Two weeks of moderate-intensity continuous training, but not high-intensity interval training, increases insulin-stimulated intestinal glucose uptake.

Kumail K Motiani,Minna Yli-Karjanmaa,Kirsi A Virtanen,Tamiko Ishizu,Tove J Grönroos,Pirjo Nuutila,Eliisa Löyttyniemi,Nina Savisto,Jukka Kapanen,Kari K Kalliokoski,Jari-Joonas Eskelinen,Juhani Knuuti,Jussi Toivanen,Merja Haaparanta-Solin,Olof Solin,Riitta Parkkola,Markku Ahotupa,Jarna C Hannukainen,Anna M Savolainen

doi:10.1152/japplphysiol.00431.2016

Abstract

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 & NOTEWORTHY This 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.

Highlights

NEW & NOTEWORTHY This is the first study where the effects of exercise training on the intestinal substrate uptake have been investi
Colonic insulin-stimulated glucose uptake (GU) improved in the moderate-intensity continuous training (MICT) group (ϩ37%), while no response was observed in the high-intensity interval training (HIIT) group (Ϯ0%) (P ϭ 0.02 time ϫ training) (Fig. 2)
The data show that MICT increases insulin-stimulated GU, while both training modes decrease free fatty acid uptake (FFAU) in the intestine, and that intestinal insulin-stimulated GU correlates positively with aerobic capacity and negatively with visceral fat and HbA1c

Summary

Introduction

NEW & NOTEWORTHY This is the first study where the effects of exercise training on the intestinal substrate uptake have been investi-. Splanchnic GU is impaired and plays a role in the pathogenesis of hyperglycemia in type 2 diabetes [10, 27]. Mainly the liver and pancreas, and data are limited about the effects of exercise on intestine [28, 33, 36]. It is not known whether exercise training could enhance intestinal substrate metabolism, and whether any possible changes would be reflected in the insulin sensitivity of the whole body

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Conclusion