Walking and running comparably reduce CHD risk factors

Williams PT, Thompson PD.
Arterioscler Thromb Vasc Biol. 2013 May;33(5):1085-91. doi: 10.1161/ATVBAHA.112.300878.

Background

Guidelines on physical activity assume that activities of different intensities can be combined to achieve a minimum recommended dose. Moderate activities are those that expend 3- to 6-fold the energy expenditure of sitting at rest (3-6 metabolic equivalents (METs). Walking is generally of moderate intensity and is specifically recommended by  some health institutes [1-4]. It is, however, unknown, whether equivalent doses of moderate and vigorous (>6 METs) give the same health benefits [5].
The current analysis therefore aimed to determine whether equivalent energy expenditure by moderate and vigorous exercise produces similar reductions in coronary heart disease (CHD) risk factors. Associations are investigated of incident hypertension, hypercholesterolemia and type 2 diabetes mellitus to reported exercise in the National Runners’ Health Study II and the National Walkers’ Health Study [6-8]. In these studies, energy expenditure is assessed from weekly distance run or walked, as opposed to time spent exercising in many other studies.

Main results

• Runners expended more than twice as much energy by running than did walkers by walking. The majority of other reported exercise was vigorous, for both runners and walkers.
• Equivalent energy spent running or walking was associated with comparable risk reductions for hypertension (runners: HR: 0.958, 95%CI: 0.944-0.973, P<0.0001, walkers: HR: 0.928, 95%CI: 0.899-0.957, P<0.0001), hypercholesterolemia (runners: HR: 0.957, 95%CI: 0.946-0.968, P<10^-14, walkers: HR: 0.930, 95%CI: 0.908-0.953, P<0.0001) and diabetes mellitus (runners: HR: 0.9798, 95%CI: 0.832-0.929, P<0.0001, walkers: HR: 0.877, 95%CI: 0.824-0.934, P<0.0001). Increasing MET hours per day (METh/d) run or walk were associated with significantly lower risks for all three risk factors.
• Faster pace, in both runners (HR: 0.609, 95%CI: 0.553-0.67, P<10^-15) and walkers (HR: 0.758, 95%CI: 0.639-0.899, P=0.002), was associated with lower risks of hypertension, as well as hypercholesterolemia (runners: HR: 0.667; 95% CI, 0.619–0.720; P<10⁻¹⁵; walkers: HR: 0.823; 95% CI, 0.720–0.942; P=0.005), and diabetes mellitus (runners: HR: 0.433; 95% CI, 0.334–0.574; P<10−7; walkers: HR: 0.427; 95% CI, 0.331–0.573; P<10⁻⁹). These effects were mostly independent of exercise dose, but could largely be explained by BMI.
• There was limited statistical power to test for reductions in CHD risk due to low number of incident cases, but runners showed 52% lower CHD risk than the walkers (P<10^-5), which dropped to 43% reduction of risk after adjustment for BMI (P=0.002). METh/d run (HR: 0.955, 95%CI: 0.912-1.000, P=0.05) and METh/d walk (HR: 0.907, 95%CI: 0.839-0.981, P=0.01)  were both associated with lower CHD risk, which did not differ statistically significantly.

Conclusion

These data suggest that equivalent doses of running (a vigorous exercise) and walking (moderate) are both associated with grossly equivalent risks reductions of new onset hypertension, hypercholesterolemia and diabetes mellitus. Risk is further reduced when exercise dose exceeds 1.1-1.8 METh/d, where type of exercise does not seem to matter.
Runners had an on average more than twice exercise dose, and it is proposed that the higher estimated caloric expenditure(per time) accompanied with it may account for reducing CHD risk factors and possibly CHD events. This may explain why some studies that measures exercise by time spent indicate that vigorous exercise seems more beneficial, simply because more calories can be expended per minute in vigorous exercise as opposed to moderate exercise. Therefore, the authors claim and demonstrate that exercise energy expenditure is better calculated from distance than from time.

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References

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