Associations among Motor Competence, Physical Activity, Perceived Motor Competence, and Aerobic Fitness in 10-15-Year-Old Youth.

(1) Background: The developmental model describes possible mechanisms that could impact the trajectory of children and adolescents' health behaviors related to obesity; however, few data are available that support this model in the adolescent population. This study investigated the associations among motor competence (MC), moderate-to-vigorous physical activity (MVPA), perceived motor competence (PMC), and aerobic fitness in children and adolescents and the mediating and moderating effects of PMC, aerobic fitness, and weight status on the MC-MVPA relationship. (2) Methods: Participants included 47 adolescents (12.2 ± 1.6 y; 55% male) who completed the Bruininks-Oseretsky Test of Motor Proficiency, 2nd Edition (MC), Harter's perceived self-competency questionnaire (PMC), and the PACER test (aerobic fitness) and whose MVPA was measured via accelerometry. The body mass index (BMI) was calculated from measured height and weight. (3) Results: There were positive correlations between MC and fitness [rs(47) = 0.469, p < 0.01], PMC and fitness [rs(47) = 0.682, p < 0.01], and PMC and MC [rs(47) = 0.416, p < 0.01]. There were no associations among MVPA and MC, PMC, or fitness (p > 0.05). There were inverse associations between BMI and both MVPA [rs(44) = -0.410, p < 0.01] and fitness [rs(47) = 0.295, p < 0.05]. The association between MC and MVPA was mediated by fitness (ß = 0.3984; 95% CI (0.0564-0.7985)). (4) Conclusions: The associations among MC, PMC, and fitness highlight the critical role of MC in health and partially support the proposed developmental model concerning the relationships that exist among MC, MVPA, PMC, fitness, and BMI.

Exploration of parental rewards in incentivizing children's physical activity.

The purpose of this study was to explore the prevalence, varieties, and motivations behind parent-selected incentivization for children's physical activity (PA). Parents (n = 90; 30.0 ± 8.5 years) of children (8.7 ± 2.1 years) completed a web-based survey that included items regarding the use of PA rewards, children's moderate-to-vigorous PA (MVPA, min·week-1), access to electronic devices, and demographic characteristics. Open-ended questions were used to determine the type of activity rewarded, type of reward given, and parents' reasoning for not using PA rewards. Independent sample t-tests were used to determine differences between reward groups (reward and no reward) and parent-reported children's MVPA. Open-ended responses underwent thematic analysis. Over half (55%) of the respondents provided PA rewards. There was no difference between reward groups for MVPA. Parents reported their children having access to various technology modes, including TV, tablets, video game systems, computers, and cellphones. Most of the parents (78.2%) reported restricting their child's technology time in some capacity. Rewarded PAs were thematized as "children responsibilities", "non-sport activity", and "sport". Two themes regarding types of rewards included "tangible" and "nontangible". Two underlying themes as to why parents did not give rewards were deemed "built-in-habit" and "enjoyment". Rewarding children's PA is prevalent among this sample of parents. Substantial variety exists regarding the type of PA incentivized and the type of reward provided. Future studies should explore whether parents use reward structures and how they conceptualize nontangible, electronics-based rewards versus tangible rewards to incentivize children's PA to promote lifelong behavior.

The Test-Retest Reliability of the Bruininks-Oseretsky Test of Motor Proficiency-Short Form in Youth with Down Syndrome-A Pilot Study.

