Muscle Oxygen Dynamics During Cycling Exercise in Angina Pectoris Patients

Abstract

Muscle O₂ 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 O₂ saturation (SmO₂) and relative change in deoxygenated (∆deoxy-Hb) and total hemoglobin concentration (∆total-Hb) were measured continuously during exercise in the vastus lateralis (VL) by near infrared spatial resolved spectroscopy. Pulmonary O₂ uptake (VO₂) was also monitored throughout exercise to determine peak VO₂. In AP, SmO₂ was significantly higher, and ∆deoxy-Hb was significantly lower during exercise, compared to CON. In all subjects, ∆SmO₂ (values at peak exercise minus values at resting) was negatively correlated to peak VO₂ (r = −0.52, p < 0.05), and ∆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.