Physical activity and arterial stiffness: is body fat a mediator?

PURPOSE: Physical activity (PA) and body fat percentage (%BF) are independently associated with arterial stiffness, but it has not been explored if there is an associative pathway among these variables. This study examined whether %BF mediates the relationship between PA or sedentary behavior levels with arterial stiffness. METHODS: Fifty adults (1:1 men:women; age 28 ± 11 year) had carotid-femoral pulse wave velocity (CF-PWV) measured by applanation tonometry, %BF by bioelectrical impedance, and PA levels by accelerometry. Accelerometer data determined minutes per day spent in sedentary, light, moderate-to-vigorous physical activity (MVPA), and Total PA. RESULTS: Pearson correlation indicated statistically significant associations among age, %BF, CF-PWV, MVPA, and Total PA (r = 0.34-0.65, p < 0.05). Sedentary and light PA were not associated with CF-PWV. Mediation analysis indicated significant total effects of MVPA (ß = - 0.34, p = 0.044) and age (ß = 0.65, p < 0.001) on CF-PWV. %BF mediated the relationship between Total PA and CF-PWV due to indirect effect of Total PA on %BF (ß = - 0.34, p = 0.02) and %BF on CF-PWV (ß = 0.44, p = 0.002), and partially mediated the relationship between age and CF-PWV (ß = 0.54, p < 0.001). Total PA retained its significant effect on %BF (ß = - 0.28, p = 0.04) and the effect of %BF on CF-PWV remained significant (ß = 0.26, p = 0.03), despite age having a significant effect on both %BF (ß = 0.31, p = 0.023) and CF-PWV (ß = 0.54, p < 0.001). CONCLUSIONS: %BF mediated the relationship between Total PA and arterial stiffness, even after accounting for age. Engagement in more Total PA may help to reduce %BF, resulting in decreased arterial stiffness.

Analysis of sedentary behaviour levels and patterns in adults with Down syndrome.

BACKGROUND: Sedentary behaviour (SB) among adults with Down syndrome (DS) may differ based on personal or environmental factors. OBJECTIVE: Investigate differences in SB levels and patterns of adults with DS based on sex, age, and residence-type across weekdays and weekends. METHODS: Thirty-four adults with DS (15 men; 37 ± 12 years) underwent accelerometry-based measurements of sedentary time, bouts, and breaks for 7 days. We evaluated differences with 2 × 2 mixed-model (group-by-day) ANOVA. RESULTS: Younger (19-36 years) individuals had less sedentary time (p = .042), and shorter (p = .048) and fewer (p = .012) bouts than older (37-60 years) individuals. Group home residents had more bouts on weekends than adults living with parent/guardians (p = .015). CONCLUSIONS: Adults with DS spent half their waking hours in SB of short bouts. Age and residence may influence SB.

Factors That Influence Physical Activity in Individuals With Down Syndrome: Perspectives of Guardians and Health Professionals.

Identifying factors that influence physical activity (PA) among individuals with Down syndrome is essential for PA promotion. Insight can be gained from guardians and health professionals. The purpose of this study was to explore the perspectives of guardians and health professionals on facilitators and barriers of PA in individuals with Down syndrome. Interviews were conducted with 11 guardians (five mothers, four fathers, and two legal guardians) and 11 professionals (four PA specialists, three physical therapists, and four occupational therapists). Grounded theory was applied. Barriers and facilitators fit the levels of the ecological model of health behavior: (a) intrapersonal (perceived rewards), (b) interpersonal (interaction), (c) community (availability of programs), (d) organizational (school systems), and (e) policy (education). Guardians and professionals agreed on the importance of enjoyment, interaction, and programs to promote PA. Differences between groups were identified at the organizational and policy levels. PA in persons with Down syndrome is influenced by interactions between individual and environmental factors.

Health Outcomes of Physical Activity Interventions in Adults With Down Syndrome: A Systematic Review.

This systematic review examined whether physical activity interventions improve health outcomes in adults with Down syndrome (DS). We searched PubMed, APA PsycInfo, SPORTDiscus, APA PsycARTICLES, and Psychology and Behavioral Sciences Collection using keywords related to DS and physical activity. We included 35 studies published in English since January 1, 1990. Modes of exercise training programs included aerobic exercise, strength training, combined aerobic and strength training, aquatic, sport and gaming, and aerobic and strength exercise interventions combined with health education. The evidence base indicates that aerobic and strength exercise training improve physical fitness variables including maximal oxygen uptake, maximal heart rate, upper and lower body strength, body weight, and body fat percentage. Sport and gaming interventions improve functional mobility, work task performance, and sport skill performance. We concluded that adults with DS can accrue health benefits from properly designed physical activity and exercise interventions.

