1. The physiological responses to repeated continuous (progressive) exercise together with the relationship between continuous and discontinuous work tests on an upright bicycle ergometer have been studied in healthy male subjects.2. The results show a marked decline in mean cardiac frequency (fH) from 145 beats/ min to 124 beats/min during the first four experiments at a given submaximal oxygen intake of 1.5 l/min and thereafter a smaller decline to reach 118 beats/min on the final (sixteenth) day of the investigation. This latter decrease was associated with a small but significant rise in maximum oxygen intake @02 max) which occurred from Day 8 onwards. Pulmonary minute ventilation at an oxygen intake of 1.5 l/min PE decreased by about 5 l/min immediately following the first occasion of submaximal work but thereafter remained unchanged. There was however no decrease in 0, cost of exercise, as 00, at a k e d rate of external work remained unchanged throughout the investigation.3. At maximal effort there was no significant decrease in either vEmax or fHmax, but the f H at which the 00, max was reached declined significantly from Day 8.Thus the asymptotic nature of the fH/002 curve which was very pronounced on Day 1 virtually disappeared following the third visit to the laboratory. The accuracy of predicting 00, max from f H and 00, increased noticeably from -15.4 & 8.9% on Day 1 to -6.5 10.5% on Day 7 and -0.9 3.4% on Day 15. The possible physiological basis and implications of the results are discussed. 4. No significant differences were found between continuous and discontinuous work. Thus in large scale population studies of work capacity or in the evaluation of training programmes in rehabilitation studies, a continuous test may be used but attention must be paid to familiarization procedures. At least three preliminary test periods are necessary before the results become reproducible and reliable.The maximum aerobic power PO, max) is now widely accepted by exercise physiologists as a

A description of the fitness, physical activity of lifestyle, and some aspects of health status and attitudes in a population of male factory workers aged 35-60 is presented as the first part of a report on a study of morbidity in this population. A total of 1394 subjects were included, undergoing medical examination, fitness testing by bicycle ergometry, assessment of body fat, and interview questionnaire. The inter-relation of fitness, body composition, habitual exertion, health risk factors, and attitudes to exercise are discussed. Fitness levels are compared with those reported in other studies and discussed in terms of capacity for walking and running and in relation to criteria for health benefit. In these two latter respects fitness appears to be inadequate among the great majority of those tested, although it is comparable with that reported by several other recent studies. Fitness is associated with physical activity of leisure but not that of work. Only relatively strenuous physical activity in leisure time appears to be related to fitness, and is only participated in by some 28% of the sample. Cycling has the strongest association with fitness of all the physical activity variables. Blood pressure and percentage body fat are also associated, inversely, with fitness, the latter not unexpectedly because of the weight related measure of fitness.The relation between physical activity and health has been extensively studied over the past 30 years and comprehensively reviewed,`-7 interest focusing particularly on the possible significance of activity level in the aetiology of ischaemic heart disease (IHD). Despite the difficulty of using evidence of an epidemiological nature in establishing and verifying relations between different risk factors, a growing consensus of lay and medical opinion believes that physical activity may protect against heart disease. If so then its relative importance may well increase as the impact of other risk factors, particularly smoking, is reduced. A substantial decrease in incidence of fatal heart attacks in the United States has occurred recently alongside a major public response to specific health education programmes which have led to reduced smoking, modified diet, and increases in level and in incidence of exercise. It is not, however, possible to say which, if any, of these responses have been the effectors. If increased exercise has indeed contributed to the improved cardiac health of Americans further investigation will still be necessary to determine whether exercise is of direct benefit or whether its effect is to modify other risk factors, perhaps proAccepted 3 February 1986 moting greater tolerance, particularly of dietary factors. Encouraging evidence for this last explanation is accumulating from studies of serum lipids,8 9 especially when exercise is accompanied by weight loss.Population studies of the relation between physical activity and incidence of IHD seldom include information about the physical condition of individuals, describing only physical...

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In order to identify risk factors (e.g. physical inactivity, dietary composition) associated with blood pressure within a given population, it is necessary to adjust for differences in known associations (e.g. age, body weight) using a method such as the analysis of covariance. However, the blood pressure results from the Allied Dunbar National Fitness Survey (ADNFS) were found to be non-linear with age, positively skewed (with heteroscedastic errors) and therefore non-normally distributed. Hence, before valid inferences can be drawn from such data, there is a clear need to formulate an appropriate model for blood pressure that will overcome these undesirable characteristics. A multiplicative model (with allometric body size components) was proposed and fitted to the ADNFS blood pressure results. After a logarithmic transformation the parsimonious solution was able to confirm the association with BMI, the non-linear changes with age, and overcome the heteroscedastic and positively skewed errors, i.e. the residuals from the fitted log-linear models for both systolic and diastolic blood pressure were symmetric and normally distributed. Other factors were found to make a significant additional contribution to the prediction of blood pressure. Cyclists, participants in vigorous physical activity and those subjects who consumed more fresh fruit, rice or pasta, and wine were found to have significantly lower mean levels of blood pressure. Indeed, the gap in blood pressure between participants and non-participants in vigorous physical activity increased further with age. However, subjects who drank more beer tended to have significantly higher mean levels of blood pressure. Thus by developing an appropriate model for arterial blood pressure, some well known, and some less well known, associations with arterial blood pressure have been identified. The results suggest that physical activity and other lifestyle factors may protect against hypertension.

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