Exercise is generally good for health, and one form of exercise that I advocate strongly is walking. Regular walking has been associated with protection from chronic diseases such as heart disease and type 2 diabetes. It also is an activity that tends to take people outdoors. This may have spin-off benefits in terms of, say, enhanced sunlight exposure. Other boons related to walking is that it is relatively gentle on the body, requires little or no ‘kit’, and can be partaken in by almost everyone, including individuals who do not regard themselves as ‘sporty’.
For someone to get maximum benefit from walking, I generally recommend that individuals spend at least some of the time walking briskly. Getting speed and effort up to a point where one is mildly breathless but still able to talk is likely to be intense enough to enhance fitness and general health. Just this week, a study was published which links increased walking speed with benefits for health in terms of reduced risk of death, specifically from cardiovascular diseases (e.g. heart attacks and stroke).
The study, published on-line in the British Medical Journal, followed about 3200 men and women aged 65 or over (average age 73) over an average of 5 years [1]. At the beginning of the study the walking speed of study participants was assessed. Over time, the researchers kept tabs on whether the participants. In cases where someone had died, cause of death was also ascertained.
The analysis of this study entailed assessing the relationship between walking speed and risk of death (overall risk of death, as well as death due to specific conditions). The study participants were split into thirds according to walking speed (slow, medium, fast). Essentially, compared to faster walkers, those in the ‘slow’ category were found to be at increased risk of death from cardiovascular disease, but not other causes (e.g. cancer).
The researchers, in their analysis, attempted to ‘control for’ various ‘confounding factors’. It is possible the slower walkers smoked more or were at higher risk of high blood pressure, and that these factors might account for the relationship between slower walking speed and increased risk of death. Factoring these so-called confounding factors into an analysis of the data will give us a better idea if walking speed is genuinely associated with risk of mortality in a meaningful way. In this study, the researchers attempted to account for a huge array of potential confounders, including age, sex, body weight and medical history.
Even after accounting for these factors, the relationship between slow walking and increased risk of mortality remained. Compared to fast walkers, individuals in the slow category were at a 44 per cent increased risk of death overall. Their risk of death from cardiovascular disease was about three times higher than fast walkers. Risk of death from other causes, including cancer, was not higher.
Now, epidemiological studies of this nature cannot be used to conclude that fast walking speeds have direct benefits for health. However, the fact that the association remained after so many confounding factors were accounted for at least suggests a real relationship. The association held true for both men and women, those exercising a lot and a little, those at high and low risk of cardiovascular disease, and the young and old.
The data in this study suggested what is known as a ‘threshold effect’, which means that benefits were associated with increased walking speed up to a certain speed, beyond which increased speed is not associated with additional benefit. Unfortunately, there was not enough data to allow the researchers to assess where this threshold lies.
However, it is probably useful to know that individuals in the slow category were walking at speeds of less than 1.5 and 1.35 metres per second in men and women respectively. For men, this equates to walking a mile in about 18 mins (and a kilometre in about 11 minutes). For women, mile and kilometre times come out at about 20 and 12.5 minutes respectively.
I continue to be a huge advocate of walking for improved health and wellbeing. This study suggests that brisk walking might reduce risk of death, specifically from cardiovascular disease, over time.
References:
1. Dumurgier J, et al. Slow walking speed and cardiovascular death in well-functioning older adults: a prospective cohort study. BMJ 2009;339:b4460
