The early years are characterized by dramatic growth and the development of healthy behaviours, such as physical activity (PA). The objectives of this thesis were to assess one year tracking of fitness and PA in preschoolers and to investigate the relationship between fitness and PA over a one-year period. Four hundred preschoolers (201 boys, 199 girls; 4.5±0.9 years) participated in year 1 and year 2 assessments, 12.1±0.7 months apart. Height and weight were measured to calculate body mass index (BMI) and body fat percentage (%BF) was assessed with bioelectrical impedance analysis (BIA). Two components of fitness were assessed: short-term muscle power (STMP) with a 10-second modified Wingate Anaerobic Test, and aerobic fitness with the Bruce Protocol progressive treadmill (TM) test. Peak Power (PP) and Mean Power (MP) were measures of STMP. TM time and 60-sec heart rate recovery (HRR) were indicators of aerobic fitness. PA data were collected for 7 days with ActiGraph accelerometers, and PA was quantified as the % of wear time (%WT) spent in moderate-to-vigorous PA (MVPA) and vigorous PA (VPA). At year 2, participants were significantly heavier (year 1: 17.9±3.2; year 2: 20.3±3.8kg; p=0.000) and taller (year 1: 106.6±7.8; year 2: 113.5±7.8 cm; p=0.000). From year 1 to year 2, BMI decreased from 15.7±1.3 to 15.6±1.4 m/kg2 (p=0.008) and %BF decreased from 23.2±4.6 to 21.1±4.7% (p=0.000). Both PP and MP improved approximately 30 Watts (p=0.000) from year 1 (PP: 94.1±37.3; MP: 84.1±30.9) to year 2 (PP: 125.6±36.2; MP: 112.3±32.2). TM time increased 2.4±1.4 minutes (p=0.000) from 9.4±2.3 to 11.8±2.3 minutes and HRR was unchanged at 65±14 beats per minute (bpm). MVPA increased from 13.3±2.9 to 13.9±3.0 %WT (p=0.003) and VPA increased from 5.8±1.7 to 6.3±1.8 %WT (p=0.000). PP and MP tracked moderately to substantially (PP: r=0.89, κ=0.61; MP: r=0.86, κ=0.56). TM time and HRR tracked fairly to strongly (TM time: r=0.82, κ=0.56; HRR: r=0.52, κ=0.23). MVPA and VPA tracked fairly to moderately (MVPA: r=0.59, κ=0.28; VPA: r=0.37, κ=0.38). At year 1 and year 2, PP, MP and HRR were weakly correlated to PA variables (r=0.13-0.23, p=0.000-0.02). TM time was correlated to VPA at year 1 (r=0.131, p=0.016) and to MVPA and VPA at year 2 (r=0.12-0.15, p=0.006-0.023). Boys engaged in more MVPA at year 1 and year 2 (p=0.000). Boys and girls were separately divided into groups that decreased, maintained or increased MVPA or VPA from year 1 to year 2. Girls who maintained MVPA had higher weight %iles and %BF than girls who increased MVPA, at both year 1 and year 2. Boys who increased VPA saw a greater increase in HRR than those who maintained VPA (p=0.000). Our findings indicate that fitness tracks better than PA over a 12-month period during the early years, and that a weak, positive relationship between these variables exists. Other factors, including measures of body composition, are likely influencing these relationships. / Thesis / Master of Science in Kinesiology
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/16001 |
| Date | 11 1900 |
| Creators | Caldwell, Hilary A.T. |
| Contributors | Timmons, Brian W., Kinesiology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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