This dissertation was designed to determine the effects of body mass index (BMI) and walking speed on activity monitor outputs. A secondary purpose was to compare the activity monitors’ performance in a free-living environment. In the first experiment, 71 participants wore three waist-mounted activity monitors (Actical, ActiGraph, and NL-2000) and an ankle-mounted device (StepWatch 3) while walking on a treadmill (40, 67 and 94 m/min). The tilt angle of each device was measured. The Actical recorded 26% higher activity counts (P < 0.01) in obese persons with a tilt <10 degrees, compared to normal weight persons. The ActiGraph was unaffected by BMI or tilt angle. In the second experiment, the steps recorded by the devices were compared to actual steps. Speed had the greatest influence on the accuracy these devices. At 40 m/min, the ActiGraph was the least accurate device for normal weight (38%), overweight (46%) and obese (48%) individuals. The Actical, NL-2000 and StepWatch averaged 65%, 73% and 99% of steps taken, respectively. Lastly, several generations of the ActiGraph (7164, GT1M, and GT3X), and other research grade activity monitors (Actical; ActivPAL; and Digi-Walker) were compared to a criterion measure of steps. Fifty-six participants performed treadmill walking (40, 54, 67, 80 and 94 m/min) and wore the devices for 24-hours under free-living conditions. BMI did not affect step count accuracy during treadmill walking. The StepWatch, PAL, and the AG7164 were the most accurate across all speeds; the other devices were only accurate at the faster speeds. In the free-living environment, all devices recorded about 75% of StepWatch-determined steps, except the AG7164 (99%). Based on these findings, we conclude that BMI does not affect the output of these activity monitors. However, waist-borne activity monitors are highly susceptible to under-counting steps at walking speeds below 67 m/min, or stepping rates below 100 steps/min. An activity monitor worn on the ankle is less susceptible to these speed effects and provides the greatest accuracy for step counting.

Thesis (M.S.)--Brigham Young University. Dept. of Physical Education, 2004. / Includes bibliographical references.

The assessment of physical activity is of great interest to the public and to researchers. One of the most popular and objective methods of assessing physical activity is using motion sensors such as pedometers and accelerometers. The purpose of this study was to assess the accuracy and reliability of step counting and energy expenditure estimation of two popular electronic pedometers and one accelerometer during running. In all step-counting trials, actual step counts were determined using a hand tally counter. Twenty subjects (18-40 years) were asked to volunteer to participate in the study. During the initial assessment subjects ran at five, six, seven, and eight miles per hour on a motor driven treadmill for ten minutes at each speed. While running they wore two pedometers and an accelerometer while oxygen consumption was measured. In the second assessment, all subjects ran a timed, self-paced mile around a 200-meter track while wearing all three activity monitors. In the third assessment, thirteen subjects ran at five, six, seven and eight miles per hour on a motor driven treadmill for three minutes at each speed to assess the step counting reliability of the devices. The three devices were accurate to within 1% at all speeds on the treadmill and on the self-paced track run. In addition, all three devices were reliable (r = 0.80). Caloric expenditure estimation accuracy the NL-2000 was ± 21% when expressed in both net and gross kcals. The Digi-walker was f 22% when assumed to be net kcals and ± 45% when assumed to be gross kcals. The Actigraph was accurate to ± 49% in terms of net calories. The results of the current study have shown that these devices are accurate and reliable for step counting at speeds between five and eight mph. However, their ability to assess caloric expenditure is not accurate at the same speeds. In conclusion, the application of these devices to runners is limited to highly accurate and reliable step counters. / School of Physical Education, Sport, and Exercise Science

Thesis (Ph. D.)--Florida State University, 2006. / Advisor: Charles Imwold, Florida State University, College of Education, Dept. of Sport Management, Recreation Management, and Physical Education. Title and description from dissertation home page (viewed June 13, 2006). Document formatted into pages; contains vii, 82 pages. Includes bibliographical references.

