Cardiorespiratory fitness, adiposity, and hypertension.

T he authors evaluated whether the effects of cardiorespiratory fitness and adiposity jointly are related to mortality in hypertensive men.1 They found that the effect of cardiorespiratory fitness is a powerful modifier of the association between adiposity and mortality in men with hypertension. It has been shown, in a well-known long-term prospective study in a general population, that cardiorespiratory fitness has the effect of reducing all-cause mortality, and negating cardiovascular disease (CVD)–related mortality associated with obesity. The study relates to patients examined at the Cooper Clinic in Dallas, Texas. Most of the participants were Caucasian and from middle and upper socioeconomic strata. It comprised male subjects who were free of cancer and of CVDs such as myocardial infarction and stroke, and who were able to complete an exercise test to a level of at least 85% of their age-predicted maximal heart rate. All the participants in the study were men with hypertension, who had been followed up for at least 12 years. It would be interesting to see whether the results from future studies are consistent as regards women subjects: a recent study has shown that there were no significant interactions between gender and risk factors.1 Our study showed that cardiorespiratory fitness is related to coronary heart disease-related death in hypertensive and normotensive men, and as well as in obese and nonobese men.2 Similar findings have been found in those with different combinations of common risk factors. In previous studies too, investigators have consistently observed that low cardiorespiratory fitness is related to the risk of death in normal-weight, overweight, and obese subjects.3 These findings support those from cohort studies suggesting that the risk of death associated with low cardiorespiratory fitness is comparable with those associated with conventional risk factors including smoking, hypertension, hypercholesterolemia, obesity, and diabetes. The use of antihypertensive medication is a typical feature among subjects with high blood pressure. However, in this study, the treatment received by the subjects for hypertension is not known, and this is a limitation of the study.1 The use of antihypertensive medication would have an effect on the data obtained from these patients. For example, some patients on β-blockers would find it difficult to attain their age-predicted maximal heart rate. The authors have acknowledged that the access to good medical care was high among men from upper socioeconomic strata. The methods adopted for measurement of risk factors including smoking, alcohol consumption, and physical activity (PA) are fairly crude. In a recent study, PA habits were obtained from a standardized questionnaire whereas physical inactivity was defined as reporting no leisure-time PA in the 3 months prior to the examination. Regular PA may be related to lower blood pressure, although the effect of PA alone on blood pressure is reported to be low. Is it viable to make comparisons between assessments of cardiorespiratory fitness which have been arrived at using different testing methods? Directly measured oxygen consumption is considered to be the gold standard for the definition of cardiorespiratory fitness. The authors estimate metabolic equivalents (METs) on the basis of final treadmill speed and grade.1 The differences in exercise testing protocols should also be taken into account while interpreting the data, although differences between the protocols are small when maximal standard exercise testing is employed.4 When exercise capacity is reported in METs, comparisons can be easily made.