Heart rate variability assessment of the effect of physical training on autonomic cardiac control

BACKGROUND: The effect of exercise interventions on autonomic nervous system (ANS) control of the heart by heart rate variability (HRV) is often investigated in just one position. It was hypothesized that results of exercise-induced changes on ANS are dependent on body position and that it is possible to distinguish between exercise induced changes in vagal and sympathetic influence by taking measurements in different body positions. METHODS: One hundred eighty-three (male=100, female=83) healthy volunteers, between 18 and 22 years, participated in a prospective twelve week medium to high intensity exercise intervention study with a self-control design. The influence of the exercise intervention was investigated on supine, rising, and standing as well as on the orthostatic response. Time domain, frequency domain and nonlinear (Poincar´e) HRV analysis were performed. RESULTS: The exercise intervention lead to a significant increase (P < 0.05) in vagal influence during supine, rising, and standing. Sympathetic control in the supine position was decreased and increased during rising and standing. In the initial orthostatic response to rising from the supine position, the exercise intervention lead to increased (P < 0.05) vagal withdrawal as well as increased sympathetic control. The orthostatic response measured as the difference between standing and supine indicated only an exercise induced increase in sympathetic control. CONCLUSIONS: Exercise-induced changes in sympathetic and parasympathetic ANS control differ, depending on posture and period of measurement. Exercise induced changes in parasympathetic and sympathetic outflow, respectively, can be extracted from measurements from supine, through the orthostatic response, to standing, thereby detecting changes in ANS that are otherwise obscured.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1542-474

Stress response of the autonomic nervous system on skydiving and freefall

<em>This study investigated the influence of skydiving and freefall, as well as that of visualisation, on the autonomic nervous system balance. The results showed a shift towards sympathetic dominance in the autonomic nervous system balance during skydiving and freefall. This shift was statistically significant in the inexperienced, but not in the experienced skydivers. A similar autonomic stress response was seen in the laboratory during visualisation of skydiving. Further studies are necessary to ascertain whether a difference exists between the extent to which experienced and inexperienced skydivers can induce the biological stress response through visualisation.</em

Stress response of the autonomic nervous system on skydiving and freefall

In hierdie studie is die effek van valskermspring en vryval, sowel as van visualisering, op die balans van die outonome senuweestelsel ondersoek. Die resultate toon 'n verskuiwing na simpatiese oorheersing in die balans van die outonome senuweestelsel tydens valskermspring en vryval. Hierdie verskuiwing was statisties betekenisvol in die geval van relatief onervare springers, maar nie in ervare springers nie. 'n Soortgelyke outonome stresrespons is ook geïnduseer deur visualisering van die sprong in die laboratorium. Verdere studies is nodig om te bepaal of daar 'n verskil is in die mate waartoe die ervare en onervare springers die biologiese stresrespons deur visualisering kan induseer. This study investigated the influence of skydiving and freefall, as well as that of visualisation, on the autonomic nervous system balance. The results showed a shift towards sympathetic dominance in the autonomic nervous system balance during skydiving and freefall. This shift was statistically significant in the inexperienced, but not in the experienced skydivers. A similar autonomic stress response was seen in the laboratory during visualisation of skydiving. Further studies are necessary to ascertain whether a difference exists between the extent to which experienced and inexperienced skydivers can induce the biological stress response through visualisation

Determining heart rate variation: a comparison between direct results from V6 of the ECG and time domain, frequency domain and non-liniar analysis

