Perimenopausal women show modulation of excitatory and inhibitory neuromuscular mechanisms

Abstract

Background Menopausal transition exposes women to an early decline in muscle force and motor function. Changes in muscle quality and function, especially in lower limbs, are crucial, as they expose individuals to increased risk of falls. To elucidate some of the related neuromuscular mechanisms, we investigated cortical inhibition and peripheral muscle twitch force potentiation in women during the early and late stages of perimenopause. Methods Participants were 63 women aged 48–55 years categorized as early (EP, n = 25) or late (LP, n = 38) perimenopausal according to serum follicle-stimulating hormone (FSH) levels and menstrual diaries. EP women had an irregular menstrual cycle and FSH < 25 IU/L, while LP women had an irregular cycle and > 25 IU/L. We examined motor evoked potential (MEP) and silent period (SP) elicited by transcranial magnetic stimulation (TMS), in the tibialis anterior muscle at 20%, 40%, and 60% of maximal voluntary contraction (MVC) levels, and twitch force potentiation in plantar flexors. Results EP group showed a longer SP duration in 40% MVC condition and larger motor evoked potential amplitude in 20% MVC condition compared to the LP group. No group difference was detected in twitch force potentiation; however, it correlated negatively with FSH levels. Other factors, such as age, height, body mass index, or physical activity did not explain group differences. Conclusions Our preliminary results indicate subtle modulation in both TMS-induced inhibitory and excitatory mechanisms and twitch force potentiation in women already in the late perimenopausal stage. This suggests that the reduction of estrogens may have an accelerating role in the aging process of neuromuscular control.

The Role of Oestrogen in Female Skeletal Muscle Ageing: A Systematic Review

“…Finally, when comparing 25 early to 38 late perimenopausal females, no differences in muscle function were reported, except for significantly lower plantar flexor strength in late perimenopausal females (Pesonen et al, 2021).…”

Propulsive forces and muscle activation during gait: comparisons between premenopausal and postmenopausal midlife women

“…18,19 Furthermore, estrogen plays a crucial neuroprotective role 21 ; therefore, its reduction can expedite the aging process of neuromuscular control. 21,22 However, it remains uncertain whether the menopausal transition negatively affects the propulsive force during gait. Consequently, the aim of this study was to test the hypothesis that postmenopausal women have a lower propulsive force during gait compared with premenopausal women.…”

“…This relationship may be influenced by changes in signaling pathways mediated by estrogen deficiency, including apoptotic signaling, alterations in contractile proteins, a decrease in the phosphorylation of the myosin light chain (which reduces the probability of cross-bridge attachment), and a reduction in muscle satellite cells 18,19 . Furthermore, estrogen plays a crucial neuroprotective role 21 ; therefore, its reduction can expedite the aging process of neuromuscular control 21,22 . However, it remains uncertain whether the menopausal transition negatively affects the propulsive force during gait.…”