Research shows it’s not just how much you run, but how hard you go that plays a key role in improving health and performance.Even small amounts of higher-effort activity added to your routine can make a meaningful difference.
When it comes to boosting performance and health, many runners tend to focus on frequency and duration of activity—for example, how many days a week you run, along with total weekly mileage. But there’s another variable that is just as important when it comes to progress and disease prevention: intensity.
A new study published in the European Heart Journal, looking at data from about 475,000 people, found those who incorporated vigorous physical activity into their regular routines were at the lowest risk of developing major chronic diseases.
“The main message from this research is that how hard you move matters, not just how much you move,” says the study’s principal investigator, Minxue Shen, PhD, professor and vice director of Xiangya School of Public Health at Central South University in Hunan, China.
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To determine the effect of vigorous activity, researchers looked at fitness tracker data from more than 96,000 men and women, as well as self-reported activity levels from more than 375,000 individuals, shared with the UK Biobank. They compared the amount of intense daily activity—even if done for just a few minutes every day—to the incidence of death and eight chronic diseases.
Researchers defined vigorous activity in a couple ways: For those wearing fitness trackers, they looked at wrist acceleration, measured in milligravity (mg), with vigorous activity measuring greater than 400 mg and light activity ranging from 30 to 125 mg. For self-reported data, vigorous activity meant efforts that substantially elevated heart rate and breathing. (The American Heart Association also defines vigorous activity as not being able to talk much without getting out of breath.)
The diseases assessed included major adverse cardiovascular events, atrial fibrillation (irregular heartbeat), type 2 diabetes, chronic respiratory diseases, chronic kidney disease, dementia, and a few other metabolic and inflammatory conditions.
“For runners and cyclists, this is encouraging, because they’re often already doing higher-intensity efforts like hill training and sprinting,” Shen says. “Those appear to provide meaningful health benefits, even more than you’d see by simply logging more miles at an easy pace.”
What’s also notable: Study participants with at least 4 percent of vigorous physical activity had significantly lower risk of death and chronic disease, compared with those with no intense activity at all. “For most people, the encouraging message is that even brief efforts count,” Shen says.
In terms of how that percentage translates into minutes of effort, it depends on how much total activity someone does, but Shen notes that if you’re physically active for about two hours daily—including walking, household tasks, and other everyday movement—then 4 percent would translate to roughly five minutes of vigorous activity.
For athletes who may be active for longer periods, 4 percent of their total activity time would naturally be higher, but he notes that the key point remains: The threshold is surprisingly low.
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These study findings are in line with past studies highlighting the advantages of very brief bursts of activity and high-intensity exercise. For example, a study in BMJ Open Sport & Exercise Medicine looked at how five- to 10-minute bouts of moderate-intensity exercise affected 53 study participants who were normally sedentary. Researchers found 24 weeks of completing these brief sessions boosted oxygen consumption and improved cardiovascular function.
Another study, in Applied Physiology, Nutrition, and Metabolism, assessed the benefits of sprinting up a three-flight staircase three times a day—what they called “exercise snacks”—three times a week for six weeks. Researchers determined the effects on 24 young, sedentary adults, and found the sprinting resulted in higher cardiorespiratory fitness, compared with the control group at the end of the study. (Better cardio fitness has also been linked to lower cancer mortality, as well as improved running performance.)
Although the most recent study was observational and didn’t directly test potential mechanisms for why vigorous activity would affect disease risk, Shen says that previous research points to several plausible pathways.
“Total activity volume is broadly beneficial for improving insulin sensitivity, lowering blood pressure, and reducing systemic inflammation,” he explains. “Vigorous activity, however, appears to trigger additional physiological responses.”
Higher-intensity exercise places greater demand on the cardiovascular system, and that can improve the ability of your heart, lungs, and blood vessels to supply oxygen to your working muscles during exercise. It also improves how your blood vessels work and how your heart functions.
Intense exercise also produces stronger metabolic and hormonal responses, which may help improve how the body uses energy and regulates inflammation, Shen says. All of that contributes to reducing risk for major chronic conditions like cardiovascular disease, type 2 diabetes, and others studied by the researchers.
“There is also emerging evidence that vigorous activity may have specific effects on immune regulation and inflammatory pathways, which could help explain why we saw particularly strong associations between intensity and certain immune-related diseases in our study,” he says. “However, more research is needed to confirm these mechanisms.”
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Shen recommends you build intensity gradually over time and avoid sudden increases, as that can increase your chances of injury.
Here are some practical methods you can include in your running schedule to gain serious health benefits, according to Shen:
Adding short pick-ups or strides. Including four to six brief accelerations (around 20 to 30 seconds) during or at the end of an easy run is a simple way to introduce higher intensity without greatly increasing injury risk.Conquering hills. Running uphill naturally increases intensity without requiring a large increase in speed, so it’s an easy way to reach a vigorous effort.Including short, faster segments. Even a few minutes of “comfortably hard” running within an otherwise easy session can provide a meaningful stimulus.
“Overall, the key idea is not that runners need long or very intense workouts, but that small amounts of higher effort—introduced gradually—can be meaningful,” Shen says. “You don’t need to turn every run into a hard workout; just a few moments of higher effort can make a difference.”
By doing this, you not only benefit your overall health and improve your longevity but you’ll also run faster and perform better.
Elizabeth Millard is a freelance writer focusing on health, wellness, fitness, and food.