Brief report: Caregiver perceived physical activity preferences of adults with Down syndrome.

BACKGROUND: Adults with Down syndrome commonly have low levels of physical activity and face social barriers to engaging in physical activity, including boredom and companionship concerns. Adults with Down syndrome are at increased risk for several co-occurring medial conditions known to benefit from physical activity, including obesity and dementia. METHOD: This study surveyed 140 caregivers of adults with Down syndrome to determine the physical activity preferences of their adult with Down syndrome. RESULTS: Dancing was the most frequently caregiver-reported physical activity preference for adults with Down syndrome, followed by walking and active video gaming. Rowing, using an elliptical machine, and jogging were the least preferred activities. Most caregivers reported that their adult with Down syndrome has a companion available for physical activity. CONCLUSION: Promoting dance in adults with Down syndrome, a caregiver-reported preferred form of physical activity, may help improve physical activity levels and decrease sedentary behaviours in this population.

Age-Group Differences in Body Mass Index, Weight, and Height in Adults With Down Syndrome and Adults With Intellectual Disability From the United States.

The authors examined if body mass index (BMI), weight, and height across age groups differ between adults with Down syndrome (DS) and adults with intellectual disability but without DS. They conducted secondary analyses of cross-sectional data from 45,803 individuals from the United States from 2009 to 2014 of the National Core Indicators Adult Consumer Survey across five age groups: 18-29, 30-39, 40-49, 50-59, and 60+ years. For both men and women with DS, BMI and weight increased between the 18- to 29- and the 30- to 39-year age groups and decreased thereafter. For both men and women with intellectual disability, BMI and weight increased between the 18- to 29- and the 30- to 39-year age groups, stayed about the same until the 50- to 59-year age group, and decreased thereafter. Height demonstrated a small but significant decrease with older age in all groups. These cross-sectional comparisons indicate that BMI and weight may start decreasing at a younger age in adults with DS than in adults with intellectual disability.

Is Physical Activity Associated With Physical Performance in Adults With Intellectual Disability?

Physical activity (PA) and sedentary behavior may contribute to physical function in adults with intellectual disability (ID). This study examined whether objectively measured PA and sedentary behavior levels are associated with physical performance in adults with ID. Fifty-eight adults with ID (29 women and 29 men, age 44 ± 14 years) underwent a measurement of physical performance with the Short Physical Performance Battery (SPPB) and PA and sedentary time using a hip-worn accelerometer (wGT3X-BT; ActiGraph, Pensacola, FL). Moderate PA and age were significantly associated with the SPPB score (r = .39 and .34, respectively; p < .01). A hierarchical-regression model with moderate PA and age as independent variables indicated that moderate PA was a significant predictor of SPPB (p < .001; R2 = .153), but age was not (p = .123; R2 change = .036). Overall, moderate PA was significantly associated with the SPPB score, even after accounting for age, in adults with ID.

Systematic review of sedentary behaviour in people with Down syndrome across the lifespan: A clarion call.

BACKGROUND: Individuals with Down syndrome (DS) experience health disparities possibly associated with high levels of sedentary behaviour (SB). We systematically reviewed SB measurement, levels, patterns, correlates, consequences and interventions in people with DS across the lifespan. METHOD: We searched these databases: Embase; PubMed; Web of Science; Scopus; CINAHL; PsycINFO; SPORTDiscus; and Cochrane Library. We included quantitative studies published in English since 1 January 1990. RESULTS: We identified 17 eligible articles. Across studies, accelerometer-determined sedentary time was 552 min/day (median: 542; range 392-680 min/day). Sedentary time appeared higher than previously reported values in the general population, especially for youth with DS. Multivariate SB correlates were primarily familial and environmental. Sedentary behaviour consequences have not been exclusively studied. Motor skills training reduced SB in youth with DS. CONCLUSIONS: Sedentary behaviour research in this population is in early stages. Individuals with DS have high levels of SB that may be responsive to interventions.

Development and Cross-Validation of a Prediction Equation for Estimating Percentage Body Fat From Body Mass Index in Young People With Intellectual Disability.

