The goal of this observational study is to learn how the menstrual cycle affects immune cell activation, recruitment, and recovery responses after resistance exercise in healthy, resistance-trained women aged 18-40. The main questions it aims to answer are: Does the menstrual cycle influence neutrophil recruitment and adhesion after resistance exercise? Does the menstrual cycle affect markers of muscle damage and functional recovery? Researchers will compare three menstrual phases (early follicular, late follicular, and mid-luteal) to see if immune responses and recovery outcomes differ across these phases. Participants will: Complete resistance exercise protocols across three different menstrual cycle phases. Provide blood samples to assess immune cell activation and muscle damage markers. Track sleep, mood, and recovery with questionnaires and wear an accelerometer.
Study Type
OBSERVATIONAL
Enrollment
40
Resistance Exercise Protocols: Participants will perform exercises, including belt squats, hex bar deadlifts, and plyometric drop jumps. The load and intensity will be standardized based on each participant's 1-repetition maximum (1RM) to ensure uniformity across trials.
Menstrual Cycle Phases: The key exposure variable is the phase of the menstrual cycle, with participants being assessed during the early follicular, late follicular, and mid-luteal phases.
University of Central Florida
Orlando, Florida, United States
RECRUITINGNeutrophil Recruitment and Adhesion Dynamics
Measure: Neutrophil cell index (impedance reflecting neutrophil migration) using Real-Time Cell Analysis (RTCA). Objective: To assess the differences in neutrophil recruitment and adhesion across menstrual cycle phases (early follicular, late follicular, and mid-luteal). Time Frame: Assessed at 2 time points (baseline and 4 hours post exercise) on 3 experimental trial days (1 per menstrual cycle; up to 4 cycles per participant, over approximately 16 weeks).
Time frame: From enrollment, through study completion, an average of 4 months.
Systemic Concentrations of CXCL8
Measure: Plasma levels of CXCL8 (interleukin-8). Objective: To evaluate if menstrual cycle phases influence systemic chemokine levels in response to exercise. Time Frame: Collected at 2 time points (baseline and 4 hours post exercise) on 3 experimental trial days (1 per menstrual cycle; up to 4 cycles per participant, over approximately 16 weeks).
Time frame: From enrollment, through study completion, an average of 4 months.
Muscle Function and Recovery- Active Range of Motion
Measure: Changes in active range of motion (AROM). Objective: To examine the impact of the menstrual cycle on functional recovery following resistance exercise. Time Frame: Assessed at 5 time points (baseline, immediately post-exercise, 4 hours post, 24 hours post, and 48 hours post) on 3 experimental trial days (1 per menstrual cycle; up to 4 cycles per participant, over approximately 16 weeks).
Time frame: From enrollment, through study completion, an average of 4 months.
Muscle Function and Recovery- Pain Pressure Threshold
Measure: Changes in pain pressure threshold (PPT). Objective: To examine the impact of the menstrual cycle on functional recovery following resistance exercise. Time Frame: Assessed at 5 time points (baseline, immediately post-exercise, 4 hours post, 24 hours post, and 48 hours post) on 3 experimental trial days (1 per menstrual cycle; up to 4 cycles per participant, over approximately 16 weeks).
Time frame: From enrollment, through study completion, an average of 4 months.
Muscle Function and Recovery - Countermovement Jump
Measure: Changes in countermovement jump (CMJ) height. Objective: To examine the impact of the menstrual cycle on functional recovery following resistance exercise. Time Frame: Assessed at 5 time points (baseline, immediately post-exercise, 4 hours post, 24 hours post, and 48 hours post) on 3 experimental trial days (1 per menstrual cycle; up to 4 cycles per participant, over approximately 16 weeks).
Time frame: From enrollment, through study completion, an average of 4 months.
Muscle Function and Recovery - Maximal Voluntary Isometric Contraction
Measure: Changes in maximal voluntary isometric contraction (MVIC). Objective: To examine the impact of the menstrual cycle on functional recovery following resistance exercise. Time Frame: Assessed at 5 time points (baseline, immediately post-exercise, 4 hours post, 24 hours post, and 48 hours post) on 3 experimental trial days (1 per menstrual cycle; up to 4 cycles per participant, over approximately 16 weeks).
Time frame: From enrollment, through study completion, an average of 4 months.
Systemic Concentrations of Myoglobin
Measure: Plasma levels of myoglobin (MYB). Objective: To determine how menstrual cycle phases affect muscle damage/inflammation markers after resistance exercise. Time Frame: Collected at 5 time points (baseline, immediately post-exercise, 4 hours post, 24 hours post, and 48 hours post) on 3 experimental trial days per participant (approximately 16 weeks total).
