The answer to the question of what time to run is “It depends!” Some runners prefer to get their run out of the way before they go to work. Others prefer to run over their lunch break, so it doesn’t cut into their free time before and after work. Still others prefer to run after work.
If you go by when it is best for your body to run, then a run between 4 and 8 p.m. wins hands down. Why? Because that is the window of time when certain bio-rhythms, affecting how well you run, tend to peak.
If you go by body temperature, running in the morning is the worst time of day. With your temperature at its lowest in the morning, your muscles will feel stiff, so it takes some time to get your body warmed up. A morning run requires a certain amount of extra exertion to get the same benefit. In the late afternoon, your body temperature is peaked, so your muscles are warmed up and stretched from the day’s activities.
At night you don’t breathe as deep as you do during the day, so in the morning your lungs don’t expand out as far or as easily as they do later on in the day. It takes a certain amount of time at the beginning of a morning run to get into a deep breathing mode. In the afternoon, your lungs expand out and contract in very easily.
We know you don’t want to run early in the morning on a full stomach, but after fasting all night, your energy level is down in the morning before breakfast. By running in the late afternoon, you still have energy left from eating lunch to fuel you through a run.
Physiological Vs Psychological
And then there is the psychological (mental) aspect of running, which is completely opposite of the physiological (bio-rhythms) part. Mentally, you are your sharpest right after waking up. So while your body may not be at its best yet, your mind is ready to go. Some people find it harder to motivate themselves to run in the afternoon after a day at work. While they are at their peak physically, mentally they are not.
So in the end, the correct answer is it depends the time of day that works best for you. Between your mental state, bio-rhythms, and daily activities, only you can judge when the time is best. However, the fact that you do run is more important than when you run and definitely a better option than not running at all.