Purpose: Interventions targeting sedentary time are needed. We used detailed EMG recordings to study the short-term effectiveness of simple sedentary-time targeted tailored counseling on the total physical activity spectrum.
Methods: This cluster RCT was conducted between 2011-2013 (InPact, ISRCTN28668090) and short-term effectiveness of counseling is reported in the present study. 133 office workers volunteered to participate, from which muscle activity data were analyzed from 48 (intervention n=24, control n=24). Following a lecture, face-to-face tailored counseling was used to set contractually binding goals regarding breaking up sitting periods and increasing family-based physical activity. Primary outcome measures were assessed 11.8+/-1.1 hours before and a maximum of two weeks after counseling including quadriceps and hamstring muscle inactivity time, sum of the five longest muscle inactivity periods and light muscle activity time during work, commute and leisure time.
Results: Compared to the controls, counseling decreased the intervention group's muscle inactivity time by 32.6+/-71.8 min from 69.1+/-8.5% to 64.6+/-10.9% (whole day p<.05, work p<.05, leisure p<.05), and the sum of the 5 longest inactivity periods from 35.6+/-14.8 min to 29.7+/-10.1 min (whole day p<.05, leisure p<.01). Concomitantly, light muscle activity time increased by 20.6+/-52.6 min, from 22.2+/-7.9% to 25.0+/-9.7% (whole day p<.05, work p<.01, leisure p<.05), and during work time average EMG amplitude (%EMGMVC) increased from 1.6+/-0.9% to 1.8+/-1.0% (p<.05) in the intervention group compared to controls.
Conclusion: A simple tailored counseling was able to reduce muscle inactivity time by 33 min which was reallocated to 21 min of light muscle activity. During work time, average EMG amplitude increased by 13% reaching an average of 1.8% of EMGMVC. If maintained, this observed short term effect may have health benefitting consequences.
(C) 2014 American College of Sports Medicine