An algorithm based on heart rate is a better way to track physical activity than steps or minutes of exercise, according to a recently published study in the American Journal of Medicine. Mio Global is using the new metric, called Personalized Activity Intelligence in its Mio Slice device, announced at CES this year and set to launch December 1st.
“Worldwide, the way typically exercise is quantified is minutes of exercise: The recommendation generally is 150 minutes of moderate exercise or 75 minutes of vigorous exercise per week to prevent cardiovascular mortality or overall mortality,” Dr. Chip Lavie, an Ochsner physician who was one of the lead researchers on the study, told MobiHealthNews. “And then another way it’s been frequently measured is by steps. And the problem with the steps is that, all steps aren’t created equally because all steps don’t increase your heart rate. Theoretically one could walk extremely slowly for hours and your heart rate’s not going up, but you are taking a lot of steps.”
Personalized Activity Intelligence, or PAI, converts the user’s heart rate to a number of points based on their age, gender, resting heart rate and maximum heart rate. Users earn different number of points based on the intensity and duration of heart rate-affecting workouts. So to meet the goal of 100 PAI points per week, that might involve just 40 minutes of very vigorous activity or many hours of light activity over the course of the week.
The study analyzed old data from a large Norwegian study called the HUNT study, which tracked 45,000 individuals for 25 years. Researchers created the algorithm based on a 2006 study of a portion of the HUNT cohort and then validated it using data from the whole cohort.
“Using the PAI during a week of follow-up, they showed that those who reached this 100 cut point had about a 20 percent reduced risk of cardiovascular mortality and approximately a 15 percent reduced risk of all-cause mortality compared to those who didn’t reach a PAI of 100,” Lavie said. “But what was more interesting was in those individuals who exercised to the federal guidelines, meaning 150 minutes of moderate physical activity or 75 minutes of vigorous, but who didn’t get a PAI over 100 still had 25 to 30 percent higher mortality rate than those who reached a PAI of 100. And vice-versa those who reached the PAI but didn’t reach the minutes-per-week cutoff, didn’t have an increased risk of dying.”
Because the study used old, historical data it doesn’t address the potential benefits of monitoring PAI in near-realtime using a wrist-worn heart rate tracker and an app with the algorithm built in. But Mio CEO Liz Dickinson says PAI is also more motivating than a step goal.
“What’s great about PAI is it eases people in in a way that’s optimally effective for their physiology and it grows with them as their fitness level improves. So I think it’s a good way to motivate people. It’s not defeating like trying to do 10,000 steps every day,” she said. “What I love about PAI is I can actually bank my PAI. So I make sure I can get over 120 or 130 because I might know that I’m going to be traveling for the next couple of days, or I’m going to be in a series of meetings that’s going to make it difficult for me to get out and exercise and so I don’t have to worry about my protection against lifestyle diseases until my PAI score drops down to 100 or less.”
Dickinson hopes PAI will spread to other tracker companies as well. The company is developing an app to bring the metric to the Apple Watch, for instance.
“There’s millions of devices out there with heart rate and the fundamental, universal problem with those devices is lack of engagement,” she said. “People don’t know what to do with that heart rate sensor. Doesn’t matter if it’s accurate or not accurate — What should they use it for? When should they use it? What does that data mean? PAI answers all those questions and can impact people’s health and fitness.”
