BMI and Fitness From Childhood to Adolescence

Background/Purpose: Overweight and obesity have become serious problems in modern society especially in developed countries. People who are overweight/obese have a greater risk of cardiovascular disease, hypertension, diabetes and cancer. There is an urgent need to examine how overweight/obesity tracks during different ages so that preventive strategies can be conducted. However, limited studies have examined the tracking of weight status during elementary years. The association between lower fitness and higher coronary risk and other health problems has also attracted researchers’ attention in examining the tracking of fitness in recent years.  However, few studies have examined the tracking of fitness components using a standard test battery across elementary school years. Thus, the purpose of the current study was to examine the degree of tracking on participants’ body composition and fitness components across elementary school years.

Method: Fitness data including BMI, endurance run/walk, shuttle run, curl ups, sit-and-reach, and flexed arm hang using the President’s Challenge battery were collected for 150 participants when they were enrolled in k, 1^st, and 2^nd grade (baseline). The same data were collected on the same students using the same fitness testing battery after five years when they were in 6^th, 7^th, and 8^th grades (follow-up).

Analysis/Results: Tracking of BMI and fitness were examined using Pearson correlation coefficients and the number/percentage of participants who maintained their weight status based on the CDC’s gender- and age-specific growth charts, and the number/percentage of participants who remained within certain rank based on the norm-referenced standards of the President’s Challenge program across elementary years. The results indicated that BMI at baseline was highly correlated with BMI at follow up (r=.64 to .76).  More than 60% of boys and girls remained in normal weight category from baseline to follow up. Moderate correlations were found for flexed arm hang, sit and reach, and sit ups (r=.38 to .59). The results found that most participants’ fitness levels stayed below 50 percentile across elementary years.  Few students’ fitness rank improved especially improved to or above 85th percentile.

Conclusions: Although BMI tracks across elementary years and most children stayed within normal weight, many participants shifted from normal weight to overweight. Fitness components also tracked well and most participants’ fitness components’ levels were below 50 percentile from baseline to follow up assessment. Early interventions that positively influence children’s weight status and improve their fitness levels at an early age are presented.