RC Grant Findings: Development of a Model to Estimate Aerobic Fitness from PACER Performance in Adolescents

Background/Purpose The FITNESSGRAM® is a widely used youth fitness assessment program. Although the PACER 20-m multistage shuttle run is the recommended test of aerobic fitness in the FITNESSGRAM®, few published studies have examined the validity evidence for the PACER in 15- to 16-year-old youth by comparison with a criterion of measured VO2peak. The current equation used in the FITNESSGRAM® software to predict VO2peak from PACER performance was published by Leger et al. (1988). The purposes of this study were to: (a) develop a regression model to estimate VO2peak from PACER performance, gender, and body mass index (BMI); (b) cross-validate the Leger et al. PACER prediction model; and (c) compare VO2peak measured with a COSMED portable metabolic system during a maximal treadmill test and during PACER performance.

Method Forty 15- to 16-year-old males and females had VO2peak assessed during a graded treadmill exercise test and a PACER test with a COSMED K4b2 portable metabolic system. Height and weight were assessed and BMI was calculated (mean BMI = 21.8 ± 4.0 kg.m-2).

Analysis/Results Mean VO2peak was 50.4 ± 11.2 ml.kg-1.min-1 and mean PACER score was 53.2 ± 19.7 laps. The newly developed multiple regression model was: VO2peak = 40.87554 + (0.44632 * PACER laps) – (0.00114 * PACER laps squared) + (5.67988 * gender [M=1; F=0]) – (BMI * 0.64501), multiple R = .83, SEE = 6.3 ml.kg-1.min-1. Cross-validation results of the Leger et al. equation were: R = .77, SEE = 10.1 ml.kg-1.min-1. VO2peak measured during the treadmill test was highly correlated (r = .84) with VO2peak measured during PACER performance and mean values did not differ significantly (mean difference = 1.4 ml.kg-1.min-1, p = .17, ES = 0.13). Maximal heart rate values measured during treadmill and PACER performance differed by less than 1 b.min-1.

Conclusions The regression model developed in this study to estimate VO2peak from PACER performance was more accurate than the Leger et al. model. Cross-validation of the Leger et al. model on 15- to 16-year-old participants resulted in inaccurate estimates of aerobic fitness. Aerobic fitness and maximal heart rate were similar when measured during the treadmill and PACER tests, with small mean differences. Results suggest that VO2peak measured with portable metabolic systems during treadmill and PACER tests provide similar measures of aerobic fitness in this age group.