Tydens die normale funksionering van die hart fluktueer die intervalle tussen opeenvolgende hartslae (R-R-intervalle) rondom 'n gemiddelde waarde. Hierdie fluktuering staan bekend as harttempovariasie (HTV). Verskillende metodes word gebruik om HTV te bepaal maar dit is nie bekend tot watter mate daar ooreenstemming is tussen die resultate van die verskillende metodes waarmee HTV ondersoek word nie. In hierdie studie word HTV, soos bepaal vanaf die EKG, vergelyk met resultate soos verkry met behulp van tyddomeinanalise, frekwensiedomeinanalise, Poincaré-grafieke en fraktaalanalise. Die resultate van hierdie studie toon dat, in individue met laer HTV, met tyddomeinanalise, frekwensiedomeinanalise, Poincaré en Alfa 1 van fraktale analise dieselfde tendense in HTV waardes verkry word as deur direkte meting van die V6- variasie op die EKG. Die resultate toon egter verder dat tyddomeinanalise, frekwensiedomeinanalise, Poincaré en fraktale analise minder sensitief is by hoër HTV waardes. Oscillation around a mean value is found in the intervals between consecutive heartbeats (R-R intervals). This oscillation is known as heart rate variability (HRV). Various methods can be used to estimate HRV, but the extent to which agreement exists between the results obtained by the different methods is not known. In this study HRV, as determined directly from the ECG, is compared to results obtained by time domain analysis, frequency domain analysis, Poincaré graphs and fractal analysis. Results showed that, in individuals with low HRV values, the results obtained by time domain analysis, frequency domain analysis, Poincaré graphs and alpha 1 of fractal analysis are comparable to those calculated directly from the ECG. However, time domain analysis, frequency domain analysis, Poincaré graphs and fractal analysis are less sensitive than direct ECG measurements in individuals with higher HRV

Determining heart rate variation a comparison between direct results from V6 of the ECG and time domain frequency domain and non-liniar analysis

Tydens die normale funksionering van die hart fluktueer die intervalle tussen opeenvolgende hartslae (R-R-intervalle) rondom 'n gemiddelde waarde. Hierdie fluktuering staan bekend as harttempovariasie (HTV). Verskillende metodes word gebruik om HTV te bepaal maar dit is nie bekend tot watter mate daar ooreenstemming is tussen die resultate van die verskillende metodes waarmee HTV ondersoek word nie. In hierdie studie word HTV, soos bepaal vanaf die EKG, vergelyk met resultate soos verkry met behulp van tyddomeinanalise, frekwensiedomeinanalise, Poincaré-grafieke en fraktaalanalise. Die resultate van hierdie studie toon dat, in individue met laer HTV, met tyddomeinanalise, frekwensiedomeinanalise, Poincaré en Alfa 1 van fraktale analise dieselfde tendense in HTV waardes verkry word as deur direkte meting van die V6- variasie op die EKG. Die resultate toon egter verder dat tyddomeinanalise, frekwensiedomeinanalise, Poincaré en fraktale analise minder sensitief is by hoër HTV waardes. Oscillation around a mean value is found in the intervals between consecutive heartbeats (R-R intervals). This oscillation is known as heart rate variability (HRV). Various methods can be used to estimate HRV, but the extent to which agreement exists between the results obtained by the different methods is not known. In this study HRV, as determined directly from the ECG, is compared to results obtained by time domain analysis, frequency domain analysis, Poincaré graphs and fractal analysis. Results showed that, in individuals with low HRV values, the results obtained by time domain analysis, frequency domain analysis, Poincaré graphs and alpha 1 of fractal analysis are comparable to those calculated directly from the ECG. However, time domain analysis, frequency domain analysis, Poincaré graphs and fractal analysis are less sensitive than direct ECG measurements in individuals with higher HRV

Relationship between exercise capacity and heart rate variability : supine and in response to an orthostatic stressor

The study investigated whether supine-measured HRV indicators, and/or HRV indicators measured during orthostatic stress are related to conventional measures of exercise and performance ability such as VO2max. Only two significant correlations (pb0.05) out of 30 tests were found between supine-determined HRV indicators and conventional measures. In contrast, fifteen of the 30 relationships calculated during orthostatic stress were significant. Relationships were at best low to moderate (0.2b|corr|b0.4). As expected, the relationships obtained during orthostatic stress were reversed from that obtained in the supine position. In summary, although HRV indicators are related to cardiovascular fitness, correlations between VO2max and these parameters are found only under very specific conditions. HRV parameters explain very little of the variance in VO2max. In addition, estimating the exercise capacity from HRV indicators requires experience and extreme caution