Muscle oxygen dynamics in elite climbers during finger-hang tests at varying intensities

Introduction: Failure in elite sport climbing is associated with an inability to maintain isometric muscle contraction. The ability to supply and utilise oxygen is the primary bioenergetic contributor to muscle contraction and can be examined locally using near-infrared spectroscopy (NIRS). Examining changes in NIRS derived muscle oxygenation (SmO2) have shown to be related to changes in performance output during gripping exercises. Purpose: The aim of this study is to measure SmO2 dynamics in a climbing specific test until task failure in varying conditions. Our prediction is that SmO2 should be a good marker to predict task failure. Methods: Eight elite level climbers performed a finger-hang test with four different intensities maintaining grip until voluntary exhaustion. During each trial SmO2 and time to failure (TTF) were measured. TTF was then compared to the minimally attainable value of SmO2 (SmO2min) and time to SmO2min (TTmin). Results Two-one-sided tests (TOST) resulted in SmO2min equivalence for the high intensity conditions (M1 = 21.9% SD1 = 5.0%; M2 = 25.4%; SD2 = 6.5%; M3 = 24.1%, SD3 = 5.9%), t(7) = 2.72, p = 0.015; t(7) = 3.85, p = 0.003, but failed to show equality for the fourth and lowest intensity condition (M4 = 32.4%, SD4 = 8.8%), t(7) = -1.01, p = 0.173. Equivalence was also found between TTF and TTmin for the high intensity conditions. Conclusion: The duration with which oxygen is extracted and utilised changes, while the attainable SmO2min remains constant at high intensity conditions and is related to the ability to maintain task performance