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Biomedical subjects

J R Sutton

Publications and source records attributed to J R Sutton.

At least 127 records · Page 7Linked to original sources
PubMed1980

Heat injuries in Canadian mass participation runs.

In two Canadian runs with a total of approximately 2900 participants 26 people collapsed with heat injury and were taken to hospital. All were relatively young (13 to 38 years old). A retrospective survey showed that all were novices to 10-km races and that many had collapsed even though they had consumed fluids before and during the run. A review of etiologic factors suggested that the extremes in the Canadian climate, which preclude heat acclimatization in the spring and early summer, may be an important influence on the incidence of heat injury.

Adolescent↗
PubMed1980

Exertional heat stroke: the runner's nemesis.

Heat stroke in distance runners is increasing in frequency. A case is reported of a 41-year-old man who collapsed during a 10-km "fun run" held when the temperature was 31.6 degrees C and the humidity 80%. Acute renal failure (serum creatinine level 1530 mumol/l [17.3 mg/dl]), rhabdomyolysis, disseminated intravascular coagulation and hepatic damage complicated the clinical picture. Repeated peritoneal dialysis and one cycle of hemodialysis because of a very high serum level of uric acid (1.23 mmol/l [20.7 mg/dl]) were required. Although the illness was prolonged, recovery was almost complete, and 4 months after the man's collapse the serum creatinine level had fallen to 133 mumol/l (1.5 mg/dl).

Acute Kidney Injury↗
PubMed1980

Effects of strength training and immobilization on human muscle fibres.

Seven healthy male subjects were studied under control conditions and following 5-6 months of heavy resistance training and 5-6 weeks of immobilization in elbow casts. Cross-sectional fibre areas and nuclei-to-fibre ratios were calculated from cryostat sections of needle biopsies taken from triceps brachii. Training resulted in a 98% increase in maximal elbow extension strength as measured by a Cybex dynamometer, while immobilization resulted in a 41% decrease in strength. Both fast twitch (FT) and slow twitch (ST) fibre areas increased significantly with training by 39% and 31%, respectively. Immobilization resulted in significant decreases in fibre area by 33% for FT and 25% for ST fibres. The observed nuclei-to-fibre ratio was 10% greater following the training programme. However, this change was non-significant. There was also a non-significant correlation between the magnitude of the changes in fibre size and the changes in maximal strength following either training or immobilization.

Adult↗
PubMed1980

Purine metabolism during strenuous muscular exercise in man.

This study was designed to examine the influence of exercise on purine metabolism in man. In 15 men, the plasma uric acid concentration increased from 6.9 to 8.5 mg/dl following a 5000-m race and from 6.2 to 7.9 mg/dl in 11 men following a 42-km marathon. During a progressive exercise test on a cycle ergometer, the plasma uric acid ocnentration did not change significantly in 11 subjects. However, the plasma oxypurines increased from 19 micrM at rest to 50 microM at exhaustion and the urinary excretion of oxypurines increased from 140 to 400 mumol/g creatinine. Intracellular ATP decreased from 5.17 to 2.91 mumol/g and ADP and AMP increased from 0.85 to 1.29 and from 0.12 to 0.15 mumol/g wet weight, respectively. These observations suggest that there is an accelerated degradation of purine nucleotides to the precursors of uric acid in skeletal muscle during vigorous exercise.

Adenine Nucleotides↗
PubMed1980

Fat metabolism in heavy exercise.

1. To investigate differences between the metabolic effects of light and heavy exercise, five healthy males (mean maximal oxygen intake 3.92 litres/min) exercised for 40 min at 36% maximum power (light work) and 70% maximum power (heavy work) on separate days, after an overnight fast. 2. A steady state was achieved in both studies between 20 and 40 min in: oxygen intake (1.42 and 2.64 litres/min respectively); respiratory exchange ratio (0.89 and 1.01); plasma lactate concentration (1.78 and 9.94 mmol/l). 3. Plasma palmitate turnover rate (14C) was unchanged from resting values in light work but was decreased by 40% (from 104 +/- 16 to 63 +/- 8 micronml/min) in heavy work. Heavy work was associated with falls in the plasma concentrations of all free fatty acids measured: palmitic acid (C16:0), oleic acid (C18:1), stearic acid (C18:0), linoleic acid (C18:2) and palmitoleic acid (C16:1). 4. In contrast to th fall in palmitate turnover the increase in plasma glycerol was greater in heavy exercise (0.054-0.229 mmol/l) than in light exercise (0.053-0.094 mmol/l), suggesting that lipolysis was occurring which did not lead to influx of free fatty acids into plasma. 5. In light exercise fat metabolism may be controlled to favour adipose tissue lipolysis and extraction of free fatty acids by muscle from the circulation, whereas in heavy exercise adipose tissue lipolysis is inhibited and hydrolysis of muscle triglycerides may play a more important part. 6. The finding of a high respiratory exchange ratio may not exclude the use of fat as a major fuel source in exercise associated with lactate production.

