Differences in oxygenation kinetics between the dominant and non-dominant flexor digitorum profundus in rock climbers

Purpose. This study examined differences in oxygenation kinetics in the non-dominant and dominant flexor digitorum profundus (FDP) of rock climbers. Methods. Participants consisted of 28 sport climbers with a range of on-sight abilities (6a+ to 8a French Sport). Using near infrared spectroscopy, oxygenation kinetics of the FDP was assessed by calculating the time to half recovery (t½ recovery) of the tissue saturation index (TSI) following 3-5 min of ischemia. Results. A 2-way mixed model ANOVA found a non-significant interaction (p =0.112) for TSI x sex. However, there was a significant the main effect (p =0.027) handedness (dominant vs. non-dominant FDP). The dominant forearm recovered 13.6% quicker (t½ recovery mean difference = 1.12 sec, 95% CI 0.13 to 2.10 sec) compared to the non-dominant FDP. This was not affected by 6-month on-sight climbing ability or sex (p =0.839, p =0.683). Conclusions. Significant intra-individual differences in oxygenation kinetics of the FDP were found. Improvements in oxygenation kinetics within the FDP are likely due to the abilities of the muscle to deliver, perfuse and consume oxygen. These enhancements may be due to structural adaptations in the microvasculature such as an increase in capillary density and an enhanced improvement in capillary filtration.

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