Kirsi H. Pietiläinen, Bram Berntzen, Riitta Simonen, Jaakko Kaprio, Tuija Tammelin, Nina Lundbom, Antti Hakkarainen, Sakari Jukarainen, Aila Rissanen, Jesper Lundbom, E. Juulia Paavonen, Päivi Piirilä, Mikko Kataja
This study aims to investigate 1) how monozygotic (MZ) twin pairs who are discordant for body mass index (BMI) differ for objectively and subjectively measured physical activity (PA) and cardiorespiratory fitness (VO2max), and 2) associations of PA and VO2max with adiposity and measures of metabolic health, in individual twins and independent of genetic and shared environmental effects within twin pairs.
We examined 27 BMI-discordant and 14 BMI-concordant MZ twin pairs. Fat and fat free mass (ffm) were measured by dual energy x-ray absorptiometry and VO2max by spiroergometry. PA was measured objectively by accelerometers using ActiGraph GT1M for daytime activity and Actiwatch AW7 for 24h/day. Self-reported PA was obtained through the Baecke and IPAQ long-form questionnaires.
Objectively measured moderate to vigorous PA (MVPA, min/day), steps/day and VO2max/kg were significantly lower, by 30%, 21% and 14% respectively in the heavy compared with the lean co-twins of the BMI-discordant twin pairs. There were no significant differences in self-reported PA or VO2max/ffm. As expected, PA and VO2max/ffm were similar in the BMI-concordant co-twins. Furthermore, the 24-h recording of activity suggested that the heavier co-twins had more restless sleep during the night, whereas the leaner co-twins were more active during the day. Within all twin pairs, higher MVPA and steps per day were associated with lower fat percentage and improved metabolic health measures.
Objectively, but not subjectively measured PA is associated with lower adiposity and better metabolic health, independent of genetic and shared environmental factors.
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