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Use of Heart Rate Variability to Estimate Lactate Threshold in Coronary Artery Disease Patients during Resistance
Rodrigo P Simões1, Renata G Mendes1, Viviane Castello-Simões1
1Cardiopulmonary Physical Therapy Laboratory, Department of Physical Therapy, Federal University of Sao Carlos , Sao Carlos - Sao Paulo, Brazil.
Insights
Heart rate variability (HRV) effectively estimates the first lactate threshold (LT1) during resistance exercise in coronary artery disease (CAD) patients. This finding supports using HRV for exercise prescription in CAD populations.
Area of Science:
- Exercise Physiology
- Cardiovascular Health
- Biomedical Engineering
Background:
- Assessing exercise intensity in coronary artery disease (CAD) patients is crucial for safe and effective training.
- The first lactate threshold (LT1) is a key indicator of exercise intensity, but its determination during resistance exercise can be challenging.
- Heart rate variability (HRV) offers a non-invasive method to assess autonomic nervous system responses during exercise.
Purpose of the Study:
- To investigate the feasibility of identifying the first lactate threshold (LT1) during discontinuous resistance exercise in CAD patients.
- To determine if heart rate variability (HRV) responses correlate with blood lactate (BL) responses during this protocol.
- To explore the potential of HRV as a tool for estimating LT1 in CAD.
Main Methods:
- A discontinuous resistance exercise protocol was administered to elderly men, including those with CAD and a healthy control group (CG).
- One-repetition maximum (1RM) testing was performed, followed by incremental resistance exercise loads.
- Blood lactate (BL) concentrations and heart rate variability (HRV) were measured throughout the exercise test.
Main Results:
- The estimated LT1 occurred at approximately 30% 1RM in both CAD and CG groups.
- HRV indices showed decreased parasympathetic modulation until LT1 and stabilization thereafter in both groups.
- Sympathetic and parasympathetic modulation indices increased in the CAD group from 30% 1RM compared to the CG.
Conclusions:
- HRV is a viable tool for estimating LT1 during discontinuous resistance exercise in CAD patients.
- The findings suggest that HRV monitoring can aid in prescribing endurance resistance exercise for cardiovascular protection in CAD.
- Autonomic responses, particularly cardiac vagal modulation, are important indicators for managing cardiovascular risk in CAD populations.
Abstract:
The aim of this study was to investigate whether it is possible to identify the first turn point of blood lactate (BL) concentration (1st lactate 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.
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