Researchers from Vancouver Coastal Health (VCH), UBC, and SportsCardiologyBC are in the final phase of recruiting for a study that will follow 126 recreational and competitive athletes for 10 years.
The Time of Day Study will determine the safest time of day to exercise based on the presence of arrhythmia—or irregular heartbeats—during exercise.
“There is no disputing the tremendous benefits of exercise,” says Dr. James McKinney, the study’s lead author and cardiologist. “But we want to find out if there is a time of day when moderate to vigorous exercise is safest, from a cardiac standpoint.”
Research suggests that sudden cardiac death may also be linked to circadian rhythm. A study of more than 2,000 people in Massachusetts who died of sudden cardiac arrest found the patients’ circadian rhythms were more varied in the morning.
“There is a body of research that shows a higher rate of sudden cardiac death in the general population in the early morning,” says Dr. Saul Isserow, cardiologist and founder of SportsCardiologyBC.
The Time of Day Study is open to competitive and recreational athletes over the age of 18 who engage in four hours of endurance exercise per week and are able to reach a target heart rate of 60 to 70 percent.
Participants fill out a questionnaire and undergo an electrocardiogram (ECG) and stress test.
The participants are then outfitted with a Holter monitor to record their heartbeats for 24 hours. They exercise with the Holter monitor in the morning and the evening, so the results can be compared. They will be retested after the first year, then again in five and 10 years.
“Being part of this study gives me a sense of comfort,” says Eleanor. “I would probably never undergo cardiac screening, so I see this as an opportunity to evaluate myself as an athlete and get a head start on my heart health.”