Evaluating the Effects of Hormone Replacement Therapy Termination on Skeletal Muscle and Physical Independence in Postmenopausal Women

Wullems, Antonin Jorgen, Degens, Hans ORCID: https://orcid.org/0000-0001-7399-4841, Morse, Christopher ORCID: https://orcid.org/0000-0002-5261-2637 and Pearson, Gladys ORCID: https://orcid.org/0000-0002-1466-3265 (2024) Evaluating the Effects of Hormone Replacement Therapy Termination on Skeletal Muscle and Physical Independence in Postmenopausal Women. Menopause: The Journal of the North American Menopause Society. ISSN 1072-3714 (In Press)

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Abstract

Objective: In women, the age-related decline in skeletal muscle structure and function is accelerated post menopause, which implicates the role of decreased circulating oestrogen levels. Indeed, boosting oestrogen, by means of postmenopausal hormone replacement therapy (HRT), generally proves beneficial to skeletal muscle. The evidence regarding whether these benefits persist even after cessation of HRT is limited, nor is it clear how physical behaviour (PB) impacts on benefits. Hence, this exploratory study focused on the interplay between HRT administration/cessation, PB and in vivo skeletal muscle structure and function. Methods: Fifty healthy women (≥60 years) were included; 19 had an HRT administration history (≥9 months, with now ~8-years hiatus in treatment) and 31 no such history. On seven continuous days PB data was collected using triaxial accelerometry and analysed using compositional data analysis. Gastrocnemius medialis (GM) muscle volume, architecture and function were determined using ultrasonography, electromyography, dual x-ray absorptiometry and dynamometry. Current serum oestradiol levels were measured using ELISA. Results: Only fascicle length and duration of HRT administration were positively associated. With respect to PB levels, we found a pattern suggesting greater vitality (higher physical activity and lower sedentarism) in previous HRT users, compared to non-users, despite the two groups currently no longer exhibiting significantly different levels of circulating oestradiol. Conclusion: After an 8-year hiatus in treatment, HRT provides limited advantages in GM muscle properties. Interestingly it perhaps enhances vitality despite prolonged cessation, which in the longer term would facilitate greater physical independence, especially considering the association of SB with greater frailty.