Physiological effects of the amphetamines during exercise

Oxygen consumption, heart rate, minute ventilation and blood lactate were measured on two champion cyclists at work rates from 45 to 362 W (2 000 - 16 000 ft-Ib / min) on a bicycle ergometer after administration of a placebo and after 10 mg of methamphetamine, without their knowledge of which was given. No differences could be detected due to the ingestion of the amphetamine in submaximum or maximum oxygen consumption, heart rate, minute ventilation or blood lactic acid. However, after the amphetamine the men were able to continue to cycle at maximum effort for a longer period and in a run to exhaustion at 90 - 95% maximum effort one man increased the time 61 % and the other 29% with marked increases in blood lactic acid. Thus the study shows that amphetamines do not increase the men's capacity for aerobic exercise. It does, however, allow them to continue to exercise at high levels of effort for a longer period and endure a higher level of anaerobic metabolism. In short-distance events this may not be dangerous but in events lasting for more than an hour the failure to be aware of 'danger signals' and to react to them couid be a threat to life as was seen in the death from 'heat-stroke' of a British champion cyclist in a 'Tour de France' some years ago.SAMJ, 45(6): 247-25

Bioethical and medico-legal implications of withdrawing artificial nutrition and hydration from adults in critical care

The withdrawal of artificial nutrition and hydration or other life-sustaining treatments is a clinical decision, made in ICUs or in other settings, involving patients suffering from serious and irreversible diseases or impaired consciousness. Such clinical decisions must be made in the best interests of the patient, and must respect the wishes previously expressed by patients, laid down in their wills, in advance directives or in information passed on by relatives or legally appointed health-care agents, and in observance of common bioethical and legal rules in individual nations. Intensivists who are expert in the management of lifesustaining treatments are also involved in deciding when to withdraw futile therapies and instigate end-of-life care procedures for dying patients, with the sole aim of providing comfort and ensuring that suffering is not prolonged unnecessaril

Induction and decay of short-term heat acclimation

“The original publication is available at www.springerlink.com”. Copyright SpringerThe purpose of this work was to investigate adaptation and decay from short-term (5-day) heat acclimation (STHA). Ten moderately trained males (mean ± SD age 28 ± 7 years; body mass 74.6 ± 4.4 kg; 4.26 ± 0.37 l min−1) underwent heat acclimation (Acc) for 90-min on 5-days consecutively (T a = 39.5°C, 60% RH), under controlled hyperthermia (rectal temperature 38.5°C). Participants completed a heat stress test (HST) 1 week before acclimation (Acc), then on the 2nd and 8th day (1 week) following Acc (T a = 35°C, 60% RH). Seven participants completed HSTs 2 and 3 weeks after Acc. HST consisted of 90-min cycling at 40% peak power output before an incremental performance test. Rectal temperature at rest (37.1 ± 0.4°C) was not lowered by Acc (95% CI −0.3 to 0.2°C), after 90-min exercise (38.6 ± 0.5°C) it reduced 0.3°C (−0.5 to −0.1°C) and remained at this level 1 week later (−0.5 to −0.1°C), but not two (0.1°C −0.4 to 0.5°C; n = 7) or 3 weeks. Similarly, heart rate after 90-min exercise (146 ± 21 b min−1) was reduced (−13: −6 to −20 b min−1) and remained at this level after 1 week (−13: −6 to −20 b min−1) but not two (−9: 6 to −23 b min−1; n = 7) or 3 weeks. Performance (746 s) increased 106 s: 59 to 152 s after Acc and remained higher after one (76 s: 31 to 122) but not two (15 s: −88 to 142 s; n = 7) or 3 weeks. Therefore, STHA (5-day) induced adaptations permitting increased heat loss and this persisted 1 week but not 2 weeks following Acc.Peer reviewe