Muscle and tendon properties during menstrual cycle

Area of Science:

• Exercise Physiology
• Reproductive Endocrinology
• Biomechanics

Background:

• Hormonal fluctuations during the menstrual cycle may influence musculoskeletal function.
• Understanding these potential effects is crucial for female athletes and active individuals.

Purpose of the Study:

• To investigate in vivo changes in human muscle and tendon mechanical properties throughout the menstrual cycle.
• To determine if estradiol and progesterone variations impact muscle strength, activation, and tendon biomechanics.

Main Methods:

• Assessed maximal isometric voluntary contraction (MVC) and muscle activation via interpolated twitch in knee extensors and plantar flexors.
• Utilized ultrasonography to evaluate tendon properties, including maximal elongation and stiffness.
• Categorized cycle phases into menstrual, ovulatory, and luteal based on hormone concentrations.

Main Results:

• No significant differences were observed in MVC or muscle activation levels across the menstrual, ovulatory, and luteal phases.
• Tendon maximal elongation and stiffness remained consistent throughout the different phases of the menstrual cycle.
• No statistically significant impact of hormonal changes on muscle and tendon mechanical properties was detected.

Conclusions:

• The natural fluctuations of female steroid hormones during the menstrual cycle do not appear to affect the mechanical properties of human skeletal muscle and tendons.
• These findings suggest that training and performance considerations related to hormonal changes may not be necessary for muscle and tendon function in healthy women.