Compositional Isotemporal Substitution Analysis of 24-h Movement Behaviours and Speed Capability in Preschoolers

Area of Science:

• Pediatric exercise science
• Developmental kinesiology
• Childhood motor development

Background:

• Speed capability is vital for early childhood development.
• Concerning trends in motor fitness among Chinese preschoolers (3-6 years) necessitate investigation.
• The relationship between 24-hour movement behaviors and speed is not well understood.

Purpose of the Study:

• To examine how compositional 24-hour movement behaviors (sleep, sedentary behavior [SB], light physical activity [LPA], and moderate-to-vigorous physical activity [MVPA]) relate to speed capability in preschoolers.
• To quantify the effects of reallocating time between different movement behaviors on speed performance.

Main Methods:

• Compositional data analysis and isotemporal substitution modeling were employed.
• 275 preschoolers (mean age ~5 years) underwent 20-m sprint tests and 7-day accelerometry.
• Models were adjusted for age, sex, and BMI z-scores, with pairwise behavioral substitutions analyzed for 5- to 30-minute durations.

Main Results:

• Higher relative MVPA time was a significant predictor of faster sprint times (β = -1.302, p < 0.001).
• Higher LPA was associated with slower sprint times (β = 1.570, p = 0.003).
• Reallocating 15 minutes from sleep, SB, or LPA to MVPA reduced sprint times, while reallocating MVPA to other behaviors worsened performance.

Conclusions:

• Moderate-to-vigorous physical activity (MVPA) is the primary positive predictor of speed capability in preschoolers.
• Optimizing 24-hour movement patterns by increasing MVPA at the expense of LPA or SB enhances speed performance.
• Findings support targeted interventions to improve early childhood development through movement behavior modification.