Can America’s Top Sedentary Activity be Made More Active?: Physical Activity and Leisure-time Study (PALS)

This dissertation investigated 1) the energy expenditure of stepping in place during TV commercials (commercial stepping), 2) determined the best objective tool to measure commercial stepping, 3) and assessed the efficacy of commercial stepping to increase the activity levels of sedentary, overweight adults.
First, twenty-three adults (normal to obese) had their energy expenditure measured while at rest, sitting, standing, stepping in place and walking at 3.0 mph on the treadmill, followed by one hour each of sedentary TV viewing and commercial stepping in the laboratory. Stepping in place, walking at 3.0 mph, and commercial stepping, had a higher caloric requirement than either rest, or sedentary TV viewing. One hour of commercial stepping resulted in an average of 2111 actual steps. The waist mounted Digiwalker and New Lifestyles pedometers counted 72% and 80% of steps, while the ankle mounted Omron and Stepwatch counted 100% and 98% of actual steps respectively.
Having established commercial stepping as a moderate intensity-measurable activity, eleven adults, participated in a 3-week pilot study to investigate the effects of commercial stepping at home (one week baseline, followed by two weeks commercial stepping across ≥90 min/day of TV watching). Compared to baseline, adults took more steps when watching TV, and watched 34% less TV during the 2nd two weeks. In the free-living environment, the StepWatch counted significantly more steps than the Omron pedometers (ankle and waist).
Thirdly, this study compares two physical activity prescriptions: 1) commercial stepping across ≥90 min/day of TV watching; and 2) walking ≥30 min/day in 58 sedentary overweight adults. Outcomes were daily steps, adherence, dietary intake, TV watching and weight after 12 wks in a behavioral intervention. Both groups adhered equally to their prescriptions, and daily steps significantly (P<0.05) increased (~3000 steps/day) from 0 to 12-wks, with no difference between groups. TV viewing was significantly (P<0.05) reduced in both groups. Despite a reduction (P<0.05) in self-reported dietary intake, there were no changes in weight in either group. Instructing people to step in place during 90 minutes of TV watching results in a change in daily steps roughly equivalent to encouraging people to walk 30 min/day.