Physical work capacity was measured by means of a symptom limited, near maximal cycle ergometer exercise test in two populations: a random sample of 95 military officers, and 2014 apparently healthy working males, 40-59 years old. Physical activity during leisure hours was assessed by means of a standardized questionnaire and by a personal interview with the officers and with 1769 of the other men. A 3 year total incidence of coronary heart disease (CHD) was recorded in the case of the officers and a 7 year CHD incidence and of CHD deaths was obtained for the 2014 working men. The data show that: A marked underestimation of the habitual levels of physical activity of the officers was obtained from the standardized questionnaire, as compared with that shown by the interview data. A far better agreement between the questionnaire and interview data on leisure time activity was observed among the mainly sedentary men. Physical work capacity was fairly well predicted from the questionnaire data in the sedentary men, but poorly predicted in the officers. CHD mortality in the sedentary men was highly correlated with working capacity in all age groups. Of 58 who died from CHD, 28 belonged to the lowest physical fitness quartile. This study indicates that questionnaires should be used with caution when assessing levels of habitual physical activity. It also suggests that a low physical work capacity is an important risk factor in CHD mortality.
A standardized, annual medical examination of a group of heat workers exposed to, and another group not exposed to heat in a Norwegian ferro-alloy plant over a period of six years showed no statistically significant difference in blood pressure between the two groups. However, following three years of stable blood pressure and heart rates, both parameters increased markedly in both groups. The occurrence of this sudden increase in blood pressure coincided with the plant being threatened with the possibility of closure due to inability to operate at a profit. This threat persisted for more than two years, but even afterwards, when it was quite clear that jobs at the plant were no longer threatened, the blood pressure remained markedly elevated. These findings emphasize the importance of being aware of the possible relationship between prolonged mental stress and hypertension.
A near maximal bicycle exercise test revealed a prevalence of positive exercise ECG's of 8/68 among apparently healthy sea-pilots and 93/2014 among apparently healthy men of comparable age in Oslo (P less than 0.01). This difference could not be explained in terms of differences in commonly accepted coronary heart disease risk factors (cholesterol/triglycerides, smoking habits and blood pressure). Reasons for the difference should be sought in the working environment of the pilots as well as in possible unfavourable life habits adapted during leisure time as indicated by a relative increase in body weight and somewhat lower working capacity in pilots than in age matched counterparts from Oslo.
In a prospective study of 115 patients with systemic meningococcal disease, 61 control patients and 293 population controls, environmental and other factors which preceded the illness and which might have influenced the acquisition and case fatality rate of the meningococcal disease were investigated. Passive smoking in children under 12 year of age, stressful events, and symptoms and signs of preceding illness within the last two weeks were significantly more frequent in meningococcal patients than among the population controls. In contrast, those patients who had been exposed to stressful events, or who had symptoms or signs of ill-health preceding the meningococcal disease, had significantly reduced case fatality rates as compared to those who had not had any such experiences. Passive smoking remains a factor of great interest for further studies and intervention.
BACKGROUND: Resting heart rate is directly associated and maximal exercise-induced heart rate inversely associated with cardiovascular mortality, and therefore their difference might contain prognostic information from both variables. The comparative long-term prognostic values of maximal exercise-induced heart rate and of the difference between it and resting heart rate were studied in apparently healthy middle-aged men. METHODS: Resting heart rate and maximal exercise-induced heart rate were measured, and their difference calculated, in 1960 apparently healthy men aged 40-59 years, and mortality was recorded over a period of 16 years. Conventional coronary risk factors were assessed at baseline. RESULTS: Both the difference between the two heart rates and the maximal exercise-induced heart rate were strongly, independently and inversely associated with cardiovascular mortality after adjustment for age, smoking, systolic blood pressure, lung function, glucose tolerance, serum cholesterol level, serum triglycerides level, physical fitness and exercise ECG findings. The adjusted relative risk of cardiovascular death in heart-rate difference quartiles 3 and 4 compared with that in quartile 1 (the lowest heart-rate difference quartile) was 0.54 (95% confidence interval 0.33-0.86; P = 0.009). The corresponding value for maximal exercise-induced heart rate was 0.56 (95% confidence interval 0.34-0.89; P = 0.018). Within the lowest heart-rate difference quartile, but not within the lowest maximal exercise-induced heart rate quartile, a further, strong, negative gradient in cardiovascular mortality was observed. In the high working capacity range, low heart-rate difference but not low maximal exercise-induced heart rate predicted very high cardiovascular disease mortality. Heart-rate difference and maximal exercise-induced heart rate were also inversely associated with non-cardiovascular disease mortality. CONCLUSIONS: Both heart-rate difference and maximal exercise-induced heart rate were strong, graded, long-term predictors of cardiovascular mortality among apparently healthy middle-aged men, independent of age, physical fitness and conventional coronary risk factors. However, low heart-rate difference was a better predictor than low maximal exercise-induced heart rate for recognizing individuals who were at particularly high risk of dying prematurely from cardiovascular diseases.
