While exercise is pretty much universally recommended as a disease-preventer and important contributor to good health, there's a surprising dearth of studies supporting this premise. Most recommendations for exercise have come from epidemiological studies, which may find associations between, say, activity and better health, but do not prove that it's the activity itself that's is causing improvement. Active individuals may, after all, smoke less or eat more healthily than less active individuals, and it may be these factors that are responsible for the apparent relationship between activity and enhanced health.
To properly gauge whatever benefits exercise may have, we need proper intervention studies. The most obvious model here would be to take a group of individuals and get them to up their exercise, and then compare their long-term health with that of a group who remain more sedentary. As in the area of nutrition, such studies are rare compared to the epidemiological variety, but they do come along every so often and they generally provide a valuable opportunity to get a much more accurate picture of what exercise can—and can't—do for us.
Recently, such a study was published. It essentially sought to assess the effects of walking on a group of individuals with type 2 diabetes [1]. The study started out with 102 individuals aged 35–75 who walked for 20–30 minutes per day. Their progress was followed for a period of a little less than 18 months, during which their adherence to the program and their cardiovascular health with regard to heart attack and stroke was assessed through telephone interviews.
During the course of the study, 38 individuals dropped out and ceased the exercise program. The cardiovascular health of these individuals was then compared with that of the individuals who stuck with the program.
The incidence of cardiovascular disease was about 1.5 percent in individuals who completed the program. This compared very favorably indeed with the incidence in dropouts, which was found to be more than 18 percent. The result was statistically significant and remained robust even after the researchers took into account other factors that might affect the result, including age.
This study was small and far from perfectly designed. Asking people about their exercise habits and disease experience over the phone, for instance, may not give us the most accurate picture of such factors. However, even with these limitations, I do believe this study should allow us to be quite optimistic about the real benefits to be had from regular exercise for type 2 diabetics. What I find most pleasantly surprising about the findings is the relatively short period of time it took for the benefits of exercise to became apparent.
It would be nice to see more exercise intervention studies in the future. Ideally, these should include healthy individuals and be focused on manageable, realistic forms of exercise, such as walking. Positive results from such studies and their attendant publicity may just help to inspire sedentary individuals to be more active.
References:
1. Shinji S, et al. Adherence to a Home-Based Exercise Program and Incidence of Cardiovascular Disease in Type 2 Diabetes Patients. International Journal of Sports Medicine 2007; 28:877–879
Dr. John Briffa is a London-based doctor and author with an interest in nutrition and natural medicine.
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