Relationships between physical fitness and obesity in 8-year-old greek children

Introduction

Obesity has negative effects on aerobic fitness. However, there are only few studies that have examined the relationship between obesity and other components of physical fitness (i.e. upper and lower limb strength/power and speed), particularly at the age of childhood. Thus, the aim of this study was to determine the possible influence of obesity on selected fitness parameters in 8-year-old primary schoolchildren.

Methods

Thousand and seven hundred eighty Greek schoolchildren (878 girls: age 8.1 ± 0.5 yrs; body mass 29± 6.6 Kg; height 129.7 ± 6.3 cm and 900 boys: age 8.2 ± 0.5 yrs; body mass 30.2 ± 6.9 Kg; height 130.9 ± 6.6 cm) volunteered to participate in this study. The subjects performed an overhead throw for power and strength of the upper limbs, a counter movement vertical jump for power and strength of the lower limbs, a 30 m sprint for velocity and a Eurofit shuttle run test for aerobic capacity (estimation of VO₂max). Obesity was estimated by the Body Mass Index (BMI), computed as the ratio of body mass to squared height. The 85th and 95th BMI age-and sex-related percentile values were used as cut-off points for overweight and obesity, respectively. MANOVA was used to verify the statistical significance of the observed differences.

Results

67.3% of the participants had a normal BMI, 21% were overweight and 11.8% were obese, with no statistical differences between sexes (χ²=3.47, p>.05). Overweight and obese subjects had inferior performances on all tests requiring propulsion or lifting of the body mass (vertical jump, 30-m speed and endurance shuttle run) compared with their nonobese counterparts (s. Table 1). In contrast, the obese subjects showed better scores on overhead throw, which achieved statistical significance only in boys (p<.002).

 

 

Table 1. Differences in selected fitness parameters (M±SD) by gender and BMI categories.

		Normal	Overweight	Obese
Number of subjects	girls	604	183	91
	boys	592	190	118
BMI (kg·m-2)	girls	15.5±1.4*	19.2±.8*†	23.4±2.1*†
	boys	15.7±1.4*	19.4±.8*†	23.2±2*†
Overhead throw (m)	girls	3.2±.9	3.3±.9	3.2±.9
	boys	3.8±.9*	3.7±1†	4.1±1.1*†
Vertical jump (cm)	girls	18.8±5.2*	17.4±4.4*	16.2±4.1*
	boys	20.4±5.5*	18.9±5.2*†	17.6±4.8†
30 m sprint (sec)	girls	6.4±.6*	6.6±.6*	6.9±.6*
	boys	6.2±.5*	6.4±.7*†	6.6±.6*†
Shuttle run test (ml/min/kg)	girls	25±3.8*	23.6±3.7*†	22.2±2.6*†
	boys	26.3±4.6*	24.1±3.9*	23.5±3.3*

^*  Values significantly different (p<0.05) between normal and overweight/obese.

^†  Values significantly different (p<0.05) between overweight and obese.

 

Discussion/ Conclusions

In line with previous studies [1-3], the present study demonstrated that obesity is a limiting factor for fitness performance in 8-year-old primary schoolchildren, especially as measured by vertical jump, 30-m run, and 20 meters shuttle run tests. To encourage adherence to physical activity in obese children, it is important that activities are tailored to their capabilities. Results suggest that weight-bearing activities should be limited at the start of an intervention with obese participants and alternative activities should be used.

 

References

[1].   Malina RM et al (1995). Obes Res 3(3): 221-31.

[2].   Grund A et al (2000). Eur J Appl Physiol 82 (5-6): 425-38.

[3].   Deforche B  et al (2003). Obes Res 11 (3): 434-41.