Exercise Dose and Quality of Life

Abstract

A sedentary lifestyle is a risk factor for many chronic conditions, including diabetes mellitus, heart disease, stroke, and certain types of cancers.^1-6 Regular physical activity and higher levels of cardiorespiratory fitness are associated with lower risk for premature mortality, and exercise training has been demonstrated to improve a number of important risk factors, such as cardiorespiratory fitness,⁷ weight, high-density lipoprotein cholesterol level, and fasting insulin level.⁸ Although mood, level of functioning, energy level, and other measures of quality of life (QOL) are purported to be improved by regular exercise, this claim is largely unsubstantiated in populations without significant morbidities. There is strong evidence that regular exercise substantially improves QOL in populations with serious diseases, such as cancer⁹ or chronic obstructive pulmonary disease,¹⁰ but the data are not as supportive in populations without disease. Although many, but not all, epidemiological studies have found an association between exercise and QOL, the available data from intervention trials fail to consistently find a strong effect of exercise training on QOL.^11,12 Furthermore, the data from intervention trials are difficult to interpret because of small sample sizes, inadequate control groups, and poor exercise compliance. In addition, many studies include a weight loss component, making it difficult to separate the benefits of weight loss from the benefits of increased exercise.