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Purpose: The purpose of the study was to determine the effect of moderately strenuous aerobic exercise training on heart rate variability (HRV) and heart rate turbulence (HRT) in patients with an implantable cardioverter defibrillator (ICD). Methods: Patients were randomized to a 24-week home-based aerobic exercise (EX) training program (n = 84) or to usual care (UC) (n = 76). All subjects underwent 24-h Holter monitoring at baseline, 8 and 24 weeks. Generalized estimating equations were used to test the effects of exercise on HRV and HRT outcomes. Results: The study group was comprised of n = 160 patients (124 M, 36 F, age 54.9 ± 12.2 years) with an ICD for primary (43%) or secondary prevention (57%). Compared to UC, EX was associated with a significant improvement in parasympathetic HRV for root mean square of successive differences (rMSSD; p =.05) at 8 weeks and global HRV for standard deviation of all normal (N-N) intervals (SDNN; p =.05) and standard deviation of 5-min averages N-N intervals (SDANN; p =.03) at 24 weeks. When stratified by adherence, those who were ≥80% adherent (minutes/week) had significant improvements in parasympathetic HRV (rMSSD, pNN50) and global HRV (SDNN, SDANN) at 8 weeks, and a further significant improvement in global HRV (SDNN, SDANN, SDNN index) at 24 weeks. Neither HRT nor ventricular ectopy changed with exercise training. Conclusion: Moderately strenuous aerobic exercise improved parasympathetic and global HRV indices following an ICD, with greater adherence associated with greater improvements. Clinical trial registration: Clinicaltrials.gov: NCT 00522340. [ABSTRACT FROM AUTHOR]

ObjectivesHeart rate variability (HRV) reflects the integration of the parasympathetic nervous system with the rest of the body. Studies on the effects of yoga and exercise on HRV have been mixed but suggest that exercise increases HRV. We conducted a secondary analysis of the effect of yoga and exercise on HRV based on a randomized clinical trial of treatments for vasomotor symptoms in peri/post-menopausal women.DesignRandomized clinical trial of behavioral interventions in women with vasomotor symptoms (n=335), 40-62 years old from three clinical study sites.Interventions12-weeks of a yoga program, designed specifically for mid-life women, or a supervised aerobic exercise-training program with specific intensity and energy expenditure goals, compared to a usual activity group.Main outcome measuresTime and frequency domain HRV measured at baseline and at 12 weeks for 15min using Holter monitors.ResultsWomen had a median of 7.6 vasomotor symptoms per 24h. Time and frequency domain HRV measures did not change significantly in either of the intervention groups compared to the change in the usual activity group. HRV results did not differ when the analyses were restricted to post-menopausal women.ConclusionsAlthough yoga and exercise have been shown to increase parasympathetic-mediated HRV in other populations, neither intervention increased HRV in middle-aged women with vasomotor symptoms. Mixed results in previous research may be due to sample differences. Yoga and exercise likely improve short-term health in middle-aged women through mechanisms other than HRV.

Background : Survivors of acute respiratory failure (ARF) experience long-term cognitive impairment and circadian rhythm disturbance after hospital discharge. Although prior studies in aging and neurodegenerative diseases indicate actigraphy-estimated rest-activity circadian rhythm disturbances are risk factors for cognitive impairment, it is unclear if this applies to ARF survivors. This study explored the relationships of actigraphy-estimated rest-activity circadian rhythms with cognitive functioning in ARF survivors at 3 months after discharge. Methods : 13 ARF survivors (mean age 51 years and 69% males) completed actigraphy and sleep diaries for 9 days, followed by at-home neuropsychological assessment. Principal component factor analysis created global cognition and circadian rhythm variables, and these first components were used to examine the global relationships between circadian rhythm and cognitive measure scores. Results : Global circadian function was associated with global cognition function in ARF survivors (r =.70, p =.024) after adjusting for age, education, and premorbid cognition. Also, greater fragmented rest-activity circadian rhythm (estimated by intradaily variability, r =.85, p =.002), and weaker circadian strength (estimated by amplitude, r =.66, p =.039; relative strength, r =.70, p =.024; 24-h lag serial autocorrelation, r =.67, p =.035), were associated with global cognition and individual cognitive tests. Conclusions : These results suggest circadian rhythm disturbance is associated with poorer global cognition in ARF survivors. Future prospective research with larger samples is needed to confirm these results and increase understanding of the relationship between disrupted circadian rhythms and cognitive impairment among ARF survivors. [ABSTRACT FROM AUTHOR]

Detrended fluctuation analysis (DFA) is a recently developed technique suitable for describing scaling behavior of variability in physiological signals. The purpose of this study is to explore applicability of DFA methods to intracranial pressure (ICP) signals recorded in patients with traumatic brain injury (TBI). In addition to establishing the degree of fit of the power-law scaling model of detrended fluctuations of ICP in TBI patients, we also examined the relationship of DFA coefficients (scaling exponent and intercept) to: 1) measures of initial neurological functioning; 2) measures of functional outcome at six month follow-up; and 3) measures of outcome, controlling for patient characteristics, and initial neurological status. In a sample of 147 moderate-to-severely injured TBI patients, we found that a higher DFA scaling exponent is significantly associated with poorer initial neurological functioning, and that lower DFA intercept and higher DFA scaling exponent jointly predict poorer functional outcome at six month follow-up, even after statistical control for covariates reflecting initial neurological condition. DFA describes properties of ICP signal in TBI patients that are associated with both initial neurological condition and outcome at six months postinjury. Index Terms--Detrended fluctuation analysis (DFA), intracranial pressure (ICP), monitoring, outcome, traumatic brain injury (TBI).

* BACKGROUND Clinical bedside monitoring systems do not provide prominent displays of data on cerebral perfusion pressure (CPP). Immediate visual feedback would allow more rapid intervention to prevent or minimize [...]