Search results for " variability"
showing 10 items of 853 documents
Effects of eight weeks physical training on physical performance and heart rate variability in children
2013
Kraama, Liisa. 2013. Kahdeksan viikon fyysisen harjoittelun vaikutus lasten fyysiseen suorituskykyyn ja sydämen sykevaihteluun. Jyväskylän yliopisto, Liikuntabiologian laitos. Liikuntafysiologian Pro gradu –tutkielma. 52 s. Lasten ja kasvuikäisten nuorten fyysinen aktiivisuus ja aerobinen kapasiteetti ovat vähentyneet viimeisten vuosikymmenten aikana. Fyysisesti aktiivisilla aikuisilla on todettu olevan enemmän sydämen sykevaihtelua kuin vähemmän aktiivisilla. Aikuisilla on harjoittelun aikaansaamien fyysisen suorituskyvyn muutosten todettu olevan yhteydessä sykevaihtelun, erityisesti parasympaattista aktiivisuutta kuvaavaan korkean taajuuden sykevaihtelun, kasvuun. Tässä pro gradu -tutkiel…
Physiological and autonomic stress responses after prolonged sleep restriction and subsequent recovery sleep in healthy young men
2018
Purpose Sleep restriction is increasingly common and associated with the development of health problems. We investigated how the neuroendocrine stress systems respond to prolonged sleep restriction and subsequent recovery sleep in healthy young men. Methods After two baseline (BL) nights of 8 h time in bed (TIB), TIB was restricted to 4 h per night for five nights (sleep restriction, SR, n = 15), followed by three recovery nights (REC) of 8 h TIB, representing a busy workweek and a recovery weekend. The control group (n = 8) had 8 h TIB throughout the experiment. A variety of autonomic cardiovascular parameters, together with salivary neuropeptide Y (NPY) and cortisol levels, were assessed.…
Effects of eight weeks of physical training on physical performance and heart rate variability in children
2017
Study aim: Physically active adults have been shown to have higher heart rate variability (HRV) than less active adults, but less is known about children in this regard. In adults, training-induced changes in physical performance have been shown to be related to increase in HRV, especially in its high frequency component (HF), which is a marker of parasympathetic activity. The purpose of this study was to examine whether 8 weeks of instructed physical training would improve physical performance and cardiac autonomic function (HRV) in secondary school pupils and to examine the relationship between changes in physical performance and the function of the autonomic nervous system. Material and …
Using altered states of consciousness in improvisational music therapy : the potential of resonance frequency breathing
2018
Improvisational music therapy is a type of creative arts therapy in which clients are encouraged to express themselves through the symbolic and non-verbal medium of music, by creating free music improvisations together with the therapist. The present research aims at investigating whether the efficacy of this method can be further enhanced by purposefully accessing the ego-quieting properties of altered states of consciousness. This work proceeds in three main steps. First, the notions of consciousness and its alteration are examined and reformulated, resulting in a more comprehensive theoretical model. Then, existing methods for inducing altered states of consciousness are evaluated in ter…
Physiological, Perceptual, and Performance Responses to the 2-Week Block of High- versus Low-Intensity Endurance Training
2022
Purpose This study examined the physiological, perceptual, and performance responses to a 2-week block of increased training load and compared whether responses differ between high-intensity interval (HIIT) and low-intensity (LIT) endurance training. Methods Thirty recreationally trained males and females performed a two-week block of 10 HIIT-sessions (INT, n = 15) or 70 % increased volume of LIT (VOL, n = 15). Running time in the 3000 m and basal serum and urine hormone concentrations were measured before (T1) and after the block (T2), and after a recovery week (T3). In addition, weekly averages of nocturnal heart rate variability (HRV) and perceived recovery were compared to the baseline.…
The relationship between leisure-time physical activity and stress on workdays with special reference to heart rate variability analyses
2016
The purpose of this study was to investigate how physical activity (PA), cardio- respiratory fitness, and body composition are associated with objective heart rate variability (HRV)-based indicators of stress and recovery on workdays. Additionally, the association of subjective self-reported stress with HRV-based stress was investigated. Samples of 81 healthy men (age 26–40 years), and 16 275 Finnish employees (6863 men and 9412 women; age 18–65 years) were assessed in the cross-sectional analyses. A sample of 221 overweight psychologically distressed individuals (36 men and 185 women; age 26–60 years) was examined in both cross-sectional and longitudinal analyses. HRV-based stress and reco…
Assessing game experience: Heart rate variability, in-game behavior and self-report measures
2014
Assessing game experience by means of recordings of physiological reactions elicited during game play is a technique that has gained popularity in recent years in the field of digital games research. However, since physiological signals are typically linked to several psychological processes, the use of some measures such as cardiac activity or heart rate (HR) remains problematic. The goal of the present study is to investigate to what extent game logs and self-report measures of game experience have a predictive value for heart rate variability during game play. Our results showed that the accurate registration of in-game behaviors by means of game logs carries the potential of providing r…
Single-cell analysis of population context advances RNAi screening at multiple levels
2012
Isogenic cells in culture show strong variability, which arises from dynamic adaptations to the microenvironment of individual cells. Here we study the influence of the cell population context, which determines a single cell's microenvironment, in image‐based RNAi screens. We developed a comprehensive computational approach that employs Bayesian and multivariate methods at the single‐cell level. We applied these methods to 45 RNA interference screens of various sizes, including 7 druggable genome and 2 genome‐wide screens, analysing 17 different mammalian virus infections and four related cell physiological processes. Analysing cell‐based screens at this depth reveals widespread RNAi‐induce…
The effects of heart rate variability and cardiac cycle time on learning in trace eye-blink conditioning
2017
Ärsykkeen sydämen sykkeeseen ajastamisella on huomattu olevan yhteyttä sensoriseen havainnointiin ja korkeampaan kognitiiviseen prosessointiin, kun sykevälivaihtelu (HRV)puolestaan on yhdistetty tarkkaavaisuuteen. Tässä tutkimuksessa tarkasteltiin sykevälivaihtelun sekä ärsykkeen sydämen sykkeeseen ajastamisen yhteyksiä oppimiseen. Koehenkilöt osallistuivat silmäniskuehdollistumiskokeeseen, missä ärsykkeet oli ajastettu joko sydämen sykkeen systoliseen tai diastoliseen vaiheeseen. HRV:n ja EEG:n mittaaminen aloitettiin viisi minuuttia ennen kokeen alkua ja sitä jatkettiin viisi minuuttia kokeen loppumisen jälkeen. Tutkimuksessa tarkasteltiin kuutta HRV-muuttujaa: sykevälin keskiarvo (MRR), …
Spatial and temporal variability of rainfall over the Republic of Djibouti from 1946 to 2017.
2021
20 pages; International audience; For the first time, the spatial and temporal variability of rainfall in the Republic of Djibouti is investigated using data from 14 weather stations over the period 1946–2017. Due to limited data availability, high-resolution long-term satellite rainfall products (CHIRPS, PERSIANN-CDR, TAMSATv3, ARC2) and ERA5 reanalysis also contribute to document time–space rainfall variability at monthly, seasonal and annual scales. Principal component analysis identifies two spatially coherent regions of rainfall variability in the east (coastal zone) and the west (inland zone) of the country. Annual rainfall amounts are everywhere very low (60–300 mm), but with contras…