Physical inactivity is a widespread problem associated with numerous health problems. Individuals with intellectual disabilities are at a high risk of living a sedentary lifestyle. Although a few studies have examined interventions consisting of goal-setting and reinforcement for increasing PA, no studies have evaluated the use of monetary reinforcement. Interventions using monetary reinforcement have been shown to be effective for increasing PA with typically developing adults. The present studies evaluated monetary reinforcement for increasing PA in adults with intellectual disabilities. Study 1 evaluate a session-based intervention where participants earned monetary rewards for attaining step count goals as recorded by pedometers. The intervention increased the rate of walking for all five participants, demonstrating experimental control with four participants. The study also found that a staff member implemented the intervention with fidelity and rated it as highly acceptable. Study 2 evaluated a whole-day intervention where participants earned monetary rewards for attaining daily step goals as measured by wrist-worn Fitbit Alta™ accelerometers. The whole-day intervention resulted in noticeable increases in daily steps for only two participants, with experimental control demonstrated for one participant. Discussion includes the advantages and limitations of the approaches in each study and recommendations for future studies.

Research suggests declines in physical activity may occur after age 12. The purpose of this study was to determine the relationships between adolescent physical activity, BMI, and nutrition. Adolescents, ages 12-17 (N = 223), wore pedometers for 11 consecutive days and completed a nutrition survey, the Youth Adolescent Questionnaire. Activity levels did not differ among the ages of 12-17 year old adolescents, and boys were more active than girls. There was a low, but significant relationship between BMI and physical activity levels for both boys and girls. Energy intake was not related to BMI or physical activity levels in boys or girls.

As researchers explore the benefits of using pedometers to assess physical activity they are discovering that intensity of physical activity may be estimated from steps per minute (SPM). The purpose of this study was to determine the SPM and kilocalories (kcals) expended associated with moderate physical activity in middle school students (12 - 14 years old). Methods: Ninety-three (49 boys, 44 girls) middle school youth between the ages of 12 and 14, walked on a treadmill at four different speeds (4.0, 4.8, 5.64, and 6.4 km/h) for three minutes at each speed. Each participant wore a pedometer in order to obtain their steps per minute and a heart rate monitor to record their heart rate level during each test speed. Results: Moderate physical activity was reached, on average, by girls and boys at 122 SPM (5.64 km/h) and 115 SPM (4.8 km/h), respectively. At this SPM rate boys and girls expended 232.55 kcals and 176.66 kcals per hour. This study augments previous studies that explored ways to assess activity levels using SPM calculations.

The prevalence of physical inactivity has been recognized as a risk factor for multiple chronic disease conditions in both adults and children. Recently efforts to increase healthy behaviors have been promoted through religious groups (Ken Resnicow et al., 2002). The Church of Jesus Christ of Latter-day Saints (LDS) has a unique program called Family Home Evening (FHE) that could be used to teach and potentially improve physical activity. Six FHE lessons were designed to be taught in 6 consecutive weeks within a family environment. A total of 84 families (parents and children) were recruited for participation. Participating families were randomized into either the control or intervention group. All family members were given pedometers to be worn one week prior to, and one week after the 6-week intervention. The intervention group FHE lessons covered physical activity promoting topics, and the control group was given traditional religious topics for their FHE lessons. ANOVA indicated that in children there was an increase in daily steps in the intervention group (12482.8 SD=4455.3) compared to the control group (11255.4 SD=4048.9), which was statistically significant (F (1,85) = 3.93, p=.05). In adults there was an increase in steps in the intervention group from pre to posttest of 8823.5 (SD=3858.3) to 9947.4 (SD=4222.8) this difference was statistically significant (t = -2.94, p<.01). There was no significant change in pedometer steps for the control group in either adults or children. Results of this study suggest that FHE may be a useful mechanism for increasing steps taken daily. There are other factors that may increase the effectiveness of the lessons such as readiness of the participants to change, number of lessons, lesson content and/or time between lessons.

Health experts are recommending an average of 10,000 steps daily to attain certain health benefits and suggesting the use of pedometers for calculating ambulatory activity, such as walking. A 13-week, worksite walking program was implemented with teachers at an elementary school providing pedometers, weekly walking groups, bimonthly supplemental nutrition information, and a survey upon program completion to evaluate the effectiveness. Results showed that of the 31.3% that participated, 93.6% have tried to increase their daily activity in the past and 58.1% found the Bee Active walking program to be more effective than previous attempts. Participants reported that wearing the pedometer helped motivate more physical activity and increase total daily steps taken. For non-participants (63.6%), schedule conflicts and lack of time were the top two participation barriers. As a result of providing the bimonthly nutritional information, both participants and non-participants have attempted to make healthier food choices, while increasing their daily consumption of fruits and vegetables significantly.

