Forearm oxygenation and blood flow kinetics during a sustained contraction in multiple ability groups of rock climbers

Abstract: Currently, the physiological mechanisms that allow elite level climbers to maintain intense isometric contractions for prolonged periods of time are unknown. Furthermore, it is unclear whether blood flow or muscle oxidative capacity best governs performance. This study aimed to determine the haemodynamic kinetics of 2 forearm flexor muscles in 3 ability groups of rock climbers. Thirty-eight male participants performed a sustained contraction at 40% of maximal voluntary contraction (MVC) until volitional fatigue. Oxygen saturation and blood flow was assessed using near infrared spectroscopy and Doppler ultrasound. Compared to control, intermediate, and advanced groups, the elite climbers had a significantly (P < 0.05) higher strength-to-weight ratio (MVC/N), de-oxygenated the flexor digitorum profundus significantly (P < 0.05) more (32, 34.3, and 42.8 vs. 63% O₂, respectively), and at a greater rate (0.32, 0.27, and 0.34 vs. 0.77 O₂%·s⁻¹, respectively). Furthermore, elite climbers de-oxygenated the flexor carpi radialis significantly (P < 0.05) more and at a greater rate than the intermediate group (36.5 vs. 14.6% O₂ and 0.43 vs. 0.1O₂%·s⁻¹, respectively). However, there were no significant differences in total forearm ∆ blood flow. An increased MVC/N is not associated with greater blood flow occlusion in elite climbers; therefore, oxidative capacity may be more important for governing performance.