Medical Express

ISSN (print): 2318-8111

ISSN (online): 2358-0429

Author's Articles

5 result(s) for: David M. Garner

Globally chaotic analysis of Heart Rate Variability during acute auditory stimulus by heavy metal music

Marcela Leme Nogueira; David M. Garner; Elaine Osório; Luiz Carlos de Abreu; Vitor Engrácia Valenti


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OBJECTIVE: Auditory stimulation with relaxing style music can improve cardiac autonomic regulation in subjects treated with a cardio-toxic medication. We assess the acute effect of heavy metal music on cardiac autonomic regulation, through novel high spectral chaotic global analysis techniques: (a) high spectral detrended fluctuation, (b) high spectral entropy (c) spectral multi-taper method.
METHOD: We investigated young adult women between 18 and 30 years old exposed to heavy metal (75-84 dB) music for 20 min. Normality tests were applied: (i) Anderson-Darling, (ii) Ryan-Joiner (similar to Shapiro-Wilk); (iii) Lilliefors for low number of subjects. They all indicated a non-normal data distribution. Consequently we applied the Kruskal-Wallis non-parametric test. Also because of the small population, we used a broader than usual level of significance (critical p = 0.1).
RESULTS: The application of the three tests for normality and the non-parametric test of significance by the Kruskal-Wallis technique showed that acute musical auditory stimulation with heavy metal music lead to a significant increase (p < 0.07) in one of the seven combinations of chaotic globals. The most significant combination of chaotic globals is the Chaos Forward Parameter One (CFP1), which includes all three studied chaotic globals (high spectral detrended fluctuation, high spectral entropy, spectral multi-taper method). We found significantly increased values during musical auditory stimulation for this specific CFP1.
CONLCUSION: It is suggested that acute musical stimulation with heavy metal influences cardiac autonomic regulation at a more complex level than previously reported and that this may be beneficial to heart function.

Keywords: Cardiovascular system; Autonomic nervous system; Auditory; Acoustic stimulation; High spectral chaotic globals.

Symbolic analysis of heart rate variability and its interaction with p-value of normality tests applied on RR intervals

Andrey A. Porto; Celso Ferreira; Luiz Carlos de Abreu; David M. Garner; Luana Gonzaga; Vitor E. Valenti


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OBJECTIVE: A previous study suggested that the p-value of normality test applied to RR intervals is an index able to quantify Heart Rate Variability (HRV) through correlation of traditional time and frequency domain indices. We investigate the association between the p-value of normality test applied in RR intervals and symbolic analysis of HRV.
METHOD: We evaluated 32 healthy women between 18 and 30 years old. RR intervals were used for HRV analysis and we performed symbolic analysis, where RR intervals are joined by symbols. Sets of three consecutive symbols (RR intervals) were grouped into four types of clusters, as follows: 1. Three equal symbols (zero variation); 2: two equal, one divergent symbol (one variation); 3. Three different symbols monotonically ascending or descending (two like variations); 4. Three different symbols, forming a peak or a trough (two unlike variations). Frequency of occurrence of each type of cluster was calculated. Normality tests were applied to all RR intervals and the p-value was calculated. We computed the correlations between the p-value of normality test and symbolic analysis of HRV.
RESULTS: Correlation coefficients between the p-value of normality test from Kolmorogov-Smirnov test and the four types of clusters showed no correlation for any of them. Likewise, the correlation coefficient index between the p-value of normality test calculated from the Shapiro-Wilk test and symbolic analysis produced no significant results for any of the four types of clusters.
CONCLUSION: There was no significant correlation between the p-value of normality test and HRV symbolic analysis. The physiological significance of this result is that the PNT is not related to chaotic behavior of HRV.

Keywords: Autonomic nervous system; Cardiovascular system; Cardiovascular physiology; Gaussian distribution.

