Medical Express

ISSN (print): 2318-8111

ISSN (online): 2358-0429

Author's Articles

3 result(s) for: Luiz Carlos M. Vanderlei

Responses of the geometric indices of heart rate variability to the active orthostatic test in women

Luiz Carlos de Abreu; Adriano L. Roque; Bianca C.R. de Castro; Ana C. Amorim de Souza; Luiz Carlos M. Vanderlei; Lucas L. Ferreira; Rodrigo D. Raimundo; Fernando L.A. Fonseca; Vitor E. Valenti; José R. Cisternas


Abstract PDF

OBJECTIVES: The effects of the orthostatic test on the cardiovascular system have been investigated, but there are no data on the behavior of the geometric indices of heart rate variability. We evaluated the effects of the active orthostatic test on the geometric indices of heart rate variability in women.
METHOD: The study was performed on 12 healthy women between ages 18 and 30. For the analysis of heart rate variability, heart rate was recorded beat-to-beat. The RR intervals were transformed into geometric figures, and from these we calculated the triangular index, the triangular interpolation of RR intervals, the SD1, SD2 indexes and the SD1/SD2 ratio, which were obtained from the Poincaré plot. Visual analysis of the plot was also performed. For the test, participants quickly stood up from a seated position in 3 seconds or less, and remained standing still for 15 minutes. Heart rate variability samples were collected at four moments: rest, 0-5 minutes, 5-10 minutes and 10-15 minutes at standing position.
RESULTS: The triangular index, the triangular interpolation of RR intervals, the SD1 and SD2 indices were reduced (p < 0.05) at 10-15 minutes after the volunteers stood up from seated position. The SD1/SD2 ratio was decreased at 0-15 minutes after the subjects changed from seated to orthostatic position.
CONCLUSION: The geometric indices of heart rate variability decreased in response to the active orthostatic test in healthy women.

Keywords: Autonomic Nervous System; Cardiovascular System; Nonlinear Dynamics; Physiology.

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


Abstract PDF

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


Abstract PDF

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.