Adult↗
PubMed1980

Retinal studies at 446 torr in a hypobaric chamber.

This study was designed to see if retinal haemorrhage occurred after 24 h of decompression to a pressure of 446 torr. Four subjects were studied after 24 h of decompression and had retinal photography and fluorescein angiography performed at rest and following maximum exercise. No haemorrhages or fluorescein leakage was noted, even though the subjects experienced typical symptoms of acute mountain sickness and showed an increase in lung density-consistent with subclinical pulmonary edema. We conclude that 24 h exposure to 446 torr with a period of maximal exercise is an inadequate stress, either in time and/or degree, of hypoxia to produce retinal haemorrhage or leakage, as measured by flourescein.

Adult↗
PubMed1979

Management of heat exhaustion in Sydney's the Sun City-to-Surf run runners.

Heat exhaustion (collapse with rectal temperature of, or higher than 38 degrees C) is the most common major medical complication of fun runs and is caused by dehydration and impaired heat loss with, or without, hypoglycaemia. All patients with heat exhaustion after the City-to-Surf runs from 1977 to 1979 were managed in a medical centre established at the finish of the course. Several methods of management of heat exhaustion are evaluated. Patients were allocated retrospectively to four primary treatment groups: (i) treated with ice-wet towels only; (ii) treated with ice-wet towels and intravenously administered fluids; (iii) treated with intravenously administered fluids and ice-cold packs applied to the neck, axillae, and groins; and (iv) treated with intravenously administered fluids only. There was no death or prolonged morbidity in any treatment group. In Group 1 (n=11), the mean initial rectal temperature was 40.2 +/- 1.5 degrees C. There were insufficient data to assess the mean time taken for the temperature to fall to 38 degrees C. In Group 2(n=16), the mean initial rectal temperature was higher than 40.9 +/- 1.1 degrees C. In three patients, the temperature failed to fall to 38 degrees C within 90 minutes. For the remainder, the mean time taken for the temperature to fall to 38 degrees C was 30 minutes. In Group 3 (n=16), the mean initial rectum temperature was higher than 41.2 +/- 1.0 degrees C. One patient, who had been febrile immediately before the run, was discharged with a temperature of 38.8 degrees C. For the remainder, the mean time taken for the temperature to fall to 38 degrees C was 36 +/- 10 minutes. In Group 4 (n=13), the mean initial rectal temperature was 39.6 +/- 1.1 degrees C and the mean time taken for the temperature to fall to 38 degrees C was 21 +/- 16 minutes. Heat exhaustion in fun-run casualties may be safely and effectively treated by rapid intravenous infusion of fluids with, or without, application of cold packs to the neck, axillae, and groins. The application of ice-wet towels is contraindicated.

Adolescent↗
PubMed1979

Reducing the hazards in Sydney's the Sun City-to-Surf runs, 1971 to 1979.

The hazards experienced by fun runners in Sydney's The Sun City-to-Surf run are principally physical, environmental and medical. The organizers of the event, advised by a representative of the Australian Sports Medicine Federation (N.S.W.), have progressively increased the implementation of the recommendations which were made after the inaugural run in 1971 in the areas of improved organization, competitor education, medical support, recording of competitor data, and conducting the event in cool weather. To ensure the maximum safety of the runners, the number of whom has increased from approximately 1650 in 1971 to 16200 in 1979, additional measurees have been taken. These were (i) the introduction of "spotters" with experience in sports medicine to identify and advise exhausted runners before they collapse; (ii) staffing the run's medical centre with medical and nursing specialists in intensive care; (iii) improved management of heat exhaustion; and (iv) conducting education seminars after the run to make recommendations for improving subsequent events. Since 1971, there has been a progressive reduction in the number of casualties. The incidence of casualties treated in the medical centre fell from 1.76% in 1971 to 0.1% in 1979; and the incidence of those requiring further treatment in hospital fell from 0.42% in 1971 to 0.01% in 1979. None of the participants had suffered severe complications of heat exhaustion. Improvements in the management of heat exhaustion (the most common cause of collapse) which made the use of iced water (hiterto traditional method of cooling casualties with hyperthermia) unnecessary have reduced the risk of using electrical equipment in wet surroundings. The over-all reduction in the incidence and morbidity of collapse casualties is due to a combination of factors. These factors and possibilities of further reduction of hazards are discussed.

Accident Prevention↗