Sex Specific Differences in the Response to Short Term Muscle Disuse in Middle Aged Adults

Authors

Sean P. Kilroe, The University of Texas Health Science Center at San AntonioFollow
Zach von Ruff, Rice UniversityFollow
Hanna Kalenta, The University of Texas Health Science Center at San AntonioFollow
Emily Arentson-Lantz, University of Texas Medical Branch at GalvestonFollow
Andrew J. Murton, University of Texas Medical Branch at GalvestonFollow
Douglas Paddon-Jones, University of Texas Medical Branch at GalvestonFollow
Blake B. Rasmussen, The University of Texas Health Science Center at San AntonioFollow

Abstract

Research on short term muscle disuse has demonstrated the numerous adverse effects it causes on skeletal muscle. These include reductions in function and mass, as well as insulin sensitivity, mitochondrial function and muscle protein synthesis. However, little is known about the sex specific differences in how males and females respond to muscle disuse. PURPOSE: To investigate the sex specific differences in how males and females respond to short term disuse. METHODS: Sixteen healthy, middle-aged adults (8 males; 57.9±1.8 yr; BMI 29.9±1.2 kg·m^-2; 8 females; 55.1±1.6 yr; BMI 28.9±1.0 kg·m-2) underwent 7 days of unilateral leg immobilization via unilateral lower limb suspension (ULLS). Muscle biopsies from the vastus lateralis were collected prior to and following immobilization (in both control [CON] and immobilized [IMM] legs). We applied the stable isotope tracer deuterium oxide to measure muscle protein synthesis (MPS), immunoblotting to assess mTOR signaling and assessed leg strength changes via unilateral leg extension 1 repetition maximum (1RM). We hypothesized that males would experience greater reductions in MPS, mitochondrial function and leg strength compared to females. RESULTS: MPS was 36.5±10.2 % and 16.5±15.6 % lower in the IMM leg compared to the CON leg in females (P<0.05) and males (P>0.05) respectively during immobilization. There was no difference in MPS in the IMM leg between males and females (P>0.05) during immobilization. Leg extension 1RM declined to the same extent in females 17.1±2.1 % and males 24.2±2.4 % after 7 days of IMM (both P<0.05). Markers of mTOR signaling were unaltered by IMM in both males and females (P>0.05). CONCLUSION: Middle aged males and females experience the same reduction in leg strength and muscle protein synthesis after short term disuse.

Recommended Citation

Kilroe, Sean P.; Ruff, Zach von; Kalenta, Hanna; Arentson-Lantz, Emily; Murton, Andrew J.; Paddon-Jones, Douglas; and Rasmussen, Blake B. (2025) "Sex Specific Differences in the Response to Short Term Muscle Disuse in Middle Aged Adults," International Journal of Exercise Science: Conference Proceedings: Vol. 2: Iss. 17, Article 42.
Available at: https://digitalcommons.wku.edu/ijesab/vol2/iss17/42