ABSTRACT
Stress is the reaction of the body to a change that requires physical, mental or emotional adjustments. Individual differences in stress reactivity are a potentially important risk factor for gender-specific health problems in men and women. The Autonomic regulation of the cardiovascular system is most commonly affected by stress and is assessed by means of short term heart rate variability (HRV).The present study was undertaken to investigate the difference in the cardiovascular Autonomic Nervous System response to mental stress between the genders using HRV as tool. We compared the mean RR interval, Blood pressure and indices of HRV during the StroopColor Word Test (SCWT).Twenty five male (Age19.52±0.714, BMI 22.73±2 kg/m2) and twenty five female subjects (Age 19.80±0.65, BMI 22.39±1.9) performed SCWT for five minutes. Blood Pressure (SBP p<0.01, DBP p<0.042) & Mean HR (p<0.010) values showed statistically significant difference among the genders. HRV indices like LFms2 (p<0.051), HF nu (p<0.029) and LF/HF ratio (p<0.025, p<0.052) show statistically significant difference among the genders. The response by the cardiovascular system to a simple mental stressor exhibits difference among the genders.
ABSTRACT
Obesity has been shown to affect cardiovascular function. Heart rate variability (HRV) has been an accepted method of measuring cardiovascular autonomic function. The aim of the study is to evaluate the impact of obesity on HRV using Poincaré plot (POP) analysis. A finding of sympathovagal imbalance in pre-obese adults in respiratory sinus arrhythmia (RSA) could provide important diagnostic information about early subclinical autonomic dysfunction in obesity. Thirty one obese (BMI 26.84±2.47) adult males (25.42±7.86 years) were compared with 31 normal subjects (25.38±4.61 years). In all participants, anthropometric and blood pressure (BP) measurements were performed. After rest at supine position for 5 minutes, they were asked to do control deep breathing for 1 minute. HRV was measured in terms of POP analysis. Differences in Resting heart rate (RHR) (P≤0.025), Pulse pressure (PP) (P≤0.048), SD1 (P≤0.042) and SD2 (P≤0.039) of the POP between the two groups were significant. Correlation between Body mass index (BMI) and (PP) (p=0.19); SD1 (p=0.47) and SD2 (p=0.39) of the POP were significant in obese groups. Obesity is related to sympathovagal imbalance characterized by depressed parasympathetic tone and increased sympathetic activity. Nonlinear methods like POP permit simple assessment of autonomic function, despite measuring different aspects of HRV.
ABSTRACT
Background: Benefi cial effects of Yoga have been postulated to be due to modulation of the autonomic nervous system. Objective: To assess the effect of Isha Yoga practices on cardiovascular autonomic nervous system through short-term heart rate variability (HRV). Design of the Study: Short-term HRV of long-term regular healthy 14 (12 males and 2 females) Isha Yoga practitioners was compared with that of age- and gender-matched 14 (12 males and 2 females) non-Yoga practitioners. Methods and Materials: ECG Lead II and respiratory movements were recorded in both groups using Polyrite during supine rest for 5 min and controlled deep breathing for 1 minute. Frequency domain analysis [RR interval is the mean of distance between subsequent R wave peaks in ECG], low frequency (LF) power, high frequency (HF) power, LF normalized units (nu), HF nu, LF/HF ratio] and time domain analysis [Standard Deviation of normal to normal interval (SDNN), square of mean squared difference of successive normal to normal intervals (RMSSD), normal to normal intervals which are differing by 50 ms (NN50), and percentage of NN50 (pNN50)] of HRV variables were analyzed for supine rest. Time domain analysis was recorded for deep breathing. Results: Results showed statistically signifi cant differences between Isha Yoga practitioners and controls in both frequency and time domain analyses of HRV indices, with no difference in resting heart rate between the groups. Conclusions: Practitioners of Isha Yoga showed well-balanced benefi cial activity of vagal efferents, an overall increased HRV, and sympathovagal balance, compared to non-Yoga practitioners during supine rest and deep breathing.
ABSTRACT
Hypertension (HT) is a major silent disease affecting young people because of their hereditary and modern lifestyles. Target organ damages occur before overt hypertension is diagnosed. Many offspring of HT parents show early changes in their cardiovascular autonomic functions. Heart rate variability (HRV) provides a window to understand the cardiac autonomic balance. This study was designed to quantify and to compare the HRV among the normotensive young male offspring without history of parenteral hypertension & diabetic (control group, n=25, age 20.8±2.4, BMI 24.4±3.1) with parenteral history of hypertension & non diabetic (study group n=25, age 19.7±1.9, 24.05±3.5). Blood pressure, heart rate (HR), indices of short term HRV during supine rest and quiet standing, HR variation during timed controlled deep breathing was compared between the two groups. There were significant difference in low frequency (LF) power, HF power, total power. LF and HF expressed also in normalized units at rest and standing. In time domain standard deviation of normal to normal RR interval (SDNN) at supine rest and standing were significant. Respiratory sinus arrthymia (RSA), HF in normalized units, deep breathing difference (BDD) and the ratio of maximum RR to minimum RR were also significant in the control group than study group. In the present study there was an increased sympathetic and decreased parasympathetic activity in the study group. These findings are an early marker of cardiovascular autonomic impairment in subjects with parenteral history of hypertension.