Swimming in warm water is ineffective in heat acclimation and is non-ergogenic for swimmers.

Heat acclimation (HA) in air confers adaptations that improve exercise capabilities in hot and possibly temperate air. Swimmers may benefit from HA, yet immersion may constrain adaptation. Therefore, we examined whether warm-water swimming constitutes effective HA. In a randomized-crossover study, eight male swimmers swam 60 min/day on 7 days in 33 °C (HA) or 28 °C (CON) water. They performed 20-min distance trials before and after each regime: in 33 °C water (Warm); 28 °C water (Temperate); and cycling in 29 °C air (Terrestrial) following standardized exercise. Rectal temperature (Tre ) rose ∼ 1 °C in HA sessions, and sweat loss averaged 1.4 L/h. After accounting for CON, HA did not confer any clear expansion of plasma volume [1.9% (95% CI: 7.7)], reduction in heart rate during standardized cycling exercise [1 b/min (9)], reduction in Tre during rest [+0.1 °C (0.1)] or exercise, or change in sudomotor function. Only perceived temperature and discomfort tended to improve. Performance was clearly not improved for Warm [+0.3% (1.8)] or Temperate [+0.3% (1.9)], was unclear for Terrestrial [+0.4% (17.7)], and was unrelated to changes in resting plasma volume (r < 0.3). In conclusion, short-term HA using swimming in 33 °C water confers little adaptation and is not ergogenic for warm or temperate conditions.

Increased fat oxidation and regulation of metabolic genes with ultraendurance exercise.

AIM: Regular endurance exercise stimulates muscle metabolic capacity, but effects of very prolonged endurance exercise are largely unknown. This study examined muscle substrate availability and utilization during prolonged endurance exercise, and associated metabolic genes. METHODS: Data were obtained from 11 competitors of a 4- to 5-day, almost continuous ultraendurance race (seven males, four females; age: 36 +/- 11 years; cycling Vo(2peak): males 57.4 +/- 5.9, females 48.1 +/- 4.0 mL kg(-1) min(-1)). Before and after the race muscle biopsies were obtained from vastus lateralis, respiratory gases were sampled during cycling at 25 and 50% peak aerobic power output, venous samples were obtained, and fat mass was estimated by bioimpedance under standardized conditions. RESULTS: After the race fat mass was decreased by 1.6 +/- 0.4 kg (11%; P < 0.01). Respiratory exchange ratio at the 25 and 50% workloads decreased (P < 0.01) from 0.83 +/- 0.06 and 0.93 +/- 0.03 before, to 0.71 +/- 0.01 and 0.85 +/- 0.02, respectively, after the race. Plasma fatty acids were 3.5 times higher (from 298 +/- 74 to 1407 +/- 118 micromol L(-1); P < 0.01). Muscle glycogen content fell 50% (from 554 +/- 28 to 270 +/- 25 nmol kg(-1) d.w.; n = 7, P < 0.01), whereas the decline in muscle triacylglycerol (from 32 +/- 5 to 22 +/- 3 mmol kg(-1) d.w.; P = 0.14) was not statistically significant. After the race, muscle mRNA content of lipoprotein lipase and glycogen synthase increased (P < 0.05) 3.9- and 1.7-fold, respectively, while forkhead homolog in rhabdomyosarcoma, pyruvate dehydrogenase kinase 4 and vascular endothelial growth factor mRNA tended (P < 0.10) to be higher, whereas muscle peroxisome proliferator-activated receptor gamma co-activator-1beta mRNA tended to be lower (P = 0.06). CONCLUSION: Very prolonged exercise markedly increases plasma fatty acid availability and fat utilization during exercise. Exercise-induced regulation of genes encoding proteins involved in fatty acid recruitment and oxidation may contribute to these changes.

Incidence of injuries in the New Zealand national rugby league sevens tournament.