For 110 apparently healthy Norwegian captains on ocean-going ships a near maximal bicycle exercise test revealed a pathological exercise electrocardiogram for 10.0%, while the corresponding results for a comparable group of Oslo men and a group of Norwegian sea pilots were 4.6 and 11.8%, respectively. The significant difference in prevalence between the captains and Oslo men could not be explained by differences in serum lipids, blood pressure, or a family history of coronary heart disease. The captains were taller and more physically fit than the Oslo men, but they were significantly heavier and had a more rapid age decline in physical performance capacity and a higher prevalence of heavy smokers. Ten of the 11 captains with a pathological exercise electrocardiogram were, or had been, heavy smokers (greater than or equal to 20 cigarettes/d). A high caloric intake in relation to caloric expenditure, heavy smoking, and poorly defined factors such as stress, irregular workhours, and varying climatic conditions are factors to be considered as explanations for these findings. The claim by captains that they have a higher risk than average for developing coronary heart disease was to some extent corroborated in the present study.
BACKGROUND. Despite many studies suggesting that poor physical fitness is an independent risk factor for death from cardiovascular causes, the matter has remained controversial. We studied this question in a 16-year follow-up investigation of Norwegian men that began in 1972. METHODS. Our study included 1960 healthy men 40 to 59 years of age (84 percent of those invited to participate). Conventional coronary risk factors and physical fitness were assessed at base line, with physical fitness measured as the total work performed on a bicycle ergometer during a symptom-limited exercise-tolerance test. RESULTS. After an average follow-up time of 16 years, 271 men had died, 53 percent of them from cardiovascular disease. The relative risk of death from any cause in fitness quartile 4 (highest) as compared with quartile 1 (lowest) was 0.54 (95 percent confidence interval, 0.32 to 0.89; P = 0.015) after adjustment for age, smoking status, serum lipids, blood pressure, resting heart rate, vital capacity, body-mass index, level of physical activity, and glucose tolerance. Total mortality was similar among the subjects in fitness quartiles 1, 2, and 3 when the data were adjusted for these same variables. The adjusted relative risk of death from cardiovascular causes in fitness quartile 4 as compared with quartile 1 was 0.41 (95 percent confidence interval, 0.20 to 0.84; P = 0.013). The corresponding relative risks for quartiles 3 and 2 (as compared with quartile 1) were 0.45 (95 percent confidence interval, 0.22 to 0.92; P = 0.026) and 0.59 (95 percent confidence interval, 0.28 to 1.22; P = 0.15), respectively. CONCLUSIONS. Physical fitness appears to be a graded, independent, long-term predictor of mortality from cardiovascular causes in healthy, middle-aged men. A high level of fitness was also associated with lower mortality from any cause.
Comment In: N Engl J Med. 1993 Feb 25;328(8):574-68426626
Work stress was assessed by continuous logging of heart rate in 31 air traffic control personnel at seven airports in Norway. The results showed work stress within reasonable limits in all categories of air traffic controllers. Tests of psychomotoric functions in 36 operators revealed that all categories of operative personnel, but the air traffic controllers especially, emphasized accuracy at the expense of speed. Measurements of blood pressure in nine of the 33 air traffic controllers who had shown significantly elevated blood pressure in 1981 during a serious labour conflict revealed values below what was to be expected for their age group.