Menstrual cycle phase does not influence muscle protein synthesis or whole-body myofibrillar proteolysis in response to resistance exercise

• Published in: The Journal of physiology 2024-12
• Main Authors: Colenso-Semple, Lauren M, McKendry, James, Lim, Changhyun, Atherton, Philip J, Wilkinson, Daniel J, Smith, K, Phillips, Stuart M
• Format: Article
• Language: English
• ISSN: 1469-7793; 1469-7793
• DOI: 10.1113/JP287342

It has been hypothesised that skeletal muscle protein turnover is affected by menstrual cycle phase with a more anabolic environment during the follicular vs. the luteal phase. We assessed the influence of menstrual cycle phase on muscle protein synthesis and myofibrillar protein breakdown in response to 6 days of controlled resistance exercise in young females during peak oestrogen and peak progesterone, using stable isotopes, unbiased metabolomics and muscle biopsies. We used comprehensive menstrual cycle phase-detection methods, including cycle tracking, blood samples and urinary test kits, to classify menstrual phases. Participants (n = 12) completed two 6 day study phases in a randomised order: late follicular phase and mid-luteal phase. Participants performed unilateral resistance exercise in each menstrual cycle phase, exercising the contralateral leg in each phase in a counterbalanced manner. Follicular phase myofibrillar protein synthesis (MPS) rates were 1.33 ± 0.27% h in the control leg and 1.52 ± 0.27% h in the exercise leg. Luteal phase MPS was 1.28 ± 0.27% h in the control leg and 1.46 ± 0.25% h in the exercise leg. We observed a significant effect of exercise (P