BACKGROUND: It is unclear whether assessments of motor proficiency are reliable for individuals with Down syndrome. The purpose of the study was to evaluate the test-retest reliability of the Bruininks-Oseretsky Test of Motor Proficiency-Short Form (BOT-2 SF) in youth with Down syndrome. METHODS: Ten youth (ages 13.1-20.7 years) with Down syndrome completed the BOT-2 SF (14 items) plus a standing long jump on two separate occasions. Intraclass correlation coefficients (ICC), 95% confidence intervals (CIs), and standard error of measurement (SEM) were calculated to determine the test-retest reliability of the BOT-2 SF and the standing long jump. RESULTS: The test-retest reliability of the BOT-2 SF overall scores and percentile rankings were considered excellent. The test-retest reliability of each of the subtests varied with classifications of poor (n = 5), fair to good (n = 6), and excellent (n = 4). CONCLUSION: Current evidence suggests that children with Down syndrome have reduced motor skills. However, there appears to be a lack of assessment tools that reliably evaluate the motor skills of this population. The results from this investigation suggest that the BOT-2-SF provides "excellent reliability" (≥0.75) to assess the motor skills in youth with Down syndrome.

Physical Activity and Cognitive Aspects of Self-Regulation in Preschool-Aged Children: A Systematic Review.

Previous research showed a positive relationship between physical activity and self-regulation in older children and adolescents, but few publications focused on young children. Therefore, the purpose of this review was to examine the impact of physical activity (PA) on the cognitive aspects of self-regulation (inhibition, attention, and working memory, in preschool-aged (3-6 years old) children. The following databases were searched for articles: PubMed, SPORTDiscus, PsycINFO, and ERIC. References of the reviewed papers were screened for the identification of additional articles to be included in the review. Randomized control trials were reviewed to assess the impact of PA interventions on the cognitive aspects of self-regulation. There were six articles included in this review. Each study assessed at least one cognitive aspect of self-regulation [attention (n = 4), working memory (n = 2), and inhibition (n = 5)]. Attention was the only aspect that consistently showed improvement as a result of the PA interventions (4 of 4 studies). Only one study showed a positive impact on working memory and 60% of studies (3 of 5 studies) reported a positive relationship between PA and inhibition. Overall, the findings from this review showed that a consistent relationship only existed between attention and PA. No clear relationships were evident between working memory and inhibition and PA.

Youth Metabolic Equivalents Differ Depending on Operational Definitions.

Youth metabolic equivalents (METy) are sometimes operationally defined as multiples of predicted basal metabolic rate (METyBMR) and other times as multiples of measured resting metabolic rate (METyRMR). PURPOSE: This study aimed to examine the comparability of METyBMR and METyRMR. METHODS: Indirect calorimetry data (Cosmed K4b) were analyzed from two studies, with a total sample of 245 youth (125 male participants, 6-18 yr old, 37.4% overweight or obese). The Schofield equations were used to predict BMR, and K4b data from 30 min of supine rest were used to assess RMR. Participants performed structured physical activities (PA) of various intensities, and steady-state oxygen consumption was divided by predicted BMR and measured RMR to calculate METyBMR and METyRMR, respectively. Two-way (activity-METy calculation) analysis of variance was used to compare METyBMR and METyRMR (α = 0.05), with Bonferroni-corrected post hoc tests. Intensity classifications were also compared after encoding METyBMR and METyRMR as sedentary behavior (≤1.50 METy), light PA (1.51-2.99 METy), moderate PA (3.00-5.99 METy), or vigorous PA (≥6.00 METy). RESULTS: There was a significant interaction (F(30) = 3.6, P < 0.001), and METyBMR was significantly higher than METyRMR for 28 of 31 activities (P < 0.04), by 15.6% (watching television) to 23.1% (basketball). Intensity classifications were the same for both METy calculations in 69.0% of cases. CONCLUSIONS: METyBMR and METyRMR differ considerably. Greater consensus is needed regarding how metabolic equivalents should be operationally defined in youth, and in the meantime, careful distinction is necessary between METyBMR and METyRMR.

Alternative Wear-time Estimation Methods Compared to Traditional Diary Logs for Wrist-Worn ActiGraph Accelerometers in Pregnant Women.

