EVANSTON, Ill., Oct. 21 (UPI) -- Muscle tissue is regulated by circadian clocks that control response and energy efficiency, scientists suggest in a new study.
The study was conducted by researchers at Northwestern University and published in the journal Cell Metabolism. According to the authors, all cells in the body contain a clock that regulates how they adapt to their environment over a 24-hour period. For human athletes, investigators say this means the best time to work out is during the day.
"Oxygen and the internal clock are doing a dance together inside muscle cells to produce energy, and the time of day determines how well that dance is synchronized," senior author Joseph Bass said in a press release. "The capacity for a cell to perform its most important functions, to contract, will vary according to the time of day."
Researchers concluded an organism's normal waking hours provide the optimal opportunity for fitness after observing the athletic performance of mice. During the experiment, scientists analyzed the muscle tissues and muscle fibers in mice for gene expressions associated with exercise. The nocturnal animals produced the best results during the night, suggesting the opposite should hold true for humans.
"When we manipulated the clock genetically, we noticed there were profound abnormalities in the muscle," Bass explained. "That set us on a course to understand how the inner muscle clock is important in regulating how well the muscle cell can mobilize energy."
The key to muscle performance, it was discerned, was oxygen and sugar consumption and the generation of lactic acid. However, researchers concede their findings are not yet definitive.
"We're not saying we can tell athletes when they should work out," Bass continued. "But in the future, perhaps, you may be able to take advantage of these insights to optimize muscle function."
The research team says their findings provide critical information on how to manipulate oxygen levels in muscles, which has treatment implications for diseases such as diabetes.