Widespread increases in the prevalence of childhood obesity have raised the prospect of serious public health consequences in many countries. New Zealand is no exception; according to the most recent national estimates, approximately one in three children is overweight or obese. As a consequence, an understanding of the specific risk factors that predict this condition in children is becoming increasingly important. It is generally accepted that the promotion of physical activity is a key strategy for reducing the risk of childhood obesity. However, there is limited information describing physical activity and its relationship with body fatness in young New Zealanders. The overall aim of this thesis was to gain insight into the associations between excess fatness and physical activity in New Zealand children from a diverse range of socio-demographic groups. Three related studies were conducted to achieve this aim: a large descriptive survey of obesity and physical activity patterns in primary-aged children, and two preceding studies which develop the methodology for objective assessment of physical activity in this population. The first study provided the only validation data for the NL-2000 multiday memory (MDM) pedometer in children. In a sample of 85 participants aged 5-7 and 9-11 years, the NL-2000 offered similar accuracy and better precision than the widely used SW-200 pedometer (NL-2000: mean bias = -8.5 ± 13.3%; SW-200: mean bias = -8.6 ± 14.7%). The second study investigated reactivity to wearing pedometers over four 24-hour testing periods in 62 children aged 5-11 years. The sample was divided into two groups: one was given a full explanation of the function of the pedometer, while the other received no information prior to testing. The absence of significant differences in step counts between the first and last test periods indicated that there was no evidence of reactivity to this device for either preparation procedure. The central study presented in this thesis was the measurement of physical activity, body composition, and dietary patterns in 1,226 children aged 5-12 years, from which four chapters (4-7) were derived. The sample was ethnically diverse, with 46.8% European, 33.1% Polynesian, 15.9% Asian, and 4.1% from other ethnicities. Physical activity levels over three weekdays and two weekend days were assessed using NL 2000 pedometers. Percentage body fat (%BF) was determined using hand-to-foot bioelectrical impedance analysis with a prediction equation previously developed for New Zealand children. Waist and hip girths, height, and weight were measured using standard anthropometric techniques. Parent proxy questionnaires were used to assess demographic and lifestyle factors and pedometer compliance. The first reported analyses of this dataset (Chapter 4) examined the effect of weather conditions on children’s activity levels. In boys, a 10ºC rise in ambient temperature was associated with a 10.5% increase in weekday steps and a 26.4% increase in weekend steps. Equivalent temperature changes affected girls’ step counts on weekdays only (16.2% increase). Precipitation also had a substantial impact, with decreases in weekday and weekend step counts during moderate rainfall ranging from 8.3% to 16.3% across all sex, age, and socioeconomic (SES) groups. The aim of Chapter 5 was to understand the relationship between children’s step counts and their body mass index (BMI), waist circumference (WC), and %BF. Mean step counts for this sample were 16,133 ± 3,864 (boys) and 14,124 ± 3,286 (girls) on weekdays, and 12,702 ± 5,048 (boys) and 11,158 ± 4,309 (girls) on weekends. Significant associations were detected between steps.day-1 and both WC and %BF, but not between steps.day-1 and BMI. The findings in Chapter 6 extended these results by estimating the number of steps required to reduce the risk of excess adiposity in children (16,000 and 13,000 steps.day-1 for boys and girls, respectively). Finally, the study described in Chapter 7 examined the associations between excess adiposity and a series of demographic and lifestyle variables, providing the first assessment of body fat correlates in young New Zealanders. Our results indicated that children aged 11-12 years were 15.4 times more likely to be overfat (boys, %BF ≥ 25%; girls, %BF ≥ 30%) than those aged 5-6 years. In addition, the odds of overfat were 1.8 times greater in Asian children than in European children, and 2.7 times greater in the low SES group when compared with the high SES group. Three modifiable behaviours related to fat status were also identified: low physical activity, skipping breakfast, and insufficient sleep on weekdays. Clustering of these risk factors resulted in a cumulative increase in the prevalence of overfat.