Endurance exercise, tryptophan availability to the brain, and sleep electrophysiology in older men.

Normal aging entails significant changes in serotonergic activity and function. Noteworthy, these alterations might predispose older individuals to develop depressive symptoms and contribute to age-related changes in sleep. This study verified if exercise increases tryptophan (Trp) availability to the brain and affects sleep depth and architecture in older men. Nineteen men (aged 64 ± 3 years) undertook a series of 4 tests, which was repeated at follow-up (after 16 weeks of training) as follows: (i) dual-energy X-ray absorptiometry (body composition); (ii) peak O2 consumption, ventilatory threshold, and respiratory compensation point (cardiopulmonary testing); (iii) blood withdrawals immediately before, during, and after exercise for analysis of glucose, lactate, ammonia, free fatty acids (FFA), total proteins, albumin, prolactin, valine, leucine, isoleucine, adiponectin, leptin, free and total Trp, and calculated variable: branched-chain amino acids (BCAA); and (iv) sleep electrophysiology (wake, stage 1...