Swain, D.P., & Franklin, B.A. 2006. Comparison of cardioprotective benefits of vigorous versus moderate intensity aerobic exercise. American Journal of Cardiology, 97, 141–47.

Much emphasis in exercise design now includes attempts at involving students and clients in structured exercise programs as well as in spontaneous physical activity, including standing, walking and fidgeting (Kravitz 2006). A current escalating controversy in the fitness industry is whether vigorous exercise yields greater health-related benefits than moderate-intensity exercise. In other words, once clients start getting active and fit, should the personal trainer or other fitness professional encourage the client to attain even higher levels of fitness? This article will initially describe the up-to-date health benefits of physical activity and then bring to light the results of a recent review article on the cardioprotective benefits of vigorous versus moderate-intensity aerobic exercise.

Health Benefits of Physical Activity: Current Proof

Research on the positive health benefits of physical activity attained a meaningful point in fitness/health history with the evidence presented by Paffenbarger and colleagues in the 1970s, and with their follow-up analyses of a large population of subjects, primarily men. Similar follow-up health-benefit studies by other researchers have assessed the relative risk of death from any cause for both women and men. A recent review by Warburton, Nicol and Bredin (2006), which examines data regarding the benefits of regular physical activity, is partially summarized below.

Among both men and women, those who do the most physical activity have a 20%–35% relative risk reduction for all causes of death, including cardiovascular disease (CVD) (Warburton, Nicol & Bredin 2006). An increase in energy expenditure to about 1,000 kilocalories of physical activity a week (equivalent to walking 1 hour on 5 days of the week) is associated with a mortality benefit of about 20%. From a different perspective, Warburton and colleagues note that physically inactive middle-aged women (who engage in less than 60 minutes of exercise per week) are at a 52% increased risk for all causes of mortality. The scientists further state that persons who are fit, yet have one or more CVD risk factors (such as hypertension, chronic obstructive pulmonary disease, diabetes, smoking, elevated body mass index and high cholesterol levels), may also be at lower risk of premature death than their sedentary counterparts with no CVD risk factors. In addition, it appears that there is a graded indirect (or inverse) effect for those engaging in more physical activity (e.g., accumulating more time being physically active each week) and their associated risk reduction for death from all causes. Thus, to summarize Warburton et al., there is indisputable evidence of the positive effectiveness of regular physical activity in the primary and secondary prevention of chronic diseases such as diabetes, hypertension, obesity, CVD, some forms of cancer, depression and osteoporosis. And, there clearly appears to be a linear association between increased physical activity and improved health status.

So, Which Is Better
for Cardioprotective
Benefits: Vigorous
or Moderate-Intensity Aerobic Exercise?

To answer this difficult question, Swain and Franklin (2006) reviewed epidemiologic studies (studies that report incidence or prevalence data) that assessed the benefits of physical activity, as well as clinical investigations (studies that test and analyze results) that actually trained subjects at different intensities. Swain and Franklin note that they included only studies where energy expenditure was controlled for in the research design. This was important because vigorous exercise elicits a greater energy expenditure than moderate exercise; thus, controlling for energy expenditure provides the optimal way to assess the effects of aerobic exercise intensity. Also, Swain and Franklin report that, in their review, identifying specific training levels for vigorous versus moderate-intensity exercise was somewhat imprecise owing to the fact that studies reported intensities in any of the following ways: %VO2max

improved body composition

improved weight control

improved coronary blood flow

improved cardiac function

improved endothelial function

improved high-density

lipoprotein (HDL) cholesterol

improved glucose metabolism

improved insulin sensitivity

improved autonomic

nervous system tone

improved psychological


reduced blood pressure

reduced systemic inflammation

reduced blood coagulation

reduced abdominal adiposity

reduced triglyceride levels

reduced low-density

lipoprotein (LDL) cholesterol

reduced stress, anxiety

and depression

Source: Warburton, D.E., Nicol, C.W., & Bredin, S.S. 2006. Health benefits of physical activity: The evidence. Canadian Medical Association Journal, 174 (6) 801–9.
table 1. biological and psychological mechanisms of
regular physical activity