Significance of Estrogen Status for Muscle Function, Physical Fitness, and Physiological Health Parameters - a Comparison of Age-matched Groups of Women Before and After Menopause.

As females age and transition through menopause, the decline in oestrogen level profoundly affects skeletal muscle mass and function. HER-MUSCLE aims to unravel the differences in pre and post menopausal women, in regards to muscle size, strength and function. Focusing on postmenopausal females, an increasingly at-risk demographic, HER-MUSCLE addresses a critical gap in understanding how oestrogen influences muscle mass and function. The project involves: 1. Molecular Analysis: Advanced techniques will study the muscle microenvironment, focusing on muscle stem cells (MuSCs), fibro-adipogenic progenitors (FAPs), and other cells critical for muscle regeneration and maintenance. 2. Mitochondrial Function assessed in vivo via magnetic resonance spectroscopy: The impact of oestrogen on mitochondrial health will be examined, exploring how it preserves mitochondrial function and ability to recovery and resist fatigue in response to muscle contractions. Our preliminary data indicate that oestrogen can promote muscle protein synthesis. HER-MUSCLE aims to pave the way for novel therapeutic strategies to manage sarcopenia in postmenopausal women, ultimately leading to better health outcomes and enhanced well-being for this growing population segment.

Inclusion Criteria: * Regular menstrual bleeding (21-35 days cycle). * At least 9 menstrual cycles the last year * Age \>47 years old * BMI 20-30 Exclusion Criteria: * Only premenopausal women: Follicular stimulating hormone \> 30 mmol/L * Systematic strength training during the last year (\> 1 strength training session per week) * Systematic high intensity cardiovascular training during the last year (\