Health: true or false?

How much exercise do we need to stay healthy? A brisk 15-minute walk a day is a great start

A study in France reinforces findings that regular exercise is crucial to an adult’s health – but the minimum number of minutes required is less than originally thought

PUBLISHED : Saturday, 18 June, 2016, 12:16pm
UPDATED : Saturday, 18 June, 2016, 12:15pm

Q: Do adults really need to do at least 150 minutes of moderate-intensity aerobic physical activities a week for good health?

The short answer: no The facts: Hong Kong’s Department of Health, led by World Health Organisation guidelines, recommends that adults aged 18 to 64 perform a weekly total of at least 150 minutes of moderate-intensity – or at least 75 minutes of vigorous-intensity – aerobic physical activities. But many of us fail to hit that target, the excuse being a lack of time.

The good news: just half that recommend amount can reap enormous health benefits. Just 15 minutes of daily exercise such as brisk walking is associated with a 22 per cent lower risk of death compared to being inactive, according to research from the University Hospital of Saint-Etienne in France.

The study authors looked at two cohorts: a French group of 1,011 subjects aged 65 in 2001 was followed over a period of 12 years; and an international one of 122,417 subjects aged 60 was included from a systematic review and meta-analysis of previously published studies, with an average follow-up of 10 years.

Physical activity was measured in metabolic equivalent of task (MET) minutes per week, which refers to the amount of energy (calories) expended per minute of physical activity and is dependent on intensity. One MET minute per week is equal to the amount of energy expended just sitting. Moderate intensity activity ranges between 3 and 5.9 MET minutes, while vigorous intensity activity is classified as 6 or more.

The recommended levels of exercise equate to between 500 and 1,000 MET minutes every week. The authors looked at the associated risk of death for four categories of weekly physical activity in MET minutes, defined as inactive (reference for comparison), low (1-499), medium (500-999) or high (greater than 1,000).

During the follow-up there were 88 (9 per cent) and 18,122 (15 per cent) deaths in the French and international cohorts respectively. Compared to those who were inactive, older adults with low, medium and high activity levels had a 22 per cent, 28 per cent and 35 per cent lower risk of death, respectively.

“These two studies show that the more physical activity older adults do, the greater the health benefit,” says Dr David Hupin, a physician in the university’s Department of Clinical and Exercise Physiology. “The biggest jump in benefit was achieved at the low level of exercise, with the medium and high levels bringing smaller increments of benefit.”

Hupin says age is no excuse for older adults to skip exercise. “Fifteen minutes a day could be a reasonable target for older adults. Small increases in physical activity may enable some older adults to incorporate more moderate activity and get closer to the recommended 150 minutes per week.”