Working out is no doubt one of the best ways to preserve our heart health while maximizing our overall physical and metabolic health. Now, a new study has found that exercising at particular times of the day could as well be detrimental to health.

A recent study published in the European Journal of Preventive Cardiology looked at the possible link between exercising at different times of the day and the risk of developing cardiovascular diseases or stroke in a large number of participants. They found that those who engaged in physical activity in the morning had the least risk of developing heart disease and stroke.

In the study, researchers looked at data gathered from the UK Biobank. They involved a total of 86,657 participants who were between the ages of 42 and 78 and had no history of cardiovascular disease. About slightly over half of the participants consisted of women (57.6 percent). All participants were randomly assigned to wear an activity tracker on their wrists for 7 days straight. This was done to assess the objective physical activity of the study participants over the 7 days while they go on about their daily activities. They also analyzed data on participants’ smoking status, frequency of alcohol intake, cholesterol, blood pressure drugs, and if they were early birds or night owls. They then followed up for incident cardiovascular disease which the researchers described as the first admission to the hospital or death from coronary artery disease or stroke.

During a follow-up period of over 6 years, a total of 2,911 participants developed coronary artery diseases and 796 participants developed a stroke. In comparing peak physical activity times, the researchers found that being most active at night between 12 am and 6 am is linked with a higher risk of both heart disease and stroke. On the other hand, being most active in the morning between 8 am and 11 am had the least risk of both diseases.

When carrying out the second phase of the study, the team classified the participants according to the peak time of physical activity into midday, early morning (8 am), late morning (10 am), and evening (7 pm). Researchers used data obtained from the peak time of activity of study participants to select these categories. Participants with a midday pattern of physical activity were used as a reference group when examining the link between peak time of physical activity and heart disease risk. 

Notably though, after adjusting for both age and gender, the study authors found that those who were most active at the first crack of dawn or during late morning hours had a 16 percent decreased risk of coronary artery disease and a 17 percent decreased risk of stroke when compared to the reference group.

After adjusting for just gender, the researchers found that the effects were most prominent in women than in men. Women who reported as morning persons and were most active in the early or late morning hours had 22 percent and 24 percent reduced risk of coronary artery disease, respectively than the reference group. In the same way, women with high physical activity in the late morning had 35 percent lower stroke risk than those in the reference group. 

Their findings were consistent irrespective of whether the participants reported themselves as early birds or night owls. However, being an observational study limits the ability of the researchers to conclude why women were mostly affected.

Above all, the study demonstrates morning physical activity as the most distinct cornerstone in cardiovascular disease prevention and the key to achieving maximum health benefits

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