Brian C. Rider

Detection of Lying Down, Sitting, Standing, and Stepping Using Two ActivPAL Monitors

UNLABELLED The activPAL is an accelerometer-based monitor worn on the thigh that classifies daily activities into three categories (sitting/lying down, standing, and stepping). The monitor discriminates between sitting/lying and the upright position by detecting the inclination of the thigh. It detects stepping from the acceleration versus time wave form. However, a current limitation of the activPAL is that it does not discriminate between sitting and lying down. PURPOSE This study aimed to determine whether placing a second activPAL monitor on the torso would allow the detection of seated versus lying postures. METHODS Fifteen healthy adults (18-55 yr of age) wore an activPAL on the right thigh and another activPAL over the right rib cage. Both monitors were synchronized and initialized to record data in 15-s epochs. Participants performed a semistructured routine of activities for 3 min each. Activities included lying down (while supine, prone, and on the side), sitting, standing, sweeping, treadmill walking at 3 mph, and treadmill running at 6 mph. The spatial orientation of the thigh and chest monitors was used to determine body posture, and the activPAL on the thigh was used to detect ambulation. RESULTS The use of two activPAL devices enabled four behaviors to be accurately classified. The percentages of observations that were classified accurately were as follows: lying down (100%), sitting (100%), standing/light activity in the upright position (90.8%), and stepping (100%). CONCLUSIONS The current method allows researchers to obtain more detailed information on postural allocation compared with that in the use of a single activPAL on the thigh.

Detecting indoor and outdoor environments using the ActiGraph GT3X+ light sensor in children.

INTRODUCTION Experts recommend children spend more time playing outdoors. The ambient light sensor of the ActiGraph GT3X+ provides lux measurements. A lux is the International Systems unit of illumination, equivalent to 1 lm·m. Few studies have established a lux threshold for determining whether a child is indoors or outdoors. PURPOSE This study aimed 1) to assess the reliability of the ActiGraph GT3X+ ambient light sensor, 2) to identify a lux threshold to accurately discriminate between indoor and outdoor activities in children, and 3) to test the accuracy of the lux threshold in a free-living environment. METHODS In part 1, a series of reliability tests were performed using 20 ActiGraph GT3X+ monitors under different environmental conditions. Cronbachs alpha was used to determine interinstrument reliability. In part 2, 18 children performed 11 different activities (five indoors and six outdoors) for 6 min each. The optimal threshold for detecting indoor/outdoor activity was determined using a receiver operator characteristic curve analysis. In part 3, 18 children at a preschool wore the monitor during a school day. Percent accuracy was determined for all conditions. RESULTS In part 1, the devices had Cronbachs alpha values of 0.992 and 1.000 for indoor and outdoor conditions, respectively, indicating high interinstrument reliability. In part 2, the optimal lux threshold was determined to be 240 lux (sensitivity = 0.92, specificity = 0.88, area under the curve = 0.96, 95% CI = 0.951-0.970). In part 3, results of the school-day validation demonstrated the monitor was 97.0% accurate for overall detection of indoor and outdoor conditions (outdoor = 88.9%, indoor = 99.1%). CONCLUSIONS The results demonstrate that an ActiGraph GT3X+ lux threshold of 240 can accurately assess indoor and outdoor conditions of preschool children in a free-living environment.

Monitoring capabilities of the Omron HJ-720ITC pedometer.

Abstract Purpose: The purpose of our study was to examine the monitoring capabilities of the Omron HJ-720ITC pedometer and determine the feasibility of using it in physical activity interventions. Methods: Using data from an 8-week lifestyle-intervention study, we tested the capabilities of the pedometer for recording physical activity data. Data from a total of 28 subjects were used in our analysis. The total number of patient steps per day was recorded over the duration of an intervention, as well as “aerobic steps per day” (ie, those taken at a cadence of > 60 steps per minute for ≥ 10 consecutive minutes). Daily wear time was computed in order to ascertain participant compliance in wearing the pedometer. In addition, aerobic steps per minute were computed, providing an assessment of activity intensity during continuous walking bouts. Results: Total steps per day and aerobic steps per day increased from baseline assessment to Week 8. Participants exceeded 100 steps/minute for 89% of their aerobic minutes, suggesting that they were in the moderate-intensity range (3–6 metabolic equivalent tasks) when performing continuous bouts of walking (> 10 minutes). Conclusion: The new pedometer is a reasonably priced, wearable activity monitor that is feasible for use in clinical and research settings.

Effects of television on enjoyment of exercise in college students

Purpose: Determine the effects of television viewing on enjoyment of exercise in college students. Methods: Forty-three college students (Mean ± SD; age = 19 ± 2 y, body mass index (BMI) = 23.7 ± 3.2 kg/m2) completed two 30-minute cycling exercise sessions at a moderate exercise intensity (40% peak oxygen consumption), in randomised order. Experimental session required participants to view a nature series programme (TV), while in the control session they did not watch television (No-TV). Rating of Perceived Exertion (RPE) and Feeling Scale (FS) were measured at 10, 20 and 30 minutes of exercise. The Physical Activity Enjoyment Scale was administered following each session. Enjoyment of exercise was analysed with a paired samples t-test. Additional analyses were conducted to assess the influence of potential physiological and psychological mediators of exercise enjoyment. Correlational analyses were conducted to determine the relationship between mean FS values and enjoyment of exercise for each visit. Repeated measures ANOVAs (condition x time) were performed on RPE. Results: Enjoyment of exercise was higher for TV (87 ± 19) vs. No-TV (79 ± 1 6) (p = .016) and was positively correlated with intrinsic motivation (r = 0.347) (p < .05). Mean FS values were correlated with enjoyment for both conditions (p < .05). No differences in RPE between sessions were observed (p = .127). Conclusion: Watching television during exercise may positively enhance the overall experience and promote enjoyment of exercise.

Physical activity and motivating factors of participants in a financially incentivized worksite wellness program

Worksites are continuing to use wellness programs to encourage employees to adopt and maintain healthy behaviors. Some of these programs offer financial incentives to maximize employee participation and motivate behavior change. Purpose: The purpose of this study was to gather information regarding a financially incentivized worksite wellness program at a Southeastern United States university. Participants: A 15-item electronic survey was distributed to participants enrolled in the Virgin Pulse HealthMiles (VHM) program at Belmont University. Methods: Steps per day were uploaded to the VHM website by program enrollees (N = 458). The survey inquired about physical activity habits, motivating factors, and improvements in cardiovascular disease risk factors since joining the program. Results: VHM enrollees took an average of 7321 steps/day, as measured by objective pedometer data. Among the 146 respondents, the most motivating factor for participation was the financial incentive, which was considered ‘strongly motivating’ by 64%. About 82% reported being more physically active, 71% felt better, 57% had more energy, and 56% had lost weight since joining the program. The average self-reported weight loss was 7 ± 12 lb (mean ± SD). About 87% indicated they would recommend this program to a friend. Conclusions: The enrollees in the VHM program are taking about 2000 steps/day more than the average American. Most of the people who responded to the survey reported that their physical activity had increased since starting the program. The financial incentive was the most motivating factor to participate.