Tarrah B. Mitchell

Bidirectional Associations Between Psychological States and Physical Activity in Adolescents: A mHealth Pilot Study

Objective To understand the predictors and consequences of adolescent moderate-to-vigorous physical activity (MVPA) and sedentary behavior in nearly real-time. Methods Participants were 26 adolescents ( M age = 15.96, SD  = 1.56) who provided 80 self-reports of subjective states and continuous objective reports of MVPA and sedentary behavior over 20 days. Results Random effects were observed for all of the models with affect and feeling variables predicting MVPA. There was a negative fixed effect for within-person positive affect and sedentary behavior and the inverse association for negative affect. Within-person MVPA was a significant positive predictor of positive affect and energy. There was a random effect for within-person MVPA and fatigue. There was a significant random effect for within-person sedentary behavior predicting positive affect. Within-person sedentary behavior was a significant negative predictor of energy. Conclusions Findings highlight the importance of the intrapersonal nature of the associations among subjective states and physical activity.

Impulsivity as a moderator of the associations between child maltreatment types and body mass index

Child maltreatment has emerged as an important risk factor for adult obesity (Danese & Tan, 2014; Hemmingsson et al., 2014). However, there is a need for research delineating the factors that play a role in this association. Impulsivity has been shown to be associated with both child maltreatment (Brodsky et al., 2001) and body mass index (BMI; Cortese et al., 2008; Thamotharan et al., 2013). Further, given previous research showing that adverse events interact with impulsivity to predict hazardous drinking behaviors (Fox et al., 2010), there is reason to hypothesize that child maltreatment might interact with impulsivity to predict other adverse health outcomes, such as elevated BMI. Accordingly, the current study examined whether impulsivity moderated the association between child maltreatment types (i.e., physical abuse, physical neglect, sexual abuse, emotional abuse, and emotional neglect) and BMI. The sample was comprised of 500 undergraduate students (49.6% male) between the ages of 18 and 25 years. Regression analyses suggested that maltreatment types and impulsivity were not uniquely associated with BMI. However, impulsivity moderated the association between childhood sexual abuse and adult BMI, such that BMI was highest at high levels of both sexual abuse and impulsivity. Impulsivity did not moderate the associations between the other child maltreatment types and BMI. Limitations, future directions, and clinical implications of this research are discussed.

The Effect of Body Mass Index, Negative Affect, and Disordered Eating on Health-Related Quality of Life in Preadolescent Youth

OBJECTIVE To examine the indirect effect of body mass index z-score (BMIz) on health-related quality of life (HRQOL) through disordered eating attitudes and behaviors in a community sample of preadolescent children, and the degree to which negative affect moderated the association between BMIz and disordered eating attitudes and behaviors. METHODS Participants included 165 children between 8 and 12 years of age (M = 9.41). HRQOL, disordered eating attitudes and behaviors, and negative affect were assessed using self-report measures. Height and weight were collected by research staff. RESULTS Consistent with previous research in treatment-seeking and adolescent samples, the indirect effect of BMIz on HRQOL through disordered eating attitudes and behaviors was significant. Negative affect did not moderate the relationship between BMIz and disordered eating attitudes and behaviors. CONCLUSION Intervening on disordered eating attitudes and behaviors in preadolescents with higher weight status is critical to prevent the risk for poor HRQOL.

Using Activity Monitors to Measure Sit-to-stand Transitions in Overweight/obese Youth

