Here’s a heart-smart hack that’s less about miles per hour and more about math per day: a new study from Northwestern University’s Feinberg School of Medicine introduces a fresh way to measure your cardiovascular health using data your smartwatch already tracks. It’s called daily heart rate per step—or DHRPS—and it’s as simple as dividing your average resting heart rate by your daily step count. The result? A single number that reveals how efficiently (or inefficiently) your heart is working. According to lead author and med student Zhanlin Chen, “It’s a measure of inefficiency…You’re just going to have to do a tiny bit of math.” And while DHRPS doesn’t account for exercise heart rates, the study—analyzing data from nearly 7,000 Fitbit users—found it could be a powerful predictor of chronic conditions like diabetes, stroke, and heart failure. Looks like your resting heart rate and step count just had a smarter baby.

Key Points:

• The new metric, daily heart rate per step (DHRPS), is calculated by dividing your average daily resting heart rate by the number of steps you take in a day.
• A higher DHRPS indicates your heart is working less efficiently—and could be a red flag for several conditions: Type 2 diabetes, hypertension, heart failure, stroke, and coronary artery disease.
• The study, published in Journal of the American Heart Association, used real-world Fitbit data from 6,947 smartwatch users.
• Participants with the highest DHRPS were found to be at significantly greater risk for disease than those with lower ratios.
• Experts like Dr. Peter Aziz of the Cleveland Clinic praised the metric as adding more nuance than steps or heart rate alone. “What is probably more important for cardio fitness is what your heart does for the amount of work it has to do,” he said.
• Example: Two people with 10,000 steps per day but different resting heart rates (80 vs. 120) would have DHRPS values of 0.008 and 0.012 respectively—highlighting efficiency differences even with identical activity.
• The DHRPS metric is accessible to anyone with a smartwatch and a calculator—no specialized equipment required.
• Recommended devices for tracking heart rate and steps include Fitbit smartwatches, which were used in the study, and other wearables like the Apple Watch Series 9 and Garmin Venu 3.

Takeaway: With just one division problem a day, you might uncover a powerful predictor of your heart health—and get ahead of possible future risks by spotting inefficiencies your daily step count or resting heart rate might mask on their own. Keep your steps up, your heart strong, and your math sharp.
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