a 228%, non‐significant increase at T1. C3 concentrations fell within the normal range at all times assessed. C4 concentrations before the race were within the normal range and were significantly increased 10 days (T1) into the race. C1‐INH concentrations did not change significantly throughout the race. α₁ Antitrypsin concentration before the race was at the lower end of the normal range and was only significantly raised at T2.

Conclusions

Although not as pronounced as those reported in marathon/ultramarathon runners, elite cyclists participating in a three week cycle tour experienced increases in selected proinflammatory and anti‐inflammatory acute phase proteins, indicating an acute phase/inflammatory response. It is tenable that the increase in α₁ antitrypsin and C1‐INH (anti‐inflammatory mediators) at T2 served to attenuate the acute phase/inflammatory response. The lower than normal resting concentrations of the acute phase proteins supports the notion that chronic aerobic exercise induces an anti‐inflammatory state.     

Ultrasound guided dry needling and autologous blood injection for patellar tendinosis

Objective

To evaluate the efficacy of ultrasound guided dry needling and autologous blood injection for the treatment of patellar tendinosis.

Design

Prospective cohort study.

Setting

Hospital/clinic based.

Patients

47 knees in 44 patients (40 men, 7 women, mean age 34.5 years, age range 17 to 54 years) with refractory tendinosis underwent sonographic examination of the patellar tendon following referral with a clinical diagnosis of patellar tendinosis (mean symptom duration 12.9 months).

Interventions

Ultrasound guided dry needling and injection of autologous blood into the site of patellar tendinosis was performed on two occasions four weeks apart.

Main outcome measures

Pre‐ and post‐procedure Victorian Institute of Sport Assessment scores (VISA) were collected to assess patient response to treatment. Follow up ultrasound examination was done in 21 patients (22 knees).

Results

Therapeutic intervention led to a significant improvement in VISA score: mean pre‐procedure score = 39.8 (range 8 to 72) v mean post procedure score = 74.3 (range 29 to 100), p<0.001; mean follow up 14.8 months (range 6 to 22 months). Patients were able to return to their sporting interests. Follow up sonographic assessment showed a reduction in overall tendon thickness and in the size of the area of tendinosis (hypoechoic/anechoic areas within the proximal patellar tendon). A reduction was identified in interstitial tears within the tendon substance. Neovascularity did not reduce significantly or even increased.

Conclusions

Dry needling and autologous blood injection under ultrasound guidance shows promise as a treatment for patients with patellar tendinosis.     

Influences of palatal side design and finishing on the wearability and retention of mouthguards

Objectives

To examine the influences of design and finishing on mouthguard wearability and retention.

Materials and methods

17 students at the Dental Technician Institute at Osaka University School of Dentistry, Osaka, Japan, participated in this study after providing informed consent. For each student, a single‐layer custom‐made mouthguard was fabricated from a 3.8‐mm‐thick ethylene‐vinyl acetate sheet using a standardised procedure to obtain a precise fit. Each mouthguard was modified by changing the margin location and shape through five consecutive steps. At each step, questionnaires with a visual analogue scale regarding wearability (comfort, breathing, speaking, swallowing, lip closure, temporomandibular joint fatigue and swallowing) and retention were completed by subjects after wearing the mouthguard for 5 min. Statistical analyses were carried out among the steps using Wilcoxon''s signed‐rank test with a significance level of p<0.05.

Results

Significant improvements were found for comfort, breathing, speaking and swallowing by trimming the palatal margin to the cervical area, smooth finishing and occlusal adjustment of the mouthguard (p<0.01). No significant differences were found for retention throughout the procedure.

