Abstract
Abstract Aims This study is aimed at testing the acute melatonin administration (oral; 6 mg) on aerobic tolerance at cycloergometer and analyzing the consequences on biochemical and hematological parameters. Methods The maximal aerobic capacity intensity (iMAC) at cycloergometer of eleven male healthy men (24.18±3.92 years-old; 87.07±12.48 kg; 1.82±0.05 m; 26.18±3.63 kg/m2; and 16.28±5.77 % of fat) was individually determined and used to perform a time to exhaustion (tlim) trial of 30 minutes after melatonin or placebo administration. We observed 48-72h interval between tests, performed in a double-blind experiment design. In order to determine hematological and biochemical parameters we collected venous blood samples before and after tlim. Statistical significance was set at 5%. Results The intensity and the lactatemia corresponding to the maximal aerobic capacity were 120.88±18.78 W and 3.32±1.03 mmol.L-1, respectively. The tlim with placebo (33.94±15.26 min, confidence interval = 24.92 - 42.95) was significantly lower than the tlim with melatonin (41.94±17.22 min; CI = 31.76 - 52.12; p = 0.03; 19.06%; effect size = 0.49). All of the 21 analyzed blood physiological variables resulted in no significant variation after tlim when placebo was compared to melatonin, except for total sera cholesterol (lower after exercise with melatonin). Conclusion Acute melatonin administration enhanced aerobic tolerance at iMAC in 19% at cycloergometer; however, the biochemical and hematological variables assessed were not significantly modulated.
Highlights
Despite meaningful information regarding melatonin effects on circadian rhythm modulation, sleep disorders, jet lag treatment and health application, the effects of this indoleamine on exercise performance remains uncertain
Observing the physiological effects of melatonin[3,4,5,6,7,8,9,10,11,12], our laboratory has studied the acute effects of melatonin on aerobic performance, once we interpreted the actions of this indoleamine allows advantage mainly for this kind of exercise instead of high intensity and short duration exercises
The intensity and lactatemia corresponding to the maximal aerobic capacity intensity was 120.88±18.78 W and 3.32±1.03 mmol.kg-1, respectively
Summary
Despite meaningful information regarding melatonin effects on circadian rhythm modulation, sleep disorders, jet lag treatment and health application, the effects of this indoleamine on exercise performance remains uncertain. We firstly employed the animal model with swimming rats and found an over expected ergogenic effect at wakefulness period[13] even when not reproducing melatonin’s protective effect described at literature, i.e., skeletal muscle inflammation, oxidative stress and tissue damage markers, which were significantly increased when maximal aerobic tolerance was tested with melatonin[14]. These and other studies elicited us to hypothesize an inference to human model once most of aerobic assessment employed with rats showed similar results when compared to human[15]. The scientific literature has been systematically demonstrated that the blood lactate modulation during incremental exercise in rats mimics human behavior, allowing the standardization and use of reliable and reproducible physical assessment protocols for swimming rats[16,17,18,19]
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