Intensity of Physical Activity, TV Viewing Time, and Adiposity in Young Adults: Iowa Bone Development Study

This study focused on young adults, as emerging adulthood, when the majority of young adults are exposed to unhealthy lifestyle behaviors. This study examined the relationships between Physical Activity (PA) intensity (min/d), TV viewing (h/d), and adiposities (i.e., Total Body Fat (TBF), kg and Visceral Adipose Tissue (VAT), g) in young adults. Study participants were healthy young adults aged 19.8 years (182 females and 147 males) in the Iowa Bone Development Study. ActiGraph accelerometers and a PA questionnaire were used to measure PA and TV viewing. Dual-energy X-ray absorptiometry and peripheral quantitative computed tomography scans measured the adiposities. Vigorous PA, independent of the total volume of PA, was the best predictor of TBF in males (β=-.22, p<.01). In females, moderate (β=-.25, p<.01), moderate to vigorous (β=-.27, p<.01), and vigorous (β=-.12, p<.05) intensity PA were predictive. TV viewing, independent of sedentary time and total PA, was associated with TBF (β=0.18, p<.05 in males; β=0.12, p<.05 in females) and VAT (β=0.11, p<.05 in females). This study suggests that increasing PA intensity and restricting TV viewing time rather than reducing comprehensive sedentary time may be a more effective strategy in maintaining healthy body composition. PA interventions should suggest to female young adults to “move more” and males to participate in more intense activities.