Cardiorespiratory Fitness and Adiposity as Determinants of Metabolic Health-Pooled Analysis of Two Twin Cohorts.
The joint effects of cardiorespiratory fitness (CRF) and body composition on metabolic health are not well known.



To examine the associations of CRF, fat-free mass index (FFMI), and fat mass index (FMI) with metabolic health in individual twins and controlling for genetic and shared environmental effects by studying monozygotic intrapair differences.



Two cross-sectional samples of healthy adult monozygotic and dizygotic twins were drawn from population-based Danish and Finnish national twin registries (n = 996 and n = 309).



CRF was defined as VO2max divided by fat-free mass. Insulin sensitivity and acute insulin response indices were derived from an oral glucose tolerance test. A continuous metabolic syndrome score was calculated. Visceral and liver fat were measured in the Finnish sample. Associations were analyzed separately in both cohorts with multivariate linear regression and aggregated with meta-analytic methods.



Insulin sensitivity, acute insulin response, metabolic syndrome score, visceral, and liver fat amount had strong and statistically significant associations with FMI (|β| 0.53 to 0.79), whereas their associations with CRF and FFMI were at most weak (|β| 0.02 to 0.15). The results of the monozygotic intrapair differences analysis showed the same pattern.



Although FMI is strongly associated with worsening of metabolic health traits, even after controlling for genetic and shared environmental factors, there was little evidence for the effects of CRF or FFMI on metabolic health. This suggests that changing FMI rather than CRF or FFMI may affect metabolic health irrespective of genetic or early environmental determinants.
Obesity Research Unit, Research Programs Unit, Diabetes and Obesity, University of Helsinki, 00290 Helsinki, Finland.
Sakari
S
Jukarainen
Institute of Regional Health Service Research, University of Southern Denmark, 5230 Odense, Denmark.|Oslo Centre for Biostatistics and Epidemiology, University of Oslo and Oslo University Hospital, 0313 Oslo, Norway.
René
R
Holst
Department of Public Health - Environmental Medicine, University of Southern Denmark, 5230 Odense, Denmark.|Danish Twin Registry, University of Southern Denmark, 5230 Odense, Denmark.
Christine
C
Dalgård
Unit of Clinical Physiology, Helsinki University Hospital and University of Helsinki, Meilahti Hospital, 00290 Helsinki, Finland.
Päivi
P
Piirilä
Helsinki Medical Imaging Center, Radiology, University of Helsinki, 00290 Helsinki, Finland.|Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University, 40225 Düsseldorf, Germany.
Jesper
J
Lundbom
Helsinki Medical Imaging Center, Radiology, University of Helsinki, 00290 Helsinki, Finland.
Antti
A
Hakkarainen
Helsinki Medical Imaging Center, Radiology, University of Helsinki, 00290 Helsinki, Finland.
Nina
N
Lundbom
Obesity Research Unit, Research Programs Unit, Diabetes and Obesity, University of Helsinki, 00290 Helsinki, Finland.
Aila
A
Rissanen
Department of Public Health, University of Helsinki, 00300 Helsinki, Finland.|Institute for Molecular Medicine Finland, University of Helsinki, 00290 Helsinki, Finland.
Jaakko
J
Kaprio
Odense Patient Data Explorative Network, Odense University Hospital, 5000 Odense, Denmark.|Department of Clinical Research, University of Southern Denmark, 5200 Odense, Denmark.|Danish Twin Registry, University of Southern Denmark, 5230 Odense, Denmark.
Kirsten Ohm
KO
Kyvik
Novo Nordisk Foundation Center for Basic Metabolic Research, Section on Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark.|Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark.|Department of Clinical Epidemiology (formerly Institute of Preventive Medicine), Bispebjerg and Frederiksberg Hospitals, The Capital Region, 2400 Copenhagen, Denmark.
Thorkild I A
TIA
Sørensen
Obesity Research Unit, Research Programs Unit, Diabetes and Obesity, University of Helsinki, 00290 Helsinki, Finland.|Endocrinology, Abdominal Center, Helsinki University Central Hospital and University of Helsinki, 00290 Helsinki, Finland.
Kirsi H
KH
Pietiläinen
D050154:Adiposity / Q000235:genetics / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D001823:Body Composition / Q000235:genetics / Q000502:physiology*; D000072599:Cardiorespiratory Fitness / Q000502:physiology*; D008076:Cholesterol, HDL / Q000378:metabolism; D008078:Cholesterol, LDL / Q000378:metabolism; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003718:Denmark; D017097:Electric Impedance; D005260:Female; D005387:Finland; D059647:Gene-Environment Interaction; D005951:Glucose Tolerance Test; D006801:Humans; D007333:Insulin Resistance / Q000235:genetics / Q000502:physiology*; D050152:Intra-Abdominal Fat / Q000000981:diagnostic imaging; D016014:Linear Models; D008099:Liver / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D024821:Metabolic Syndrome / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D015999:Multivariate Analysis; D010101:Oxygen Consumption / Q000235:genetics / Q000502:physiology*; D014280:Triglycerides / Q000378:metabolism; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D055815:Young Adult
D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D014280:Triglycerides