Influence of Menstrual Cycle Stages on Female Athletes

• Determination of hormone level concentrations (Procedure): Determination of concentration of 17β-oestradiol (pg/mL), progesterone (ng/mL), LH (mUI/mL), FSH (mUI/mL), prolactin (ng/mL), total testosterone (ng/mL), free testosterone (pmol/L) sex hormone binding globulin (SHBG) (nmol/L), cortisol (μg/dL), T3 (ng/dL), T4 (mcg/dL), TSH (mcU/mL), basal insulin (mcUI/mL) during the early follicular phase, late follicular phase, and mid-luteal phase.
• Jump height determination (Procedure): by Chronojump contact mat, determine five types of jump in centimeters: Squat jump without additional weight, Squat jump with 50% of body weight, Countermovement jump, Abalakov jump, and Drop jump, during the early follicular phase, late follicular phase, and mid-luteal phase.
• Grip strength determination (Procedure): measuring of changes in muscle strength by handgrip dynamometer in the hand to be tested (handgrip test) during the early follicular phase, late follicular phase, and mid-luteal phase. Three attempts on each hand.
• Flexibility determination (Procedure): measurement of changes in the range of motion of the hamstring musculature, by sit and reach test (cm), during the early follicular phase, late follicular phase, and mid-luteal phase. Three tries.
• Indirect maximum oxygen consumption determination (Procedure): by the Course Navette test, the indirect oxygen consumption is calculated using the formula: VO2max = (6xFA) - 27,4 (FA = Speed of the last stage of the test completed. It takes place during the early follicular phase, late follicular phase, and mid-luteal phase.
• Sensory and pain threshold determination (Device): by electrical muscle stimulator (Digitimer DS7A), during the early follicular phase, late follicular phase, and mid-luteal phase.
• Physical and mental symptoms associated with the menstrual cycle (Other): By The Daily Record of Severity of Problems (DRSP) questionnaire, during a full menstrual cycle.
• Daily activity (Device): by accelerometer (GENEActiv) during a full menstrual cylcle: Wrist-worn device measuring accelerations as a measure of daily activity, in cpm, counts per minute.
• Biochemical parameters determination (Procedure): Determination of concentration of iron (μg/dL), ferritin (ng/mL), and transferrin (mg/dL), during the early follicular phase, late follicular phase, and mid-luteal phase.
• Blood count determination (Procedure): Determination of concentration of hemoglobin (g/dL), red blood cells (10\^6/μL), hematocrit (%), white blood cells (10\^3/μl), platelets (10\^3/μl), during the early follicular phase, late follicular phase, and mid-luteal phase.
• Body composition parameters determination (Procedure): Determination of weight (kg), total body water (L), proteins (kg), minerals (kg), body fat mass (kg), body mass index (BMI) (kg/m2), basal metabolic rate (kcal) by Bioelectrical Impedance Analysis, during the early follicular phase, late follicular phase, and mid-luteal phase.
• Vital signs (Procedure): Determination of blood pressure (mmHg) and heart rate (bpm) at baseline, one minute and three minutes after the Course Navette test
• Checking for correct use of contraceptive methods (Other): Pre-test questions about possible forgetfulness or mishandling of the method
• Urinary LH determination (Procedure): Urine LH test strips are performed from day 8 of the cycle until positive.

Primary outcomes

• Change in 17β-oestradiol concentration (in pg/mL) [three times in a month]: concentration of 17β-oestradiol in pg/mL
• Change in T4 concentration (in mcg/dL) [three times in a month]: concentration of T4 in mcg/dL
• Change in T3 concentration (in ng/dL) [three times in a month]: concentration of T3 in ng/dL
• Change in cortisol concentration (in μg/dL) [three times in a month]: concentration of cortisol in μg/dL
• Change in TSH concentration (in mcUI/mL) [three times in a month]: concentration of thyroid-stimulating hormone (TSH) and basal insulin in mcUI/mL
• Change in SHBG concentration (in nmol/L) [three times in a month]: concentration of sex hormone binding globulin (SHBG) in nmol/L
• Change in free testosterone concentration (in pmol/L) [three times in a month]: Concentration of free testosterone in pmol/L
• Change in progesterone concentration (in ng/mL) [three times in a month]: Concentration of progesterone, prolactin and total testosterone in ng/mL
• Change in LH and FSH concentration (in mUI/mL) [three times in a month]: Concentration of luteinizing hormone (LH) and FSH (follicle stimulating hormone) in mUI/mL
• Change from baseline jumping height [three times in a month]: Measuring of change in muscle power through Squat jump without additional weight, Squat jump with 50% of body weight, Countermovement jump, Abalakov jump, and Drop jump by Chronojump contact mat, in cm. Three tries on each jump.
• Change from baseline grip strength [three times in a month]: measuring of changes in muscle strength by handgrip dynamometer in the hand to be tested (handgrip test). Three attempts on each hand.
• Change from baseline flexibility [three times in a month]: measurement of changes in the range of motion of the hamstring musculature, by sit and reach test (cm). Three tries.
• Change from baseline indirect maximum oxygen consumption [three times in a month]: by the Course Navette test
• Change from baseline sensory and pain threshold [three times in a month]: by electrical muscle stimulator (Digitimer DS7A)
• Change from baseline physical and mental symptoms associated with the menstrual cycle by The Daily Record of Severity of Problems questionnaire [Duration of a full menstrual cycle (approximately 28 days)]: By The Daily Record of Severity of Problems (DRSP) questionnaire. This scale measures symptoms subjectively from 1 to 6, where 1 corresponds to "not at all" and 6 corresponds to "extreme". The higher the score, the more severe the symptom is.
• Change from baseline daily activity [Duration of a full menstrual cycle (approximately 28 days)]: by accelerometer (GENEActiv): Wrist-worn device measuring accelerations as a measure of daily activity, in cpm, counts per minute.