BACKGROUND: This study sought to compare three sensor-based wear-time estimation methods to conventional diaries for ActiGraph wGT3X-BT accelerometers worn on the non-dominant wrist in early pregnancy. METHODS: Pregnant women (n= 108) wore ActiGraph wGT3X-BT accelerometers for 7 days and recorded their device on and off times in a diary (criterion). Average daily wear-time estimates from the Troiano and Choi algorithms and the wGT3X-BT accelerometer wear sensor were compared against the diary. The Hibbing 2-regression model was used to estimate time spent in activity (during periods of device wear) for each method. Wear-time and time spent in activity were compared with multiple repeated measures ANOVAs. Bland Altman plots assessed agreement between methods. RESULTS: Compared to the diary [825.5 minutes (795.1, 856.0)], the Choi [843.0 (95% CI 812.6, 873.5)] and Troiano [839.1 (808.7, 869.6)] algorithms slightly overestimated wear-time, whereas the sensor [774.4 (743.9, 804.9)] underestimated it, although only the sensor differed significantly from the diary (P < .0001). Upon adjustment for average daily wear-time, there were no statistically significant differences between the wear-time methods in regards to minutes per day of moderate to vigorous physical activity (MVPA), vigorous PA, and moderate PA. Bland Altman plots indicated the Troiano and Choi algorithms were similar to the diary and within ≤ 0.5% of each other for wear-time and MVPA. CONCLUSIONS: The Choi or Troiano algorithms offer a valid and efficient alternative to diaries for the estimation daily wear-time in larger-scale studies of MVPA during pregnancy, and reduce burden for study participants and research staff.

Development and Validation of a PACER Prediction Equation for VO2peak in 10- to 15-Year-Old Youth.

Previous progressive aerobic cardiovascular endurance run (PACER) equations were developed to estimate peak oxygen consumption (VO2peak) from data collected during treadmill running. No equation has been developed using VO2peak assessed during the PACER. Purpose: To develop and validate a prediction equation to estimate VO2peak from the PACER in 10- to 15-year-olds. Methods: A sample of 163 youth were recruited to develop (n = 101) and validate (n = 62) a prediction equation. VO2peak was measured using a portable metabolic unit. Regression analysis yielded a prediction equation that included laps, body mass index, and interaction between sex and age. Correlations and repeated-measures analysis of variances were used to compare the measured and estimated VO2peak from the new Scott et al equation and 2 commonly used FitnessGram™ (Mahar et al 2011 and Mahar et al 2018) equations, and the impact of sex on predicted VO2peak. Results: Predicted VO2peak from the Mahar et al 2011 and 2018 equations was significantly lower compared with measured values, and the Scott et al prediction was not different. The Mahar et al 2018 equation tended to overestimate VO2peak in males but worked well for females. The Mahar et al 2011 and Scott et al equations revealed no sex differences. Conclusions: The Scott et al equation resulted in a more accurate estimate of VO2peak, performing equally well for both sexes.

Postprandial walking reduces glucose levels in women with gestational diabetes mellitus.

The purpose of this study was to investigate blood glucose changes, as measured by a continuous glucose monitoring system, that occur in women with gestational diabetes mellitus (GDM) following an acute bout of moderate-intensity walking after consuming a high-carbohydrate/low-fat meal. This study found that moderate-intensity walking induced greater postprandial glucose control compared with sedentary activity and it appears that moderate-intensity activity may be used to reduce postprandial glucose levels in women with GDM.

Effects of Toe-In and Wider Step Width in Stair Ascent with Different Knee Alignments.

