The effect of exercise episode duration on blood pressure

OBJECTIVE

To investigate the effect on blood pressure for 10-min compared with 40-min episodes of physical activity for 4 days.

DESIGN AND METHODS

The design used a randomized crossover trial of two exercise episode durations, involving 17 subjects, which were performed in a university setting. The intervention was exercise on a stationary bicycle for four consecutive days, at 50% of maximal oxygen uptake (determined by heart rate), for episode durations of 10 or 40 min. A rest period of 10 days followed before exercise for the alternative duration was performed. The main outcome measure was blinded assessment of blood pressure 24 h after the last exercise episode.

RESULTS

Significant reductions were found in systolic and diastolic blood pressure after 4 days of 40 min but not after 4 days of 10 min stationary cycling. The reduction in blood pressure was significant for both systolic and diastolic blood pressure for 4 days of 40 min of exercise episodes.

CONCLUSION

Exercise of moderate intensity on a stationary bicycle for 10 min for 4 days is not effective in lowering blood pressure in comparison with the same exercise for 40 min for 4 days. The experimental design employed in the present study has potential for monitoring the effects of exercise on blood pressure.

The worldwide problem of stroke

Cardiovascular disease is the leading cause of death worldwide with almost one third of all cardiovascular deaths ascribed to stroke. In contrast to coronary heart disease, most of the strokes occur in developing countries; China alone has about 1 million deaths from stroke each year. From a global perspective the stroke situation is changing rapidly, and considerable progress has been made in documenting the changes in stroke mortality. Despite the favorable trends in stroke mortality in many countries, stroke will become an increasingly important health problem as the world's population continues to age.

Changes in stroke incidence and case-fatality in Auckland, New Zealand, 1981-91

The explanation for the substantial decline in stroke death rates can be investigated only by measuring trends in stroke incidence and case-fatality. Two community-based studies carried out in Auckland, New Zealand, in 1981 and 1991 used comparable methods and definitions, met criteria for well-designed studies, and had the power to detect small changes in incidence and case-fatality rates. 703 events (representing 50% of all strokes) were registered in 1981 and 1735 events in 1991. 521 (74.1%) and 1255 (72.3%) events in 1981 and 1991, respectively, were first-ever (in a lifetime) strokes. Although there was no change in overall stroke incidence between 1981 and 1991, there were changes in age and sex groups. The incidence rate among women younger than 75 years rose by a fifth (rate ratio 1.23 [95% CI 1.04-1.47]), whereas that in men of 75 years and older fell by a third (rate ratio 0.67 [0.54-0.82]). The 28-day case-fatality declined from 27.1 (21.7-32.6)% to 21.9 (18.1-25.7)% in men and from 37.6 (31.8-43.5)% to 25.8 (22.3-29.4)% in women from 1981 to 1991, but the decline was not statistically significant in any age or sex group. These findings suggest that we need to reappraise strategies for the prevention of stroke and assess the implications of improved survival in elderly stroke patients.

Trends in medical management of acute myocardial infarction, Auckland 1983-90

AIMS

To examine changes in the medical management of acute myocardial infarction in the Auckland region between 1983 and 1990.

METHODS

6190 patients aged 25-64 years with myocardial infarction were identified utilising a population based register, the ARCOS study. Data were collected on resuscitation attempts, transportation to hospital, coronary care unit (CCU) stay and medication use before and during the CCU stay.

RESULTS

The median time delay between onset of symptoms and arrival at the CCU decreased by approximately 7 minutes per year. The average length of CCU stay decreased from 2.9 to 2.7 days and there were between hospital variations in length of CCU stay. The most striking change in drug therapy before the event was the increase in the use of antiplatelet agents from 5% in 1983 to 18.3% in 1990. There was also a big increase in the proportion of patients using antiplatelets (3.5 fold) and thrombolytic drugs (5.5 fold) during the CCU stay, in 1990, 50% of patients received thrombolytic agents and 56% received antiplatelet agents.

CONCLUSION

The use of drugs of proven benefit could be further increased although it appears that major improvements in mortality rates will come primarily from primary prevention.

Does recent alcohol consumption reduce the risk of acute myocardial infarction and coronary death in regular drinkers?

