When Fitbit introduced its new Active Zone Minutes (AZM) feature earlier this year on the Charge 4, it quickly became a new way of helping people adjust how much effort they're putting into different stages of their workouts.

Recommendations from health providers like the World Health Organisation recommend at least 150 minutes of moderate activity or 75 minutes of vigorous activity every week, in order to keep a healthy heart and body.

Fitbit developed AZMs that use heart rate tracking to calculate different ‘active zones' like fat burn, cardio, and peak.

To understand how Fitbit wearers were using AZMs, the company used anonymised data from 20,000 people over a one-month period.

Fitbit studied how well weekly AZMs correlate to other health statistics like resting heart rate and body mass index (also known as the dreaded and somewhat controversial BMI).

Somewhat unsurprisingly, the result showed that the more AZMs a person gains, the more positive their health statistics are.

Fitbit data scientist Aubrey Browne says there's a clear association between AZMs and the tools users need to improve health.

According to Fitbit: “Men and women with 150 AZMs per week had a lower RHR compared to users who did not.

“The differences in RHR were also statistically significant for both genders when looking at these same cohorts: men's RHR on average was 2.45 fewer beats per minute and women's RHR was 2.7 fewer in those with 150 AZMs per week.

“For BMI, those men who had 150 AZMs had a 0.7 lower BMI, while women who had the same had a 0.9 lower BMI. For context, the BMI for someone within the normal weight range is typically 18.5 to 24.9, so a difference of 0.9 can determine if someone falls into a normal or overweight BMI category.”

But don't be fooled into thinking that by gaining a heap of AZMs from low-intensity exercise is the best strategy – the best health results come from the cardio and peak zones.

“The more cardio and peak zone minutes a user had compared to moderate minutes, the lower their resting heart rate and body mass index.

Results also show that it helps to be consistent with workouts. It seems that most people like to do their best workouts on Mondays and Tuesdays, with intensity dropping throughout the week.

Also those who work out in blocks (for example dedicated workouts with more intensity) are more likely to lower their resting heart rate and BMI than those who 'sprinkle' moderate exercise in short chunks.

“While it's not always easy, finding time every day to get your heart pumping can help you start burning fat and improve your overall health,” says Fitbit.