Use of Heart Rate Variability to Estimate LT and VT

Abstract

The purpose of this study was to determine if changes in heart rate variability during incremental exercise could be used to estimate lactate threshold and ventilatory threshold in healthy adults. Twenty-four adults performed graded maximal cycle ergometry to volitional fatigue. Blood lactate, heart rate, RR interval, and respiratory gas exchange were monitored. Heart rate variability was analyzed using time domain indices (standard deviation and mean successive difference). A marked RR interval deflection point was found in the region of lactate threshold and ventilatory threshold, and was identified as the heart rate variability threshold. Mean differences between heart rate variability threshold, ventilatory threshold, and lactate threshold ranged from 0.06 +/- 0.3 to 0.12 +/- 0.2 L.min (-1). Correlations between the different measures ranged from 0.82 - 0.89. A small but significant difference was found between ventilatory threshold and lactate threshold (p < 0.05). There was not a significant difference between heart rate variability threshold and lactate threshold (p > 0.05), nor between heart rate variability threshold and ventilatory threshold (p > 0.05). The data suggest the heart rate variability threshold coincides with lactate threshold and ventilatory threshold during graded exercise and can be used for the detection of lactate threshold in healthy adults.

Reliability of heart rate variability threshold and parasympathetic reactivation after a submaximal exercise test

“…An increasing amount of evidence shows that the HRVT point coincides with the ventilatory and lactate threshold 4,11,12,13 , which are considered simple and practical measures for estimating the aerobic/anaerobic transition. Therefore, our results suggest that, beyond being a valid indicator of parasympathetic withdrawal, HRVT is a reproducible measure in a submaximal exercise test.…”

“…Another relative limitation that should be addressed is the absence of ventilatory and/or lactate threshold assessment during the incremental stress test. However, the primary objective of this study was to evaluate the reproducibility of HRVT and r-MSSD analysis immediately after a submaximal stress test and not the validity of these tools, which has been tested in previous work 4,11,13 . Another important observation is the wide variation in BMI in the sample studied, which divides the sample in normal weight and overweight men.…”

“…The point where the values in these two parasympathetic indices are stabilized is called the heart rate variability threshold (HRVT) and is considered an indicator of parasympathetic deactivation during an incremental exercise test 6,7,11 . Recent publications demonstrated that HRVT coincided with the first ventilatory threshold and lactate threshold, suggesting that HRVT might be a practical and attractive alternative to identify adequate workload for exercise prescription 4,12,13 . Conversely, analysis of vagal activity immediately post-exercise has been considered a complementary alternative for monitoring training status and control of internal load 14,15,16 .…”

“…Assessment of cardiac autonomic nervous system modulation during an incremental stress test or during the recovery phase has been considered a promising strategy for risk stratification and exercise prescription for different populations 1,2,3,4,5 . As established, during exercise there is reciprocity in heart rate modulation between sympathetic hyperactivity and parasympathetic inhibition 6,7,8 ; short-term, post-exercise cardiovascular adaptation is associated with a simultaneous rapid increase in parasympathetic and decrease in sympathetic activity 9,10 .…”

Determination of Lactate Thresholds in Maximal Running Test by Heart Rate Variability Data Set

“…second lactate and ventilatory threshold -LT 2 and VT 2 , respectively) (3,5). As a result, studies have suggested that HRV analysis may be a potential and useful tool to estimate the exercise intensity of the first and second physiological thresholds (4,(6)(7)(8).…”