The purpose of this study was to develop and cross-validate an equation for estimating percentage body fat (%BF) from body mass index and other potential independent variables among young persons with intellectual disability. Participants were 128 persons with intellectual disability (62 women; age 16-24 years) split between development (n = 98) and cross-validation (n = 30) samples. Dual-energy X-ray absorptiometry served as the reference method for %BF. An equation including 1/body mass index and sex (0 = male; 1 = female) was highly accurate in estimating %BF (p < .001; R2 = .82; standard error of estimate = 5.22%). Mean absolute and root mean square errors were small (3.1% and 3.9%, respectively). A Bland-Altman plot indicated nearly zero mean difference between actual and predicted %BF with modest 95% confidence intervals. The prediction equation was %BF = 56.708 - (729.200 × [1/body mass index]) + (12.134 × sex). Health care professionals may use the prediction equation for monitoring %BF among young people with intellectual disability.

Prediction of energy expenditure during walking in adults with down syndrome.

BACKGROUND: When developing walking programmes for improving health in adults with Down syndrome (DS), physical activity professionals are in need of an equation for predicting energy expenditure. We therefore developed and cross-validated an equation for predicting the rate of oxygen uptake (VO2 ; an index of energy expenditure) for adults with and without DS. METHOD: A total of 469 VO2 observations during walking across different speeds were available from 54 adults with DS and 61 adults without DS. RESULTS: Significant predictors of VO2 were speed, speed square, group and group-by-speed interaction. Separate models for each group showed that speed and its square significantly predicted VO2 . Absolute per cent error was small and did not differ between groups. CONCLUSION: Adults with DS have different VO2 response to walking speed from persons without DS. VO2 is predicted from speed with acceptable accuracy for persons with DS.

Physical Activity Promotion for Persons Experiencing Disability: The Importance of Interdisciplinary Research and Practice.

This paper examines the need for interdisciplinary knowledge in the formation of public health models for health-promoting physical activity (PA) for people experiencing disability. PA promotion for people experiencing disability is a multifaceted endeavor and requires navigating a multitude of complicated and interactive factors. Both disability and health are multifaceted constructs and the relationship between PA and health is embedded within a complicated web of interactive influences. PA promotion must consider interacting biological and psychosocial factors within the person and in the sociopolitical environment. Models for research and practice need to evolve from value and belief systems that center on people experiencing disability without stigmatizing them. We argue that interdisciplinary research and practice is needed in navigating the intricacies of PA promotion toward improving the health of people experiencing disability and facilitating inclusion, empowerment, and dignity.

Growth charts for Brazilian children with Down syndrome: Birth to 20 years of age.

BACKGROUND: The growth of youth with Down syndrome (DS) differs from that of youth without DS, and growth charts specific to DS have been developed. However, little is known about the growth of Brazilian youth with DS. The objective of this study was to construct growth charts for Brazilian youth with DS and compare the growth data with the Child Growth Standards of the World Health Organization (WHO) and charts for children with DS from other studies. METHODS: Mixed longitudinal and cross-sectional data were collected at University of Campinas, 48 specialized centers for people with intellectual disabilities, and two foundations for people with DS between 2012 and 2015. A total of 10,516 growth measurements from birth to 20 years of age were available from 938 youth with DS (53.7% boys) born between 1980 and 2013. The Lambda Mu Sigma method was applied to construct the curves using generalized additive models for location, scale, and shape. RESULTS: Length/height-for-age, weight-for-age, and head circumference-for-age percentile curves were generated for Brazilian boys and girls from birth to 20 years of age. Differences in growth of Brazilian youth ranged from -0.8 to -3.2 z-scores compared to WHO standards, and -1.9 to +1.3 compared to children with DS in other studies. CONCLUSIONS: These specific growth charts may guide clinicians and families in monitoring the growth of Brazilian children and adolescents with DS.

How Do Adults With Down Syndrome Perceive Physical Activity?

Adults with Down syndrome (DS) tend to have low physical activity levels, which may relate to how they perceive participation in physical activities. The current study entailed interviews with 30 adults with DS (age 18-71 yr, 18 women) to examine how they perceived physical activity, exercise, and sport. Through qualitative analysis informed by grounded theory, the investigators found that adults with DS have positive perceptions of physical activity that center on enjoyment. Three facets of enjoyment were identified: interaction, achievement, and process. Interaction reflected enjoyment of social contact with others including relatives, peers, caregivers, and animals. Achievement involved enjoyment of achieving particular ends including accomplishment of tasks, material rewards, formation of athletic identities, and improvement of health. Process represented enjoyment from performing a particular activity itself. This multifaceted enjoyment expressed by adults with DS may facilitate physical activity and should be considered when developing programs to improve their well-being.

Step-rate thresholds for physical activity intensity in persons with multiple sclerosis.

