Exercising in the afternoon is better than the morning

By Karen Hebert Bristol

Phyllis Zee, a neurologist from Northwestern University, has challenged the view that morning workouts are better than exercising in the afternoon.

"The best time to workout is in the late afternoon," Zee told US television channel CNN. "The reason for that is that your muscle strength is at its peak, its highest. You are going to be less likely to injure yourself. It is also a time when people are most awake and alert."

According to Zee, circadian rhythms are key. These are innate rhythms that conform to the 24 hour cycle of light and dark, generated by the firing rate of neurons in the hypothalamus in the brain. Circadian rhythms are implicated in the regulation of several physiological processes that include body temperature, metabolism, and blood pressure.

The regulation of body temperature seems to be most important. Two to three hours before waking, body temperature is at it's lowest, peaking in the afternoon between 2 pm and 4 pm.

At this time of day muscles are warm and flexible, which means less injury and better performance. It is also likely that the workout is perceived as being easier than in the morning.

This viewpoint is not shared by all exercise experts. Exercise in the morning is better for fat burning. The body is required to burn calories early in the day; this increases the metabolic rate and this is sustained through the day.

Although the experts still disagree on the ideal time of day to exercise they are in agreement over one point. It is thought that the most important thing is that people exercise, and that they exercise regularly and maintain a consistent programme.