Research shows that the optimum time is 3-7 P.M. Why? For most people, body temperature and hormone levels peak at 6 p.m. Exercising 3 hours before or after the peak will give you your best workout for both endurance and building muscle. Lung function is also at its peak and muscles are warm and flexible. It is also a great time to work of the stress of your day. However, it is easy to skip the workout when other appointments and commitments crop up.
I prefer to work out early in the morning before distractions and work schedules get in the way. Early AM exercise will also increase heart rate, metabolism and sharpen mental acuity. However, hormone levels are low and muscles are cold so you must allow extra time for warming up before getting started.
A lunchtime walk with a buddy can help you control your lunch portions and your afternoon snacking. Your muscles are warm and hormone levels are higher but lung function is at its worst at mid-day. It is also difficult to get the optimum 30 minutes in so you might want to plan for an additional walk before dinner.
So- what time of day is best? Whatever time works for you and stick to it!