Introduction Reducing sedentary behavior has emerged as an important health intervention strategy. Although hip-worn, and more recently wrist-worn, accelerometers are commonly used for measuring physical activity and sedentary behavior, they may not provide accurate measures of postural changes. The current study examined the validity of commonly used hip- and wrist-worn accelerometer cut points and the thigh-worn activPAL activity monitor for measuring sit-to-stand transitions as compared with direct observation in youth with overweight and obesity. Methods Nine children wore three activity monitors while being directly observed. The monitors included a hip- and wrist-worn ActiGraph and thigh-worn activPAL. The hip-worn ActiGraph was processed with the normal- and low-frequency filters and the inclinometer function. Cut points of ⩽25 counts per 15-s epoch for the hip and ⩽105 counts per 15-s epoch for the wrist were applied to the vertical axis to identify sit-to-stand transitions. Epoch-level absolute agreement, Bland–Altman plots, mixed-effects linear regression, and intraclass correlation coefficients (ICC) were investigated. Results The hip and wrist accelerometer cut points and the hip inclinometer function overestimated the number of hourly sit-to-stand transitions by approximately triple as compared with direct observation. ICC values between the ActiGraph methods and the direct observation were all <0.12. Sit-to-stand transitions assessed from activPAL were within 17% of direct observation; ICC was 0.26. Conclusion Despite the common use of the 100-count hip-worn accelerometer cut point for assessing sedentary time, these processing decisions should be used with caution for assessing sit-to-stand transitions. Future research should investigate other processing methods for ActiGraph data, and studies investigating postural changes should consider including devices such as activPAL.

Developing Novel Machine Learning Algorithms to Improve Sedentary Assessment for Youth Health Enhancement

Sedentary behavior of youth is an important determinant of health. However, better measures are needed to improve understanding of this relationship and the mechanisms at play, as well as to evaluate health promotion interventions. Wearable accelerometers are considered as the standard for assessing physical activity in research, but do not perform well for assessing posture (i.e., sitting vs. standing), a critical component of sedentary behavior. The machine learning algorithms that we propose for assessing sedentary behavior will allow us to re-examine existing accelerometer data to better understand the association between sedentary time and health in various populations. We collected two datasets, a laboratory-controlled dataset and a free-living dataset. We trained machine learning classifiers separately on each dataset and compared performance across datasets. The classifiers predict five postures: sit, stand, sit-stand, stand-sit, and stand\walk. We compared a manually constructed Hidden Markov model (HMM) with an automated HMM from existing software. The manually constructed HMM gave more F1-Macro score on both datasets.

Factor Structure of a Spanish Translation of an Obesity-Specific Parent-Report Measure of Health-Related Quality of Life.

Objective Latino youth are disproportionately affected by pediatric obesity and consequently experience impaired health-related quality of life (HRQOL). Although many caregivers of Latino youth do not speak English fluently, no validated Spanish translations of obesity-specific HRQOL measures exist for this population. Therefore, non-English-speaking Latino parents have typically been excluded from analyses related to HRQOL. This study assesses the factor structure of a Spanish translation of a parent-report measure of obesity-specific HRQOL, Sizing Them Up, in a treatment-seeking sample of children with obesity. Methods Structural equation modeling was used to assess the factor structure of the 6-subscale, 22-item Sizing Them Up measure in 154 parents of treatment-seeking Latino youth (5-18 years of age). Analyses exploring internal consistency and convergent validity were also conducted. Results Acceptable measurement fit was achieved for the six-factor solution. However, the higher-order model assessing Total HRQOL did not reach acceptable levels, as results found that the Positive Social Attributes (PSA) subscale was not representative of Total HRQOL; internal consistency and convergent validity results also supported this finding. Conclusions The current study provides support for the utility of a modified version of Sizing Them Up, excluding the PSA Scale, as a parent-report measure of obesity-specific HRQOL in treatment-seeking Latino youth with obesity.

Bidirectional Associations Between Disordered Eating and Health-Related Quality of Life in Elementary School-Age Youth

Objective To examine longitudinal, bidirectional associations between disordered eating and physical/psychosocial health-related quality of life (HRQOL) in a nonclinical community sample of elementary school-age youth. Methods Participants included 130 children between the ages of 7 and 10 years ( M age = 8.62). Disordered eating and physical/psychosocial HRQOL were assessed using self-report measures at three time points. The potential bidirectional associations were examined using a longitudinal panel model. Results Higher disordered eating predicted lower psychosocial HRQOL during a 6-month period within the same academic year, and lower HRQOL predicted higher disordered eating during a 6-month period across academic years. Conclusion The current study found longitudinal, bidirectional associations between disordered eating and psychosocial, but not physical, HRQOL. The results provide evidence for psychosocial HRQOL as a potential predictor and consequence of disordered eating attitudes. Limitations, future directions, and implications of this research are discussed.