Also, I think for many of us who have tested our physical strength during many different parts of the day, it should be obvious why west coast teams have trouble with east coast starts. Any particular person might be different, but the general profile is inarguable: We warm to our peak body temperature and greatest strength by mid to late afternoon and hold close to that peak through the evening. This is the way we are built, physiologically. I was a little annoyed reading Sando earlier today because he seemed to suggest that east coast teams would have just as much trouble going west, which means he doesn't understand the physiological underpinnings for the problem. East coast body clocks will always be at least even, depending on where the game is played. Here's a summary of research I found on elitefitness.com:
American Council on Exercise - 2007
Warm is better
It is the influence of circadian rhythms on body temperature that seems to yield the most control over the quality of a workout. When body temperature is at its highest, your workouts will likely be more productive; when your temperature is low, chances are your exercise session may be less than optimal.
Body temperature is at its lowest about one to three hours before most of us wake up in the morning, in contrast to late afternoon when body temperature reaches its peak. If you are an early bird or a night owl your temperature peaks within an hour or two of the norm (4pm – 6pm).
Studies have consistently shown that exercise during these late-in-the-day hours produces better Performance and more power. Muscles are warm and more flexible, perceived exertion is low, reaction time is quicker, strength is at its peak, and resting heart rate and blood pressure are low.
Medical Review Board - September 2007
• For most people, body temperature and hormone levels peak at 6 p.m. Exercising 3 hours before or after the peak will give your your best workout for both endurance and building muscle.
• Research shows lung function is best at 4 p.m. to 5 p.m.
• Muscles are warm and flexible.
• Perceived exertion is lowest -- how hard you feel yourself to be working at exercise. So you may be able to work out harder or faster by doing so in the afternoon.
• Can help regulate the amount of food you feel like eating for dinner.
• Stress relief after a day at work, school, or home.
USA Today (Society for the Advancement of Education) - April, 2005
Exercise best in late afternoon
Circadian rhythms, the body's biological processes that repeat in 24-hour cycles, may have a significant effect on a person's lung function and, ultimately, help determine the best time of day for exercise and the administration of medications and medical procedures. In a study by Boris I. Medarov, a physician at Long Island Jewish Medical Center, New Hyde Park, N.Y., lung function was found to have a natural circadian rhythm, where it is at its peak during the late afternoon hours and at its lowest around midday.
"Circadian rhythms regulate our biological cycles for sleep, activity level, metabolism, and many other processes through our body's exposure to sunlight and darkness," explains Medarov. "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."
The study investigated how lung function fluctuated throughout the working hours of 8 a.m.-5 p.m. Results were compared within nine time intervals, and showed that patients' overall airway resistance was at its most prominent around 12 p.m. but reached its minimum between 4-5 p.m.
"We often associate the end of the workday with being tired and less motivated for physical exertion; however, lung function seems to be at its best during this time," notes Medarov. "As a result, exercising or engaging in other physical activities in the late afternoon may help us to achieve optimal Performance."
CNN - January 2004
"The best time to work out is in the late afternoon," Zee said. "The reason for that is your muscle strength is at its peak, its highest. You're going to be less likely to injure yourself. It's also a time when people are most awake and alert."
The science behind Zee's assertion resides with delicate rhythms of the brain called circadian rhythms. According to Zee, circadian rhythms explain why working out later in the day might be more productive and beneficial.
"One of the things that circadian rhythms does is that it determines when your best Performance time is," Zee said. "Your ability to perform changes throughout 24 hours."
Circadian rhythms operate like an internal clock in the body. Neuron signals are fired out by the hypothalamus [a region of the brain], controlling sleep patterns, blood pressure, even our moods.
"These are rhythms that are innate," Zee said. "They are in almost any organism, whether you are an animal or a plant, and they recur every 24 hours."
Circadian rhythms also control body temperature, a key element of a more productive workout. According to Zee, by the afternoon, body temperature is between one and two degrees warmer than in the morning, making muscles in the body more supple and lowering the risk of injury.
Another circadian expert agrees.
"Maximum body temperature happens between 2 and 4 p.m.," said Dr. Michael Vitiello, a professor of psychiatry and behavioral sciences at the University of Washington. "After that, [body temperature] starts to decline for most people.