title: Use of Heart Rate Variability to Estimate Lactate Threshold in Coronary Artery Disease Patients during Resistance Exercise.
abstract: The aim of this study was to investigate whether it is possible to identify the first turn point of blood lactate (BL) concentration (1stlactate threshold - LT1) during a discontinuous resistance exercise protocol in coronary artery disease (CAD) patients and verify if heart rate variability (HRV) responses are consistent with BL responses. A total of 22 elderly men, 12 with CAD and 10 apparently healthy (control group = CG), underwent one-repetition maximum (1RM) testing on an inclined leg press. Discontinuous resistance exercise testing (DRET) was initiated at 10% of the 1RM with subsequent increases of 10% until 30% and after this percentage, 5% increments of 1RM was carried out. The load corresponding to LT1 was approximately 30% 1RM in both groups; and the LT1 estimate by HRV was associated with BL responses. HRV indices representing parasympathetic modulation decreased with increasing loads until LT1 and stabilized thereafter in both groups, and HRV indices representing sympathetic and parasympathetic modulations only increased in the CAD group from 30% 1RM with higher values after this load in relation to the CG. We conclude HRV appears to be an effective tool to estimate the LT1 during discontinuous resistance exercise in patients with CAD. In addition, these results may have an impact on the prescription of endurance resistance exercise in the CAD population, as cardiac vagal modulation is an important indicator of cardiovascular protection and the over-activity of sympathetic modulation is related to cardiovascular risk.
authors.affiliation: Cardiopulmonary Physical Therapy Laboratory, Department of Physical Therapy, Federal University of Sao Carlos , Sao Carlos - Sao Paulo, Brazil.
authors.forename: Rodrigo P
authors.initials: RP
authors.lastname: Simões
authors.affiliation: Cardiopulmonary Physical Therapy Laboratory, Department of Physical Therapy, Federal University of Sao Carlos , Sao Carlos - Sao Paulo, Brazil.
authors.forename: Renata G
authors.initials: RG
authors.lastname: Mendes
authors.affiliation: Cardiopulmonary Physical Therapy Laboratory, Department of Physical Therapy, Federal University of Sao Carlos , Sao Carlos - Sao Paulo, Brazil.
authors.forename: Viviane
authors.initials: V
authors.lastname: Castello-Simões
authors.affiliation: Cardiopulmonary Physical Therapy Laboratory, Department of Physical Therapy, Federal University of Sao Carlos , Sao Carlos - Sao Paulo, Brazil.
authors.forename: Aparecida M
authors.initials: AM
authors.lastname: Catai
authors.affiliation: Department of Physical Therapy and Integrative Physiology Laboratory - College of Applied Health Sciences, University of Illinois at Chicago , Chicago, Illinois, USA.
authors.forename: Ross
authors.initials: R
authors.lastname: Arena
authors.affiliation: Cardiopulmonary Physical Therapy Laboratory, Department of Physical Therapy, Federal University of Sao Carlos , Sao Carlos - Sao Paulo, Brazil.
authors.forename: Audrey
authors.initials: A
authors.lastname: Borghi-Silva
keywords: Exercise; autonomic cardiac control; blood lactate; cardiovascular disease; strength exercise