Effects of Acute Endurance Exercise Performed in the Morning and Evening on Inflammatory Cytokine and Metabolic Hormone Responses.
OBJECTIVE
To compare the effects of endurance exercise performed in the morning and evening on inflammatory cytokine responses in young men.


METHODS
Fourteen healthy male participants aged 24.3 ± 0.8 years (mean ± standard error) performed endurance exercise in the morning (0900-1000 h) on one day and then in the evening (1700-1800 h) on another day with an interval of at least 1 week between each trial. In both the morning and evening trials, the participants walked for 60 minutes at approximately 60% of the maximal oxygen uptake (VO2max) on a treadmill. Blood samples were collected to determine hormones and inflammatory cytokines at pre-exercise, immediately post exercise, and 2 h post exercise.


RESULTS
Plasma interleukin (IL)-6 and adrenaline concentrations were significantly higher immediately after exercise in the evening trial than in the morning trial (P < 0.01, both). Serum free fatty acids concentrations were significantly higher in the evening trial than in the morning trial at 2 h after exercise (P < 0.05). Furthermore, a significant correlation was observed between the levels of IL-6 immediately post-exercise and free fatty acids 2 h post-exercise in the evening (r = 0.68, P < 0.01).


CONCLUSIONS
These findings suggest that the effect of acute endurance exercise in the evening enhances the plasma IL-6 and adrenaline concentrations compared to that in the morning. In addition, IL-6 was involved in increasing free fatty acids, suggesting that the evening is more effective for exercise-induced lipolysis compared with the morning.
Graduate School of Sport Sciences, Waseda University, Saitama, Japan; Research Fellow of the Japan Society for the Promotion of Science, Tokyo, Japan.
Hyeon-Ki
HK
Kim
Faculty of Sport Sciences, Waseda University, Saitama, Japan.
Masayuki
M
Konishi
Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
Masaki
M
Takahashi
Graduate School of Sport Sciences, Waseda University, Saitama, Japan.
Hiroki
H
Tabata
Japan Institute of Sports Sciences, Tokyo, Japan.
Naoya
N
Endo
Department of Health and Sports Sciences, Kyoto Pharmaceutical University, Kyoto, Japan; Waseda Institute for Sport Sciences, Waseda University, Tokyo, Japan.
Shigeharu
S
Numao
Department of Sports and Physical Arts, Myongji University, Seoul, Korea.
Sun-Kyoung
SK
Lee
Department of Oriental Martial Arts, Yongin University, Yongin, Korea.
Young-Hak
YH
Kim
Faculty of Sport Sciences, Waseda University, Saitama, Japan.
Katsuhiko
K
Suzuki
Faculty of Sport Sciences, Waseda University, Saitama, Japan.
Shizuo
S
Sakamoto
D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D004837:Epinephrine / Q000097:blood; D015444:Exercise; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D010807:Physical Endurance
D005230:Fatty Acids, Nonesterified; D015850:Interleukin-6; D004837:Epinephrine