This study investigated the incidence, site, nature and causes of injuries sustained in the New Zealand national rugby league sevens tournament. A total of 218 players competing in 47 matches were studied. All injuries sustained within the tournament were prospectively recorded. Injuries were categorised according to the severity assessment at the time of the injury. Information obtained included the time, site, nature and cause of the injury. The incidence of injury was 497.6 per 1000 playing hours. More than 40% (216.1 per 1000) of injuries sustained occurred within the lower limbs. The shoulder was the single most commonly injured site (78.6 per 1000). Sprains were the most common injury type (189.9 per 1000). The ball-carrier sustained significantly more (p<0.05) injuries than the tackling player (216.1 per 1000 [43.4%] versus 117.8 per 1000 [23.7%]). There were significantly more injuries on the first day of competition than on the second day of competition (600.4 per 1000 [76.3%] versus 320.9 per 1000 [23.7%]). The findings of higher injury rates on the first day of competition and during the second period of matches suggest that playing intensity and player fatigue may contribute to injuries in rugby league sevens.

Ethical issues concerning New Zealand sports doctors.

Success in sport can provide a source of national pride for a society, and vast financial and personal rewards for an individual athlete. It is therefore not surprising that many athletes will go to great lengths in pursuit of success. The provision of healthcare for elite sports people has the potential to create many ethical issues for sports doctors; however there has been little discussion of them to date. This study highlights these issues. Respondents to a questionnaire identified many ethical matters, common to other areas of medicine. However they also raised problems unique to sports medicine. Some of these ethical difficulties arise out of the place of the sports doctor within the hierarchy of sport. Yet others arise out of the special relationship between sports doctors and individual players/athletes. This study raises some important questions regarding the governance of healthcare in sport, and what support and guidance is available to sports doctors. As medical and scientific intervention in sport escalates, there is a risk that demands for enhanced performance may compromise the health of the athlete, and the role the sports doctor plays remains a critical question.

Plasma zinc and immune markers in runners in response to a moderate increase in training volume.

Changes in plasma zinc concentration and markers of immune function were examined in a group of 10 male runners (n = 10) following a moderate increase in training over four weeks. Seven sedentary males acted as controls. Fasting blood samples were taken at rest, before (T0) and after (T4) four weeks of increased (+ 16 %) training and after two weeks of reduced (-31 %) training (T6). Blood was analysed for plasma zinc concentration, differential leucocyte counts, lymphocyte subpopulations and lymphocyte proliferation using incorporation of 3H-thymidine. The runners increased their training volume by 16 % over the four weeks. When compared with the nonathletes, the runners had lower concentrations of plasma zinc (p = 0.012), CD3 + (p = 0.042) and CD19 + lymphocytes (p = 0.010) over the four weeks. Lymphocyte proliferation in response to Concanavalin A stimulation was greater in the runners (p = 0.0090). Plasma zinc concentration and immune markers remained constant during the study. Plasma zinc concentration correlated with total leucocyte counts in the athletes at T6 (r = -0.72, p < 0.05) and with Pokeweed mitogen stimulation in the nonathletes at T6 (r = -0.92, p < 0.05). Therefore, athletes are unlikely to benefit from zinc supplementation during periods of moderately increased training volume.

Open water swimming. Particular medical problems.

Open water swimming is a rapidly growing discipline within organized aquatic sport. Although endurance swimmers have been challenged by oceans, rivers, and lakes for many years, the real understanding of the science of the sport is a new development. Similarly, the clinical problems of long-distance swimming in frequently inhospitable environments now are recognized and managed more effectively. At all times, the health and safety of athletes remain our shared, prime concerns.

The New Zealand Rugby Injury and Performance Project: V. Epidemiology of a season of rugby injury.

