Habitual active transport moderates the association of TV viewing time with body mass index.
BACKGROUND
Television viewing time is associated with obesity risk independent of leisure-time physical activity (LTPA). However, it is unknown whether the relationship of TV viewing time with body mass index (BMI) is moderated by other domains of physical activity.


METHODS
A mail survey collected height; weight; TV viewing time; physical activity for transportation (habitual transport behavior; past week walking and bicycling), for recreation (LTPA), and in workplace; and sociodemographic variables in Adelaide, Australia. General linear models examined whether physical activity domains moderate the association between BMI and TV viewing time.


RESULTS
Analysis of the sample (N = 1408) found that TV time, habitual transport, and LTPA were independently associated with participant's BMI. The interaction between TV time and habitual transport with BMI was significant, while that between TV time and LTPA was not. Subgroup analyses found that adjusted mean BMI was significantly higher for the high TV viewing category, compared with the low category, among participants who were inactive and occasionally active in transport, but not among those who were regularly active.


CONCLUSIONS
Habitual active transport appeared to moderate the relationship between TV viewing time and BMI. Obesity risk associated with prolonged TV viewing may be mitigated by regular active transport.
Cancer Prevention Research Centre, The University of Queensland, Brisbane, Australia.
Takemi
T
Sugiyama
Dafna
D
Merom
Marina
M
Reeves
Eva
E
Leslie
Neville
N
Owen
D000328:Adult; D001315:Australia / Q000453:epidemiology; D001642:Bicycling; D015992:Body Mass Index; D016001:Confidence Intervals; D003625:Data Collection; D005260:Female; D015438:Health Behavior; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009765:Obesity / Q000453:epidemiology / Q000517:prevention & control*; D012111:Residence Characteristics; D012307:Risk Factors; D057185:Sedentary Behavior; D013690:Television; D013997:Time Factors; D016138:Walking; D055815:Young Adult