Miura Hajime, McCully Kevin, Nioka Shoko, Chance Britton
Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, PA 19104, Philadelphia, USA.
Eur J Appl Physiol. 2004 Mar;91(2-3):273-8. doi: 10.1007/s00421-003-0964-6. Epub 2003 Oct 22.
This study tested whether regional differences in oxygenation status could result from differences in muscle fiber architecture. Architectural properties, oxygen supply, and consumption in the medial head of the gastrocnemius muscle (GM) were determined in vivo in six men using B-mode ultrasound and functional near infrared (NIR) imaging devices. Fascicle length, fascicle angle, NIR-O(2) saturation (deoxygenated Hb or oxygenated Hb), and NIR-blood volume (sum of deoxygenated and oxygenated Hb) were obtained in the distal and proximal portions of the GM at rest and during contraction. Exercise consisted of 2 min of standing plantar flexion at 1 Hz with an additional load of 50% of each subject's weight. Plantar flexion produced larger decreases (Delta: difference between rest and exercise values) in NIR-O(2) saturation [mean saturation (SD) of 0.14 (0.05) vs 0.07 (0.04) optical density units] and NIR-blood volume [mean saturation (SD) of -0.23 (0.08) vs -0.13 (0.04) optical density units] in the distal compared with the proximal portion ( P<0.05 for all comparisons). It also produced larger changes (Delta) in fascicle length [mean length (SD) of -16.5 (4.7) vs -8.2 (4.2) mm] and fascicle angle (mean angle (SD) of 10.8 (1.4) degrees vs 3.9 (2.1) degrees ] in the distal compared with the proximal portion ( P<0.05 for all comparisons). There were significant correlations between DeltaNIR-O(2 )saturation and Deltafascicle length ( r=-0.84, P<0.05), and between DeltaNIR-O(2) saturation and Deltafascicle angle ( r=-0.90, P<0.05), between DeltaNIR-blood volume and Deltafascicle length ( r=0.91, P<0.05), between DeltaNIR-blood volume and Deltafascicle angle ( r=-0.85, P<0.05). In conclusion, the plantar flexion exercise produced regional differences in oxygenation status consistent with regional differences in muscle architecture.
本研究测试了氧合状态的区域差异是否可能由肌纤维结构差异导致。使用B型超声和功能性近红外（NIR）成像设备，在六名男性体内测定了腓肠肌内侧头（GM）的结构特性、氧气供应和消耗情况。在静息和收缩状态下，获取了GM远端和近端部分的肌束长度、肌束角度、NIR-O₂饱和度（脱氧血红蛋白或氧合血红蛋白）以及NIR血容量（脱氧血红蛋白和氧合血红蛋白之和）。运动包括以1Hz频率进行2分钟的站立位跖屈，并额外施加相当于每个受试者体重50%的负荷。与近端部分相比，跖屈导致GM远端的NIR-O₂饱和度[平均饱和度（标准差）为0.14（0.05）对0.07（0.04）光密度单位]和NIR血容量[平均饱和度（标准差）为-0.23（0.08）对-0.13（0.04）光密度单位]下降幅度更大（P<0.05，所有比较）。它还使GM远端的肌束长度[平均长度（标准差）为-16.5（4.7）对-8.2（4.2）mm]和肌束角度（平均角度（标准差）为10.8（1.4）度对3.9（2.1）度）变化幅度比近端部分更大（P<0.05，所有比较）。DeltaNIR-O₂饱和度与Delta肌束长度之间（r=-0.84，P<0.05）、DeltaNIR-O₂饱和度与Delta肌束角度之间（r=-0.90，P<0.05）、DeltaNIR血容量与Delta肌束长度之间（r=0.91，P<0.05）以及DeltaNIR血容量与Delta肌束角度之间（r=-0.85，P<0.05）均存在显著相关性。总之，跖屈运动产生的氧合状态区域差异与肌肉结构的区域差异一致。
