Abstract
Background: The amount and quality of evidence on how to effectively
promote physical activity (PA) is low compared to what is known about the
health effects of regular PA, especially in obese individuals.
Aim : To evaluate the role of social support to promote walking in
severely obese outpatients.
Methods : The main hypothesis (increased social support promotes walking)
was tested through a randomised, 2-armed, prospective (18 weeks)
intervention study in 42 severely obese outpatients (study III). Three
preparative studies were carried out. Study I was a cross-sectional
comparison of PA in severely obese outpatients and a normal weight
population. Study II evaluated the digiwalker SW-701 pedometer against
the more versatile and sensitive MTI 7164 (formerly CSA) accelerometer.
Study IV evaluated the Tanita BC-418 bioelectrical impedance monitor for
estimating body composition against dual x-ray absorptiometry (DXA).
Results : Study I found a clear inverse association between PA and BMI
that was dependent on obesity status (strong correlation in the obese
between PA and BMI, and weak or non-existent correlation in non-obese).
Study II showed that the digiwalker pedometer was of sufficient quality
to confidently detect changes in walking in the intervention study (study
III). The Tanita BC-418 bioelectrical impedance monitor correlated well
with DXA estimates of fatness, but underestimated both total and trunkal
fatness (study IV). In the intervention study (study III) the group
allocated to a more intensive support programme recorded 1794 more
steps/d than the group allocated to standard support (P<0.01).
Conclusions : Accelerometer data identified the need to promote PA in the
severely obese. Pedometers were deemed sufficiently accurate to detect
changes in walking. Finally, the intervention study provided support for
the concept that social support promotes walking in the severely obese.