This study, conducted in Auckland, New Zealand, over 2 years from March 1986, used a case-control design to investigate the hypothesis that alcohol acutely increases the risk of both nonfatal myocardial infarction and coronary death in the 24 hours after drinking, among regular drinkers. The nonfatal myocardial infarction analyses included 278 male and 60 female cases identified from a population-based coronary heart disease surveillance program and 458 male and 266 female controls randomly selected from the same population matched by age and sex. In the coronary death analyses, 172 male and 16 female coronary death cases from the same surveillance program and a population-based sample of 294 males and 165 females who were age and sex matched were examined. Information on alcohol consumption in the 24 hours before the coronary event in cases and a comparable 24-hour period in controls was collected. Study subjects all drank alcohol regularly at least once per month and were aged 25-64 years. Controls were more likely than cases to report a drinking episode in the 24-hour period examined in both sexes and for fatal and nonfatal disease. After controlling for possible confounding, the authors found that drinkers had a consistently lower estimated risk of both fatal and nonfatal coronary heart disease than participants reporting no alcohol in the previous 24 hours. The odds ratios ranged from 0.75 (95% confidence interval 0.62-0.90) for nonfatal myocardial infarction in men to 0.46 (95% confidence interval 0.19-1.10) for coronary death in women. There were no clear differences in estimated acute risk among those who drank one or two drinks, three or four drinks, or more than four drinks in the 24-hour period. These findings suggest that, contrary to previous speculation, alcohol consumption may acutely reduce coronary heart disease risk.

Setting national health goals and targets in the context of a fiscal crisis: the politics of social choice in New Zealand

The setting of national health goals and targets in New Zealand has taken place in the context of fiscal crisis. The mandate for State intervention for social goals has also been under a sustained ideological challenge. These circumstances, together with other developments within the New Zealand health service, prepared the way for the development of the first set of health goals and targets. Six criteria were used to identify health problems for which goals and targets could be set. Ten areas were included, and specific, timed and quantified targets were set in each area for the year 2000 with shorter term targets for 1995. The Minister of Health gave priority to three areas: tobacco control, secondary prevention of cervical cancer, and reduction of road accident injury and death. An important aspect of the program is that the goals and targets are to be the focus of the annual contract between the Minister of Health (the primary funder of health care) and the Area Health Boards (the primary providers of health care). A matrix of policy options is presented for resource allocation and public health. The case study described represents one solution to the set of policy choices presented by fiscal and ideological challenge; the "new managerialism" has been allied with the "new public health." The authors argue that a combination of ideological renewal and fiscal probity has preserved a vigorous role for the State in health and health care. This matrix of policy options also underlines the necessity to consider health outcomes, as well as organizational goals, in the evaluation of the performance of health systems.

Does physical activity lower blood pressure: a critical review of the clinical trials

This review critically appraises 22 recent articles of trials of physical activity, as a means of reducing blood pressure. The quality of the literature remains poor and of the 13 controlled trials of habitual activity only one did not have a major design fault. Overall, blood pressure was reduced by physical activity in both hypertensive and normotensive persons. This effect was independent of weight loss and in some studies blood pressure reduction occurred in the presence of weight gain. The average reduction in the better designed studies was approximately 6-7 mmHg for both systolic and diastolic blood pressure which compares favourably with studies of pharmacological treatment. The better designed studies reported smaller reductions than studies with poorer design. All activities, including circuit weight training, lowered blood pressure and daily activity produced greater blood pressure reduction than when performed three times per week. It is concluded that physical activity has an independent capacity to lower blood pressure.

Community demonstration programs for cardiovascular disease prevention: the Asia-Pacific experience

Cardiovascular diseases are an important and increasing cause of death in many countries in the Asia-Pacific Region. Formal demonstration programs for the prevention of cardiovascular disease are few in number and not likely to be widely used in the future. Prevention programs focused on key risk factors are widely used in the Region and have been successful. Smoking prevention remains a high priority for all countries in the Region.

Mortality from coronary heart disease and incidence of acute myocardial infarction in Auckland, Newcastle and Perth

OBJECTIVE

To confirm the existence of regional differences in coronary death rates in Australia and New Zealand and to determine whether or not these are associated with parallel differences in the incidence of acute myocardial infarction.

DESIGN

Descriptive epidemiological study.

SETTING

Community based study.

SUBJECTS

Residents of Auckland, Newcastle and Perth aged 25-64 years admitted to hospital for acute myocardial infarction or dying from coronary heart disease between 1983 and 1987.

