Relationship between cardiovascular drift and performance in marathon running

Heart rate (HR) monitoring, which reflects exercise intensity and environmental factors, is often used for pacing strategies in the marathon race. However, it is difficult to obtain appropriate feedback for only the HR value since cardiovascular drift (CV drift) occurs during prolonged exercise. Recently, cardiac cost (CC: HR divided by running velocity) has been shown to be a potential index for evaluation of CV drift during the marathon race. The aim of this study was to clarify the relationship between CV drift and performance in the marathon race. Fourteen male university student runners participated. They carried out incremental tests on a treadmill and took part in an actual marathon race. CV drift was evaluated from differences between CC in the 0-5-km section and over every 5-km section (ΔCC). The marathon performance was examined from two viewpoints: absolute performance (average running velocity during the race: Vmar), and relative performance (Vmar against velocity corresponding to ventilatory threshold: vVT achv.). Significant correlations were found between ΔCC and vVT achv. in the 25-30 km, 30-35 km and 35-40 km sections (r = −0.672, −0.671 and −0.661, respectively), suggesting that excessive CV drift had a negative impact on relative performance. We can therefore conclude that suppression of CV drift after 25 km is an important factor for improvement of relative performance.