A randomized controlled trial of continuous activity, short bouts, and a 10,000 step guideline in inactive adults

Objective

Although several studies have examined the effect of accumulated bouts on health outcomes, the impact of recommending short bouts on activity-related behavior in health promotion efforts has received minimal investigation.

Method

During this 5-week study in 2007-2008, 43 university employees (8 male, 35 female) in the Southeastern United States were randomly assigned to a group recommended to achieve (a) 10,000 steps (10 K), (b) 30-minutes (30 min) of continuous physical activity, or (c) 30-minutes of activity in bouts of at least 10 minutes (bouts).

Results and conclusions

Repeated measures ANOVA revealed that the 10 K group showed the largest increase in step counts whereas the bouts group showed the smallest change over the intervention period, p = 0.01. Condition differences were most pronounced on days in which participants met their activity recommendation. Accelerometer results revealed that the 10 K (d = 1.1) and 30 min groups (d = 0.89) showed large increases in minutes of moderate to vigorous activity (MVPA), whereas the bouts group showed minimal change (d = 0.11). Although activity recommendations did not differentially affect self-efficacy, participants from all conditions showed decreased self-efficacy across the intervention (p = 0.02), highlighting the need to develop strategies to increase self-efficacy in activity promotion efforts.     

Perceptions of sedentary African-American women about continuous versus intermittent walking

To meet current physical activity recommendations, a person may chose to adopt a continuous or an intermittent physical activity program, as long as they accumulate 30 minutes of moderate-intensity physical activity most days of the week. Sixty-four sedentary African-American women were surveyed to assess whether perceptions about continuous and intermittent walking programs differed. Specifically, we assessed whether perceptions of self-efficacy, outcome expectations, social support, and the environment varied with respect to walking programs. Results indicated that the women perceived higher self-efficacy for the intermittent walking program and associated this program with more favorable environmental factors (p < .05). However, they expected greater benefits from the continuous walking program (p < .05). Overall, 65% of the women reported that they would prefer to adopt the continuous walking program.     

Physical activity and prolonged sedentary behavior in US working adults

Using nationally representative data (N = 6,431) from the 2007–2010 National Health and Nutrition Examination Survey, we estimated the prevalence of self-reported adherence to guidelines-recommended physical activity level and prolonged sedentary behavior among US working adults 20 years of age and above by occupation. Sex and age were used for adjustment by direct standardization to the year 2000 Census population. Participants in “computer, mathematical” (47.77%) and “business, financial operations” (54.95%) occupations had the lowest prevalence of self-reported adherence to guidelines-recommended physical activity level; participants in “computer, mathematical” (72.19%) and “legal” (62.70%) occupations had the highest prevalence of prolonged sedentary behavior in all occupations. Public physical activity campaigns and workplace wellness programs should take into account the differences in physical activity and sedentary behavior patterns across occupation groups.     

Acute and chronic caffeine administration increases physical activity in sedentary adults

Caffeine is a commonly used stimulant thought to have ergogenic properties. Most studies on the ergogenic effects of caffeine have been conducted in athletes. The purpose of this study was to test the hypothesis that caffeine reduces ratings of perceived exertion and increases liking of physical activity in sedentary adults. Participants completed treadmill walking at 60% to 70% of their maximal heart rate at baseline and for 6 subsequent visits, during which half of the participants were given caffeine (3 mg/kg) and half given placebo in a sports drink vehicle. To investigate the potential synergistic effects of acute and chronic caffeine on self-determined exercise duration, participants were rerandomized to either the same or different condition for the last visit, creating 4 chronic/acute treatment groups (placebo/placebo, placebo/caffeine, caffeine/placebo, caffeine/caffeine). Participants rated how much they liked the activity and perceived exertion at each visit. There was a main effect of time on liking of physical activity, with liking increasing over time and an interaction of sex and caffeine treatment on liking, with liking of activity increasing in female participants treated with caffeine, but not with placebo. There was no effect of caffeine on ratings of perceived exertion. Individuals who received caffeine on the final test day exercised for significantly longer than those who received placebo. These data suggest that repeated exposure to physical activity significantly increases liking of exercise and reduces ratings of perceived exertion and that caffeine does little to further modify these effects.     

Measurement of neighborhood-based physical activity bouts

This study examined how buffer type (shape), size, and the allocation of activity bouts inside buffers that delineate the neighborhood spatially produce different estimates of neighborhood-based physical activity. A sample of 375 adults wore a global positioning system (GPS) data logger and accelerometer over 2 weeks under free-living conditions. Analytically, the amount of neighborhood physical activity measured objectively varies substantially, not only due to buffer shape and size, but by how GPS-based activity bouts are identified with respect to containment within neighborhood buffers. To move the “neighborhood-effects” literature forward, it is critical to delineate the spatial extent of the neighborhood, given how different ways of measuring GPS-based activity containment will result in different levels of physical activity across different buffer types and sizes.     

The relationship between sedentary behaviour and physical activity in adults: A systematic review

To ascertain, through a systematic review, the associations between sedentary behaviour (SB) and physical activity (PA) among adults aged 18–60 years. Studies published in English up to and including June 2013 were located from computerized and manual searches. Studies reporting on at least one measure of SB and an association with one measure of PA were included. 26 studies met the inclusion criteria. Six studies examined associations between SB and PA prospectively, and 20 were cross-sectional. The most commonly assessed subtype of sedentary behaviours were television viewing (11 studies), total sedentary time (10), total sitting time (4), general screen time (3) and occupational sedentary time (2). All studied types of SB were associated with lower levels of PA in adults. Findings of this review suggest inverse associations between SB and PA were weak to moderate. Objective monitoring studies reported larger negative associations between SB and light intensity activity. Current evidence, though limited, supports the notion that sedentary behaviour displaces light intensity activity.     

