Cross-Validation of Two Accelerometers for Assessment of Physical Activity and Sedentary Time in Preschool Children.

PURPOSE: The purpose of this study was to cross-validate previously developed Actiwatch (AW; Ekblom et al. 2012) and AcitGraph (AG; Sirard et al. 2005; AG-P, Pate et al. 2006) cut-point equations to categorize free-living physical activity (PA) of preschoolers using direct observation (DO) as the criterion measure. A secondary aim was to compare output from the AW and the AG from previously developed equations. METHODS: Participants' (n = 33; age = 4.4 ± 0.8 yrs; females, n=12) PA was directly observed for three 10-min periods during the preschool-day while wearing the AW (nondominant wrist) and AG (waist). Device specific cut-points were used to reduce the AW-E (Ekblom et al. 2012) and AG (AG-S, Sirard et al. 2005; AG-P, Pate et al. 2006) data into intensity categories. Spearman correlations (rsp) and agreement statistics were used to assess associations between the DO intensity categories and device data. Mixed model regression was used to identify differences in times spent in activity intensity categories. RESULTS: There was a significant correlation between AW and AG output across all data (rsp = 0.41, p < .0001) and both were associated with the DO intensity categories (AW: rsp = 0.47, AG: rsp = 0.47; p < .001). At the individual level, all devices demonstrated relatively low sensitivity but higher specificity. At the group level, AW-E and AG-P provided similar estimates of time spent in moderate-to-vigorous PA (MVPA, AW-E: 4.7 ± 4.1, AG-P: 4.4 ± 3.3), compared with DO (5.1 ± 3.5). CONCLUSION: The AW-E and AG-P estimated times spent in MVPA were similar to DO, but the weak agreement statistics indicate that neither device cut-point equations provided accurate estimates at the individual level.

Facilitators, barriers, and components of a culturally tailored afterschool physical activity program in preadolescent African American girls and their mothers.

OBJECTIVES: Traditional physical activity (PA) programs have not been effective in increasing PA in African American girls. Currently, there is limited information regarding the components of PA programs that drive participation in African American girls. The purpose of our investigation was to describe the facilitators, barriers, and components of a culturally tailored afterschool PA program that will potentially inspire the participation of African American mother-daughter dyads. METHODS: Six focus groups (n=12 mother-daughter dyads; daughters, 7-10 yrs in age) were conducted between March and May 2012. Focus group semi-structured interviews were transcribed, coded, and systematically analyzed using NVivo. RESULTS: Mothers reported a preference for non-traditional (dancing, household chores) types of PA. While daughters preferred to participate in both dance-based and traditional types (walking, riding bikes) of PA. Participants felt that the use of a culturally tailored dance program would be appealing because it highlights the cultural and historical legacy of the African American culture. Mothers wanted programs that would allow them time to spend with their daughters. Top three dance styles that mothers wanted to participate in were African, hip-hop, and Salsa/samba, while daughters reported that they would enjoy participating in hip-hop, African, and jazz. The most common responses given for resources needed for participating in a culturally tailored afterschool dance program were the location of the program, transportation, and childcare for siblings. CONCLUSIONS: Our investigation highlights some cultural factors related to facilitators and barriers of PA that should be addressed in designing PA studies for African American girls and their mothers.

Reexamining the Energy Cost of Sedentary Behaviors From the 2011 Adult Compendium.

BACKGROUND: This study reexamines the energy cost of lower intensity activities compared to the 2011 Adult Compendium of Physical Activities. METHODS: Participants (n = 32, age = 35 [13.8] y, 16 females) wore a portable metabolic system (COSMED), during 5 different conditions: sitting quietly, watching TV, sitting while working, driving, and walking at 2.0 mph. The metabolic equivalent (MET) values (VO2 mL·kg-1·min-1/3.5 mL·kg-1·min-1) were calculated. RESULTS: The mean (SD) MET value for driving (1.46 [0.24]) was significantly lower than the Adult Compendium value of 2.5 (P < .001). Driving and slow walking have similar Adult Compendium values, but driving METs were significantly lower than slow walking (P < .001). Driving was similar to sitting while working (1.32 [0.25] METs, P > .05) and yielded significantly higher MET values than quiet sitting (1.08 [0.23] METs, P < .001) and watching TV (1.12 [0.22] METs, P < .001), both of which were lower than their respective Adult Compendium MET values. CONCLUSION: Existing Adult Compendium METs are significantly higher than measured METs for driving, which more closely correspond to sedentary behaviors than slow walking. The TV and quiet sitting also differed from their Adult Compendium values, which should be updated to reflect these findings, given that researchers and practitioners rely on Adult Compendium MET values to estimate energy cost.

