Changes in vigorous physical activity and incident diabetes inmale runners
We examined the dose-response relationship between changes in reported vigorous exercise (running distance, {Delta}km/wk) and self-reported physician diagnosed diabetes in 25,988 men followed prospectively for (mean {+-} SD) 7.8 {+-} 1.8 years. Logistic regression analyses showed that the log odds for diabetes declined significantly in relation to men's {Delta}km/wk (coefficient {+-} SE: -0.012 {+-} 0.004, P < 0.01), which remained significant when adjusted for BMI (-0.018 {+-} 0.003, P < 0.0001). The decline in the log odds for diabetes was related to the distance run at the end of follow-up when adjusted for baseline distance, with (-0.024 {+-} 0.005, P < 0.0001) or without (-0.027 {+-} 0.005, P < 0.0001) adjustment for BMI. Baseline distance was unrelated to diabetes incidence when adjusted for the distance at the end of follow-up. Compared to men who ran <8 km/wk at the end of follow-up, incidence rates in those who ran {ge} 8 km/wk were 95% lower between 35-44 yrs old (P < 0.0001), 92% lower between 45-54 yrs old (P < 0.0001), 87% lower between 55 and 64 years old (P < 0.0001), and 46% lower between 65-75 yrs old (P = 0.30). For the subset of 6,208 men who maintained the same running distance during follow-up ({+-}5 km/wk), the log odds for diabetes declined with weekly distance run (-0.024 {+-} 0.010, P = 0.02) but not when adjusted for BMI (-0.005 {+-} 0.010, P = 0.65). Conclusion: Vigorous exercise significantly reduces diabetes incidence, due in part to the prevention of age-related weight gain and in part to other exercise effects. Physical activity decreases the risk of type 2 diabetes [1-10]. Moderate and vigorous exercise are purported to produce comparable reductions in diabetes risk if the energy expenditure is the same [3,10]. The optimal physical activity dose remains unclear, however, with some [4-7] but not all studies [1,8,9] showing continued reduction in diabetes for high versus intermediate energy expenditures. The National Runners Health Study [11-19] is unique among population cohorts in its focus on the health impact of higher doses of vigorously intense physical activity (i.e., {ge} 6-fold metabolic rate). The study was specifically designed to evaluate the dose-response relationship between vigorous physical activity and health for intensities and durations that exceed current physical activity recommendations [20-22]. One specific hypothesis is whether changes in vigorous physical activity affect the risk for becoming diabetic. Although women were surveyed and followed-up, only 23 developed diabetes so there is limited statistical power to establish their significance. Our analyses of diabetes and vigorous exercise are therefore restricted to men. This paper relates running distance at baseline and at the end of follow-up to self-reported, physician diagnosed diabetes in vigorously active men who were generally lean and ostensibly at low diabetic risk The benefits of greater doses of more vigorous exercise are relevant to the 27% of U.S. women and 34% of U.S. men meet or exceed the more general exercise recommendations for health benefits [23]. Specific issues to be addressed are: (1) whether maintenance of the same level of vigorous exercise over time reduces the risk of incident diabetes in relation to the exercise dose; (2) whether men who decrease their activity increase their risk for becoming diabetic; and (3) whether end of follow-up running distances are more predictive of diabetes than baseline distances, suggesting a causal, acute effect. Elsewhere we have shown that greater body weight is related to a lack of vigorous exercise [12-14] and increases the risk for diabetes even among generally lean vigorously active men [11]. In runners, leanness may be due to the exercise or due to initially lean men choosing to run further [17]. Therefore we also test whether body weight mediates the effects of vigorous exercise on diabetes, and whether this may be due to self-selection.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director, Office of Science; National Institutes ofHealth
- DOE Contract Number:
- DE-AC02-05CH11231; NIHHL72110
- OSTI ID:
- 925601
- Report Number(s):
- LBNL-63635; R&D Project: L0118; BnR: 400412000; TRN: US200810%%57
- Journal Information:
- Diabetes Care, Vol. 30; Related Information: Journal Publication Date: 2007
- Country of Publication:
- United States
- Language:
- English
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