Chaotic analysis of heart rate dynamics after an exercise with flexible pole

Ana M. S. Antonio; David M. Garner; Rodrigo D. Raimundo; Luiz Carlos de Abreu; Marcelo T. Navega; Vitor E. Valenti


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INTRODUCTION: Exercises with a flexible pole have been applied in clinical practice for upper limb rehabilitation. Nevertheless, its acute effects on cardiac autonomic regulation are unclear.
OBJECTIVE: To evaluate the acute effects of exercise with flexible pole on complex behavior of heart rate variability (HRV).
METHOD: We investigated 32 healthy female volunteers aged between 18 and 25 years who performed a session of exercise with a flexible pole. HRV was analyzed 10 minutes before and 10 minutes immediately after the exercise.
RESULTS: Exercises with a flexible pole did not significantly change time and frequency domain indices of HRV. Non-linear analysis of HRV through the Higuchi Fractal Dimension was not significantly changed during recovery from exercise compared to the control reading at rest.
CONCLUSION: Exercises with the flexible pole were unable to acutely change chaotic behavior of heart rate dynamics. This is advantageous for assessments of levels of rehabilitative treatment required in such patients; and their susceptibility to dynamical diseases.

Keywords: Autonomic Nervous System; Higuchi Fractal Dimension Rehabilitation Medicine.

Higuchi Fractal Analysis of Heart Rate Variability is Sensitive during Recovery from Exercise in Physically Active Men

Rayana L. Gomes; Luiz Carlos M. Vanderlei; David M. Garner; Franciele M. Vanderlei; Vitor E. Valenti


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OBJECTIVE: Nonlinear techniques to assess heart rate variability (HRV) have received much recent attention. We aimed to evaluate nonlinear HRV responses during recovery from exercise through the novel algorithm Higuchi Fractal Dimension.
METHOD: We examined 35 healthy male volunteers aged between 18 and 35 years old. For the training of exercise intensity we used 60% of Vmax determined through a progressive test using the Conconi threshold. HRV was analyzed 10 minutes before and 10 minutes after exercise. We analyzed the geometric indices of HRV (SD1, a measure of short-term HRV and SD2, a measure of long-term HRV) and applied the Higuchi Fractal Dimension to RR intervals.
RESULTS: During recovery from exercise the Poincaré plot indices SD1 and SD1/SD2 decreased while SD2 and SD2/SD1 increased (p<0.0001) compared to control at rest. All parameters of Higuchi Fractal Dimension analysis were lowered after exercise compared to control at rest (p<0.0001).
CONCLUSION: Physical exercise acutely decreased the chaotic behavior of HRV as measured through the Higuchi Fractal Dimension analysis. Physiologically, this indicates that we detected complex changes in HRV immediately after exercise.

Keywords: Cardiovascular system; Autonomic Nervous System; Physical Exercise; Nonlinear Dynamics; Higuchi Fractal Dimension.

Involvement of rest diastolic arterial pressure in autonomic heart rate recovery from exercise in normotensive men

Rayana L. Gomes; Luiz Carlos M. Vanderlei; Franciele M. Vanderlei; David M. Garner; Rodrigo D. Raimundo; Luiz Carlos de Abreu; Vitor E. Valenti


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OBJECTIVE: Rest arterial pressure has been shown to be associated with cardiovascular mortality. Autonomic heart rate control during recovery from exercise is estimated to detect changes in cardiovascular system, which may lead to cardiovascular diseases. We assessed the involvement of rest diastolic arterial pressure (DAP) on heart rate dynamics after exercise in normotensive physically active men.
METHOD: We evaluated healthy physically active men aged 18 to 22 years old divided into two unequal groups: G1- rest DAP between 80 and 90 mmHg (N=11) and G2- rest DAP < 80mmHg (N=24). Volunteers performed physical exercise on a treadmill with intensity equivalent to 60% of Vmax. Heart rate recovery in the first (HRR1) and third (HRR3) minute after exercise were measured and heart rate variability (HRV) was examined in the time and frequency domain. Additionally, we performed the quantitative analysis of the Poincaré plot. HRV was recorded in the following phases: the 10-minute period before exercise, during exercise and the 60 minute period after exercise.
RESULTS: We found no significant difference between G1 and G2 concerning HRV changes during exercise. The G2 group exhibited a delayed recovery of SDNN, RMSSD, RRTri, LF, HF, LF/HF, SD1 and SD2 indices during recovery from exercise. HRR1 and HRR3 was greater in the G2 group.
CONCLUSION: Normotensive physically active men with DAP between 80 and 90 mmHg presented faster heart rate recovery and an accelerated recovery of heart rate autonomic control after aerobic exercise.

Keywords: Arterial Pressure; Autonomic Nervous System; Cardiovascular Physiological Phenomena; Cardiovascular system.