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Tracking of physical activity and fitness during the early years
Hilary A T Caldwell1,2, Nicole A Proudfoot1,2, Sara King-Dowling1,2
1a Child Health and Exercise Medicine Program, Department of Pediatrics, McMaster University, Hamilton, ON L8S 4K1, Canada.
Insights
Preschoolers showed improved fitness and increased vigorous physical activity over one year. However, fitness levels tracked better than physical activity levels during this period.
Area of Science:
- Pediatric exercise science
- Childhood development
- Sports medicine
Background:
- Early childhood is a critical period for physical growth and behavioral development, including physical activity.
- Understanding the changes and stability of physical activity and fitness in preschoolers is crucial for long-term health outcomes.
Purpose of the Study:
- To assess 12-month changes in physical activity and fitness in preschoolers.
- To evaluate the tracking of physical activity and fitness over a 1-year period in this age group.
Main Methods:
- 400 preschoolers (aged 4.5 ± 0.9 years) wore accelerometers for 7 days to measure physical activity intensity and duration.
- Short-term muscle power was assessed using a modified 10-second Wingate Anaerobic Test.
- Aerobic fitness was evaluated via the Bruce Protocol treadmill test, measuring maximal treadmill time and heart rate recovery.
Main Results:
- Light physical activity decreased, while vigorous physical activity increased significantly over the 12 months.
- Muscle power and aerobic fitness (time to exhaustion) improved and showed moderate to strong tracking.
- Physical activity showed moderate to fair tracking, while heart rate recovery tracked fairly.
Conclusions:
- Fitness components, particularly muscle power and aerobic capacity, demonstrate better 12-month tracking than overall physical activity in preschoolers.
- Interventions aimed at promoting sustained physical activity may be necessary to ensure consistent fitness development in early childhood.
Abstract:
The early years are characterized by rapid physical growth and the development of behaviours such as physical activity. The objectives of this study were to assess the 12-month changes in and the tracking of physical activity and fitness in 400 preschoolers (201 boys, 4.5 ± 0.9 years of age). Physical activity data, expressed as minutes per day and as the percentage of time spent at various intensities while wearing an accelerometer, were collected in 3-s epochs for 7 days. Short-term muscle power, assessed with a 10-s modified Wingate Anaerobic Test, was expressed as absolute (W) and relative (W/kg) peak power (PP) and mean power (MP). Aerobic fitness, assessed with the Bruce Protocol progressive treadmill test, was expressed as maximal treadmill time and heart rate recovery (HRR). Light physical activity decreased by 3.2 min/day (p < 0.05), whereas vigorous physical activity increased by 3.7 min/day (p < 0.001), from year 1 to year 2. Physical activity exhibited moderate tracking on the basis of Spearman correlations (r = 0.45-0.59, p < 0.001) and fair tracking on the basis of κ statistics (κ = 0.26-0.38). PP and MP increased from year 1 (PP, 94.1 ± 37.3 W; MP, 84.1 ± 30.9 W) to year 2 (PP, 125.6 ± 36.2 W; MP, 112.3 ± 32.2 W) (p < 0.001) and tracked moderately to substantially (PP, r = 0.89, κ = 0.61; MP, r = 0.86, κ = 0.56). Time to exhaustion on the treadmill increased from 9.4 ± 2.3 min to 11.8 ± 2.3 min (p < 0.001) and tracked strongly (r = 0.82, κ = 0.56). HRR was unchanged at 65 ± 14 beats/min (p = 0.297) and tracked fairly (r = 0.52, κ = 0.23). The findings indicate that fitness tracks better than physical activity over a 12-month period during the early years.
