title: Heart-rate variability and blood-lactate threshold interaction during progressive resistance exercise in healthy older men.
abstract: The objective of this study was to (a) evaluate the impact of the leg press, at variable percentages of 1 repetition maximum (1RM), on heart rate variability (HRV) and blood lactate and (b) determine the relationship between HRV with blood lactate in a healthy elderly cohort. Ten healthy men (64 +/- 4 years) participated in a progressive leg-press protocol to maximal exertion. Initially, 1RM for the leg press was determined for all subjects. The protocol then began at 10% of 1RM, with subsequent increases of 10% until 30% of 1RM, followed by incremental adjustments of 5% until exhaustion. The measurement of instantaneous R-R interval variability from Poincare plots (SD1 and SD2) and time domain indexes (RMSSD and RMSM), blood pressure, and blood lactate were obtained at rest and all leg-press loads. Significant alterations of HRV and blood lactate were observed from 30% of 1RM leg press (p < 0.05). Additionally, significant correlations were found between the lactate threshold (LT) and the RMSSD threshold (r = 0.78; p < 0.01), and between the LT and SD1 threshold (r = 0.81, p < 0.01). We conclude that metabolic and cardiovascular alterations are apparent during relatively low resistance exercise (RE) loads in apparently healthy subjects. In addition, HRV indexes were associated with blood-lactate levels during RE. The practical applications is the possibility of using HRV as a noninvasive measure obtained at a relatively low cost may be used to identify neural and metabolic alterations during RE in older subjects.
authors.affiliation: Cardiopulmonary Physiotherapy Laboratory, Nucleus of Research in Physical Exercise, Physiotherapy Department, Federal University of Sao Carlos, Sao Carlos, Brazil.
authors.forename: Rodrigo P
authors.initials: RP
authors.lastname: Simões
authors.forename: Renata G
authors.initials: RG
authors.lastname: Mendes
authors.forename: Viviane
authors.initials: V
authors.lastname: Castello
authors.forename: Heloísa G
authors.initials: HG
authors.lastname: Machado
authors.forename: Larissa B
authors.initials: LB
authors.lastname: Almeida
authors.forename: Vilmar
authors.initials: V
authors.lastname: Baldissera
authors.forename: Aparecida M
authors.initials: AM
authors.lastname: Catai
authors.forename: Ross
authors.initials: R
authors.lastname: Arena
authors.forename: Audrey
authors.initials: A
authors.lastname: Borghi-Silva
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D015308:Anaerobic Threshold; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008875:Middle Aged; D055070:Resistance Training
chemical_list: D019344:Lactic Acid