Discover the most talked about and latest scientific content & concepts.

Concept: Heart rate variability


To assess the validity of RR intervals and short-term heart rate variability (HRV) data obtained from the Polar V800 heart rate monitor, in comparison to an electrocardiograph (ECG).

Concepts: Cardiology, Psychometrics, Heart rate, Electrocardiography, Heart rate variability, Heart rate monitor


The aim of this study was to test the possibility of the ultra-short-term lnRMSSD (measured in 1-min post-1-min stabilization period) to detect training induced adaptations in futsal players. Twenty-four elite futsal players underwent HRV assessments pre- and post-three or four weeks preseason training. From the 10-min HRV recording period, lnRMSSD was analyzed in the following time segments: 1) from 0-5 min (i.e., stabilization period); 2) from 0-1 min; 1-2 min; 2-3 min; 3-4 min; 4-5 min and; 3) from 5-10 min (i.e., criterion period). The lnRMSSD was almost certainly higher (100/00/00) using the magnitude-based inference in all periods at the post- moment. The correlation between changes in ultra-short-term lnRMSSD (i.e., 0-1 min; 1-2 min; 2-3 min; 3-4 min; 4-5 min) and lnRMSSDCriterion ranged between 0.45-0.75, with the highest value (p = 0.75; 90% CI: 0.55 - 0.85) found between ultra-short-term lnRMDSSD at 1-2 min and lnRMSSDCriterion. In conclusion, lnRMSSD determined in a short period of 1-min is sensitive to training induced changes in futsal players (based on the very large correlation to the criterion measure), and can be used to track cardiac autonomic adaptations. Key pointsThe ultra-short-term (1 min) natural log of the root-mean-square difference of successive normal RR intervals (lnRMSSD) is sensitive to training effects in futsal playersThe ultra-short-term lnRMSSD may simplify the assessment of the cardiac autonomic changes in the field compared to the traditional and lengthier (10 min duration) analysisCoaches are encouraged to implement the ultra-short-term heart rate variability in their routines to monitor team sports athletes.

Concepts: Time, Cardiology, Heart, Measurement, Assessment, Probability theory, The Criterion, Heart rate variability


The objective of this pilot study was to explore the use of a closed-loop, allostatic, acoustic stimulation neurotechnology for individuals with self-reported symptoms of post-traumatic stress, as a potential means to impact symptomatology, temporal lobe high frequency asymmetry, heart rate variability (HRV), and baroreflex sensitivity (BRS).

Concepts: Lung, Medical statistics, Cardiology, Evaluation methods, Temporal lobe, Frequency, Heart rate variability, Lobe



The aim of this study was to compare post-exercise autonomic nervous system (ANS) recovery between High-Intensity Training Protocol (HITP) and high-intensity treadmill running ™ in ten physically fit males. For each trial ANS activity was measured though the Heart Rate Variability (HRV) markers of log-transformed square root of the successive R-R differences (lnRMSSD) and high frequency power (lnHF). These markers were analyzed in 5-min segments at 5-10 min pre-exercise period (PRE), and during the post-exercise period at 15-20min (POST15-20min), 20-25min (POST20-25min), 25-30min (POST25-30min), and 1hour (POST60min). Plasma epinephrine (E) and norepinephrine (NE) were also examined at PRE, immediately post exercise (IPE), 1-hour post (1HP), and 2-hour post (2HP). The results of this study demonstrate a significant overall time-dependent decreases in lnRMSSD and lnHF (p= 0.003) (p= 0.001) respectively in both trials. Trial-dependent differences were also observed in post-exercise lnRMSSD and lnHF measures, HITP being significantly lower than TM (p= 0.002)(p= 0.000). lnRMSSD at POST60min-HITP remained significantly lower compared to PRE (p < 0.05). lnHF returned to baseline in HIPT and TM (p= 0.081)(p= 0.065). A time dependent increase in E and NE was observed in both trials at time point IPE when compared to PRE (p < 0.05). E at 1HP and 2HP returned to near resting levels (p=0.62, p=0.26), while NE remained slightly elevated in both groups (p=0.003, p=0.021). A trial dependent increase was observed with HITP eliciting a greater E response (p=0.025) and NE response (p= 0.03). HITP causes a greater disruption of the ANS than intensity matched TM exercise.

Concepts: Nervous system, Time, Brain, Acetylcholine, Autonomic nervous system, Sympathetic nervous system, Parasympathetic nervous system, Heart rate variability


Cognitive difficulties and autonomic dysfunction have been reported separately in patients with chronic fatigue syndrome (CFS). A role for heart rate variability (HRV) in cognitive flexibility has been demonstrated in healthy individuals, but this relationship has not as yet been examined in CFS. The objective of this study was to examine the relationship between HRV and cognitive performance in patients with CFS.

Concepts: Cardiology, Heart, Avicenna, Pulse, Chronic fatigue syndrome, Heart rate variability, Malaise, Electrical conduction system of the heart


Poor social integration increases risk for poor health. The psychobiological pathways underlying this effect are not well-understood.

Concepts: Cardiology, Heart rate variability


This longitudinal study aimed at comparing heart rate variability (HRV) in elite athletes identified either in ‘fatigue’ or in ‘no-fatigue’ state in ‘real life’ conditions.

Concepts: Longitudinal study, Cardiology, Repeated measures design, Heart rate variability


To analyze if live high-train low (LHTL) effectiveness is improved when daily training is guided by heart rate variability (HRV).

Concepts: Cardiology, Heart rate variability


Prupose: To investigate the effects of a 5-km high-intensity interval exercise (HIIE) on heart rate variability (HRV) and subsequent strength performance.

Concepts: Cardiology, Heart rate variability