This study examined whether the relationship between metabolic equivalent units (METs) and step-rate is altered in persons with multiple sclerosis (MS) and developed step-rate thresholds for activity intensity for these persons. Participants were 24 persons with MS (20 women; age = 44 ± 12) and 24 healthy persons without MS (20 women; age = 41 ± 11). The MS group was divided using the 12-item MS Walking Scale (MSWS-12) into two walking impairment subgroups: (a) minimal (n = 13, MSWS-12 ≤ 12.5) and (b) mild-moderate (n = 11, MSWS-12 > 12.5). METs were measured with spirometry and step-rate with hand-tally. Step-rate, height, group, the step-rate by group interaction, and the square of step-rate significantly predicted METs. At a given height, the step-rate thresholds at 3 and 6 METs were lower for persons with minimal impairment than persons without MS and even lower for persons with mild-moderate impairment. The relationship between METs and step-rate is altered in persons with MS, lowering their step-rate thresholds for activity intensity, especially for persons with MS who have higher levels of walking impairment.

Evaluation of carotid wave intensity in firefighters following firefighting.

Sudden cardiac events are the leading cause of line-of-duty firefighter deaths, but little information exists elucidating the physiologic responses. Wave intensity (WI) is a new hemodynamic index that provides information about the dynamic behavior of the heart and the vascular system and their interaction. The larger first peak wave (W1) occurs during early systole and is associated with cardiac contractility. The second smaller peak (W2) follows a period of relatively little net wave (NA) production and may be caused by reflected waves from the brain. This study aimed at determining arterial WI changes in response to live firefighting activities. We examined the WI of 39 firefighters (2 females) with a mean age of 28 ± 1 years and BMI of 26.6 ± 0.7 kg m(-2) at rest, and immediately after 3 h of live firefighting drills. WI was assessed on the right common carotid artery using an Aloka high-resolution ultrasound. The magnitude of the W1 decreased significantly from 15,925 ± 1,341 to 11,540 ± 886 mmHg m s(-3), p < 0.05. The magnitude of W2 remained unchanged (W2: from 2,080 ± 200 to 2,144 ± 358 mmHg m s(-3)). Net NA decreased from 53 ± 5 to 40 ± 4 mmHg m s(-2). In conclusions, our data suggest that left ventricular function and arterial-ventricular coupling decreased following live firefighting, and this may be related to the documented increase in risk of clinical events during and after firefighting activities.

Prediction of energy expenditure from wrist accelerometry in people with and without Down syndrome.

This study examined the relationship between energy expenditure and wrist accelerometer output during walking in persons with and without Down syndrome (DS). Energy expenditure in metabolic equivalent units (METs) and activity-count rate were respectively measured with portable spirometry and a uniaxial wrist accelerometer in 17 persons with DS (age: 24.7±6.9 years; 9 women) and 21 persons without DS (age: 26.3±5.2 years; 12 women) during six over-ground walking trials. Combined groups regression showed that the relationship between METs and activity-count rate differed between groups (p<.001). Separate models for each group included activity-count rate and squared activity-count rate as significant predictors of METs (p≤.005). Prediction of METs appeared accurate based on Bland-Altman plots and the lack of between-group difference in mean absolute prediction error (DS: 17.07%; Non-DS: 18.74%). Although persons with DS show altered METs to activity-count rate relationship during walking, prediction of their energy expenditure from wrist accelerometry appears feasible.

Estimation of body fat in children with intellectual disability: development and cross-validation of a simple anthropometric method.

OBJECTIVE: Population-level monitoring of body composition requires accurate, biologically-relevant, yet feasible methods for estimating percent body fat (%BF). The aim of this study was to develop and cross-validate an equation for %BF from Body Mass Index (BMI), age, and sex among children with intellectual disability (ID). This study further aimed to examine the performance of an existing BMI-based equation (Deurenberg equation) for %BF in children with ID. METHOD: Participants were 107 children (63 boys; aged 6-15 years) with ID randomly allocated to development (n = 81) and cross-validation (n = 26) samples. Dual-Energy X-Ray Absorptiometry provided the criterion %BF. RESULTS: The model including BMI, age, and sex (0 = male; 1 = female) had a significant goodness-of-fit in determining %BF (p < 0.001; R2 = 0.69; SEE =5.68%). The equation was: %BF = - 15.416 + (1.394 × BMI) + (4.538 × age) - (0.262 × age2) + (5.489 × sex). The equation was cross-validated in the separate sample based on (i) strong correlation (r = 0.82; p < 0.001) and non-significant differences between actual and predicted %BF (28.6 ± 9.6% and 30.1 ± 7.1%, respectively); (ii) mean absolute error (MAE) = 4.4%; and (iii) reasonable %BF estimations in Bland-Altman plot (mean: 1.48%; 95% CI: 12.5, -9.6). The Deurenberg equation had a large %BF underestimation (mean: -7.1%; 95% CI: 5.3, -19.5), significant difference between actual and estimated %BF (28.6 ± 9.7% and 21.5 ± 7.0%, respectively; p < 0.001), and MAE = 8.1%. CONCLUSIONS: The developed equation with BMI, sex, and age provides valid %BF estimates for facilitating population-level body fat screening among children with ID.

