The Reliability and Variability of Running Economy in 7-, 8-, and 9-Year-Old Children

This study was designed to examine the reliability and variability of running economy in 7-, 8-, and 9-year-old boys and girls. Forty-two children (21 boys and 21 girls) participated in two submaximal treadmill tests to determine running economy at two absolute work rates (5 mph and 6 mph). Reliability and variability were determined for oxygen consumption (V̇O 2 ), heart rate (HR), respiratory exchange ratio (RER), stride frequency, and stride length. With the exception of RER and V̇O 2 relative to body surface area, reliability estimates were moderate to high (.80 to .94). Mean variability of all responses were similar to those reported for adults, however, the range of intraindividual variability was slightly greater. These results indicate that two submaximal measurements result in higher reliability estimates than a single test and may therefore provide a more appropriate description of a child’s running economy.