Exposure to red light makes top athletes fitter
Serious athletes' endurance capacity improves if they bathe in artificial red light for half an hour each evening, researchers at the China Institute of Sport Science in Beijing discovered. Exposure to red light boosts melatonin production during sleep and increases the distance athletes cover in the classic Cooper test.
Performance, sleep & light
You can improve your performance through training, nutrition, supplements, doping – and by sleeping better. In the 1990s sleep researchers at Stanford University discovered that you can improve your sleep quality by exposing yourself to daylight early on in the day. [Arch Intern Med. 1995 Apr 24; 155(8): 838-44.] Early daylight contains a relatively high amount of blue light and that breaks down melatonin. The less melatonin there is in your blood during the day, the more melatonin your body produces in the evening, and the better you sleep.
Red light has the opposite effect. Exposure to red light at the end of the day stimulates the production of melatonin. Researchers at Indiana University have speculated whether exposure to red light might delay aging through the same mechanism. [Med Hypotheses. 2007; 69(2): 372-6.] In 2007 they wrote in Medical Hypotheses that "red light therapy - 670 nm, 4J/cm2 - has been shown to restore glutathione redox balance upon toxicological insult and enhance both cytochrome c oxidase and energy production, all of which may be affected by melatonin".
Energy production? Glutathione redox balance? Smacks of performance improvement to us. And indeed, there's a handful of studies that show that red laser light helps post-exertion muscle recovery. [Lasers Med Sci. 2009 May; 24(3): 425-31.] [J Orthup Sports Phys Ther. 2010 Aug; 40(8): 524-32.] [Lasers Surg Med. 2009 Oct; 41(8): 572-7.]
That's why the Chinese decided to do an experiment in which twenty female basketball players functioned as guinea pigs. For fourteen consecutive days they lay in a swimsuit for thirty minutes every evening under the piece of equipment made by Shanghai Dayou PDT Technology Co shown below. The light had an average wavelength of 658 nm, and its strength was 30 J per square centimetre. Half of the women were exposed to the red light [Red-light treatment], half were not. The women were blindfolded while under the lamps.
The red light treatment improved the quality of the women's sleep: their Pittsburgh Sleep Quality Index went down. The researchers found more melatonin in their blood early in the morning.
Before and after the treatment period the researchers got the women to do the Cooper test. The figure above shows that the women who had had the red light therapy covered a 12.8 percent greater distance during the 12 minutes that the test lasted. The women in the placebo group only covered a 5.5 percent greater distance.
"Based on previous studies, we can infer that red-light treatment contributes to increased melatonin secretion in the pineal gland and muscle regeneration", the researchers write. "Although more studies involving phototherapy, sleep, and exercise performance need to be performed, red-light treatment is a possible nonpharmacologic and noninvasive therapy to prevent sleep disorders after training."
J Athl Train. 2012;47(6):673-8.
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