Power Loading-Induced Fatigue Is Influenced by Menstrual Cycle Phase.

Area of Science:

• Exercise Physiology
• Sports Science
• Neuromuscular Physiology

Background:

• The menstrual cycle significantly influences female physiology, potentially affecting exercise performance and recovery.
• Understanding these hormonal fluctuations is crucial for optimizing training and predicting athletic capabilities.

Purpose of the Study:

• To investigate the impact of fatiguing exercise on neuromuscular properties, force output, and metabolic responses.
• To compare these effects across four distinct phases of the menstrual cycle: menstruation, mid-follicular, ovulation, and mid-luteal.

Main Methods:

• Sixteen women completed a fatiguing leg press protocol (2x10 reps at 60% 1RM).
• Neuromuscular responses, including maximal voluntary force (MVC) and activation level (AL), were measured.
• Serum hormone levels and blood lactate were analyzed.

Main Results:

• Fatiguing exercise reduced power, MVC, and AL across all menstrual cycle phases.
• Decreases in AL were more pronounced during the mid-luteal phase compared to ovulation.
• Resting twitch force declined significantly during the mid-follicular and mid-luteal phases, with greater reductions in the mid-luteal phase.
• Blood lactate increased more during menstruation than the mid-luteal phase.

Conclusions:

• Ovulation may provide a more advantageous hormonal environment for acute neural adaptations to fatigue.
• The mid-follicular and mid-luteal phases appear more conducive to acute muscular adaptations following fatiguing exercise.
• Hormonal fluctuations across the menstrual cycle differentially modulate neuromuscular responses to exercise-induced fatigue.