Coronary Heart Disease and Physical Activity - A Fresh Look

Incidences of fatal coronary heart disease in White South African males increased significantly between 1951 and 1970. In those under 60 years of age, the incidence exceeds that in USA. Prevention lies in the early recognition of raised blood Iipids and hypertension, and in stopping smoking. The role of physical inactivity is less certain. The physiological knowledge needed for determining the correct speed of walking and running is proposed.S. Afr. Med. J., 48, 571 (1974

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

Trends and determinants of excess winter mortality in New Zealand: 1980 to 2000

<p>Abstract</p> <p>Background</p> <p>Although many countries experience an increase in mortality during winter, the magnitude of this increase varies considerably, suggesting that some winter excess may be avoidable. Conflicting evidence has been presented on the role of gender, region and deprivation. Little has been published on the magnitude of excess winter mortality (EWM) in New Zealand (NZ) and other Southern Hemisphere countries.</p> <p>Methods</p> <p>Monthly mortality rates per 100,000 population were calculated from routinely collected national mortality data for 1980 to 2000. Generalised negative binomial regression models were used to compare mortality rates between winter (June–September) and the warmer months (October–May).</p> <p>Results</p> <p>From 1980–2000 around 1600 excess winter deaths occurred each year with winter mortality rates 18% higher than expected from non-winter rates. Patterns of EWM by age group showed the young and the elderly to be particularly vulnerable. After adjusting for all major covariates, the winter:non-winter mortality rate ratio from 1996–2000 in females was 9% higher than in males. Mortality caused by diseases of the circulatory system accounted for 47% of all excess winter deaths from 1996–2000 with mortality from diseases of the respiratory system accounting for 31%. There was no evidence to suggest that patterns of EWM differed by ethnicity, region or local-area based deprivation level. No decline in seasonal mortality was evident over the two decades.</p> <p>Conclusion</p> <p>EWM in NZ is substantial and at the upper end of the range observed internationally. Interventions to reduce EWM are important, but the surprising lack of variation in EWM by ethnicity, region and deprivation, provides little guidance for how such mortality can be reduced.</p

Long-Term Exposure to Silica Dust and Risk of Total and Cause-Specific Mortality in Chinese Workers: A Cohort Study

A retro-prospective cohort study by Weihong Chen and colleagues provides new estimates for the risk of total and cause-specific mortality due to long-term silica dust exposure among Chinese workers

Thermal discomfort with cold extremities in relation to age, gender, and body mass index in a random sample of a Swiss urban population

<p>Abstract</p> <p>Background</p> <p>The aim of this epidemiological study was to investigate the relationship of thermal discomfort with cold extremities (TDCE) to age, gender, and body mass index (BMI) in a Swiss urban population.</p> <p>Methods</p> <p>In a random population sample of Basel city, 2,800 subjects aged 20-40 years were asked to complete a questionnaire evaluating the extent of cold extremities. Values of cold extremities were based on questionnaire-derived scores. The correlation of age, gender, and BMI to TDCE was analyzed using multiple regression analysis.</p> <p>Results</p> <p>A total of 1,001 women (72.3% response rate) and 809 men (60% response rate) returned a completed questionnaire. Statistical analyses revealed the following findings: Younger subjects suffered more intensely from cold extremities than the elderly, and women suffered more than men (particularly younger women). Slimmer subjects suffered significantly more often from cold extremities than subjects with higher BMIs.</p> <p>Conclusions</p> <p>Thermal discomfort with cold extremities (a relevant symptom of primary vascular dysregulation) occurs at highest intensity in younger, slimmer women and at lowest intensity in elderly, stouter men.</p

Copeptin reflects physiological strain during thermal stress.

PURPOSE: To prevent heat-related illnesses, guidelines recommend limiting core body temperature (T c) ≤ 38 °C during thermal stress. Copeptin, a surrogate for arginine vasopressin secretion, could provide useful information about fluid balance, thermal strain and health risks. It was hypothesised that plasma copeptin would rise with dehydration from occupational heat stress, concurrent with sympathoadrenal activation and reduced glomerular filtration, and that these changes would reflect T c responses. METHODS: Volunteers (n = 15) were recruited from a British Army unit deployed to East Africa. During a simulated combat assault (3.5 h, final ambient temperature 27 °C), T c was recorded by radiotelemetry to differentiate volunteers with maximum T c > 38 °C versus ≤ 38 °C. Blood was sampled beforehand and afterwards, for measurement of copeptin, cortisol, free normetanephrine, osmolality and creatinine. RESULTS: There was a significant (P  38 °C (n = 8) vs ≤ 38 °C (n = 7) there were significantly greater elevations in copeptin (10.4 vs. 2.4 pmol L(-1)) and creatinine (10 vs. 2 μmol L(-1)), but no differences in cortisol, free normetanephrine or osmolality. CONCLUSIONS: Changes in copeptin reflected T c response more closely than sympathoadrenal markers or osmolality. Dynamic relationships with tonicity and kidney function may help to explain this finding. As a surrogate for integrated physiological strain during work in a field environment, copeptin assay could inform future measures to prevent heat-related illnesses