Menstrual Cycle Phase Does Not Affect Carbohydrate Supplementation Ergogenic Effect After Heavy Intensity Cycling

Area of Science:

• Exercise Physiology
• Sports Nutrition
• Women's Health

Background:

• Menstrual cycle phases can influence physiological responses to exercise.
• The role of carbohydrate (CHO) supplementation on endurance performance and fatigability across different menstrual phases requires further investigation.
• Understanding these interactions is crucial for optimizing training and nutrition strategies in female athletes.

Purpose of the Study:

• To determine if CHO supplementation impacts endurance performance and fatigability during heavy intensity exercise.
• To compare these effects across the mid-follicular and mid-luteal phases of the menstrual cycle.
• To assess perceived and performance fatigability markers in recreationally trained females.

Main Methods:

• Twelve recreationally trained females underwent a graded exercise test to determine gas exchange threshold (GET) and estimated maximal metabolic steady state (MMSSest).
• Participants completed four 90-minute constant-load exercise bouts at 20% above GET (between GET and MMSSest) in both mid-follicular and mid-luteal phases, consuming either a CHO or placebo beverage.
• A 4km time trial (TT) followed each bout, with measurements including rating of perceived exertion (RPE), rating of fatigue (RoF), and neuromuscular function (e.g., isometric maximal voluntary contraction, potentiated twitch).

Main Results:

• Carbohydrate supplementation significantly improved 4km time trial performance (p=0.005) in both menstrual cycle phases compared to placebo.
• CHO supplementation led to a greater decline in potentiated twitch (Qtwpot) (p=0.044), indicating altered performance fatigability.
• Increased dyspnea was reported with CHO in the luteal phase (p=0.020), but no significant differences were found for RPE, RoF, leg pain, or other neuromuscular fatigue markers.

Conclusions:

• No significant differences in endurance performance or performance fatigability were observed between the mid-follicular and mid-luteal phases after heavy exercise in recreationally trained females.
• Carbohydrate supplementation demonstrably improves endurance performance and influences performance fatigability consistently across these menstrual cycle phases.
• These findings suggest that CHO intake is beneficial for endurance regardless of the menstrual cycle phase studied, though it may impact specific fatigue sensations.