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 (V-O2) 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 V-O2 during 5-m shuttle running at different speeds. Methods: V-O2 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 V-O2 (HR/V-O2) were individually determined, in both protocols. The HR measured during the shuttle test was used in the FW HR/V-O2 to estimate V-O2 at each shuttle speed. A paired Student's t-test compared slopes and intercepts of the two HR/V-O2. A two-way RM-ANOVA and an equality test examined, respectively, the differences and the equality between measured and estimated V-O2. Lastly, a Bland-Altman plot described the accuracy and precision of the estimated V-O2 at each shuttle intensity. Results: Slopes and intercepts of the HR/V-O2 appeared not different between FW and shuttle running. At 50%MAS, HR underestimated the V-O2 (similar to 7%), whereas returned accurate values at the two higher velocities, although with high variability (+/- 18%). Conclusions: When using HR as V-O2 indicator during shuttle running over short paths, a separated analysis of the HR validity as V-O2 indicator is recommended especially when administering different exercise intensities.