OBJECTIVE: To describe the incidence, nature, and circumstances of injury experienced by a cohort of rugby union players during a full competitive club season. METHODS: A prospective cohort study followed up 356 male and female rugby players throughout the 1993 competitive club season. Players were interviewed by telephone each week to obtain information on the amount of rugby played and the injury experienced. RESULTS: Detailed information was collected for 4403 player-games and 8653 player-practices. A total of 671 injury events were reported, of which 569 were rugby related. The injury rate for games was higher than that for practices (rate ratio 8.3). At 10.9 injuries per 100 player-games, males had a higher rate of injury than females at 6.1 injuries per 100 player-games (p<0.001). Injury rates varied by position, with male locks (13.0 injuries per 100 player-games) and female inside backs (12.3 injuries per 100 player-games) having the highest rate in their respective sexes. The lower limb was the body region most often injured in games (42.5%) and practices (58.4%). Sprains/strains were the most common type of injury in games (46.7%) and practices (76.1%). In games the tackle was the phase of play in which the most injuries occurred (40%), followed by rucks (17%) and mauls (12%). Thirteen per cent of game injury events were the result of foul play. CONCLUSIONS: Rugby injury was common among the study subjects and varied according to grade and gender. Identifying the causes of injuries in the tackle, lower limb injuries, and dealing with the issue of foul play are priority areas for the prevention of rugby injury.

DEXA: a practical and accurate tool to demonstrate total and regional bone loss, lean tissue loss and fat mass gain in paraplegia.

Persons with spinal cord injury lose lean tissue mass and bone but gain body fat. There is a need to quantify the magnitude of these changes in body composition because there are associated skeletal and cardiovascular health risks. We have compared total body and regional (lower limb) differences in body composition in a group of males with paraplegia and in healthy able-bodied males matched for age, and height using dual energy X-ray absorptiometry. Although patients and controls had similar body mass indices, significant reductions in lean tissue mass (16% less) and bone (12% less) were observed in those with spinal cord injury. Group differences were even more pronounced in the lower limb. DEXA also revealed large increases in fat mass in subjects who did not look obese, total fat mass being 47% higher in the paraplegic group. We suggest that DEXA provides a simple and practical means to quantify both whole body and regional changes in body composition associated with spinal cord injury.

External knee support in rugby union. Effectiveness of bracing and taping.

Rugby football is associated with a number of biomechanical stresses which are frequently associated with knee injury. Consequently, there has been a significant interest within the game regarding the techniques of knee surgery and accelerated rehabilitation and the prophylactic use of external knee support. Knee bracing and strapping techniques are widely practised by rugby players but their results vary and there are mixed opinions over their usefulness. This article discusses the current trends in external knee support, draws on the experiences of other professional football codes and extrapolates these to the rugby union setting. Widespread opinion confirms that improper or incomplete rehabilitation is linked to re-injury. There is also a general acceptance that external support for the knee in sport should never be used to mask an injury. There is no evidence that the prophylactic taping of the knee joint provides any significant external stabilisation for more than the first few minutes of play. This lack of lasting stabilisation is due to the vigorous physical activity associated with rugby which results in a rapid loss of the custom fit of the external support to the profile of the joint. The taping the patella to reduce the pain associated with poor patellar alignment is considered to be effective; however, the correction of other biomechanical influences is also important. Adhesive tape, when applied correctly, will reposition the patella but this technique is limited by factors such as sweating and movement. A number of knee braces are currently available and these are classified according to their prophylactic, rehabilitative or functional design. In this article, their use in rugby applies to external support as an aid to rehabilitation rather than injury prevention.

Effectiveness of external ankle support. Bracing and taping in rugby union.

