Muscle Oxygen Dynamics During Cycling Exercise in Angina Pectoris Patients

Muscle O-2 dynamics during ramp cycling exercise were compared between angina pectoris patients (AP; n = 7, age: 73 +/- 6 years) after coronary artery bypass grafting and age-, height-, and body weight-matched elderly control subjects (CON; n = 7, age: 74 +/- 8 years). Muscle O-2 saturation (SmO2) and relative change in deoxygenated (Delta deoxy-Hb) and total hemoglobin concentration (Delta total-Hb) were measured continuously during exercise in the vastus lateralis (VL) by near infrared spatial resolved spectroscopy. Pulmonary O-2 uptake (VO2) was also monitored throughout exercise to determine peak VO2. In AP, SmO2 was significantly higher, and Delta deoxy-Hb was significantly lower during exercise, compared to CON. In all subjects, Delta SmO2 (values at peak exercise minus values at resting) was negatively correlated to peak VO2 (r = -0.52, p < 0.05), and Delta deoxy-Hb at peak exercise tended to be negatively associated with peak VO2 (r = 0.48, p = 0.07). Blunted skeletal muscle deoxygenation response was observed in AP patients, which may be related to lower aerobic capacity in AP patients.