Friday April 5 2013
Walkers are advised to try to take 10,000 steps a day
A brisk walk is "healthier than running", The Guardian reports, while the Daily Mail more accurately claims that walking "is as good as a run for cutting the risk of heart disease".
This news was based on a large and long-term study of runners and walkers, which found that when the same total energy was used, both activities were associated with largely similar reductions in the risk of:
The study does have limitations but, generally, it seems to confirm that moderate intensity exercise (such as brisk walking) has important health benefits.
For anyone now thinking that a stroll to the shops is as good as running the marathon, there is a catch. The study compared the reductions in risk associated with the same amount of energy expenditure, whether from walking or running. Running is a vigorous intensity exercise, meaning runners use more energy than walkers over the same period. Using up the equivalent energy in walking is always going to mean you’ll have to cover more ground.
Where did the story come from?
The study was carried out by researchers from the Lawrence Berkeley National Laboratory and Hartford Hospital, both in the US. It was funded by the US National Heart, Lung and Blood Institute.
The study was published in the peer-reviewed journal Arteriosclerosis, Thrombosis and Vascular Biology.
Generally, the science was reported accurately in the media, with the Mail correctly pointing out that those walking would have to spend the same amount of energy as those running to achieve the same benefits. The Mail also included a comment from an independent UK expert. The Guardian’s claim that walking is associated with greater health benefits than running was misleading. There was no significant difference between the benefits of running and those of walking.
What kind of research was this?
The research was based on two national cohort studies. It set out to examine whether equivalent energy expended on walking (a moderate intensity exercise) and running (a vigorous intensity exercise) was associated with equivalent reductions in risk of:
- high blood pressure
- high cholesterol
- coronary heart disease
The researchers say that while both moderate and vigorous physical intensity is recommended in national guidelines, it remains uncertain whether the same “dose” of both types has the same long-term health benefits.
What did the research involve?
Participants for national runners’ and national walkers’ health studies were originally recruited in 1998 and 1999, respectively, and they comprised more than 63,000 runners and 42,000 walkers. For the current research, 33,060 runners (21% men) and 15,945 walkers (51.4% men) participated. This was about half of the original runners and about a third of the original walkers. The participants were 18 to 80 years old and they completed baseline and regular follow-up questionnaires on their height, weight, medical history, lifestyle and education.
The participants were also asked how many miles they walked or ran each week and how many hours a week on average they spent on running, walking and other exercises. They were also asked for their usual pace (minutes per mile) during walking or running.
Researchers calculated from this their estimated energy expenditure, called the metabolic equivalent hours per day (or MET h/d). A MET is the measure of energy expended at rest, with 3-6 METs being the energy expended in moderate exercise. In this study the runners used up the equivalent of about 5.3 METs in an hour each day and the walkers 4.7.
During 6.2 years of follow-up, participants also self-reported any new diagnoses of high blood pressure, high cholesterol, diabetes and coronary heart disease (including heart attack and angina) or surgical treatment for CHD (including coronary artery bypass and coronary angioplasty). They also reported whether they had started medications for any of these conditions since the beginning of the study.
Researchers compared energy expenditure in both groups with the risks of these cardiovascular conditions occurring during follow-up. They analysed the data using standard statistical methods and adjusted their results for confounders such as age, sex, race, education and smoking.
What were the basic results?
For each MET h/d, running was associated with:
- a 4.2% reduction in the risk of high blood pressure
- a 4.3% reduction in the risk of high cholesterol
- a 12.1% reduction in the risk of diabetes
- a 4.5% reduction in the risk of CHD
The corresponding reductions for walking were:
- a 7.2% reduction in the risk of high blood pressure
- a 7.0% reduction in the risk of high cholesterol
- a 12.3% reduction in the risk of diabetes
- a 9.3% reduction in the risk of CHD
Researchers also found that the more energy used the greater the reduction in risk of these conditions.
How did the researchers interpret the results?
The researchers say that the equivalent energy expenditure from walking and running exercise produced similar risk reductions for high blood pressure, high cholesterol, diabetes and possibly CHD.
They also point out that there were additional benefits associated with exceeding current US guidelines for exercise levels.
This large study appears to show that moderate exercise such as brisk walking is as beneficial for health as vigorous exercise such as running, when the same energy is expended.
This study had several limitations, including its dependence on people self-reporting both their exercise levels and whether they had been diagnosed with the conditions being studied. However, this may be unavoidable in cohort studies of this type.
As the comparison was made between the results of two separate cohort studies combined as one (an indirect comparison), it is possible that the populations differed by some factor other than the intensity of exercise and particularly in how the participants were selected for study. The researchers explain that both cohorts were recruited over the same time interval, using the same questionnaire (modified slightly for the different activities). They say that both studies used subscription lists to running and walking publications and running and walking events for recruitment and the same people carried out the surveys, all funded by the same grant. This negates some of the concerns about whether the studies can be compared.
If the results of this study hold true there are a few things to bear in mind. First, in order to get the health benefits, walking needs to be faster than a stroll. To achieve ‘moderate intensity exercise’ your heart rate needs to be raised and you should experience a mild sweat.
Adults need to do around 150 minutes of moderate intensity physical activity a week. The current advice for people trying to stay fit through walking is to try to walk 10,000 steps a day.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.