Middle-aged women who did many short bursts of vigorous-intensity exercise — amounting to as little as 3 min/d — had a 45% lower risk for major adverse cardiovascular events, reported investigators.
This doesn’t mean just a walk in the park, explained Emmanuel Stamatakis, PhD, a researcher with the University of Sydney in Sydney, Australia. He said the activity can be as short as 20-30 seconds, but it must be high intensity — “movement that gets us out of breath, gets our heart rate up” — and repeated several times daily.
Stamatakis and his colleagues call this type of exercise vigorous intermittent lifestyle physical activity, and it involves intense movement in very short bouts that are part of daily life, like a quick stair climb or running for a bus.
In their study, published in the British Journal of Sports Medicine, most exercise bursts were less than a minute, and few were over 2 minutes.
This is the third study in which the international network of researchers has shown the health benefits of vigorous physical activity. They are upending the common view that “any physical activity under 10 minutes doesn’t count for health,” said Stamatakis.
Bursts of Energy
The three studies looked at data for thousands of middle-aged men and women aged 40-69 years collected in the UK Biobank. Their daily activity was measured using accelerometers worn on the wrist for 7 days. This is preferable to survey data, which Stamatakis said is often unreliable.
The analysis looked at people who reported that they did not do any other exercise, taking no more than a single walk during the week. Then their cardiovascular health was tracked for almost 8 years.
Previous studies of the same data have shown benefits of vigorous physical activity for risk for cancer and for risk for death, both overall and due to cardiovascular disease or cancer.
In this study, women who did even less than 2 minutes of vigorous physical activity a day but no other exercise had a lower risk for all major cardiovascular events and for heart attack and heart failure. Women who did the median daily vigorous exercise time — 3.4 minutes — had an even lower risk. In fact, in women, there was a direct relationship between daily exercise time and risk reduction.
In men, the study showed some benefit of vigorous physical activity, but the relationship was not as clear, said Stamatakis. “The effects were much subtler and, in most cases, did not reach statistical significance.”
Good News for Women
Stamatakis said it is unclear why there was such a gap in the benefits between men and women. “Studies like ours are not designed to explain the difference,” he added.
“This study does not show that [vigorous physical activity] is effective in women but not men,” said Yasina Somani, PhD, an exercise physiology researcher at the University of Leeds, Leeds, England, who was not involved in the work. Because the study just observed people’s behavior, rather than studying people in controlled conditions such as a lab, she said you cannot reach conclusions about the benefits for men. “You still need some further research.”
Somani pointed out that a study like this one cannot determine how vigorous physical activity protects the heart. In her research, she has studied the ways that exercise exerts effects on the heart. Exercise stresses the cardiovascular system, leading to physiological adaptation, and this may differ between men and women.
“Seeing this article motivates me to understand why women are responding even more than men. Do men need a greater volume of this exercise? If you’re carrying a 10-pound grocery bag up a flight of stairs, who is getting the greater stimulus?”
In fact, the study researchers think women’s exercise bursts might simply be harder for them. For some of the sample, the researchers had data on maximal oxygen consumption (VO2 max), a measure of cardiovascular fitness. During vigorous physical activity bouts, this measure showed that the effort for women averaged 83.2% of VO2 max, whereas it was 70.5% for men.
Somani said, “For men, there needs to be more clarity and more understanding of what it is that provides that stimulus — the intensity, the mode of exercise.”
“People are very surprised that 20-30 seconds of high-intensity exercise several times a day can make a difference to their health,” said Stamatakis. “They think they need to do structured exercise,” such as at a gym, to benefit.
He said the message that even quick exercise hits are beneficial can help healthcare professionals foster preventive behavior. “Any health professional who deals with patients on a regular basis knows that physical activity is important for people’s overall well-being and prevention of chronic disease.” The difficulty is that many people cannot or simply do not exercise. “Some people cannot afford it, and some do not have the motivation to stick to a structured exercise program.”
But anyone can do vigorous physical activity, he said. “The entry level is very low. There are no special preparations, no special clothes, no money to spend, no time commitment. You are interspersing exercise across your day.”
The researchers are currently studying how to foster vigorous physical activity in everyday behavior. “We are codesigning programs with participants, engaging with middle-aged people who have never exercised, so that the program has the highest chance to be successful.” Stamatakis is looking at encouraging vigorous physical activity through wearable devices and coaching, including online options.
Somani said the study adds weight to the message that any exercise is worthwhile. “These are simple choices that you can make that don’t require engaging in more structured exercise. Whatever you can do — little things outside of a gym — can have a lot of benefit for you.”