MAIN OUTCOME MEASURES

Definite acute myocardial infarction or coronary death classified according to the criteria of the World Health Organization MONICA project.

RESULTS

This study confirms the marked variation, evident from official statistics, in mortality rates from ischaemic heart disease between Newcastle (high), Auckland and Perth (low). A different pattern is observed for the incidence of acute myocardial infarction and there are also obvious differences between centres in the case fatality ratios for all acute coronary events combined. Newcastle has the highest rate for all coronary events, particularly in women. Auckland is characterised by substantially higher case fatality ratios compared with the two Australian cities. This is due especially to higher rates of coronary death outside hospital. Perth, which has the lowest mortality rates and case fatality ratios in both men and women, has rates for admission to hospital for acute myocardial infarction and all cases of ischaemic heart disease that are disproportionately high in relation to the corresponding mortality rates.

CONCLUSION

The differences in case fatality ratios between these three centres are not readily explained by artefacts related to enumeration or classification. Rather, they are most likely related to differences in the natural history of ischaemic heart disease in the three populations. Differences in medical management may also contribute to the substantial variation in mortality rates.

Potential misclassification in studies of physical activity

Regular physical activity is associated with a reduced risk of coronary heart disease, although debate still occurs over the level of intensity required for cardioprotection. The use in epidemiological studies of the arbitrarily defined categories of light, moderate, and hard, as proxy measures of relative intensity has administrative merit but risks potential misclassification, particularly in women and the elderly. This potential misclassification is the result of the inappropriate categorizing of activity based upon absolute intensity values regardless of age or gender. Coronary heart disease is more common in the elderly and recent activity more important than remote for cardiac benefit. It is thus essential to resolve the issue of the level(s) of exercise intensity needed to provide health benefits. Only when this information is available will it be possible to give rational and safe public health advice.

Alcohol consumption and risk of coronary heart disease

OBJECTIVE

To investigate the hypothesis that the apparent protective effect of habitual alcohol consumption on coronary heart disease is due to drinkers at high risk of coronary heart disease becoming non-drinkers.

DESIGN

Case-control population based study. Data were obtained from interviews with patients with non-fatal myocardial infarction and their controls and with the next of kin of those who had died of coronary heart disease and their controls.

SETTING

Auckland, New Zealand.

SUBJECTS

Two groups of cases were studied. The first comprised 227 men and 72 women with non-fatal myocardial infarction identified from a population based surveillance programme for coronary heart disease; controls were 525 men and 341 women randomly selected from the same population group and matched for age and sex. The second group comprised 128 men and 30 women who had died of coronary heart disease and had been identified from the surveillance programme; controls were a sample of the previous control group and comprised 330 men and 214 women matched for age and sex. All participants were aged 25-64 years and without diagnosed coronary heart disease.

MAIN OUTCOME MEASURES

Regular alcohol consumption; high density lipoprotein cholesterol and low density lipoprotein concentrations.

RESULTS

Men with myocardial infarction and men who had died of coronary heart disease were more likely to have been never drinkers (had never drunk more than once a month) than controls (18% v 12% and 23% v 13% respectively). After possible confounding factors had been controlled for, people in all categories of drinking (up to more than 56 drinks per week) had at least a 40% reduction in risk of fatal and non-fatal coronary heart disease compared with never drinkers. Former drinkers also had a lower risk of non-fatal myocardial infarction than never drinkers (relative risks 0.41 and 0.10 in men and women respectively) but a similar risk of death from coronary heart disease. The reduction in risk was consistently greater in women than in men in all drinking categories but there was no clear dose-response effect in either sex.

CONCLUSIONS

The results support the hypothesis that light and moderate alcohol consumption reduces the risk of coronary heart disease. This protective effect in this population was not due to the misclassification of former drinkers with a high risk of coronary heart disease as non-drinkers.

Validation of a three-month physical activity recall questionnaire with a seven-day food intake and physical activity diary

We assessed the validity of a three-month physical activity questionnaire. The validation instrument was a seven-day self-report diary of physical activity and food intake, given to 113 randomly selected persons. We obtained Spearman correlations of 0.60, 0.48, and 0.91 and kappa scores of 0.36, 0.23, and 0.62 from the physical activity recall and diary for moderate, vigorous, and total activity. We conclude that the three-month recall questionnaire reasonably reflects activity in this community-based sample.