Investigating The Effects of The Menstrual Cycle on Glycogen Utilisation and Metabolic Activity During Exercise: A 13C MRS Study

Motivation: The menstrual cycle (MC) has been shown to effect muscle glycogen utilisation during exercise but little is known about the full metabolic or glycogenic effects at varying phases. Goal(s): To explore MC effects on exercise-induced changes in metabolites and glycogen stores. Approach: 13C MRS and bloods were acquired from the liver and leg before and after 45 minutes of moderate exercise in healthy females. Test day was repeated 4 times 1 week apart throughout the MC. Results: Previous findings of hormonal effects on muscle glycogen utilization were confirmed. Also, liver glycogen stores appear reduced in later MC days and correlated negatively with progesterone. Impact: This study provides pilot data for future research. 13C MRS allows for the repeated monitoring of glycogen storage and turnover in an ethically viable way. This work has implications in understanding metabolic disorders, medical research and sports science.