Nov. 30, 2022 – If there’s one public health message Americans have heard loud and clear, it’s this one:
Take more steps.
Spend more time doing physical activity – at least 150 minutes a week, according to the latest guidelines.
But hearing the message doesn’t mean we act on it. A whopping 25% of Americans don’t get any physical activity beyond what they do in their job, according to a CDC survey.
A new study suggests 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 growing evidence that suggests exercise intensity matters just as much as the amount. So, something as simple as turning a leisurely stroll into a brisk walk can, over time, lead to significant reductions in your risk of cardiovascular disease. No additional moves, steps, or minutes needed.
Step It Up
Researchers at 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 activity they did and the intensity of that movement – that is, how fast they walked or how hard they pushed themselves.
The researchers then calculated their physical activity energy expenditure (the number of calories they burned when they were up and moving) and the percentage that came from moderate to vigorous physical activity.
What’s the difference?
- Physical activity means any and every movement you do throughout the day. Mostly it’s mundane tasks like shopping, walking to the mailbox, playing with your dog, or cooking.
- Moderate-intensity physical activity includes things you do at a faster pace. Maybe you’re walking for exercise, doing yardwork or household chores, or maybe you’re running late and just trying to get somewhere faster. You’re breathing a little harder and possibly working up a sweat.
- Vigorous-intensity physical activity is usually an exercise session – a run, a strenuous hike, a tough workout in the gym. It can also be an exhausting chore like shoveling snow, which feels like a workout. You’re definitely breathing harder, and you’re probably working up a sweat, even in the middle of winter.
Over the next 6 to 7 years, there were 4,000 new cases of cardiovascular disease among the people in the study.
Those who got at least 20% of their physical activity energy expenditure from moderate to vigorous activities had significantly less risk of heart disease, compared to those whose higher-effort activities were about 10%.
That was true even for those whose total activity was relatively low. As long as higher-effort activities reached 20% of their total, they were 14% less likely to be diagnosed with a heart condition.
And for those with relatively high activity levels, there was little extra benefit if their moderate and vigorous activities remained around 10%.
That finding surprised Paddy Dempsey, PhD, a medical research scientist at Cambridge and the study’s lead author. But it also makes sense.
“People can improve their cardiorespiratory fitness to a greater degree with 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 provide your muscles during exercise, a measure known as VO2 max.
Raising your VO2 max is the best way to reduce your risk of early death, especially death from heart disease. Simply moving up from the lowest conditioning category to a higher one will cut your risk of dying in any given year by as much as 60%.
The study builds on previous research that shows the benefits of moving faster.
Walking faster will naturally increase your stride length, another predictor 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 major adverse event (like an injury that leads to a loss of independence), and 69% more likely to die over the next several years.
Quality vs. Quantity
We’ve focused so far on the quality of your physical activity – moving faster, taking longer strides.
But there’s still a lot to be said for movement quantity.
“It would be a mistake to say volume doesn't matter,” Dempsey cautions.
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 about 6,000 to 8,000 steps a day for adults 60 and over, and at 8,000 to 10,000 steps for those under 60.
“The relative value of the quality and quantity of exercise are very specific to a person's goals,” says Chhanda Dutta, PhD, chief of the Clinical Gerontology Branch at the National Institute on Aging. “If performance is the goal, quality matters at least as much as quantity.”
Dempsey agrees that it’s not a cage match between two. Every step you take is a step in the right direction.
“People can choose or gravitate 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 when possible.
What matters most is that you choose something, Dutta says. “You have more to risk by not exercising.”