Comparison of continuous vs intermittent nasogastric enteral feeding in trauma patients: perceptions and practice.

Enteral nutrition support (ENS) may be administered by continuous administration or by intermittent bolus, but few studies have compared the advantages and limitations associated with these methods in the trauma patient population. The purpose of this prospective randomized study was to evaluate the impact of continuous vs intermittent nasogastric enteral feeding on gastrointestinal tolerance, pulmonary aspiration, and nutritional indices. A survey of medical and surgical intensive care unit nursing staff was performed to assess perceptions and attitudes toward these 2 delivery methods. Eighteen trauma patients [Injury Severity Score (ISS) > or = 20] were enrolled in the study; 9 received continuous ENS (CENS) and 9 received intermittent bolus ENS (IENS). Interruption of ENS delivery occurred in more IENS than CENS patients due to elevated residuals and emesis. Diarrhea occurred in more patients (5/9 vs 2/9) and for a longer duration (14/65 vs 6/49 ENS days) in the IENS group compared with the CENS group. Aspiration was detected in 1 IENS patient. Method of nutrient delivery did not seem to influence urine urea nitrogen (UUN) measurements or prealbumin concentrations. Nurses surveyed in the study (n = 25) preferred CENS (84%) compared with IENS (12%). Data from this study suggest that CENS through a nasoenteric feeding tube may facilitate nutrient intake with less gastrointestinal complications in severely injured trauma patients compared with IENS. In addition, the majority of nurses surveyed preferred the continuous method for nutrient delivery.     

Joint associations of multiple leisure-time sedentary behaviours and physical activity with obesity in Australian adults

Background  

Television viewing and physical inactivity are independently associated with risk of obesity. However, how the combination of multiple leisure-time sedentary behaviours (LTSB) and physical activity (LTPA) may contribute to the risk of obesity is not well understood. We examined the joint associations of multiple sedentary behaviours and physical activity with the odds of being overweight or obese.     

The efficacy of accumulated short bouts versus single daily bouts of brisk walking in improving aerobic fitness and blood lipid profiles

Fifty-six subjects (19 men and 37 woman) aged between 40 and 66 completed the study. They were allocated into three walking groups and a control group (C). The three walking groups performed the same total amount of walking for 18 weeks, but completed it in bouts of differing durations and frequencies. These were Long Walkers (LW; 20-40 min/bout), Intermediate Walkers (IW; 10-15 min/bout) and Short Walkers (SW; 5-10 min/bout); with the IW and SW performing more than one bout of walking a day. Following the 18 week walking programme, compared to the C group all walking groups showed similar improvements in fitness as determined by a reduction in blood lactate during a graded treadmill walking test (LW 1.0 mmol/l; IW 0. 8 mmol/l; SW 1.2 mmol/l; C 0.2 mmol/l; P = 0.003) and reduction in final heart rate (LW 8 beats/min; IW 6 beats/min; SW 10 beats/min; C 0 beats/min; P = 0.056). Also compared to the C group, the LW and IW groups recorded statistically significant decreases in low-density lipoprotein cholesterol (LW 0.29 mmol/l; IW 0.41 mmol/l; P = 0.024), whereas the control group showed a mean increase of 0.22 mmol/l. The LW and IW groups also showed significant reductions in apolipoprotein (apo) A-II (LW 0.05 g/l; IW 0.02 g/l; SW 0.01 g/l; C 0.00 g/l; P = 0.012) with the LW recording a statistically significant increase in the ratio of apo A-I/A-II (LW, 0.19, P = 0. 044). In conclusion, some health benefits were achieved from all walking programmes. However, whilst the changes in aerobic fitness were similar, the effects upon blood lipid profiles were not. The findings from this study suggest that the LW regimen was most effective in benefiting blood lipid profile, followed by the IW regimen, with the SW being least potent. Nevertheless, for the sedentary/low-active members of society, any improvement in health may be considered as important. Therefore accumulated bouts of moderate intensity exercise, which according to theories of exercise behaviour may be more easily incorporated into an individual's lifestyle than single prolonged bouts, may be advocated for health promotion but may not be as effective as the traditionally prescribed 20-40 min bouts.     

Levels and patterns of physical activity and sedentary behavior in adults with and without visual impairment

BackgroundLimited data are available on objectively measured physical activity (PA) and sedentary behavior (SB) among adults with and without visual impairment (VI).ObjectiveTo compare PA and SB levels and patterns in adults with and without VI and to examine how these differ based on sex and day of the week.MethodsThirty-two participants with VI and 32 participants without VI participated in this cross-sectional study. PA and SB were assessed using GT3X ActiGraph accelerometers during waking hours for 7 days, and variables were examined in terms of disability group, sex, and day of the week. Nonparametric Mann–Whitney U test and Wilcoxon signed-rank test were used, and significance was set at p < 0.05.ResultsPA did not differ in terms of sex or day of the week in participants with VI. The PA of participants without VI was significantly higher for men than it was for women and was significantly higher during weekdays than on weekend days. Total sedentary time and the duration of SB breaks were significantly longer for female participants with VI than for those without VI. The number of sedentary bouts lasting ≥10 min during weekend days was significantly higher for participants with VI than for those without VI.ConclusionsMost adults with and without VI did not meet the recommended levels of daily PA and spend a large portion of the day being sedentary. Interventions to enhance PA and reduce sedentary time in adults with and without VI are required.