Effect Of Frequent Daily Walking Bouts On Sedentary Time And Self-perceived Fatigue In Free-living Adults

Abstract

PURPOSE: Breaking up sedentary time with frequent short bouts of activity has been suggested as a novel strategy to reduce sedentary behaviors, but whether this strategy will be effective at reducing sedentary time in free-living conditions is unknown. In this pilot study, objective measures of physical activity and self-reported measures of fatigue and vigor were compared over 3-days among the following free-living conditions (1) microburst activity (MICRO: 5-min of brisk walking every hour for 9 hours), (2) one 45-min bout of brisk walking (ONE), and (3) a sedentary control condition (SED). METHODS: Eighteen sedentary overweight adults (12F/6 M, mean±SD; age=32.2± 6.1 yo, BMI= 30.8±2.5 kg/m2) completed each condition (MICRO, ONE, SED) in a randomized crossover study. The percentage of time spent in sedentary, light-intensity (LPA) and moderate-to-vigorous intensity physical activity (MVPA) were measured by accelerometry (ActiGraph GT3X+). At the end of each day, participants self-reported their level of fatigue and vigor using visual analog scales (VAS). RESULTS: Both MICRO (7.5±3.3%, p=0.04) and ONE (9.5 ± 3.3%, p < 0.0001) increased the percentage of time spent in MVPA during waking hours compared to SED (5.2±2.4%). However, MVPA decreased between the first (10.1±2.5%) and the third day (8.2±2.5%, p=0.02) of ONE, while no changes occurred in MICRO. ONE (79.3 ± 5.9%, p<0.0001), but not MICRO (83.1±5.4%) reduced the percentage of time spent sedentary during waking compared to SED (84.4±5.7%). The fact that LPA was lower with MICRO (10.6±4.1%) than with ONE (12.9±5.4%, p=0.03) suggests a spontaneous displacement from LPA towards sedentary time. Participants reported feeling less “worn out” (34.3±25.9 vs. 42.8±26.1, p = 0.04), “bushed” (33.8±25 vs. 41.6±24.1, p=0.05), and had a lower desire to close their eyes (37.3±27.5 vs. 44.1±26.6, p=0.05) and lie down (39.5±28.0 vs. 47.6±27.7, p=0.055) during MICRO compared to ONE conditions. CONCLUSIONS: Performing a continuous bout of brisk walking per day seems to be more potent at increasing MVPA and reducing time spent sitting, however, the effects may not be long lasting. Small lifestyle changes such as those induced by microbouts of activity may be easier to implement in at-risk populations. Long term studies are needed to confirm this hypothesis.