No Change in Executive Function or Stress Hormones Following a Bout of Moderate Treadmill Exercise in Preadolescent Children.

Several studies suggest that acute bouts of exercise improve executive function in preadolescent children. However, the mechanisms underlying these effects are not completely understood. Specifically, no studies have examined the relationship between the stress hormone response to exercise and improvements in executive function in preadolescent children. The purpose of this study was to examine the effects of a bout of moderate intensity exercise versus rest on working memory (List Sorting Working Memory Task) and selective inhibition/attention (Eriksen flanker task) in preadolescent children, as well as to investigate whether changes in stress hormones (salivary cortisol and alpha-amylase) could explain any differences in performance on these tasks. Twenty-four children completed both a 30-minute moderate intensity bout of treadmill walking and seated rest in a laboratory setting. Tests of executive function and salivary stress hormone analyses were completed before and after each condition. 2x2 Repeated Measures ANOVAs were used to test the effects of time, condition, and time*condition on all executive function and hormonal outcomes. Linear regression models were used to determine if changes in executive function measures were related to changes in stress hormones in the exercise condition. Likely due to methodological limitations, there were no effects of time, condition, nor an interactive effect on working memory, selective inhibition, salivary cortisol, or salivary alpha-amylase. However, there was a trend observed, where the magnitude of the increase in salivary alpha-amylase levels in the exercise condition marginally predicted the improvement in reaction time on the Eriksen flanker task. This suggests that exercise-induced changes in alpha-amylase may underlie improvements in executive function and highlights the need for additional research to more fully understand these relationships in preadolescent children.

Aerobic Fitness Markers Associated with Post-Paddling Breath-hold Capacity in Competitive Surfers.

Competitive surfing is a growing sport with evolving performance and safety demands. One particular challenge surfers face is the need to endure long breath-holds following bouts of surf paddling. The purpose of this study was to examine the association between aerobic fitness markers, such as VO2peak and ventilatory thresholds, and post-paddling breath-hold capacity in competitive surfers. Eleven male collegiate level competitive surfers completed both a maximal graded exercise test and a simulated post-paddling breath-hold challenge on a modified paddling ergometer. Associations between markers of aerobic fitness and post-paddling breath-hold capacity were tested using linear regression modeling. The overall regression model indicated a positive linear association between the assessed markers of aerobic fitness and post-paddling breath-hold capacity (r = .828, r 2 = 0.686, p = 0.035). This association was explained by differences in VO2peak (ß = 0.975, p = .034). These findings suggest that VO2peak may be an important training target for programs aimed at improving breath-hold capacity in surfers.

Feasibility of Integrating Physical Activity Into Early Education Learning Standards on Preschooler's Physical Activity Levels.

BACKGROUND: For a health behavior intervention to be sustainable within preschool centers, the intervention should be implemented by classroom teachers. Unfortunately, teachers are constrained by demands such as meeting early childhood education standards. Therefore, the purpose of this pilot study was to examine the feasibility and preliminary efficacy of integrating a health behavior intervention into early education learning standards on physical activity (PA), diet, and sleep (PADS) behavior of preschoolers. METHODS: Two preschool centers were randomized to either the PADS (children, n = 60) or the control (CON; children, n = 54) group. The PADS intervention consisted of PADS lesson plans and activities embedded into Massachusetts early learning standards and were implemented for 4 days per week for 12 weeks. The CON preschool participated in their usual curriculum. PA was assessed using accelerometers for 7 consecutive days at baseline, 6 weeks, and 12 weeks. Other outcome variables were assessed with parental surveys at baseline and 12 weeks. RESULTS: Significant group by time interactions were observed for moderate to vigorous PA (percentage of time) during the preschool day (PADS: baseline = 10.6% (4.2%), 12 wk = 13.2% (2.3%); CON: baseline = 12.4% (3.9%), 12 wk = 11.2% (3.6%); P = .02). CONCLUSION: This pilot study provides preliminary evidence that integrating health behaviors into learning standards is feasible and potentially an effective way for increasing preschoolers' PA levels.

Effect of a culturally-tailored mother-daughter physical activity intervention on pre-adolescent African-American girls' physical activity levels.

