Effects of age and physical activity on the autonomic control of heart rate in healthy men

Abstract

The effects of the aging process and an active life-style on the autonomic control of heart rate (HR) were investigated in nine young sedentary (YS, 23 ± 2.4 years), 16 young active (YA, 22 ± 2.1 years), 8 older sedentary (OS, 63 ± 2.4 years) and 8 older active (OA, 61 ± 1.1 years) healthy men. Electrocardiogram was continuously recorded for 15 min at rest and for 4 min in the deep breathing test, with a breath rate of 5 to 6 cycles/min in the supine position. Resting HR and RR intervals were analyzed by time (RMSSD index) and frequency domain methods. The power spectral components are reported in normalized units (nu) at low (LF) and high (HF) frequency, and as the LF/HF ratio. The deep breathing test was analyzed by the respiratory sinus arrhythmia indices: expiration/inspiration ratio (E/I) and inspiration-expiration difference (∆IE). The active groups had lower HR and higher RMSSD index than the sedentary groups (life-style condition: sedentary vs active, P < 0.05). The older groups showed lower HFnu, higher LFnu and higher LF/HF ratio than the young groups (aging effect: young vs older, P < 0.05). The OS group had a lower E/ I ratio (1.16) and ∆IE (9.7 bpm) than the other groups studied (YS: 1.38, 22.4 bpm; YA: 1.40, 21.3 bpm; OA: 1.38, 18.5 bpm). The interaction between aging and life-style effects had a P < 0.05. These results suggest that aging reduces HR variability. However, regular physical activity positively affects vagal activity on the heart and consequently attenuates the effects of aging in the autonomic control of HR.

Complexity analysis of sleep and alterations with insomnia based on non-invasive techniques

“…It was hypothesized that, although night-time activity may be 'complex' for all subjects, the results would be less complex for normal sleepers, with high levels of 1/f-scaling possibly being a sign of too much activity in the underlying regulatory systems resulting in night-time arousals. This hypothesis, although contrary to most literature surrounding complexity studies in physiological health [14][15][16][17][19][20][21][22], was indeed found to be true for this investigation into sleep actigraphy.…”

Autonomic response to exercise as measured by cardiovascular variability

“…4,8,[10][11][12][13]15,17,18,[19][20][21]25,27,[30][31][32][34][35][36]38,39,45,47 The results of 10 articles on ANS response measured during exercise are shown in Table I. Some authors expressed concern about the measurement of spectral analysis of HRV during exercise, while others reported increases (↑), decreases (↓) and no changes in variability indicators (↔) of sympathetic (SNS) and parasympathetic (PNS) influence.…”

Effect of the Postural Challenge on the Dependence of the Cardiovascular Control Complexity on Age

“…These findings are in agreement with those reported in [18,57,58] and can be explained by the reduced effect of the change of posture on the cardiovascular variables with age. The progressively limited influence of the orthostatic challenge has been attributed to the impairment of beta-adrenergic receptor stimulation [7,31], reduced efficiency of post-synaptic-adrenergic signaling [52], reduced vagal autonomic modulation to the sinus node [3,[5][6][7][8][9]59], reduced sympathetic modulation to the vessels [48], and decreased baroreflex efficiency [48,58,60].…”

“…These changes are mirrored by a reduction in heart period (HP) variability [2][3][4][5][6][7][8][9], by an increase of systolic blood pressure (SAP) variability [10][11][12], and by a reduction in complexity of physiological dynamics [2][3][4][13][14][15][16][17][18][19][20][21][22][23]. Although the abovementioned studies indicate that aging reduces the complexity of the cardiovascular control and prove the gender dependence, it is still unclear whether the complexity reduction and the gender relation are similarly observable from HP and SAP variabilities and if it persists during a cardiovascular control challenge.…”