Two weeks of moderate-intensity continuous training, but not high-intensity interval training, increases insulin-stimulated intestinal glucose uptake.
Similar to muscles, the intestine is also insulin resistant in obese subjects and subjects with impaired glucose tolerance. Exercise training improves muscle insulin sensitivity, but its effects on intestinal metabolism are not known. We studied the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on intestinal glucose and free fatty acid uptake from circulation in humans. Twenty-eight healthy, middle-aged, sedentary men were randomized for 2 wk of HIIT or MICT. Intestinal insulin-stimulated glucose uptake and fasting free fatty acid uptake from circulation were measured using positron emission tomography and [18F]FDG and [18F]FTHA. In addition, effects of HIIT and MICT on intestinal GLUT2 and CD36 protein expression were studied in rats. Training improved aerobic capacity (P= 0.001) and whole body insulin sensitivity (P= 0.04), but not differently between HIIT and MICT. Insulin-stimulated glucose uptake increased only after the MICT in the colon (HIIT = 0%; MICT = 37%) (P= 0.02 for time × training) and tended to increase in the jejunum (HIIT = -4%; MICT = 13%) (P= 0.08 for time × training). Fasting free fatty acid uptake decreased in the duodenum in both groups (HIIT = -6%; MICT = -48%) (P= 0.001 time) and tended to decrease in the colon in the MICT group (HIIT = 0%; MICT = -38%) (P= 0.08 for time × training). In rats, both training groups had higher GLUT2 and CD36 expression compared with control animals. This study shows that already 2 wk of MICT enhances insulin-stimulated glucose uptake, while both training modes reduce fasting free fatty acid uptake in the intestine in healthy, middle-aged men, providing an additional mechanism by which exercise training can improve whole body metabolism.NEW & NOTEWORTHYThis is the first study where the effects of exercise training on the intestinal substrate uptake have been investigated using the most advanced techniques available. We also show the importance of exercise intensity in inducing these changes.
Turku PET Centre, University of Turku, Turku, Finland.
Kumail K
http://orcid.org/0000-0001-7366-0120
KK
Motiani
Turku PET Centre, University of Turku, Turku, Finland.
Anna M
AM
Savolainen
Turku PET Centre, University of Turku, Turku, Finland.
Jari-Joonas
JJ
Eskelinen
Turku PET Centre, University of Turku, Turku, Finland.
Jussi
J
Toivanen
Turku PET Centre, University of Turku, Turku, Finland.|Medicity Research Laboratory, University of Turku, Turku, Finland.|Department of Cell Biology and Anatomy, Institute of Biomedicine, University of Turku, Turku, Finland.
Tamiko
T
Ishizu
Turku PET Centre, University of Turku, Turku, Finland.
Minna
M
Yli-Karjanmaa
Turku PET Centre, Turku University Hospital, Turku, Finland.
Kirsi A
KA
Virtanen
Department of Radiology, Turku University Hospital, Turku, Finland.
Riitta
R
Parkkola
Paavo Nurmi Centre, Turku, Finland.
Jukka
J
Kapanen
Turku PET Centre, University of Turku, Turku, Finland.|Medicity Research Laboratory, University of Turku, Turku, Finland.
Tove J
TJ
Grönroos
Turku PET Centre, University of Turku, Turku, Finland.
Merja
M
Haaparanta-Solin
Turku PET Centre, Abo Akademi University, Turku, Finland.
Olof
O
Solin
Turku PET Centre, University of Turku, Turku, Finland.
Nina
N
Savisto
Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku, Finland.
Markku
M
Ahotupa
Department of Biostatistics, University of Turku, Finland; and.
Eliisa
E
Löyttyniemi
Turku PET Centre, University of Turku, Turku, Finland.
Juhani
J
Knuuti
Turku PET Centre, University of Turku, Turku, Finland.|Department of Endocrinology, Turku University Hospital, Turku, Finland.
Pirjo
P
Nuutila
Turku PET Centre, University of Turku, Turku, Finland.
Kari K
KK
Kalliokoski
Turku PET Centre, University of Turku, Turku, Finland; jarna.hannukainen@tyks.fi.
Jarna C
JC
Hannukainen
D000328:Adult; D000818:Animals; D015444:Exercise / Q000502:physiology; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D000072696:High-Intensity Interval Training / Q000379:methods; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance / Q000502:physiology; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010805:Physical Conditioning, Animal / Q000379:methods; D049268:Positron-Emission Tomography / Q000379:methods; D051381:Rats; D017208:Rats, Wistar
D005230:Fatty Acids, Nonesterified; D007328:Insulin; D005947:Glucose
exercise; high-intensity interval training; intestinal metabolism; intestine; moderate-intensity continuous training; positron emission tomography