Researchers from the Netherlands Medical Center at Leiden University proposed to set their watches to exercise in the morning.
According to scientists, this is the time to exercise will reduce the risk of cardiovascular disease.
The researchers' work was published in the European Journal of Preventive Cardiology.
The experiment involved 85,000 people from 42 to 78 years old with no cardiac or vascular disease.
Volunteers wore the tracker on their arm all week. Over 8 years of observation by scientists, 2,911 participants developed coronary heart disease and 796 experienced a stroke.
According to scientists, athletic training between 8 a.m. and 11 a.m. has the lowest risk of heart problems and stroke.
Physical activity during this time interval showed an 11% and 16% lower chance of developing coronary heart disease compared to other times. At the same time, there was also a 17% lower chance of stroke.