Positive parent-child attachment can be determined by opportunities for the child to interact with his/her parent and can influence a child's physical activity (PA) behavior. Therefore, an intervention that provides children and their parent more time to interact positively could impact children's PA. We examined the efficacy of a 12-week mother-daughter intervention on African-American girls' PA levels. In Spring of 2013 and 2014, mother-daughter dyads (n = 76) from Springfield, MA, were randomly assigned to one of three groups [child-mother (CH-M, n = 28), child alone (CH, n = 25), or control (CON, n = 23)] that participated in an afterschool culturally-tailored dance intervention (60 min/day, 3 days/week, 12 weeks). Girls in the CH-M group participated in the intervention with their maternal figure, while girls in the CH group participated in the intervention alone. CON group participants received weekly health-related newsletters. PA was assessed with accelerometers for seven days at baseline, 6-weeks, and 12-weeks. Hierarchical linear modeling was used to examine rates of change in PA. During the afterschool intervention time, girls in the CH-M group displayed a significantly steeper rate of increase in their percent time spent in vigorous PA compared to both the CON (γ = 0.80, p < 0.001) and the CH group (χ2 (1)=13.01, p < 0.001). Mothers in the CH-M group displayed a significantly steeper rate of increase in their percent time spent in total daily moderate-to-vigorous PA compared to CH group's mothers (γ = 0.07, p = 0.01). This culturally-tailored mother-daughter afterschool intervention influenced African-American girls' afterschool hour PA levels, but not total daily PA. Trial Registration: Study is registered at www.clinicaltrials.govNCT01588379.

Associations among physical activity, screen time, and sleep in low socioeconomic status urban girls.

Insufficient sleep is associated with higher risk of poor health outcomes in low socioeconomic status (SES) urban elementary age girls. Decreased physical activity (PA) and increased screen time may be associated with poor sleep. This study examined if PA and screen time are associated with sleep in girls from a low SES urban community. Baseline data from 7 to 12 year-old girls (n = 55) from two interventions conducted in Springfield, MA between 2012 and 2015 were used. PA was measured via accelerometry for seven days. Screen time and sleep were assessed via validated questionnaires. Sleep was also assessed via accelerometry in a subsample of girls (n = 24) for 7 days. Associations among PA, screen time, and sleep were analyzed using multiple linear regression. More minutes of screen time per day (p = 0.01, r2 = 0.35, r2 adjusted = 0.23) was associated with worse sleep quality (ß = 0.50, p = 0.02). There were negative correlations between PA and the number of awakenings per night (r = - 0.45, p = 0.04) and between counts per minute and sleep fragmentation (r = - 0.65, p = 0.002) assessed by accelerometer. In this population, increased screen time was associated with worse sleep quality and decreased PA was correlated with more awakenings per night and higher sleep fragmentation. These findings suggest that screen time and PA may be modifiable risk factors for interventions seeking to improve sleep in this population.

Objective Analysis of Preschoolers' Physical Activity Patterns During Free Playtime.

BACKGROUND: The purpose of this study was to examine the temporal patterns of preschoolers' physical activity (PA) levels during a typical outdoor free playtime. METHODS: Baseline playtime accelerometer counts (4.3 ± 0.8 days) from 3 preschool PA intervention studies were used (n = 326 children, age = 4.0 ± 0.8 years). Data were collected using 15-second epochs and classified into sedentary, light, or moderate-to-vigorous physical activity (MVPA). Patterns of change during playtime were analyzed using orthogonal polynomial comparisons. RESULTS: For all ages, there was a U-shaped pattern of change for the percent of epochs classified as sedentary [F(1, 323) = 47.12, P < .001) and an inverted U-shaped pattern of change for the percent of epochs classified as MVPA [F(1,323) = 32.15, P < .001]. Age-stratified analyses indicated that the 3-year-olds maintained the decrease in sedentary time [F(2,323) = 6.408, P = .002] and the increase in MVPA [F(2,323) = 3.2, P = .04] to a greater extent than the 4- and 5-year-olds. CONCLUSIONS: Preschool children gradually became more active during the first 10 to 15 minutes of outdoor gross motor playtime and less active over the final 10 to 15 minutes of playtime. During the second half of playtime 3-year-olds maintained these changes to a greater degree than 4- and 5-year-olds.

Skeletal muscle architectural adaptations to marathon run training.

We assessed lateral gastrocnemius (LG) and vastus lateralis (VL) architecture in 16 recreational runners before and after 12 weeks of marathon training. LG fascicle length decreased 10% while pennation angle increased 17% (p < 0.05). There was a significant correlation between diminished blood lactate levels and LG pennation angle change (r = 0.90). No changes were observed in VL. This is the first evidence that run training can modify skeletal muscle architectural features.