Abstract

The purposes of the study were to describe V̇O2 among recreational runners under self-selected cadence (SS) and manipulated cadence 10 steps per minute faster (SS + 10) during a single treadmill running assessment, examine predictive ability of several variables on V̇O2, and compare estimates of energy expenditure from treadmill software with direct measure of V̇O2. Airflow and percent of expired O2 were used to calculate V̇O2 from thirteen (7 females and 6 males) runners at self-selected speed at both SS and SS + 10. Respiratory rates and mean tidal volumes were calculated from the collected data. Among all subjects there was no significant difference in V̇O2 between SS and SS + 10. There was a significant increase in V̇O2 from SS to SS + 10 in males, but not females. We observed several patterns of changes in respiratory variables at SS + 10.One pattern (N = 3, all female) was characterized by a modest increase in respiratory rate and large decrease in tidal volume, which resulted in a decrease in total ventilation and accompanied by increases in V̇O2 efficiency at SS + 10. Changes in tidal volume and ventilation were positively correlated with changes in V̇O2 between SS and SS + 10 conditions. None of the other potential predictor variables were significantly correlated with changes in V̇O2. Correlation of treadmill predicted energy expenditure of the Wood way Pro 27 with direct measure of V̇O2 was 0.81. It appears that a quarter of recreational runners may have large improvements in their running efficiency through an increase in cadence.

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