November 30, 2022 – If there’s one public health message Americans have heard loud and clear, it’s this:
Take more steps.
Spend more time doing physical activity – at least 150 minutes per week according to the latest guidelines.
But hearing the message doesn’t mean we act on it. a throw 25% of Americans do not get any physical activity beyond what they do at work, according to a CDC survey.
A new study proposes a different approach: you don’t have to do more. Just do what you’re already doing, but with a little more effort.
The study builds on accumulating evidence suggesting exercise intensity is just as important as quantity. So, turning something as simple as a leisurely stroll into a brisk walk can lead to a significant reduction in your risk of cardiovascular disease over time. No extra movements, steps or minutes required.
Researchers from Cambridge University and the University of Leicester in England looked at data from 88,000 middle-aged adults who wore an activity tracking device for 7 days.
The devices tracked both the total amount of their activity and the intensity of that movement—that is, how fast they walked or how hard they exerted themselves.
The researchers then calculated their physical activity energy expenditure (the number of calories they burned getting up and moving) and the percentage that came from moderate to vigorous physical activity.
What is the difference?
Over the next 6 to 7 years, 4,000 new cases of cardiovascular disease emerged among study participants.
Those who obtained at least 20% of their physical activity energy expenditure from moderate-to-intensity activity had a significantly lower risk of heart disease than those whose higher-intensity activity was about 10%.
This was true even for those whose overall activity was relatively low. As long as higher-exertion activities reached 20% of their total effort, they were 14% less likely to be diagnosed with heart disease.
And for those with relatively high activity levels, there was little additional benefit if their moderate and vigorous activities stayed at around 10%.
This finding surprised Paddy Dempsey, PhD, a medical research scientist at Cambridge and lead author of the study. But it also makes sense.
“People can improve their cardiorespiratory fitness to a greater extent through higher-intensity activity,” he says. “More intensity will stress the system and lead to greater adaptation.”
The key is an increase in the amount of oxygen your heart and lungs can deliver to your muscles during exercise, a measure known as VO2 max.
Increasing your VO2max is the best way to reduce your risk of early death, especially death from heart disease. Simply moving from the lowest conditioning category to a higher one will reduce your risk of death by up to 60% in any given year.
The study builds on previous research showing the benefits of moving faster.
Walking faster naturally increases your stride length, another indicator of longevity and future health. A review study published in 2021 found that older adults who took shorter steps were 26% more likely to have a disability, 34% more likely to have a serious adverse event (such as an injury that leads to loss of independence), and 69% more likely to die from it next few years.
Quality vs. Quantity
So far we’ve focused on the quality of your physical activity – moving faster, taking longer strides.
But there is still a lot to be said about the amount of movement.
“It would be a mistake to say volume doesn’t matter,” Dempsey warns.
A 2022 study in the journal The lancet found that the risk of dying during a given period decreases with each increase in daily steps. The protective effect peaks at around 6,000 to 8,000 steps per day for adults over 60 years of age and at 8,000 to 10,000 steps for people under 60 years of age.
“The relative value of the quality and quantity of exercise is very specific to a person’s goals,” he says Chhanda Dutta, PhD, Head of the Department of Clinical Gerontology at the National Institute on Aging. “When performance is the goal, quality counts at least as much as quantity.”
Dempsey agrees it’s not a cage fight between two. Every step you take is a step in the right direction.
“People can choose or be drawn to an approach that works best for them,” he says. “It’s also helpful to think about where some everyday activities can be punctuated with intensity,” which could be as simple as walking faster, if possible.
What matters most is that you choose some, says Dutta. “You risk more if you don’t train.”