EVALUATION OF CARDIORESPIRATORY FITNESS FROM A 20-MINUTE STEADY STATE JOG INDEPENDENT OF BODY COMPOSITION IN ADOLESCENTS

Abstract

The purpose of this study was to determine the relationship between sum of two-site (triceps and medial calf) skinfold thickness and performance on a 20-minute steady state jog (20MSSJ) test of cardiorespiratory function in adolescents. This study also evaluated the effect of adjusting 20MSSJ performances for skinfold thickness on the achievement of criterion-referenced standards for the 20MSSJ. Subjects were 75 adolescents (32 females and 43 males), ages 13–18 years. Following an eight-week conditioning period, each subject performed the 20MSSJ on an indoor running surface. Performances were recorded to the nearest tenth of a mile. Twenty-eight subjects achieved the criterion standard (2.2 miles for females and 2.4 miles for males), while 47 subjects did not achieve that standard. Triceps and medial calf skinfolds (mm) were also measured for each subject. The relationship between 20MSSJ performance and sum of two-site skinfolds was quadratic (F1,72 = 4.4, p < .05). The equation for predicting 20MSSJ performance (miles) from sum of two-site skinfolds (mm) is: 20MSSJ = 3.667 - 0.087(sum) + 0.001(sum)2 (R = .64, SEE = 0.41 miles). 20MSSJ performances were adjusted for sum of two-site skinfolds by adding the mean 20MSSJ value to the residual for estimating 20MSSJ from sum of two-site skinfolds for each subject. After 20MSSJ performances had been adjusted for sum of two-site skinfolds, 27 subjects achieved the 20MSSJ criterion standard, while 48 subjects did not achieve that standard. There was only 72 percent agreement between the unadjusted and adjusted classifications (χ2 = 11.8, p < .05). These data suggest that the relationship between 20MSSJ performance and sum of two-site skinfolds is strong enough to justify the adjustment of 20MSSJ performances for sum of two-site skinfolds. 20MSSJ performances adjusted for sum of two-site skinfolds may be more appropriate for evaluating cardiorespiratory fitness independent of body composition than unadjusted 20MSSJ performances in adolescents.