0000000001257068
AUTHOR
Kaisu Martinmäki
Transient changes in heart rate variability in response to orthostatic task, endurance exersice and training : with special reference to autonomic blockades and time-frequency analysis
Heart rate variability (HRV) is generally accepted as an estimate of the autonomic, particularly vagal, control of the heart. The quantitative relationship of HRV to vagal heart rate (HR) control is, however, unclear. In addition, the conventional analysis methods of HRV are not suitable for analyzing rapid adjustments of autonomic control. Time-frequency analysis methods, including short-time Fourier transform (STFT), have been developed for analyzing non-stationary signals.The present study was designed to evaluate the ability of HRV to quantify within-subject changes in autonomic HR control by using autonomic blockades and an active orthostatic task, and to study transient changes in HRV…
Heart rate variability related to effort at work
Changes in autonomic nervous system function have been related to work stress induced increases in cardiovascular morbidity and mortality. Our purpose was to examine whether various heart rate variability (HRV) measures and new HRV-based relaxation measures are related to self-reported chronic work stress and daily emotions. The relaxation measures are based on neural network modelling of individual baseline heart rate and HRV information. Nineteen healthy hospital workers were studied during two work days during the same work period. Daytime, work time and night time heart rate, as well as physical activity were recorded. An effort-reward imbalance (ERI) questionnaire was used to assess ch…
Post-exercise heart rate variability of endurance athletes after different high-intensity exercise interventions
Methodological problems have limited the number of studies on heart rate variability (HRV) dynamics immediately after exercise. We used the short-time Fourier transform method to study immediate (5 min) and slow (30 min) recovery of HRV after different high-intensity exercise interventions. Eight male athletes performed two interval interventions at 85% and 93% (IV(85) and IV(93)) and two continuous interventions at 80% and 85% (CO(80) and CO(85)) of the velocity at VO2max (vVO2max). We found no increase in high frequency power (HFP), but low frequency (LFP) and total power (TP) increased (P<0.05) during the first 5 min of the recovery after each intervention. During the 30-min recovery, HF…
Sydämen parasympaattisen säätelyn arvioiminen sykevaihtelun avulla - autonomisen hermoston salpaustutkimus
Martinmäki Kaisu. 2002. Sydämen parasympaattisen säätelyn arvioiminen sykevaihtelun avulla - autonomisen hermoston salpaustutkimus. Jyväskylän yliopisto. Liikuntafysiologian pro gradu -tutkielma. Parasympaattista hermoaktiivisuutta ei voida ihmisillä mitata suoraan, mutta sitä voidaan arvioida sydämen syketaajuudesta määritettyjen muuttujien avulla. Sykevaihtelua mitataan rutiininomaisesti ja sitä kuvaavat muuttujat ovat suhteellisen vakiintuneita. Sykemuuttujia tulkitaan ikään kuin niiden ja parasympaattisen aktiivisuuden välinen yhteys olisi lineaarinen, vaikka muuttujien mittateoreettisia ominaisuuksia ei ole tutkittu systemaattisesti. Tämän tutkimuksen tarkoituksena oli tarkastella, mil…
Effects of vigorous late-night exercise on sleep quality and cardiac autonomic activity
Sleep is the most important period for recovery from daily load. Regular physical activity enhances overall sleep quality, but the effects of acute exercise on sleep are not well defined. In sleep hygiene recommendations, intensive exercising is not suggested within the last 3 h before bed time, but this recommendation has not been adequately tested experimentally. Therefore, the effects of vigorous late-night exercise on sleep were examined by measuring polysomnographic, actigraphic and subjective sleep quality, as well as cardiac autonomic activity. Eleven (seven men, four women) physically fit young adults (VO(2max) 54±8 mL·kg(-1)·min(-1) , age 26±3 years) were monitored in a sleep labor…
Ability of short-time Fourier transform method to detect transient changes in vagal effects on hearts: a pharmacological blocking study.
Conventional spectral analyses of heart rate variability (HRV) have been limited to stationary signals and have not allowed the obtainment of information during transient autonomic cardiac responses. In the present study, we evaluated the ability of the short-time Fourier transform (STFT) method to detect transient changes in vagal effects on the heart. We derived high-frequency power (HFP, 0.20–0.40 Hz) as a function of time during active orthostatic task (AOT) from the sitting to standing posture before and after selective vagal (atropine sulfate 0.04 mg/kg) and sympathetic (metoprolol 0.20 mg/kg) blockades. The HFP minimum point during the first 30 s after standing up was calculated and…