Vagal modulation of heart rate during exercise: effects of age and physical fitness

Abstract

This study was designed to assess the effects of age and physical fitness on vagal modulation of heart rate (HR) during exercise by analyzing the instantaneous R-R interval variability from Poincaré plots (SD1) at rest and at different phases of a bicycle exercise test in a population of healthy males. SD1 normalized for the average R-R interval (SD1n), a measure of vagal activity, was compared at rest and during exercise among subjects of ages 24–34 (young, n = 25), 35–46 (middle-aged, n = 30), and 47–64 yr (old, n = 25) matched for peak O2 consumption (V˙o 2 peak) and among subjects withV˙o 2 peak of 28–37 (poor, n = 25), 38–45 (average, n = 36), and 46–60 ml ⋅ kg−1 ⋅ min−1(good, n = 25) matched for age. SD1n was higher at rest in the young subjects than in the middle-aged or old subjects (39 ± 14, 27 ± 16, and 21 ± 8, respectively; P < 0.001), but the age-related differences in SD1n were smaller during exercise [e.g., 11 ± 5, 9 ± 5, and 8 ± 4 at the level of 100 W; P = not significant (NS)]. The age-matched subjects with good, average, and poor V˙o 2 peakshowed no difference in SD1n at rest (32 ± 17, 28 ± 13, and 26 ± 11, respectively; P = NS), but SD1n differed significantly among the groups from a low to a moderate exercise intensity level (e.g., 13 ± 6, 10 ± 5, and 6 ± 3 for good, average, and poor fitness groups, respectively; P < 0.001, 100 W). These data show that poor physical fitness is associated with an impairment of cardiac vagal function during exercise, whereas aging itself results in more evident impairment of vagal function at rest.

Heart rate variability is related to training load variables in interval running exercises

“…The lowest exercise intensity in the present study was 50 % of the VO2max of untrained women, based on knowledge of the approximate intensity at which vagal activity diminishes (Casadei et al 1995;Perini et al 1990;Tulppo et al 1998). After 3.5 km or 7.0 km of exercise at such intensity, a fast increase of HFP and TP almost to the pre-exercise levels was detected already during the first recovery minute after exercise cessation.…”

“…It could be speculated that the large individual variation in vagal modulation during rest may affect the results of MODE exercise. Vagal activation decreases significantly around 50 -60 % of VO2max (Hautala et al 2003;Tulppo et al 1998), so the recovery after the exercise with the lowest physical TL, without significant contribution of anaerobic processes, might be near the individual resting level. When physical TL of exercise is increased, either by increased intensity or duration, HRV might better describe the actual physiological TL instead of the individual level of resting vagal modulation.…”

“…SDNN) methods, HRV is greatly diminished during exercise when compared to rest (Arai et al 1989;Casadei et al 1995;Macor et al 1996;Perini et al 1990;Pichon et al 2004). HRV decreases as a function of exercise intensity, almost disappearing at exercise intensities exceeding 50-60% of VO2max (Hautala et al 2003;Tulppo et al 1998) or the ventilatory threshold (Yamamoto et al 1991). Therefore, intensity seems to be the main factor affecting HRV during exercise.…”

“…It is known (Casadei et al 1995;Nakamura et al 1993;Perini et al 1990;Tulppo et al 1998) that when the intensity of exercise exceeds 50-60 % of VO2max, vagal contribution to HR regulation diminishes, and finally disappears. Based on that, the lowest intensity chosen was 50% of vVO2max.…”

Comparação Da Modulação Autonômica Cardíaca Durante Esforço De Fumantes E Não Fumantes

“…Com o aumento do tempo e/ou da intensidade do exercício (FC em torno de 100 bpm) um efeito crescente da ativação simpática passa a ser o mecanismo principal pelo aumento da FC 19 . Entretanto, a intensidade de esforço na qual há o desaparecimento da influência vagal cardíaca é mais alta naqueles indivíduos que realizam atividades aeróbias habitualmente 20 . E mais, apesar da retirada vagal ser mais rápida em indivíduos ativos, ela ocorre em menor magnitude, fazendo com que, durante exercício, a retirada vagal seja menor no individuo mais condicionado 19 .…”