Angina pectoris and blood lactate concentration during graded exercise

Nineteen patients with angina pectoris referred for preoperative evaluation were studied by psychophysical scaling of the chest pain according to Borg and blood lactate determination at rest and during a graded exercise test. The exercise tests consisted of stepwise increments of 10 W every min. Anginal pain, systolic blood pressure, heart rate (HR), and blood lactate concentration were determined at the end of each work load. The exercise test was interrupted at a rated anginal pain level (RAP) of 5-6/9 ("strong"), and this load was referred to as Wmax. The patients were divided into three groups: A with a Wmax less than or equal to 74 W, B 75-124 W, and C greater than or equal to 125 W. At submaximal loads HR was almost identical at the same absolute work load in all three groups. The heart rate at Wmax varied, however, and averaged 98 (A), 118 (B), and 136 (C), respectively. Corresponding peak values for RAP were 3.8, 4.5, and 4.8. Blood lactate at rest ranged from 1.0-1.6 mmol X 1-1 and increased curvilinearly with intensity, which was also the case for RAP. RAP was almost linearly related to blood lactate in all three groups suggesting a causal relationship between these two parameters.