Secondary outcomes

• Change in iron concentration (in μg/dL) [three times in a month]: concentration of iron in μg/dL
• Change in transferrin concentration (in mg/dL) [three times in a month]: concentration of transferrin in mg/dL
• Change in ferritin concentration (in ng/mL) [three times in a month]: concentration of ferritin in ng/mL
• Change in hemoglobin concentration (in g/dL) [three times in a month]: concentration of hemoglobin in g/dL
• Change in white blood cells and platelets concentration (in 10^3/μl) [three times in a month]: concentration of white blood cells and platelets in 10\^3/μl
• Change in hematocrit concentration (in %) [three times in a month]: concentration of hematocrit in %
• Change in red blood cells concentration (in 10^6/μl) [three times in a month]: concentration of red blood cells in 10\^6/μL
• Change in weight, proteins, minerals and body fat mass in kg [three times in a month]: Weight, proteins, minerals and body fat mass in kg by Bioelectrical Impedance Analysis
• Change in Body Mass Index (BMI) in kg/m2 [three times in a month]: Body Mass Index (BMI) in kg/m2 by Bioelectrical Impedance Analysis and measuring tape
• Change in Basal metabolic rate in kcal [three times in a month]: Basal metabolic rate in kcal by Bioelectrical Impedance Analysis
• Change in total body water in liters (L) [three times in a month]: total body water in liters (L) by Bioelectrical Impedance Analysis
• Change in Blood pressure in mmHg [three times in a month]: Blood pressure (systolic and diastolic pressure) in mmHg at baseline, one minute and three minutes after the Course Navette test by blood pressure monitor
• Change in heart rate in bpm [three times in a month]: Heart rate in bpm at baseline, one minute and three minutes after the Course Navette test by blood pressure monitor

Sex: Female, ages: 18 Years to 40 Years, accepts healthy volunteers

Inclusion Criteria:

Inclusion criteria natural cycles group:

* Female sex
* Women between 18 and 40 years of age
* Women who are members of a federation and who compete in a sport doing at least 240 minutes of exercise per week.
* Women with regular menstrual cycles (between 23 and 38 days long).
* Women who have not taken hormonal contraceptives (HA) for 6 months or more.

Inclusion criteria artificial cycles group:

* Female sex
* Women between 18-40 years of age
* Women federated and competed in a sport doing at least 240 minutes of exercise per week.
* Long-term users of HA (minimum 6 months).

Exclusion Criteria:

Exclusion criteria group natural cycles:

* Refusal to participate in the study
* Sedentary women
* Women on HA currently or in the 6 months before the study
* Women with irregular menstrual cycles, less than 23 or more than 38 days in length
* Any existing metabolic disease or disorder
* Regular use of medications or dietary supplements that could affect the results
* Pregnancy or breastfeeding

Exclusion criteria artificial cycles group:

* Refusal to participate in the study
* Sedentary women
* Any existing metabolic disease or disorder
* Regular use of medications or dietary supplements that could affect the results
* Inability to manage contraception in a disciplined manner

• Results publication: Recacha-Ponce P, Suarez-Alcazar P, Hernando C, Salas-Medina P, Muriach M, Balino P, Guisado-Cuadrado I, Collado-Boira E. Hormonal balance, anovulatory cycles and luteal phase deficiency: exploring relationships between hematological variables, sex hormones and V̇O2max in athletes. Reprod Fertil. 2025 Apr 28;6(2):e240119. doi: 10.1530/RAF-24-0119. Print 2025 Apr 1. PMID 40232947

• Paula Recacha-Ponce, Midwife, Principal investigator, Universitat Jaume I
• Eladio Collado-Boira, Doctor, Study director, Universitat Jaume I
• Carlos Hernando-Domingo, Doctor, Study director, Universitat Jaume I