PURPOSE: Toe-in (TI) and toe-in with wider step width (TIW) gait modifications have successfully reduced the internal peak knee adduction moment (KAM) during level walking and stair ascent tasks, respectively, for healthy and knee osteoarthritis populations. However, the concurrent effects of these modifications have not previously been combined to reduce both the first and the second peak KAM during stair ascent or tested among the different knee alignment groups. Therefore, the purpose of this study was to examine effects of TI and TIW gait modifications on knee biomechanics during stair ascent in individuals with varus, neutral, and valgus knee alignments. METHODS: Thirty-eight healthy individuals (age 18-30 yr) with varus, neutral, and valgus knee alignments confirmed using radiographs, performed stair ascent in normal, TI, and TIW gait conditions. A 3 × 3 (group × condition) mixed model repeated-measures ANOVA compared alignment groups across the stair ascent gait conditions (P < 0.05). RESULTS: The TI and the TIW reduced the first peak KAM and KAM impulses compared with normal stair ascent. The TIW also reduced the second peak KAM compared with normal gait and reduced KAM impulses compared with TI. The varus group had increased first peak KAM compared with neutral and valgus groups. The TI and the TIW also reduced peak knee flexion moments compared with normal gait. The TIW also reduced peak external rotation moments compared with normal gait. CONCLUSIONS: The TIW gait modification seems to be successful in reducing knee joint loading in all three planes during stair ascent, regardless of knee alignment. The success of TIW in varus knee alignments may have important implications for people with medial knee osteoarthritis, or those susceptible to knee osteoarthritis.

Influence of Total Knee Arthroplasty on Gait Mechanics of the Replaced and Non-Replaced Limb During Stair Negotiation.

This study compared biomechanics during stair ascent in replaced and non-replaced limbs of total knee arthroplasty (TKA) patients with control limbs of healthy participants. Thirteen TKA patients and fifteen controls performed stair ascent. Replaced and non-replaced knees of TKA patients were less flexed at contact compared to controls. The loading response peak knee extension moment was greater in control and non-replaced knees compared with replaced. The push-off peak knee abduction moment was elevated in replaced limbs compared to controls. Loading and push-off peak hip abduction moments were greater in replaced limbs compared to controls. The push-off peak hip abduction moment was greater in non-replaced limbs compared to controls. Future rehabilitation protocols should consider the replaced knee and also the non-replaced knee and surrounding joints.

Trends in Physical Activity and Sedentary Behaviors of United States Youth.

BACKGROUND: Increases in childhood and adolescent obesity are a growing concern in the United States (U.S.), and in most countries throughout the world. Declines in physical activity are often postulated to have contributed to the rise in obesity rates during the past 40 years. METHODS: We searched for studies of trends in physical activity and sedentary behaviors of U.S. youth, using nontraditional data sources. Literature searches were conducted for active commuting, physical education, high-school sports, and outdoor play. In addition, trends in sedentary behaviors were examined. RESULTS: Data from the Youth Risk Behavior Surveillance System (YRBSS) and other national surveys, as well as longitudinal studies in the transportation, education, electronic media, and recreation sectors showed evidence of changes in several indicators. Active commuting, high school physical education, and outdoor play (in 3- to 12-year-olds) declined over time, while sports participation in high school girls increased from 1971 to 2012. In addition, electronic entertainment and computer use increased during the first decade of the 21st century. CONCLUSIONS: Technological and societal changes have impacted the types of physical activities performed by U.S. youth. These data are helpful in understanding the factors associated with the rise in obesity, and in proposing potential solutions.

Development of a prediction model to predict VO2(peak) in adolescent girls using the Bruce protocol to exhaustion.

PURPOSE: The purpose of this study was to develop a prediction model based on a submaximal workload during the Bruce treadmill protocol to estimate peak oxygen consumption (VO2(peak)) in adolescent girls. METHOD: Adolescent girls (N = 116, M(age) = 13.2 +/- 2.0 years) performed a Bruce Treadmill Test to exhaustion. Expired respiratory gases and heart rate (HR) were collected and measured continuously via indirect calorimetry and telemetry. To be included in the analysis, each participant met 2 of 3 criteria: attain 95% of age-predicted HR(peak), respiratory exchange ratio > 1.05, or plateau of VO2. VO2 and HR at Stage 1 and Stage 2 of the Bruce test were entered into a regression model to predict VO2(peak). RESULTS: A regression model, constructed using the predicted sum of squares statistic, was developed using VO2 (VO(2)2) and HR (HR2) attained at the 2nd 3-min stage of the Bruce treadmill protocol: VO2(peak) = 46.77 - (0.2854155 x HR2) + (1.46732912 x VO(2)2). Actual average (+/- SD) VO2(peak) was 36.2 +/- 6.9 ml x kg(-1) x min(-1) (range = 22.9-55.9). Predicted VO2(peak) was 36.2 +/- 5.5 ml x kg(-1) x min(-1) (range = 24.3-56.2). The correlation between actual and predicted VO2(peak) was r = .80, standard error of estimate = 4.2 ml x kg(-1) x min(-1), with no bias relative to participant aerobic fitness. CONCLUSION: Based on this model, the VO2(peak) of healthy adolescent girls can be predicted within 4.2 ml x kg(-1) x min(-1) using submaximal Bruce data.

