McCully K K, Iotti S, Kendrick K, Wang Z, Posner J D, Leigh J, Chance B
Department of Medicine, Medical College of Pennsylvania, Philadelphia 19131.
J Appl Physiol (1985). 1994 Jul;77(1):5-10. doi: 10.1152/jappl.1994.77.1.5.
Simultaneous measurements of phosphocreatine (PCr) and oxyhemoglobin (HbO2) saturation were made during recovery from exercise in calf muscles of five male subjects. PCr was measured using magnetic resonance spectroscopy in a 2.0-T 78-cm-bore magnet with a 9-cm-diam surface coil. Relative HbO2 saturation was measured as the difference in absorption of 750- and 850-nm light with use of near-infrared spectroscopy. The light source and detectors were 3 cm apart. Exercise consisted of isokinetic plantar flexion in a supine position. Two 5-min submaximal protocols were performed with PCr depletion to 60% of resting values and with pH values of > 7.0. Then two 1-min protocols of rapid plantar flexion were performed to deplete PCr values to 5-20% of resting values with pH values of < 6.8. Areas of PCr peaks (every 8 s) and HbO2 saturation (every 1 s) were fit to a monoexponential function, and a time constant was calculated. The PCr time constant was larger after maximal exercise (68.3 +/- 10.5 s) than after submaximal exercise (36.0 +/- 6.5 s), which is consistent with the effects of low pH on PCr recovery. HbO2 resaturation approximated submaximal PCr recovery and was not different between maximal (29.4 +/- 5.5 s) and submaximal (27.6 +/- 6.0 s) exercise. We conclude that magnetic resonance spectroscopy measurements of PCr recovery and near-infrared spectroscopy measurements of recovery of HbO2 saturation provide similar information as long as muscle pH remains near 7.0.
对五名男性受试者小腿肌肉运动恢复过程中的磷酸肌酸（PCr）和氧合血红蛋白（HbO2）饱和度进行了同步测量。PCr采用磁共振波谱法在一台2.0-T、78厘米孔径的磁体中，使用直径9厘米的表面线圈进行测量。相对HbO2饱和度通过使用近红外光谱法测量750纳米和850纳米光吸收的差异来测定。光源和探测器相距3厘米。运动包括仰卧位的等速跖屈。进行了两个5分钟的次最大强度方案，使PCr耗尽至静息值的60%，且pH值>7.0。然后进行了两个1分钟的快速跖屈方案，使PCr值耗尽至静息值的5%-20%，且pH值<6.8。对PCr峰面积（每8秒）和HbO2饱和度（每1秒）拟合单指数函数，并计算时间常数。最大运动后PCr的时间常数（68.3±10.5秒）大于次最大运动后（36.0±6.5秒），这与低pH对PCr恢复的影响一致。HbO2再饱和接近次最大运动时的PCr恢复，且在最大运动（29.4±5.5秒）和次最大运动（27.6±6.0秒）之间无差异。我们得出结论，只要肌肉pH值保持在7.0左右，PCr恢复的磁共振波谱测量和HbO2饱和度恢复的近红外光谱测量提供的信息相似。
