Intensity versus duration of walking, impact on mortality: the Copenhagen City Heart Study

Background Current recommendations prescribe that every adult should accumulate 30 min or more of moderate-intensity physical activity in leisure time, preferably all days of the week. To further support these recommendations we examined the impact of walking intensity and walking duration on all-cause mortality. Design Relative intensity and duration of walking were recorded in 7308 healthy women and men aged 20-93 at the third examination (1991-1994) of the Copenhagen City Heart Study. During an average of 12 years of follow-up 1391 deaths were recorded. Results For both sexes we found a significant inverse association between walking intensity and risk of death, but only a weak inverse association to walking duration. For women walking with average intensity, the adjusted hazard ratio (HR) of death was 0.75 [95% confidence interval (Cl) 0.61-0.92; P<0.01] and walking with fast intensity 0.48 (95% Cl 0.35-0.66; P<0.001) compared to women walking with slow intensity. For men the relative risks were 0.54 (95% Cl 0.45-0.67; P<0.001) and 0.43 (95% CI 0.32-0.59; P<0.001), respectively. Conclusion Our findings indicate that the relative intensity and not the duration of walking is of most importance in relation to all-cause mortality. Thus our general recommendation to all adults would be that brisk walking is preferable to slow.