Validity of the Bite Counter device in a controlled laboratory setting.

UNLABELLED: Body-borne sensors may be useful in assessing eating behaviors and have the potential to overcome some of the limitations of self-report instruments. The Bite Counter is a new commercial device, worn on the wrist that purports to track the number of bites taken per day. It contains a tri-axial accelerometer that detects an upward, arcing motion from the table to the mouth, known as a wrist roll. PURPOSE: To examine the validity of the Bite Counter device for measuring bites in individuals while consuming various foods and beverages. METHODS: 15 adults (23-58 years old) wore the device on the wrist of their dominant hand. They were presented with a meal consisting of foods/beverages, each consumed with different utensils: meat (knife and fork), side items (fork), soup (spoon), pizza (hands), can of soda (hands), and a smoothie (straw). Each food or drink was consumed by itself, in consecutive order. A researcher observed them through a one-way mirror and counted the number of bites taken. RESULTS: The percentage of actual bites taken varied as follows: Meat (127%), side items (82.6%), soup (60.2%), pizza (87.3%), soda (81.7%), and smoothie (57.7%). The overall mean was 81.2% of bites taken. CONCLUSION: The results indicate that the Bite Counter holds promise for being able to count the number of hand-to-mouth movements. In general, it underestimated hand-to-mouth movements, but some types of hand movements caused overestimation of bites. Future studies should be undertaken to improve the sensitivity and specificity of the Bite Counter device.

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 System's 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. Cronbach's 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 Cronbach's 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.

Physical fitness, academic achievement, and socioeconomic status in school-aged youth.

BACKGROUND: This study examined the association between physical fitness and academic achievement and determined the influence of socioeconomic status (SES) on the association between fitness and academic achievement in school-aged youth. METHODS: Overall, 1,701 third-, sixth-, and ninth-grade students from 5 school districts participated in the assessments. Fitness was assessed using FITNESSGRAM (aerobic fitness, muscular strength, muscular endurance, flexibility, and body composition). Results were used to determine individual fitness scores. Academic achievement was measured by standardized tests for Math (all grades), English (all grades), and Social Studies (sixth and ninth grades only). The SES was determined using eligibility for free and reduced lunch program. RESULTS: There were no significant differences between fitness groups for Math and English in third-grade students. Sixth- and ninth-grade students with high fitness scored significantly better on Math and Social Studies tests compared with less fit students. Lower SES students scored significantly worse on all tests. Muscular strength and muscular endurance were significantly associated with academic achievement in all grades. CONCLUSIONS: Compared with all other variables, SES appears to have the strongest association with academic achievement. However, it also appears that high fitness levels are positively associated with academic achievement in school-aged youth.

The ability of the PACER to elicit peak exercise response in youth [corrected].

