If you just don't seem to be as strong during that midday run or treadmill workout, there's a reason for it. Our lungs lose power at lunchtime.
Our lungs are governed by a cycle of circadian rhythms that dip and rise over a 24-hour period. The time of peak lung performance for most people is the late afternoon, making it the best time of day to exercise. But since lung performance tends to drop in the very early morning hours and again at noon, you won't get the optimal benefit from a very early morning or lunchtime workout, according to researchers from the Long Island Jewish Medical Center in New York.
The BBC News Online reports that not only does this new research tell us the best and worst times of day to exercise, but also the best time to take respiratory medications for asthma and other ailments, as well as the timing of certain types of respiratory medical procedures so they will have the greatest effect.
It's long been known that lung performance is weak in the wee hours of the morning, but this five-year study of 4,835 patients focused on the hours of 8 a.m. to 5 p.m. For most of the patients, lung function was at its least effective around midday, rising to a peak between 4 p.m. and 5 p.m., notes the BBC.
"Circadian rhythms regulate our biological cycles for sleep, activity level, metabolism, and many other processes through our body's exposure to sunlight and darkness," lead researcher Dr. Boris Medarov told the BBC. "Our study finds that lung function has its own rhythm that may govern how much energy we exert throughout the day and the best times to engage in certain activities. We often associate the end of the work day with being tired and less motivated for physical exertion; however, lung function seems to be at its best during this time. As a result, exercising or engaging in other physical activities in the late afternoon may help us to achieve optimal performance."
The difference is significant. This study showed there is a 15 percent to 20 percent difference in lung performance between noon and late afternoon. The good news is that healthy people have strong lungs, so the change shouldn't be too noticeable.
The study was presented at an American College of Chest Physicians meeting.