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

The aim of this study was to measure muscle oxygen saturation (SmO₂) dynamics during a climbing specific task until failure in varying conditions. Our prediction was that SmO₂ should be a good marker to predict task failure. Eleven elite level climbers performed a finger-hang test on a 23 mm wooden rung under four different weighted conditions, 1. body weight (BW), 2. body weight +20% (BW +20), 3. body weight -20% (BW -20) and 4. body weight -40% (BW -40), maintaining half crimp grip until voluntary exhaustion. During each trial SmO₂ and time to task failure (TTF) were measured. TTF was then compared to the minimally attainable value of SmO₂ (SmO₂min) and time to SmO₂min (TTmin). There is a considerable degree of agreement between attainable SmO₂min at high intensity conditions (M_BW = 21.6% ± 6.4; M_BW+20 = 24.0% ± 7.0; M_BW-20 = 23.0% ± 7.3). Bland-Altman plot with an a priori set equivalency interval of ±5% indicate that these conditions are statistically not different (M_{BW-BW + 20} = -2.4%, 95% CI [1.4, -6.2]; M_BW-Bw-20 = -1.3, 95% CI [2.5, -5.1]). The fourth and lowest intensity condition (M_{BW -40} = 32.4% ± 8.8) was statistically different and not equivalent (M_{BW-BW -40} = -8.8%, 95% CI [-5.0, -12.6]). The same agreement was found between TTF and TTmin for the high intensity conditions plotted via Bland-Altman. While the rate with which oxygen was extracted and utilised changed with the conditions, the attainable SmO₂min remained constant at high intensity conditions and was related to TTF.