Conclusions

Within the limitations of this experimental study, design and finishing at the palatal side appear to have significant influences on mouthguard wearability, but not retention.Using a mouthguard is an effective measure for preventing or reducing traumatic injuries to the orofacial region during various types of sporting events such as American football, basketball, rugby and ice hockey.^1,2,3,4,5 However, some athletes are reluctant to wear a mouthguard. The main reasons for this reluctance are generally related to wearability, including concerns such as discomfort, and difficulties in breathing and speaking.DeYoung et al⁶ reported that athletes preferred the custom‐made mouthguards to self‐adapted mouthguards in terms of comfort and wearability. McClelland et al⁷ reported the effects of labial extension, occlusal contact and peripheral finishing of custom‐made mouthguards on their wearability. They indicated that comfort is likely to increase if mouthguards are extended labially to within 2 mm of the vestibular reflection, adjusted to allow even occlusal contact, rounded at the buccal peripheries and tapered at the palatal edges. Kenyon and Loos⁸ compared the wearabilities of single‐layered vacuum‐formed ethylene‐vinyl acetate (EVA) mouthguards and double‐layered heat‐laminated and pressure‐laminated EVA mouthguards.Although the palatal side of oral appliances is critical to pronunciation and breathing, the palatal side design of mouthguards has been studied mainly in relationship to the shock absorption capability and retention, rather than in relation to wearability.⁹The working hypothesis of the present study was as follows: if a mouthguard can be ensured to fit properly, the palatal margin can be shortened to the cervical area to improve wearability, including aspects such as comfort, breathing and pronunciation, without sacrificing retention. The purpose of this study was to test the above‐mentioned hypothesis by examining the influences of palatal side design and finishing on the wearability of mouthguards.     

Injuries in West Indies cricket 2003-2004

Objective

To analyse injuries in West Indies Cricket and compare them with those of other cricket playing nations.

Methods

Injuries between June 2003 and December 2004 were surveyed prospectively in all major matches of the West Indies Cricket Board.

Results

Most injuries occurred in the West Indies Test and one day international teams. Mean match injury incidence was 48.7 per 10 000 player‐hours in Test cricket, and 40.6 per 10 000 player‐hours in one day international cricket, with injury prevalence of 11.3% and 8.1% respectively. In domestic cricket, the match injury incidence was 13.9 per 10 000 player‐hours for first class cricket, and 25.4 per 10 000 player‐hours in one day domestic competitions. There were more injuries on tour for the West Indies team than at home. The batsmen and fast bowlers sustained 80% of injuries, with many leading to long absence from the game, although many of these injuries were sustained while fielding. Most injuries were of the phalanges (22%) and the lumbar spine (20%) sustained mainly while fielding (including catching) and fast bowling respectively.

Conclusions

Injuries in West Indies cricket may be reduced by (a) early detection and management of injuries on tour, (b) attention to fielding and catching techniques, and (c) monitoring of young fast bowlers.     

Classification of functional recovery of anterior cruciate ligament copers, non-copers, and adapters

Objectives

(a) To identify whether differences exist in the pattern of recovery with respect to functional outcomes for acutely ruptured anterior cruciate ligament deficient (ACLD) copers, adapters, and non‐copers. (b) To identify clinically relevant outcomes that could distinguish between three functional subgroups.

Methods

A longitudinal study was used to measure gait variables and distance hop at regular intervals after injury using a digital camcorder and computer for quantitative analysis. A sample of 63 ACLD subjects entered the study; 42 subjects were measured at least three times. At 12–36 months after injury, subjects were classified as functional copers, adapters, or non‐copers on the basis of which of their preinjury activities they had resumed. To determine the pattern of recovery, repeated measurements were analysed using a least squares fit of the data.

Results

17% of ACLD subjects were classified as functional copers, 45% as adapters, and 38% as non‐copers. Only 5% of those who participated in high demand activities before injury returned to them. ACLD copers had recovered above the control mean for all gait variables by 40 days after the injury. Hopping distance did not recover to the control mean. Non‐copers struggled to recover to control limits and remained borderline for all the gait variables.

Conclusions

Distinctive patterns of functional recovery for three subgroups of ACLD subjects have been identified. Gait variables and activity level before injury were the most useful variables for distinguishing between the subgroups. If potential for recovery is identified early after injury, then appropriate treatment can be given.     

Does stretching increase ankle dorsiflexion range of motion? A systematic review

Background

Many lower limb disorders are related to calf muscle tightness and reduced dorsiflexion of the ankle. To treat such disorders, stretches of the calf muscles are commonly prescribed to increase available dorsiflexion of the ankle joint.