PURPOSE: A graded exercise test (GXT) is the standard laboratory method of determining peak aerobic fitness (V˙O2peak). The FITNESSGRAM's Progressive Aerobic Cardiovascular Endurance Run (PACER) test is commonly used to estimate the peak oxygen consumption in the youth in the field.The objective of this study is to compare the peak physiological variables and RPEpeak during a treadmill GXT and the PACER test in 10- to 15-yr-old youths. METHODS: Participants (20 boys and 25 girls, 12.7 ± 1.7 yr) completed the PACER and treadmill GXT in a randomized order, separated by at least 24 h. HRpeak was measured via telemetry, V˙O2peak and RERpeak were measured using a portable metabolic system, and participants reported RPEpeak at the end of each test. RESULTS: No significant differences were found between the GXT and PACER HRpeak (197 vs 197 beats·min), RERpeak (1.13 vs 1.12), V˙O2peak (45.0 vs 45.9 mL·kg·min), and RPEpeak (8.4 vs 8.3). The SE of the measurement between the GXT V˙O2peak and PACER V˙O2peak was 1.4 mL·kg·min. CONCLUSIONS: It appears that the PACER elicits similar peak exercise responses compared with a treadmill GXT. The PACER can also be administered for fitness and functional capacity assessments in healthy and clinical populations.

Effect of BMI on pedometers in early adolescents under free-living conditions.

PURPOSE: Pedometers may provide valuable information regarding the ambulatory patterns of adolescents, but the effects of body mass index (BMI) on pedometer accuracy in this population are unknown.The purpose of this study was twofold: 1) to determine whether the New Lifestyles NL-2000 (NL) and the Digi-Walker SW-200 (DW) (New Lifestyles, Inc., Lees Summit, MO) yield similar step counts as compared with an ankle-mounted criterion, StepWatch 3, when worn by early adolescents in a free-living environment and 2) to study whether BMI percentile affects the accuracy of waist-mounted pedometers in adolescents. METHODS: Seventy-four early adolescents (13.0 ± 1.1 yr) wore the devices during one weekday. The study population included 33 normal weight, 21 overweight, and 20 obese participants. Two-way repeated-measures ANOVA was used to determine whether the BMI and the device were related to the number of steps per day and percentage of actual steps. RESULTS: The NL and DW recorded fewer steps than the StepWatch 3 in each BMI category (P < 0.05). In the obese group, the DW underestimated the steps more than the NL (P < 0.001). For the normal weight, overweight, and obese groups, the NL counted 89.1%, 89.1%, and 91.6% of the steps, respectively, whereas the DW counted 86.7%, 84.6%, and 72.7%, respectively. CONCLUSION: Researchers must be cognizant of the limitations of waist-mounted pedometers and carefully choose a device that suits the needs of their investigations. Because of the inaccuracies of the DW when measuring steps in obese adolescents, careful consideration must be given before choosing this device for research and interventions. The NL is a better device for assessment of adolescents' steps than the DW, especially for those who are obese.

Accuracy of physical activity monitors in pregnant women.

PURPOSE: To determine the step count accuracy of three pedometers and one accelerometer in pregnant women during treadmill walking. METHODS: Participants were 30 women in the second or third trimester (20-34 wk) who were screened for pregnancy-related risk factors. Each participant was fitted with a belt containing three physical activity monitors: Yamax Digiwalker SW-200 (DW), New Lifestyles NL 2000 (NL), and GT3X ActiGraph accelerometer (ACT). The Omron HJ-720ITC (HJ) was placed in the pants' front pocket. Participants walked at 54, 67, 80, and 94 m · min for 2 min each. Actual steps were determined by an investigator using a hand-tally counter. The mean percent of steps recorded was calculated for each device at each speed and compared. Pearson correlations were used to determine the effect of body mass index and tilt angle on pedometer accuracy. RESULTS: There was a significant interaction between speed and device (F9,20 = 7.574, P < 0.001). Across all speeds, the NL and HJ had the lowest error. The ACT and DW underestimated the actual steps taken, particularly at the slower walking speeds. At 54 m · min, the ACT averaged 77.5% of steps and the DW averaged 56.9% of steps. Significant differences in the mean percent of steps recorded were found between devices at all speeds. Body mass index was only significantly correlated with percent of steps recorded by the NL, and there were no significant correlations between steps recorded and tilt angle. CONCLUSIONS: In pregnant women, the ACT and DW had more error than the NL and HJ. On the basis of these results, the NL and HJ should be considered for use in further research studies and physical activity programs that focus on walking during pregnancy.