Speed Effects on the Accuracy of Heart Rate as Oxygen-Uptake Indicator in Short-Distance Shuttle Running

Purpose: Despite the accuracy of heart rate (HR) as an indicator of the aerobic engagement has been evaluated in several intermittent on-court activities, its validity as an oxygen uptake ($$) indicator during shuttle running over short paths remains uncertain. Moreover, it is unclear whether speed may affect such validity. This study evaluated the HR ability in estimating the $$ during 5-m shuttle running at different speeds. Methods: $$ and HR of 12 physically active young men were recorded during an incremental forward running (FW) protocol and a 5-m shuttle test at 50%, 60%, and 75% of maximal aerobic speed (MAS). Slope and intercept of the relationship between HR and $$ (HR/$$) were individually determined, in both protocols. The HR measured during the shuttle test was used in the FW HR/$$ to estimate $$ at each shuttle speed. A paired Student's t-test compared slopes and intercepts of the two HR/$$. A two-way RM-ANOVA and an equality test examined, respectively, the differences and the equality between measured and estimated $$. Lastly, a Bland-Altman plot described the accuracy and precision of the estimated $$ at each shuttle intensity. Results: Slopes and intercepts of the HR/$$ appeared not different between FW and shuttle running. At 50%MAS, HR underestimated the $$ (~7%), whereas returned accurate values at the two higher velocities, although with high variability (±18%). Conclusions: When using HR as $$ indicator during shuttle running over short paths, a separated analysis of the HR validity as $$ indicator is recommended especially when administering different exercise intensities.