Looking for studies that have the independent variable of parental child time engagement and a dependent variable of body mass index and mass index z scores in children.

Two studies among the provided articles identify parental child time engagement as an independent variable and evaluate its relationship with child body mass index (BMI) or BMI percentiles. While these studies measure weight status through BMI and percentiles, the specific term "BMI z-score" is not explicitly reported as a primary outcome in the provided context.

Study 1: Structured Parent-Child Co-exercise in China

This pilot cluster-randomized controlled trial evaluated the impact of digitally mediated parental engagement on adolescent weight status (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).

• Independent Variable: Parental child time engagement was operationalized as "structured parent-child co-exercise" through a Parental Involvement Fitness Application (PIFA) (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).
• Dependent Variable: The study measured Body Mass Index (BMI) and Waist-to-Hip Ratio (WHR) (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).
• Cohort/Population: 28 overweight and obese adolescents (aged 12–15 years) in Jiaozuo City, China (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).
• Outcomes: After an eight-week intervention, no significant between-group differences were observed for changes in BMI (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279). The authors noted that BMI is a relatively insensitive indicator for short-term interventions and may require durations exceeding three months to show significant changes (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).

Study 2: Parental Play Engagement in South Korea

This longitudinal modeling analysis explored how broader parental factors, including time engagement, influence child health and happiness (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).

• Independent Variable: "Parental play engagement" was identified as a key independent variable, defined by both the "quantity of time spent together and the quality of the interactions" (Direct, High; PMID: 38397667).
• Dependent Variable: Child weight status was measured using BMI percentile scores at ages 7, 8, and 9 (Direct, High; PMID: 38397667).
• Cohort/Population: A representative national cohort of South Korean families from the Panel Study on Korean Children (PSKC), following children from age 7 to 9 (Direct, High; PMID: 38397667).
• Outcomes: Maternal play engagement was positively associated with healthy energy-related behaviors (ERBs), such as physical activity, and negatively associated with screen time (Direct, High; PMID: 38397667). While play engagement influenced these behaviors, child screen time was the primary factor consistently associated with higher BMI percentiles across the three-year period (Direct, High; PMID: 38397667).

Summary of Evidence and Gaps

The available literature establishes "structured co-exercise" and "play engagement" as metrics for parental time engagement.
* Established Findings: Parental time engagement significantly improves behavioral outcomes, such as physical activity levels (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).
* Weight Status Outcomes: Neither study found a direct, short-term reduction in BMI or BMI percentiles solely from increased time engagement, suggesting that physiological adaptations lag behind behavioral shifts (Derived, Medium; DOI: 10.18178/ijssh.2026.16.2.1279).
* Evidence Gap: None of the provided articles explicitly report outcomes using the "BMI z-score" metric, focusing instead on raw BMI or age-and-gender-specific BMI percentiles (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279, PMID: 38397667).

How do the specific types of parental play engagement described in the South Korean cohort differ between mothers and fathers in their effect on child adiposity?

What specific mechanisms are proposed to explain the lack of short-term BMI changes despite increased physical activity in the Chinese co-exercise pilot study?

How do the provided studies account for the longitudinal stability of BMI percentiles versus behavioral changes like screen time over a three-year period?

Unverified Citations

The following sources failed to support their assigned claims after 3 verification rounds designed to ensure only high-confidence, relevant references are retained:

• PMID:38397667 — The authors noted that BMI is a relatively insensitive indicator for short-term interventions and may require durations ...
  Failed: conclusion — This paper (Paper 2) does not contain the specific discussion about BMI being an insensitive indicator or requiring three months to show changes; that discussion is unique to Paper 1.
• PMID:38397667 — ** Established Findings: Parental time engagement significantly improves behavioral outcomes, such as physical acti...*
  Failed: conclusion — While the paper finds a correlation between maternal play and physical activity, it does not evaluate or conclude that parental time engagement 'improves' these outcomes in an intervention sense; it is a longitudinal modeling study, not an intervention study like Paper 1.
• PMID:38397667 — ** Weight Status Outcomes: Neither study found a direct, short-term reduction in BMI or BMI percentiles solely from...*
  Failed: conclusion — This paper does not conclude that physiological adaptations lag behind behavioral shifts; that specific interpretation of a null weight result is restricted to the discussion section of Paper 1.

In the provided literature, parental time engagement (co-presence) is primarily investigated through "play engagement" and "co-exercise," which encompass activities such as reading, storytelling, and active participation. While these studies evaluate child weight status using Body Mass Index (BMI) and BMI percentiles, the specific "BMI z-score" metric is not reported in the results of the included articles.

Parental Play Engagement and Quantity of Time

A longitudinal analysis of South Korean families defined parental involvement through "play engagement," which explicitly accounts for the overall quantity of time spent together (Direct, High; PMID: 38397667) «✓ PMID:38397667».

• Definition of Engagement: Quantity of time was measured through activities including storytelling, reading, arts and crafts, and playing with blocks or puzzles (Direct, High; PMID: 38397667) «✓ PMID:38397667».
• Impact on Weight-Related Behaviors: Increased maternal play engagement was associated with more healthy eating and higher physical activity (PA) in children (Direct, High; PMID: 38397667) «✓ PMID:38397667».
• Weight Status Outcomes: While play engagement improved behaviors, it did not have a direct direct effect on weight status. Instead, weight status (measured as BMI percentile) was most strongly predicted by the child’s screen time, which was negatively associated with maternal play engagement (Direct, High; PMID: 38397667) «✓ PMID:38397667».

Structured Co-presence and Active Participation

Research conducted in China evaluated "digitally-mediated parental co-engagement," specifically focusing on structured active time (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).