Ankle inversion sprain is common in rugby. This review outlines research evidence relating to the effects of external ankle support by means of bracing and taping, on the incidence of ankle injuries, how performance is affected by support, how support may act at the joint (with respect to end range of motion, strength, resistive torque, muscle activation patterns and proprioception) to prevent injury, and how exercise changes the effectiveness of support. In addition, the implications of the laws of rugby for the use of external support are discussed. Prospective epidemiological studies have shown a decrease in the incidence of ankle injury with external ankle support use. The effectiveness of external ankle support was dependent upon the material properties and application method of the tape or brace, and on the athlete's status of ankle stability or previous injury. Experimental studies have indicated that the degree of ankle inversion restriction provided, and the degree of loss of restriction after exercise, were dependent upon the external support tested. External ankle support has been reported to have no effect on performance, or to have an adverse effect on performance in a variety of movement tasks. No prophylactic external ankle support has been shown to improve performance. If an external support is to provide mechanical support to a ligament it should exceed the strength of the ligament, which for the anterior fibular ligament is a force limit of between 6 and 56 kg. Tape can provide only limited mechanical support of the ankle joint complex, but it may have proprioceptive effects. Taping may work as a psychological reminder, so that the athlete consciously moderates lower limb-loading behaviour. There is equivocal evidence of the effect of brace use on ground reaction force excursions, balance ability and ankle strength. It is concluded that while there have been many investigations of the effects of tape and some forms of brace on ankle range of motion with and without exercise, there is equivocal evidence regarding the mechanism by which an external support acts. It is recommended that future research address the effects of external ankle support during dynamic exercise and that brace manufacturers utilise the information in the development of future brace designs to help reduce the risk of ankle inversion sprain injury. As external support can decrease the incidence of ankle inversion sprain the International Rugby Board should consider the use of ankle braces in rugby, allowing for stiff lateral components of the brace.

The use of padding in rugby union. An overview.

In any contact sport where impact and collision are an accepted feature, the use of various forms of external padding has become more common. Rugby union players experience a combination of characteristic extrinsic forces through the acts of tackling and scrummaging. The laws which are part of the international regulation of rugby union only permit the wearing of certain, clearly delineated forms of padding. Only then is such padding permitted on medical recommendation, provided that this padding is attached to the body or sewn into the jersey. This article discusses the padding of the shoulders, shins and thighs of rugby union players and highlights the need to address these issues with respect to the increasing number of women who are now playing this sport, particularly in the Southern hemisphere. There is little evidence to show that shoulder pads decrease the incidence of severe shoulder injuries. However, well-fitting shoulder pads constructed of materials that effectively disperse the force of impact appear to reduce the effect of direct contact and reduce the potential for soft tissue damage. Shin guards that are made of light, soft, compliant materials are effective in reducing impact to the shin and thereby reduce the risk of bruising injuries which are common to the pretibial region. Similarly, thigh pads are considered to be able to modify the effects of direct contact forces to the anterior thigh where deep contusional injuries with the potential for myositis ossificans are well reported. Informed advice for women rugby players regarding the use of specific padding is unavailable at present. Current information is anecdotal and not confirmed by statistical studies or well-conducted research. In these circumstances, women rugby players should observe the same recommendations that apply to their male counterparts.

The relationship of strength and muscle balance to shoulder pain and impingement syndrome in elite quadriplegic wheelchair rugby players.

Wheelchair athletes are susceptible to injuries related to overuse of the shoulder, in particular shoulder impingement syndrome. The present study examined the relationship of shoulder pain to demographic details, isokinetic strength and muscle balance in 8 elite quadriplegic rugby players. Demographic data were collected using personal interviews and each subject was clinically examined for signs of impingement syndrome by a physician. In addition each subject underwent bilateral isokinetic strength testing of the shoulder at 60 and 180 deg/s for abduction/adduction and internal/external rotation. A series of step-wise multiple discriminant analysis successfully predicted clinical symptoms from demographic, muscular strength and balance data. In particular, there was a significant deficit in adductor strength and this was related to shoulder pain and wasting of the scapular muscles. This strength deficit may be due to the high level of spinal lesions in the quadriplegic population. The level of spinal lesion may contribute to the aetiology of shoulder pathology in quadriplegia, and differentiate it from that observed in able-bodied athletes who exhibit weak abductors.

The New Zealand Rugby Injury and Performance Project: II. Previous injury experience of a rugby-playing cohort.

