Exercise-associated hyponatraemia after a marathon: case series.

OBJECTIVES: To review the presentation, treatment and response of those runners from the London Marathon who presented to St Thomas' Hospital with exercise induced hyponatraemia. DESIGN: Observational case series. SETTING: St Thomas' Hospital, a tertiary hospital situated near the finish line of the 2003 London Marathon. PARTICIPANTS: All runners who presented to St Thomas' Hospital on the day of the 2003 London Marathon with altered mental state whose serum sodium concentration was less than 135 mmol/L. MAIN OUTCOME MEASURES: Presenting symptoms, volume and type of fluids administered and response to treatment (biochemical and clinical). RESULTS: Fourteen patients were diagnosed with exercise associated hyponatraemia with serum sodium concentrations ranging from 116 to 133 mmol/L. Eleven presented with confusion. There were long delays between the finish time and presentation time for some runners. Anecdotal descriptions suggested some runners finished the race with normal mental state then became confused. There was no correlation between running time and serum sodium level. All patients received 0.9% saline and six received 1.8% saline. Despite this, some patients demonstrated falls in serum sodium concentrations. Thirteen to fourteen patients were symptomatically well the following morning, with the remaining patient significantly improved. CONCLUSION: Presentation of exercise associated hyponatraemia may be delayed. Optimal treatment is controversial, but the use of isotonic saline may not result in rises of serum sodium and we would suggest the early use of hypertonic fluids in symptomatic patients.

An epidemiological investigation of training and injury patterns in British triathletes.

During the competitive season of 1990, 155 British triathletes whose competitive distances varied from sprint to full ironman, and who self-classified themselves as recreational, intermediate or élite, kept a training diary for an 8-week period. They gave details of injuries sustained while training for, or competing in, triathlons. The mean(s.d.) distances covered each week were: swimming, 4.2(2.6) km; cycling, 100.2(70.6) km; and running 23.4(15.2) km; mean(s.d.) training time was 7(3.4) h per week, and a mean(s.d.) of 7.9(3.4) training sessions were completed per week. At least one injury was reported by 37% of the participants. The most frequently affected sites were the ankle/foot, thigh, knee, lower leg and the back. Overuse was the reported cause in 41% of the injuries, two-thirds of which occurred during running. The likelihood of an injury was positively associated with experience in triathlon. Average injury rate was 5.4 injuries per 1000 h of training (95% confidence interval: 4-7.2) and 17.4 per 1000 h of competition (95% confidence interval: 10.9-27.9). Injury incidence was unrelated to the mean amount of weekly training or competition, intensity or frequency of training.

Pneumococcal endocarditis and disseminated infection.

A 61 year old woman presented with back pain and clinical signs of meningitis. Pleocytosis in the cerebrospinal fluid was found, but although Streptococcus pneumoniae was cultured from her blood it failed to grow from the cerebrospinal fluid. An echocardiogram detected vegetations on the mitral valve and a lesion at S1/S2 was demonstrated on a bone scan. Treatment for one month with benzylpenicillin (1200 mg four hourly) was successful for both the cardiac and neurological components of her infection, but her back pain only resolved after treatment was changed to clindamycin. The clinical presentation and metastatic spread of the S pneumoniae infection is much more commonly seen in the context of S aureus endocarditis. It is rare for the pneumococcus to be associated with endocarditis and when it is mortality is usually high. This case shows the metastatic potential of the organism and the requirement for appropriate antibiotics with regard not only to the sensitivity of the organism, but also for the site of infection.

Blood doping--a literature review.

There is increasing evidence that the technique of reinfusing an athlete's stored blood prior to competition to improve performance has been used on many occasions. Although early experimental results were controversial and the precise mechanism by which the technique improves performance is still debated, there is now strong evidence that if the blood doping produces a sufficient rise in total red cell mass there are significant improvements in physiological variables such as maximum oxygen uptake, lactate buffering and thermoregulation. These physiological changes are matched by improvements in endurance performance. These may persist in diminishing degree for several weeks, but have to be weighed against the detraining effect produced by the repeated venesection required to obtain an adequate amount of stored blood for autologous reinfusion. Experimental evidence suggests that the transient increase in blood volume and cardiac output following reinfusion is too short lived to be of any real importance and the major effect is related to the increase in total red blood cell mass and haemoglobin enabling an increased transport of oxygen and therefore a potentially greater reserve of blood which can be diverted to non-exercising tissues to improve thermoregulation. The increased red cell mass also improves lactate buffering. Although these benefits have been shown in several studies the increases in performance and measured physiological parameters do not bear a direct relationship to the changes in haematological variables. Blood doping is of considerable importance, not only as an abuse of fair competition, but also because of the light it throws on the physiological limits to endurance performance. It has reawakened controversy as to whether oxygen transport is the limiting factor in endurance.

The detection of peaks in luteinizing hormone secretion.

Fluctations in luteinizing hormone are believed to consist of irregularly spaced sharp increases separated by periods of exponential decay. A simple method is presented for analysing such fluctuations when the data consist of uniformly sampled observations of hormone. Specific allowance for the exponential decay in the absence of pulses is made via a time series model before assessing the number and extent of pulses. All calculations are done using MINITAB regression programs. The results have been compared with those obtained by three established models and are in general agreement.

Use of continuous wave Doppler ultrasound velocimetry to assess the severity of coarctation of the aorta by measurement of aortic flow velocities.

Peak ascending and descending aortic blood flow velocities were measured using continuous wave Doppler ultrasound velocimetry in 30 children with coarctation or recoarctation of the aorta and in 13 control subjects. The results were compared with the arm to leg systolic blood pressure difference. The peak flow velocities in the descending aorta were significantly higher in the patients than in the control subjects and there was a close correlation with the systolic blood pressure gradient. Since there was no overlap of flow velocities between the patients and the control subjects the Doppler technique enables coarctation confidently to be excluded as well as demonstrating its presence and severity. The method is simple, rapid, independent of the condition of the aortic valve, and is applicable to neonates in whom the diagnosis of coarctation may otherwise be difficult. In older children it is useful for detecting recoarctation and following its progress, particularly in patients in whom a reliable estimate of the systolic blood pressure gradient cannot be obtained.