Counting 100 steps a minute may be an easy way to maintain pace during brisk walks, burning calories and reducing the risk of diabetes or cardiovascular disease, a study suggests.
The study by researchers at the San Diego State University in the US has shown that 30 minutes of moderate intensity exercise translates into 3,000 steps on a pedometer, a device that helps count steps.
Doctors typically prescribe 30 minutes of moderate intensity exercise each day for at least five days a week as a means to check obesity, improve blood pressure readings and reduce the risk of cardiovascular diseases.
In the new study, Simon Marshall at the department of exercise and nutritional sciences and his colleagues at the San Diego university monitored oxygen uptake and heart rates of 58 women and 39 men walking a treadmill at different speeds. They found moderate-intensity exercise was achieved by women at counts between 91 and 115 steps per minute and by men at 92 to 102 steps per minute.
The study will appear shortly in the American Journal of Preventive Medicine.
“This data supports the general recommendation of walking at more than 100 steps per minute on level terrain,” said Marshall, who is investigating the use of step counts in the promotion of physical activity.
Preventive medicine specialists believe many people who exercise routinely don’t derive full benefits because they don’t push their hearts to required activity levels.
“To achieve moderate-intensity exercise, the heart rate has to touch 60 to 70 per cent of the maximum rate, which is linked to the age of a person,” said Dorairajan Prabhakaran, a cardiologist at the Centre for Chronic Diseases in New Delhi.
The maximum heart rate is computed by subtracting the age from 220. A 40-year-old would thus have a maximum heart rate of 180, and moderate-intensity exercise at that age would mean pushing the rate to 108 beats a minute.
The difference in the counts of women and men emerge because of stride lengths — men are taller and take fewer steps in 30 minutes, Marshall said. Step counts would be a simple method to help people gauge exercise intensity, Prabhakaran told The Telegraph.
But doctors warn that the 100-steps-a-minute target may not be appropriate for all.
“People above 40 who may have undetected cardiovascular risk or who have previous heart disease should ideally consult doctors before they embark on an exercise plan that is appropriate for them,” said Prabkaharan.
For otherwise healthy people, while the target should be 3,000 steps in 30 minutes, doctors say it may be approached gradually — starting with 1,000 steps in 10 minutes and increasing it steadily to reach 3,000 steps in 30 minutes.
The actual calories burnt depend on several factors, including the pace of exercise, body mass, the proportion of muscle mass, age and gender. But the burn-up rate is about 3kcal per kg per hour. A 70kg man will, therefore, expend 105 kcal during a 30-minute walk.
Sources: The Telegraph (Kolkata, India)