Abstract
This study was conducted to investigate growth and development of physique and motor fitness in junior sports athletes by applying the polynomial to age. A total of 322 junior athletes （179 boys and 143 girls aged 5-15 years） performed 3 physique measures and 6 motor fitness test. Measuring items of physique were body height, body weight and body fat. Lean body mass was calculated from body weight and body fat. Motor fitness tests were 20 m dash, Pro Agility test, vertical jump, standing long jump, side step and rebound jump index. Polynomial set up age between 8 years to 13 years as horizontal axis was applied to significant statistics to gain results for the analysis of variance and the age at maximum peak velocity （MPV） and local peak velocity （LPV） was derived from the velocity curve. There was clear association with age at MPV or LPV of between body height, lean body mass, standing long jump and side step in boys and between body height and all of motor fitness items in girls. These results suggest that speed, explosive power and agility increases in accordance with the onset of the body height spurt both sexes in junior sports athletes.
