Search results for "HEART RATE"
showing 10 items of 887 documents
The value of the short-term fetal heart rate variation for timing the delivery of growth-retarded fetuses.
2008
OBJECTIVE: To assess the clinical value of the short-term fetal heart rate variation (STV) for timing the delivery of severely growth-retarded fetuses, many associated with pre-eclampsia. DESIGN: Retrospective cohort study. SETTING: John Radcliffe Maternity Hospital, Oxford, UK. POPULATION: Two hundred and fifty-seven fetuses with a birthweight less than third percentile and a last computerised cardiotocography performed within 24 h of delivery. METHODS: Analysis of the relationship between antepartum STV and the perinatal outcome. MAIN OUTCOME MEASURES: Stillbirth rate and the acid-base status at birth. RESULTS: There were no stillbirths or neonatal deaths (NNDs) within 24 h in the study p…
Comparison of the 45-Second/15-Second Intermittent Running Field Test and the Continuous Treadmill Test
2012
Purposes:To compare the physiological responses and maximal aerobic running velocity (MAV) during an incremental intermittent (45-s run/15-s rest) field test (45-15FIT) vs an incremental continuous treadmill test (TR) and to demonstrate that the MAV obtained during 45-15FIT (MAV45-15) was relevant to elicit a high percentage of maximal oxygen uptake (VO2max) during a 30-s/30-s intermittent training session.Methods:Oxygen uptake (VO2), heart rate (HR), and lactate concentration ([La]) were measured in 20 subjects during 2 maximal incremental tests and four 15-min intermittent tests. The time spent above 90% and 95% VO2max (t90% and t95% VO2max, respectively) was determined.Results:Maximal ph…
Categorizing the Role of Respiration in Cardiovascular and Cerebrovascular Variability Interactions
2022
Objective: Respiration disturbs cardiovascular and cerebrovascular controls but its role is not fully elucidated. Methods: Respiration can be classified as a confounder if its observation reduces the strength of the causal relationship from source to target. Respiration is a suppressor if the opposite situation holds. We prove that a confounding/suppression (C/S) test can be accomplished by evaluating the sign of net redundancy/synergy balance in the predictability framework based on multivariate autoregressive modelling. In addition, we suggest that, under the hypothesis of Gaussian processes, the C/S test can be given in the transfer entropy decomposition framework as well. Experimental p…
Muscle metabolism, blood lactate and oxygen uptake in steady state exercise at aerobic and anaerobic thresholds
1986
Muscle metabolites and blood lactate concentration were studied in five male subjects during five constant-load cycling exercises. The power outputs were below, equal to and above aerobic (AerT) and anaerobic (AnT) threshold as determined during an incremental leg cycling test. At AerT, muscle lactate had increased significantly (p less than 0.05) from the rest value of 2.31 to 5.56 mmol X kg-1 wet wt. This was accompanied by a significant reduction in CP by 28% (p less than 0.05), whereas only a minor change (9%) was observed for ATP. At AnT muscle lactate had further increased and CP decreased although not significantly as compared with values at AerT. At the highest power outputs (greate…
Autonomic cardiac regulation in obstructive sleep apnea syndrome: evidence from spontaneous baroreflex analysis during sleep
1997
Objective. To assess spontaneous baroreceptor-heart rate reflex sensitivity during sleep in patients with obstructive sleep apnea syndrome, a condition associated with increased cardiovascular morbidity and mortality and characterized by marked sympathetic activation, which is believed to originate from hypoxic chemoreceptor stimulation, although little is known of other possible mechanisms such as baroreflex impairment. Design and methods. In 11 patients with severe obstructive sleep apnea syndrome (mean ± SD age 46.8 ± 8.1 years, apnea/hypopnea index 67.9 ± 19.1 h), who were normotensive or borderline hypertensive during wakefulness by clinic blood pressure measurements, finger blood pres…
Strength of memory encoding affects physiological responses in the Guilty Actions Test
2009
The Guilty Actions Test (GAT) is a valid and scientifically sound technique of forensic psychophysiology that allows for the detection of concealed memories. However, its application has been challenged because the results might be affected by the culprit's forgetting of crime details as well as the leakage of information to innocents. In the current study, these aspects were examined by varying the amount of time between a mock crime and the subsequent GAT, as well as by contrasting culprits with informed innocents. It turned out that culprits specifically forgot peripheral crime details during a period of 2 weeks whereas informed innocents showed similar forgetting for all details. As a c…
Baroreflex control of heart rate during sleep in severe obstructive sleep apnoea: effects of acute CPAP
2006
Baroreflex control of heart rate during sleep (baroreflex sensitivity; BRS) has been shown to be depressed in obstructive sleep apnoea (OSA), and improved after treatment with continuous positive airway pressure (CPAP). Whether CPAP also acutely affects BRS during sleep in uncomplicated severe OSA is still debatable. Blood pressure was monitored during nocturnal polysomnography in 18 patients at baseline and during first-time CPAP application. Spontaneous BRS was analysed by the sequence method, and estimated as the mean sequence slope. CPAP did not acutely affect mean blood pressure or heart rate but decreased cardiovascular variability during sleep. Mean BRS increased slightly during CPAP…
Effects of Water Immersion Methods on Postexercise Recovery of Physical and Mental Performance.
2019
Ahokas, EK, Ihalainen, JK, Kyrolainen, H, and Mero, AA. Effects of water immersion methods on postexercise recovery of physical and mental performance. J Strength Cond Res 33(6): 1488-1495, 2019-The aim of this study was to compare the effectiveness of 3 water immersion interventions performed after active recovery compared with active recovery only on physical and mental performance measures and physiological responses. The subjects were physically active men (age 20-35 years, mean ± SD 26 ± 3.7 years). All subjects performed a short-term exercise protocol, including maximal jumps and sprinting. Four different recovery methods (10 minutes) were used in random order: cold water immersion (C…
Heart rate variability related to effort at work
2011
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…
Psychophysiological differentiation of deception: the effects of electrodermal lability and mode of responding on skin conductance and heart rate
2001
The differentiation-of-deception paradigm enables the examination of deception as a psychophysiological process by varying, within subjects, two conditions which differ only with respect to honesty and deception. The present experiment assessed the effects of two group factors - electrodermal lability and mode of responding - on the deception phenomenon in a situation with low emotional involvement and mental load. Skin conductance responses, phasic heart rate, self-rated relaxation, calmness, and concentration were the dependent variables. Twenty questions referring to general knowledge were presented on a monitor. The 88 male participants answered half of the questions deceptively and the…