Time frame: From enrollment, through study completion, an average of 4 months.
Systemic Concentrations of Creatine kinase
Measure: Plasma levels of creatine kinase (CK). Objective: To determine how menstrual cycle phases affect muscle damage/inflammation markers after resistance exercise. Time Frame: Collected at 5 time points (baseline, immediately post-exercise, 4 hours post, 24 hours post, and 48 hours post) on 3 experimental trial days per participant (approximately 16 weeks total).
Time frame: From enrollment, through study completion, an average of 4 months.
Systemic Concentrations of C-Reactive Protein
Measure: Plasma levels of C-reactive protein (CRP). Objective: To determine how menstrual cycle phases affect muscle damage/inflammation markers after resistance exercise. Time Frame: Collected at 5 time points (baseline, immediately post-exercise, 4 hours post, 24 hours post, and 48 hours post) on 3 experimental trial days per participant (approximately 16 weeks total).
Time frame: From enrollment, through study completion, an average of 4 months.
Subjective Measures of Perceived Recovery
Measure: Perceived Recovery Status Scale score. Objective: To assess perceived recovery and performance across menstrual cycle phases. Time Frame: Assessed at 5 time points (baseline, immediately post, 4 hours, 24 hours, and 48 hours post-exercise) on up to 3 experimental trial days (approximately 16 weeks total).
Time frame: From enrollment, through study completion, an average of 4 months.
Subjective Measures of Perceived Recovery
Measure: Visual Analog Scale (VAS) ratings for recovery. Objective: To assess perceived recovery across menstrual cycle phases. Time Frame: Assessed at 5 time points (baseline, immediately post-exercise, 4 hours post, 24 hours post, and 48 hours post) on up to 4 experimental trial days per participant (approximately 16 weeks total).
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Time frame: From enrollment, through study completion, an average of 4 months.
Subjective Measures of Fatigue
Measure: Visual Analog Scale (VAS) ratings for fatigue. Objective: To assess perceived fatigue across menstrual cycle phases. Time Frame: Assessed at 5 time points (baseline, immediately post-exercise, 4 hours post, 24 hours post, and 48 hours post) on 3 experimental trial days per participant (approximately 16 weeks total).
Time frame: From enrollment, through study completion, an average of 4 months.
Subjective Measures of Soreness
Measure: Visual Analog Scale (VAS) ratings for soreness. Objective: To assess perceived soreness across menstrual cycle phases. Time Frame: Assessed at 5 time points (baseline, immediately post-exercise, 4 hours post, 24 hours post, and 48 hours post) on 3 experimental trial days per participant (approximately 16 weeks total).
Time frame: From enrollment, through study completion, an average of 4 months.
Subjective Sleep Quality
Measure: Groningen Sleep Quality Questionnaire (GSQQ). Objective: To investigate whether menstrual cycle phases impact subjective sleep quality. Time Frame: Assessed at 3 time points (baseline, 24 hours post, and 48 hours post) on 3 experimental trial days per participant (approximately 16 weeks total)
Time frame: Time Frame: From enrollment, through study completion, an average of 4 months.
Subjective Sleep Quality
Measure: Self-Assessment of Sleep Survey (SASS-Y). Objective: To investigate whether menstrual cycle phases impact subjective sleep quality. Time Frame: Assessed at 1 time point (baseline) on 3 experimental trial days per participant (approximately 16 weeks total)
Time frame: From enrollment, through study completion, an average of 4 months.
Objective Sleep Quality
Measure: Actigraph Accelerometer data. Objective: To investigate whether menstrual cycle phases impact objective sleep quality. Time Frame: Continuously monitored from 72 hours before to 48 hours after exercise on each of 3 experimental trial days (approximately 16 weeks total).
Time frame: From enrollment, through study completion, an average of 4 months.
Mood
Measure: Profile of Mood States (POMS). Objective: To examine the influence of the menstrual cycle on mood during recovery from exercise. Time Frame: Assessed at 5 time points (baseline, immediately post-exercise, 4 hours post, 24 hours post, and 48 hours post) on 3 experimental trial days per participant (approximately 16 weeks total).
Time frame: From enrollment, through study completion, an average of 4 months.
Menstrual Distress
Description: Measure: Menstrual Distress Questionnaire (MEDI-Q). Objective: To examine the influence of the menstrual cycle on menstrual distress reporting. Time Frame: Assessed at 1 time point (baseline) on 3 experimental trial days per participant (approximately 16 weeks total)
Time frame: From enrollment, through study completion, an average of 4 months.