Hypothesis

To determine the effect of static calf muscle stretching on ankle joint dorsiflexion range of motion.

Study design

A systematic review with meta‐analyses.

Methods

A systematic review of randomised trials examining static calf muscle stretches compared with no stretching. Trials were identified by searching Cinahl, Embase, Medline, SportDiscus, and Central and by recursive checking of bibliographies. Data were extracted from trial publications, and meta‐analyses performed that calculated a weighted mean difference (WMD) for the continuous outcome of ankle dorsiflexion. Sensitivity analyses excluded poorer quality trials. Statistical heterogeneity was assessed using the quantity I².

Results

Five trials met inclusion criteria and reported sufficient data on ankle dorsiflexion to be included in the meta‐analyses. The meta‐analyses showed that calf muscle stretching increases ankle dorsiflexion after stretching for ⩽15 minutes (WMD 2.07°; 95% confidence interval 0.86 to 3.27), >15–30 minutes (WMD 3.03°; 95% confidence interval 0.31 to 5.75), and >30 minutes (WMD 2.49°; 95% confidence interval 0.16 to 4.82). There was a very low to moderate statistical heterogeneity between trials. The meta‐analysis results for ⩽15 minutes and >15–30 minutes of stretching were considered robust when compared with sensitivity analyses that excluded lower quality trials.

Conclusions

Calf muscle stretching provides a small and statistically significant increase in ankle dorsiflexion. However, it is unclear whether the change is clinically important.     

Movement discrimination after intra-articular local anaesthetic of the ankle joint

Background

The effect on clinical safety of dampening articular mechanoreceptor feedback at the ankle is unknown. Injection of the ankle joint for pain control may result in such dampening. Athletes receiving intra‐articular local anaesthetic may therefore be at increased risk of sustaining ankle injuries, which are a common reason for missed sporting participation.

Objective

To determine the effect of intra‐articular local anaesthetic on movement discrimination at the ankle joint.

Design

Prospective, randomised, double‐blinded, placebo‐controlled, cross‐over trial.

Setting

Australian Institute of Sport Medical Centre, Canberra, Australia.

Patients

Twenty two healthy subjects (44 ankles) aged 18–26 were recruited for the three visits of the study.

Interventions

Subjects were tested for their initial movement discrimination scores using the active movement extent discrimination apparatus (AMEDA). They then received ultrasound‐guided intra‐articular injections of local anaesthetic (2% lignocaine hydrochloride) or normal saline, on two separate later occasions, before further AMEDA assessment.

Main outcome measures

Change in movement discrimination scores after intra‐articular injection of local anaesthetic or saline.

Results

Movement discrimination scores were not significantly different from control ankles after injection of either local anaesthetic or saline into the ankle joint.

Conclusions

The intra‐articular injection of neither 2 ml lignocaine nor an equivalent amount of normal saline resulted in significant effects on movement discrimination at the ankle joint. These results suggest that injections of local anaesthetic into the ankle joint are unlikely to significantly affect proprioception and thereby increase injury risk.     

Left ventricular chamber size predicts the race time of Japanese participants in a 100 km ultramarathon

Objective

As a subanalysis of an echocardiographic study performed on 291 Japanese participants in a 100 km ultramarathon, to estimate predictors of race time.

Methods

A total of 247 male participants in a 100 km ultramarathon (age 20–73 years) were examined by echocardiography. Correlations between age, body surface area, monthly running distance, or echocardiographic variables and the race time were examined.

Results

According to simple regression analysis, age (r  =  0.299, p<0.0001), monthly running distance (r  =  −0.388, p<0.0001), left ventricular end diastolic diameter (r  =  −0.300, p<0.0001), and left ventricular end systolic diameter (r  =  −0.325, p<0.0001) correlated significantly with the race time. When multiple regression analysis was performed, age (f  =  2.364), monthly running distance (f  =  −0.113), and left ventricular end systolic diameter (f  =  −2.361) remained significant predictors of the race time.

Conclusion

Left ventricular diameter predicts the race time for a 100 km ultramarathon, in addition to age and amount of training.