Increased physical activity decreases hepatic free fatty acid uptake: a study in human monozygotic twins.
Exercise is considered to be beneficial for free fatty acid (FFA) metabolism, although reports of the effects of increased physical activity on FFA uptake and oxidation in different tissues in vivo in humans have been inconsistent. To investigate the heredity-independent effects of physical activity and fitness on FFA uptake in skeletal muscle, the myocardium, and liver we used positron emission tomography (PET) in nine healthy young male monozygotic twin pairs discordant for physical activity and fitness. The cotwins with higher physical activity constituting the more active group had a similar body mass index but less body fat and 18 +/- 10% higher (P < 0.001) compared to the less active brothers with lower physical activity. Low-intensity knee-extension exercise increased skeletal muscle FFA and oxygen uptake six to 10 times compared to resting values but no differences were observed between the groups at rest or during exercise. At rest the more active group had lower hepatic FFA uptake compared to the less active group (5.5 +/- 4.3 versus 9.0 +/- 6.1 micromol (100 ml)(-1) min(-1), P = 0.04). Hepatic FFA uptake associated significantly with body fat percentage (P = 0.05). Myocardial FFA uptake was similar between the groups. In conclusion, in the absence of the confounding effects of genetic factors, moderately increased physical activity and aerobic fitness decrease body adiposity even in normal-weighted healthy young adult men. Further, increased physical activity together with decreased intra-abdominal adiposity seems to decrease hepatic FFA uptake but has no effects on skeletal muscle or myocardial FFA uptake.
Hannukainen
Jarna C
JC
Turku PET Centre, University of Turku, Turku, Finland. jarna.hannukainen@tyks.fi
Nuutila
Pirjo
P
Borra
Ronald
R
Ronald
Borra
B
Kaprio
Jaakko
J
Kujala
Urho M
UM
Janatuinen
Tuula
T
Heinonen
Olli J
OJ
Kapanen
Jukka
J
Viljanen
Tapio
T
Haaparanta
Merja
M
Rönnemaa
Tapani
T
Parkkola
Riitta
R
Knuuti
Juhani
J
Kalliokoski
Kari K
KK
D000273:Adipose Tissue / Q000378:metabolism; D015308:Anaerobic Threshold / Q000502:physiology; D000886:Anthropometry; D001823:Body Composition / Q000502:physiology; D015331:Cohort Studies; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008099:Liver / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D014430:Twins, Monozygotic
D005230:Fatty Acids, Nonesterified; D019275:Radiopharmaceuticals