The Rugby Injury and Performance Project (RIPP) is a prospective cohort study by a multidisciplinary research group. Rugby injuries constitute an important area for research because rugby union is New Zealand's national sport and because of the considerable cost of all sports injury acknowledged by the Accident Rehabilitation and Compensation Insurance Corporation (ACC). The initial phase of data collection in the RIPP involved a pre-season questionnaire which, among other things, sought to establish variables relating to the past injury experience of players. The influence of previous injury, the use of safety equipment and the availability and significance of medical advice were among the variables identified by individual questionnaires. This paper analyses the responses to pre-season questions about injury experience in the previous 12 months. In so doing, it identifies baseline data which will be used to address a possible relationship between past injury experience and the prediction of injury during the season.

Indomethacin potentiates exercise-induced reduction in renal hemodynamics in athletes.

Nonsteroidal anti-inflammatory drugs (NSAID) are frequently used in sports medicine but few studies have documented their potential importance in modifying exercise-induced changes in renal function. The effects of indomethacin (50 mg orally every 8 h for 36 h) on renal blood flow (RBF) and glomerular filtration rate (GFR) were investigated in eight fit healthy males (age 21-42) before and after 30-min treadmill exercise at 80% VO2max and during 120-min recovery. Each volunteer served as their own control. There were no differences between control and indomethacin for the resting values of RBF, GFR, or renal vascular resistance (RVR). Using analysis of variance for repeated measures, indomethacin produced a significant reduction in RBF compared with control (P = 0.009) that was associated with a significant elevation in RVR (P = 0.027). Changes in GFR mirrored the changes in RBF but differences failed to reach statistical significance. These results suggest that with sustained exercise indomethacin can compromise renal function and potentiate the risk of developing acute renal failure. Indomethacin and other NSAID are widely used in the sports arena, and athletes should be warned of the potential danger of their use when renal function may be compromised.

Overuse injury and growing bones: the young athlete at risk.

Increasing numbers of children are becoming involved in competitive sport. International trends in pre-adolescent sports participation are mirrored in New Zealand, where promising young athletes are being exposed to high-intensity training from an earlier age. As a consequence, overuse injuries which were traditionally described in more mature athletes are now becoming recognized in pre-adolescents. The immature musculoskeletal system is less able to cope with repetitive biomechanical stress. Sites of overuse injury reflect the sites of rapid musculoskeletal development. It therefore behoves all medical practitioners, but particularly those in primary care, to be aware of the young athlete at risk. Inherent in the presentation of such musculoskeletal insult there often lurks an over-enthusiastic parent. We are all well reminded of the covert pressures adults may bring to bear upon children. Psychological, as well as physical injury often results.

Effect of moderate exercise on esophageal function in asymptomatic athletes.

It has been thought that upper intestinal symptoms of heartburn, regurgitation, belching, and chest pain experienced during exercise may represent esophageal dysfunction. The aim of this study is to examine esophageal function during moderate exercise in asymptomatic healthy athletes. Six healthy male athletes were exercised for 2 h on a treadmill set at a workload of 50% of their maximum oxygen uptake. Esophageal motility studies were performed immediately before, immediately after, and 1 h after the exercise. The mean lower esophageal sphincter pressure increased from a base line of 24 to 32 mm Hg immediately postexercise (p less than .01), reducing to 27 mm Hg after 1 hour rest. The mean amplitude and duration of esophageal peristalsis remained unchanged throughout the study. The significance of the lower esophageal sphincter pressure increase with moderate exercise is unknown but may relate to the observed exercise-induced increase in serum motilin, gastrin, and catecholamines.

Gastrointestinal symptoms during exercise in Enduro athletes: prevalence and speculations on the aetiology.

A study of the prevalence of gastrointestinal symptoms during exercise was carried out on athletes who participated in the recent Enduro event in Dunedin. Of 119 competitors, 70 (59%) responded to our questionnaire and demonstrated a prevalence of gastrointestinal symptoms of 81%. Upper gastrointestinal symptoms were noticed in 58% with lower gastrointestinal symptoms, tending to be more severe and significant to the athlete, noticed in 61%. Speculations on the aetiology of these symptoms are included. The demonstrated high prevalence of symptoms during exercise and the relative lack of knowledge in this area provides a fertile ground for further objective research.