The Apple Watch already comes with a built-in heart rate monitor, but certain factors can prevent it from getting an accurate reading. The way the …

Apple Watch band closely monitors your heart rate and rhythm<p>The Apple Watch already comes with a built-in heart rate monitor, but certain factors can prevent it from getting an accurate reading. The way the strap fits on a user’s wrist, how he or she moves their wrist, and the presence of tattoos …