RESUMEN
Evidence demonstrating the potential value of noninvasive cardiopulmonary exercise testing (CPET) to accurately detect exercise-induced myocardial ischemia is emerging. This case-based concept report describes CPET abnormalities in an asymptomatic at-risk man with suspected early-stage ischemic heart disease. When CPET was repeated 1 year after baseline assessment, his cardiovascular function had worsened, and an anti-atherosclerotic regimen was initiated. When the patient was retested after 3.3 years, the diminished left ventricular function had reversed with pharmacotherapy directed at decreasing cardiovascular events in patients with coronary artery disease. Thus, in addition to identifying appropriate patients in need of escalating therapy for atherosclerosis, CPET was useful in monitoring progression and reversal of abnormalities of the coronary circulation in a safe and cost-effective manner without the use of radiation. Serial CPET parameters may be useful to track changes marking the progression and/or regression of the underlying global ischemic burden.
Asunto(s)
Umbral Anaerobio/fisiología , Prueba de Esfuerzo/estadística & datos numéricos , Isquemia Miocárdica/diagnóstico , Adulto , LDL-Colesterol/sangre , Progresión de la Enfermedad , Prueba de Esfuerzo/métodos , Estudios de Seguimiento , Frecuencia Cardíaca , Humanos , Masculino , Isquemia Miocárdica/sangre , Isquemia Miocárdica/fisiopatología , Consumo de Oxígeno/fisiología , Reproducibilidad de los ResultadosRESUMEN
PURPOSE: The purpose of this study was to determine the relationship between various lactate-threshold (LT) definitions and the average running velocity during a 10-km and a 21.1-km time trial (TT). METHODS: Thirteen well-trained runners completed an incremental maximal exercise test, a 10-km TT, and a 21.1-km TT on a motorized treadmill. Blood samples were collected through a venous catheter placed in an antecubital vein. Pearson's correlation coefficients were used to determine the relationship between the running velocity at the different LT definitions and the average running velocity during each TT. A dependent t test was used to determine statistical differences for the mean lactate response between the 2 running distances. RESULTS: The LT(Dmax), the point on the regression curve that yielded the maximal perpendicular distance to the straight line formed by the 2 endpoints, was the LT definition with the highest correlation for both 10-km (r = .844) and 21.1-km TTs (r = .783). The velocity at the LT(Dmax) was not, however, the velocity closest to the performance velocity for either distance. The mean running velocity at each LT was significantly different and tended to overestimate the mean TT performance velocities. The mean lactate concentration during the 10-km TT (3.52 + or - 1.58 mmol) was significantly higher than during the 21.1-km TT (1.86 + or - 0.90 mmol). CONCLUSION: These results indicate that a single LT point cannot be reliably associated with different running distances. Furthermore, these data suggest that a different methodology for estimating the LT that considers individual responses might be required for different running distances.