Weight management recommendations for youth with Down syndrome: Expert recommendations.

Youth with Down syndrome (DS) have a higher prevalence of overweight and obesity compared to the general youth population. Due to physiological and cognitive differences observed in youth with DS, weight management recommendations developed for the general population, may not be suitable for youth with DS. However, there are no recent recommendations for weight management in youth with DS. A workgroup of clinicians and researchers with extensive experience working with youth with DS came together to give clinicians and families guidance for weight management in youth with DS. Recommendations were developed by the workgroup via a methodical, deliberative process. After the initial development of the recommendations, they were shared with an expert review panel and caregivers who rated the strength of the recommendation and strength of the evidence. The workgroup moved forward the recommendations which the review panels rated as strong. Eight recommendations were developed which focused on screening for overweight and obesity, screening for health conditions that may impact dietary intake and physical activity, screening for feeding difficulties, setting appropriate recommendations for dietary intake and physical activity, and well as prevention and treatment of overweight and obesity using evidence-based strategies. These recommendations can be implemented by clinicians working with youth with Down syndrome as well as the family, school, and other relevant entities.

Association between sleep quality and physical functioning in adults with Down syndrome: A brief report.

BACKGROUND: Sleep quality is associated with physical functioning in adults, but this has not been examined in those with Down syndrome (DS). High body mass index (BMI) and accelerated aging, both common in adults with DS, may alter the relationship between sleep quality and physical functioning in this population. OBJECTIVE: To examine sleep quality indicators and its association with physical functioning in adults with DS, and whether associations are altered by BMI and age. METHODS: Participants were 15 adults with DS (8 women; age 29 ± 14 years). We evaluated sleep quality over seven days with wrist-worn accelerometers and physical functioning with the timed-up-and-go (TUG) and 6-min walk (6 MW) tests. We examined the associations between sleep quality and physical functioning variables using Spearman's rho. RESULTS: Sleep quality indicators were: total sleep time 407 ± 54 min; latency 26.8 ± 21 min; efficiency 73.9 ± 12 %; wake after sleep onset 122.8 ± 65.2 min; number of awakenings 21.0 ± 6.2; and average length of awakenings 6.1 ± 3 min. Total sleep time and average length of awakenings were significantly associated with 6 MW distances (rho = 0.58 and -0.69; p < 0.05, respectively). After controlling for age and BMI, 6 MW distance was significantly associated with total sleep time, latency, efficiency, and average length of awakenings (rho = 0.56, -0.73, 0.60, and -0.87; p < 0.05, respectively). TUG was significantly associated with total time in bed (rho = 0.71); p < 0.05). CONCLUSIONS: Sleep quality indicators are associated with walking performance in adults with DS. Age and BMI strengthen the relationship between sleep quality and physical functioning.

Health behaviors and obesity among US children with attention deficit hyperactivity disorder by gender and medication use.

OBJECTIVE: We examined the levels of physical activity, sedentary behaviors, and obesity among children with attention deficit hyperactivity disorder (ADHD) by gender and medication use and estimated the associations between health behaviors and obesity. METHODS: Cross-sectional analysis of children 6-17 years-old enrolled in the National Survey of Children's Health 2003 (n=66,707). Odds ratios were adjusted for multistage-sampling and survey-design effects. RESULTS: ADHD prevalence was 8.6%. In general, children with ADHD engaged in less physical activity, organized sports, and reading than their counterparts. Children with ADHD had increased risk of obesity for boys [24.9% vs. 21.6%, OR(95% CI): 1.42(1.13-1.77)] and girls [21.9% vs. 16%, 1.85(1.26-2.73)], if not medicated. Only girls with ADHD and not on medication were more likely to have higher media time (52.7% vs. 42%) and this was associated with higher odds for obesity [27.7% vs. 19.5%, 2.51 (1.24-5.08)]. Children with ADHD on medication had higher prevalence of depression than those not taking medication [boys: 29.5% vs. 26.3%; girls: 30.9% vs. 23.6%] and the odds of being depressed remained significant after controlling for obesity [boys: 1.45 (1.09-1.94); girls: 2.27 (1.48-3.49)]. CONCLUSIONS: Health promotion and obesity prevention programs targeting children with ADHD should take gender and medication use into consideration.