**7. Conclusions**

176 Fourier Transform Applications

women than in postmenopausal women and men in the same age group, illustrating the importance of estrogens in the autonomic differences brought about by menopause. Similar findings, also analyzed in the time domain, were reported by Brockbank et al. (2000) for premenopausal women compared to women after more than one year of menopause. Davy et al. (1998) reported that young women have higher HRV than menopausal women, and that HRV in both active and sedentary women tends to decline with advancing age. In earlier studies conducted in our laboratory (Ribeiro et al., 2001; Neves et al., 2007), lower levels of HRV in menopausal women compared to young

To ascertain if a physical training program could promote physiological adaptations and improved sympathovagal balance of the heart, attenuating the deleterious effects of menopause on the cardiovascular system, Sakabe (2007) evaluated 18 sedentary women divided into two groups: Control Group – 10 postmenopausal women (50 to 60 years old) without hormone therapy (HT); and HT Group – 8 postmenopausal women (50 to 60 years old) undergoing HT (estradiol plus levonorgestrel). Both groups were assessed at two different times: before (assessment) and after (reassessment) a 3-month physical training program (PTP). Protocol 1 – to evaluate the autonomic modulation of the HR, the HR was recorded under resting conditions, supine and sitting positions, for 15 minutes in each position. The indices evaluated in Protocol 1 were: mean HR and R-R intervals (RRI), RMSSD index of the RRI, low (LF) and high (HF) frequency bands of the spectral analysis, in normalized units, and LF/HF ratio. It was concluded that hormone replacement therapy did

Postmenopausal women have greater sympathetic and less parasympathetic activity than premenopausal women (Brockbank et al., 2000; Earnest et al., 2010). Moreover, Mercuro et al.'s study (2000) reveals the harmful effects of hypoestrogenism on the autonomic modulation of the HR, while other studies have demonstrated numerous evidences that endogenous hormones (estrogen and progesterone) contribute to a cardioprotective

Parasympathetic modulation shifts to a lower range with normal aging. Although parasympathetic modulation is generally higher in women than men, aging reduces the difference between genders, with changes in HRV beginning approximately at menopause (Earnest et al., 2010). Boettger (2010) examined changes in cardiovascular autonomic parameters obtained from short-term recordings over time. The data he collected indicated a lifelong shift in autonomic balance toward sympathetic predominance, starting at the age of

Zuttin (2009) evaluated and compared autonomic modulation of the HR at rest in healthy young, premenopausal and postmenopausal women leading a sedentary lifestyle, to verify cardiovascular adjustment in response to postural changes. This investigation involved 113 healthy sedentary women, who were divided into a young group (YG) with an average age of 23±3.4 years (n=40), a premenopausal group (PreMG) aged 36±3.1 years (n= 39), and a

postmenopausal group (PostMG) with an average age of 55±4.5 years (n=34).

women were also recorded.

not have a significant effect on HRV.

**6. Heart rate variability and menopause** 

phenotype in women (Vitale et al., 2009).

30 years.

This chapter discussed the measurement and analysis of HRV, as well as results of data for women and the relationship between aging, hormonal changes (oral contraceptives and hormone replacement therapy) which contribute to modifications in the autonomic control of heart rate.
