Abstract

In this study quantitative near-infrared-spectroscopy (NIRS) was investigated as a potential tool to measure local O₂ consumption (mVO₂) in human bone (tibia) in comparison with muscle (musculus tibialis anterior). Both tissues were examined at rest and during 80% maximum voluntary isometric muscle contraction. Fifteen subjects were tested. Local variations in oxy-hemoglobin (O₂Hb), desoxy-hemoglobin (HHb), and total hemoglobin (tHb) were investigated with a continuously operating NIRS system. mVO₂ was determined in phases of applied arterial occlusion. At rest mVO₂ was five times higher in muscle than in bone. However, both mVO₂ values showed a distinct correlation with skin-fold thickness. At rest and only in bone we recorded a periodical variation of O₂Hb. HHb was almost constant. This variation of O₂Hb and the resulting variation in tHb indicated chances in blood volume, which are not compatible with the solid nature of bone. During muscle contraction, mVO₂ in muscle increased about twenty fold. As expected, mVO₂ in bone did not significantly increase during muscle contraction. In conclusion, NIRS was confirmed as a valid method to determine the excess mVO₂ in muscle during contraction. For mVO₂ measurements in bone more sophisticated localization techniques are required to separate the effects derived from bone and skin.

© 2003 SPIE