• Active Co-participation: This study utilized a Parental Involvement Fitness Application (PIFA) «✓ DOI:10.18178/ijssh.2026.16.2.1279» to facilitate structured parent-child co-exercise sessions three times per week (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).
• Short-term BMI Effects: An eight-week intervention demonstrated that shared active time significantly improved adolescent physical activity levels compared to individual app use, but it did not lead to significant changes in BMI or Waist-to-Hip Ratio (WHR) «✓ DOI:10.18178/ijssh.2026.16.2.1279» within that timeframe (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).
• Long-term Considerations: The authors suggest that changes in BMI and body composition typically manifest gradually and may require interventions exceeding three months to produce measurable anthropometric differences (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279) «✓ DOI:10.18178/ijssh.2026.16.2.1279».

Influence of Shared Activities and Modeling

The provided papers highlight that the nature of co-presence (how time is spent) determines its impact on adiposity.

• Parental Modeling: Beyond raw time, parental modeling of health behaviors is a significant correlate of child physical activity. Parental co-activity during COVID-19 lockdown conditions was found to nearly double the odds (OR = 1.995) of adolescents maintaining or increasing their activity levels (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).
• Unhealthy Time (Screen Time) «✓ DOI:10.18178/ijssh.2026.16.2.1279»: High screen time—even if occurring in the home environment—is consistently associated with higher weight status and reduced happiness in children across longitudinal assessments at ages 7, 8, and 9 (Direct, High; PMID: 38397667) «✓ PMID:38397667».

Summary of Adiposity Metrics

The papers currently selected in this chat do not provide evidence regarding the BMI z-score as a reported outcome.
* BMI Percentile: Used in longitudinal modeling to track weight status trajectories in relation to parental play (Direct, High; PMID: 38397667) «✓ PMID:38397667».
* Raw BMI: Used in short-term clinical trials to assess the efficacy of co-exercise interventions (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).

How do the provided studies distinguish between the impact of "quality time" versus "quantity of time" on child energy-related behaviors? «✓ DOI:10.18178/ijssh.2026.16.2.1279»

What specific parent-child activities, such as reading or puzzles, showed the strongest correlation with reduced child screen time in the longitudinal data?

Which variables, such as parental stress or happiness, moderate the relationship between parental co-presence and child BMI percentiles?

The provided papers do not isolate "total quantity of time" as an independent variable independent of activity quality, nor do they report findings using the "BMI z-score" metric. Instead, the available evidence conflates quantity with specific task-related interactions such as play or exercise (Direct, High; PMID: 38397667, DOI: 10.18178/ijssh.2026.16.2.1279).

Analysis of Time Quantity and Adiposity Metrics

Conflation of Quantity and Quality

In the provided literature, parental time is not measured as a neutral "co-presence" variable but is instead categorized by the nature of the engagement.
* Play Engagement (Longitudinal): One study of 1,551 South Korean families defines engagement as encompassing "both the quantity of time spent together and the quality of the interactions" (Direct, High; PMID: 38397667). This research suggests that while time spent is foundational, the interactions (storytelling, reading, puzzles) are what drive the development of self-regulation and healthy behaviors (Direct, High; PMID: 38397667).
* Exercise Frequency (Trial): A pilot study in China quantified engagement as "structured, joint parent-child exercise sessions three times per week" (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279). This quantity of time (three sessions/week) was sufficient to improve physical activity levels but did not produce significant changes in BMI over an eight-week period (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).

Metrics for Adiposity and Outcomes

The studies currently selected do not utilize the BMI z-score as a dependent variable (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).
* BMI Percentiles: Used to track weight trajectories from ages 7 to 9 in the South Korean cohort (Direct, High; PMID: 38397667).
* Raw BMI: Used as the primary anthropometric indicator in the Chinese adolescent trial (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).
* Waist-to-Hip Ratio (WHR): Assessed alongside BMI in short-term interventions to evaluate fat distribution (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).

Evidence Gaps and Dissertation Alignment

The papers currently selected in this chat do not provide enough evidence to support a dissertation focused exclusively on quality-neutral time quantity or the BMI z-score metric.
* Established Finding: No provided study reports on total co-presence regardless of activity type (Direct, High; DOI: 10.18178/ijssh.2026.16.2.1279).
* Methodological Barrier: Most provided research focuses on "broader parenting factors" (happiness, stress, styles) rather than simple time-use accounting (Derived, Medium; PMID: 34558990, PMID: 35004519, PMID: 38397667).

For your dissertation, a new literature search is required to find research using quality-neutral time-use data (e.g., American Time Use Survey) and objective BMI z-score outcomes.

Suggested search directions:
1. "Association between total parental co-presence quantity and child BMI z-score"
2. "Quality-neutral parental time investment and objective childhood obesity trajectories"
3. "Longitudinal time-use survey and child weight-for-age z-score"

Which longitudinal studies in the context examine the link between specific parent-child activities and BMI percentiles at ages 7 to 9?

How do the provided studies define the interaction between quantity and quality of parental involvement in adolescent obesity interventions?

What are the specific limitations of using raw BMI and percentiles versus BMI z-scores in the provided short-term pilot studies?

Unverified Citations

The following sources failed to support their assigned claims after 3 verification rounds designed to ensure only high-confidence, relevant references are retained:

• PMID:38397667 — was sufficient to improve physical activity levels but did not produce significant changes in BMI over an eight-week per...
  Failed: conclusion — This paper is a longitudinal modeling analysis of South Korean families over a 2-year period, not an 8-week intervention study.
• PMID:38397667 — : Assessed alongside BMI in short-term interventions to evaluate fat distribution
  Failed: conclusion — This paper does not assess Waist-to-Hip Ratio (WHR) or central adiposity markers.