Ferreira Leonardo F, Hueber Dennis M, Barstow Thomas J
Department of Kinesiology, Kansas State University, Manhattan, KS 66506-0302, USA.
J Appl Physiol (1985). 2007 Jan;102(1):358-67. doi: 10.1152/japplphysiol.00920.2005. Epub 2006 Oct 5.
The aim of this study was to examine the effects of assuming constant reduced scattering coefficient (mu'(s)) on the muscle oxygenation response to incremental exercise and its recovery kinetics. Fifteen subjects (age: 24 +/- 5 yr) underwent incremental cycling exercise. Frequency domain near-infrared spectroscopy (NIRS) was used to estimate deoxyhemoglobin concentration {[deoxy(Hb+Mb)]} (where Mb is myoglobin), oxyhemoglobin concentration {[oxy(Hb+Mb)]}, total Hb concentration (Total[Hb+Mb]), and tissue O(2) saturation (Sti(O(2))), incorporating both continuous measurements of mu'(s) and assuming constant mu'(s). When measuring mu'(s), we observed significant changes in NIRS variables at peak work rate Delta[deoxy(Hb+Mb)] (15.0 +/- 7.8 microM), Delta[oxy(Hb+Mb)] (-4.8 +/- 5.8 microM), DeltaTotal[Hb+Mb] (10.9 +/- 8.4 microM), and DeltaSti(O(2))(-11.8 +/- 4.1%). Assuming constant mu'(s) resulted in greater (P < 0.01 vs. measured mu'(s)) changes in the NIRS variables at peak work rate, where Delta[deoxy(Hb+Mb)] = 24.5 +/- 15.6 microM, Delta[oxy(Hb+Mb)] = -9.7 +/- 8.2 microM, DeltaTotal[Hb+Mb] = 14.8 +/- 8.7 microM, and DeltaSti(O(2))= -18.7 +/- 8.4%. Regarding the recovery kinetics, the large 95% confidence intervals (CI) for the difference between those determine measuring mu'(s) and assuming constant mu'(s) suggested poor agreement between methods. For the mean response time (MRT), which describes the overall kinetics, the 95% confidence intervals were MRT - [deoxy(Hb+Mb)] = 26.7 s; MRT - [oxy(Hb+Mb)] = 11.8 s, and MRT - Sti(O(2))= 11.8 s. In conclusion, mu'(s) changed from light to peak exercise. Furthermore, assuming a constant mu'(s) led to an overestimation of the changes in NIRS variables during exercise and distortion of the recovery kinetics.
本研究的目的是探讨假设散射系数（μ'(s)）恒定对递增运动时肌肉氧合反应及其恢复动力学的影响。15名受试者（年龄：24±5岁）进行递增式自行车运动。采用频域近红外光谱（NIRS）估计脱氧血红蛋白浓度{[脱氧（Hb+Mb）]}（其中Mb为肌红蛋白）、氧合血红蛋白浓度{[氧合（Hb+Mb）]}、总血红蛋白浓度（Total[Hb+Mb]）和组织氧饱和度（Sti(O₂)），同时进行μ'(s)的连续测量并假设μ'(s)恒定。在测量μ'(s)时，我们观察到在峰值工作率时NIRS变量有显著变化，Δ[脱氧（Hb+Mb）]（15.0±7.8μM）、Δ[氧合（Hb+Mb）]（-4.8±5.8μM）、ΔTotal[Hb+Mb]（10.9±8.4μM）和ΔSti(O₂)（-11.8±4.1%）。假设μ'(s)恒定导致在峰值工作率时NIRS变量的变化更大（与测量的μ'(s)相比，P<0.01），其中Δ[脱氧（Hb+Mb）]=24.5±15.6μM、Δ[氧合（Hb+Mb）]=-9.7±8.2μM、ΔTotal[Hb+Mb]=14.8±8.7μM和ΔSti(O₂)=-18.7±8.4%。关于恢复动力学，测量μ'(s)和假设μ'(s)恒定之间差异的95%置信区间（CI）较大，表明两种方法之间的一致性较差。对于描述总体动力学的平均反应时间（MRT），95%置信区间为MRT-[脱氧（Hb+Mb）]=26.7秒；MRT-[氧合（Hb+Mb）]=11.8秒以及MRT-Sti(O₂)=11.8秒。总之，μ'(s)在从轻运动到峰值运动过程中发生变化。此外，假设μ'(s)恒定会导致运动期间NIRS变量变化的高估以及恢复动力学的扭曲。
