Study leader Kathleen Sluka, PhD., found a protein included in muscle pain works in conjunction with the male hormone testosterone to protect against muscle fatigue.
The researchers compared exercise-induced muscle fatigue in male and female mice with and without ASIC3 -- an acid-activated ion channel protein shown to be involved in musculoskeletal pain. Male mice with ASIC3 were less fatigued than female mice, but male mice without the ASIC3 protein showed levels of fatigue similar to the female mice.
The study found the difference in fatigue between male and female mice rely on both the presence of testosterone and the activation of ASIC3 channels, suggesting that they are interacting somehow to protect against fatigue.
Chronic pain and fatigue often occur together -- as many 75 per cent of people with chronic, widespread musculoskeletal pain report having fatigue; and about 94 percent who have chronic fatigue syndromes report muscle pain.
The study was published in the Feb. 28 issue of the American Journal of Physiology -- Regulatory, Integrative and Comparative Physiology.
