Marit Kotte1, Soraya de Kam1, Ivo Habets1, Merel Timmermans1, Tineke van de
Weijer1, Denis Blondin2, André C. Carpentier2, Patrick Schrauwen3,4, Joris Hoeks1
1 Maastricht University, Universiteitssingel 50, Maastricht, The Netherlands. 2 Faculty
of medicine and health sciences, Université de Sherbrooke, Sherbrooke, Canada 3
Institute for Clinical Diabetology, German Diabetes Center, Leibniz Institute for
Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany
4Clinical Epidemiology, Leiden University Medical Center, The Netherlands
m.kotte@maastrichtuniversity.nl
Background: We previously reported that 24h rhythmicity in substrate metabolism is
blunted and nocturnal respiratory exchange ratio (RER) is elevated in older
individuals at risk of developing type 2 diabetes (T2D) compared to young healthy
lean individuals. Here, we investigated whether an acute bout of high-intensity
exercise performed either in the morning or afternoon has a differential effect on 24h
rhythmicity in substrate metabolism.
Methods: Four females and 10 males (40-75 years, BMI >25 kg/m2) at risk of
developing T2D participated in this randomized crossover study, which consisted of
three separate 24h stays in a respiration chamber to measure energy and substrate
metabolism: 1) control (no exercise), 2) AM (exercise at 09:00) and 3) PM (exercise
at 17:00) with a wash-out period of at least 4 weeks between each stay.
Results: Directly after exercise (3.5-hours), RER was significantly lower (p<0.05) and
fat oxidation significantly higher (p<0.05) in both AM (RER 0,83, fat ox 0,09 g/min)
and PM (RER 0,86, fat ox 0,085 g/min) when compared to no exercise (RER 0,86, fat
ox 0,07 g/min for AM, RER 0,89, fat ox 0,067 g/min for PM) . Energy expenditure was
significantly higher directly after AM exercise (7,74 kJ/min) (p<0.05), but not after PM
exercise, compared to no exercise (7,37 kJ/min for AM). Nocturnal RER was
significantly lower (p<0.05) and fat oxidation significantly higher after PM exercise
(RER 0,85, fat ox 0,056 g/min), compared to AM exercise (RER 0,87, fat ox 0,044
g/min) (p<0.05).
Conclusion: Exercise performed in the afternoon lowers RER and stimulates fat
oxidation during the night compared to exercise performed in the morning. Afternoon
exercise might therefore have beneficial effects on 24h substrate rhythmicity in
individuals at risk of developing T2D.