Heart Rate Zones

What are heart rate zones?

Heart rate zones are levels that provide various benefits the higher up you go.
They are calculated by percentages of one's maximum heart rate.

Like any muscle, the heart also needs to be regularly pushed to its limits to stretch its elasticity: 
The harder you push it, with more frequency, the better it will be to recover
from various environmental and medical factors that my put strain to it, such as stress. Regular heart exercise also allows for better prevention of heart related health problems, such as high/low blood pressure, clotted arteries, and other heart diseases.

Differences between sexes

Among some factors we've considered when personalizing your heart rate zones is sex. Generally, women have smaller hearts compared to men. Thus to compensate for less blood pumped per beat, the heart must beat faster. [a]

Below is a chart of the heart rate zones we've based off of our research. You may find the links at the end of this article. [b] These levels take in just a few factors (sex and age) at the moment. However, we're working hard to fine-tune our formula and levels to better guide our users for better heart fitness [c]

How did we calculate these zones? 

We've simplified our heart rate zones to three levels: 
Relaxed (resting intensity, meditative)
Moderate (moderate intensity, fat burning)
Vigorous (high intensity, cardio strength)

The American Heart Association recommends [d] individuals to participate in at least 45 minutes of high intensity exercise per week, and 30-45 minutes of moderate intensity exercise per day.

Our basic formula [e] is: 
Moderate: Maximum Heartrate (220-age) * 65%
Vigorous: Maximum Heartrate (220-age) * 77%

Of course, the intensity in which you should exercise depends on many factors such as lifestyle, weight, fitness level, stress levels, smoking/drinking habits, preexisting health conditions, and much more.
For the time being, these are general guides; and we plan on incorporating adjustable BPM goals by intensity in the near future!

References

[a] Females vs Male heart sizes article.
[b] Similar graphs are published by the International Fitness association of America here.
[c] If you want to get technical, here's a study published by the American CDC.
[d] Read the recommended heart activity levels reported by American Heart Association (AHA) here.
[e] You can read up on this formula here.