Effects of Resistance Training on Women With Functional Hypothalamic Amenorrhea

• Resistance Training Program (Other): Supervised 8-week resistance training program consisting of three non-consecutive full-body sessions per week. Each session included four multi-joint exercises targeting upper and lower body muscle groups. Training dosage: Volume: Two working sets of 6-8 repetitions per exercise. Intensity: Individualized loads progressed weekly from 60% to 80% of estimated 1RM. 1RM was estimated using the Epley equation. Effort: Performed at 0-1 repetitions in reserve (RIR). Rest:Standardized 1-minute intervals between sets. Adherence was tracked via a mobile application, recording load, sets, repetitions, and session RPE. Training was conducted under professional supervision to ensure safety and protocol compliance.

Primary outcomes

• Incidence of Menstrual Recovery [8 weeks]: Number of participants in the Functional Hypothalamic Amenorrhea (FHA) group who experience at least one spontaneous menstrual bleeding episode during the 8-week intervention. Menstrual status is monitored daily using non-invasive methods: self-reported menstrual diaries and basal body temperature (BBT) tracking with a digital thermometer (SENTI2) to identify hormonal fluctuations. Recovery is defined as the occurrence of the first menses post-intervention commencement.

Secondary outcomes

• Change in Neuromuscular Performance (Lower Limb Power) [Baseline and 8 weeks]: Evaluation of lower-limb power through the Countermovement Jump (CMJ) test performed on a force platform. Jump height (cm) and power output (W/kg) were recorded to assess neuromuscular adaptations.
• Change in Neuromuscular Performance (Upper Limb Power) [Baseline and 8 weeks]: Evaluation of upper-limb strength through handgrip dynamometry testing. Grip strength (kg) was recorded to assess changes in maximal upper-limb force production.
• Change in Body Mass [Baseline and 8 weeks]: Evaluation of body mass using bioelectrical impedance analysis. Body mass (kg) will be assessed before and after the intervention to monitor changes associated with menstrual recovery and the exercise intervention.
• Change in Fat Mass [Baseline and 8 weeks]: Evaluation of fat mass using bioelectrical impedance analysis. Fat mass (%) will be assessed before and after the intervention to determine body composition changes during menstrual recovery.
• Change in Body Mass Index [Baseline and 8 weeks]: Body mass index (BMI, kg/m²) will be calculated from body mass and height measurements to evaluate anthropometric changes following the intervention.
• Change in Health-Related Quality of Life [Baseline and 8 weeks]: Assessment of psychological well-being using the Short Form-36 (SF-36) questionnaire. This tool evaluates eight health domains, with total scores ranging from 0 to 100; higher scores indicate better health status and quality of life.
• Pittsburgh Sleep Quality Index [Baseline and 8 weeks]: A 19-item questionnaire generating seven component scores and one global score used to assess sleep quality. The global PSQI score ranges from 0 to 21 points, with higher scores reflecting poorer sleep quality. A global score >5 indicates poor sleep quality.
• Low Energy Availability in Females Questionnaire [Baseline and 8 weeks]: The Low Energy Availability in Females Questionnaire (LEAF-Q) is a 25-item instrument designed to assess risk factors associated with low energy availability in physically active females, including menstrual function, gastrointestinal symptoms, and injury history. The questionnaire provides a total score ranging from 0 to 25 points, with higher scores indicating greater risk of low energy availability and related conditions. A total score ≥8 is considered indicative of increased risk for low energy availability and the Female Athlete Triad/Relative Energy Deficiency in Sport (RED-S).
• Eating Attitudes Test [Baseline and 8 weeks]: The Eating Attitudes Test-26 (EAT-26) is a 26-item questionnaire assessing symptoms and concerns characteristic of eating disorders. It provides a total score and three subscales: dieting, bulimia and food preoccupation, and oral control. Total scores range from 0 to 78 points, with higher scores indicating greater disordered eating symptomatology. A total score ≥20 suggests potentially problematic eating behaviors and risk of eating disorders.
• Menstrual Distress Questionnaire [Baseline and 8 weeks]: The Menstrual Distress Questionnaire (MDQ) is a 22-item Likert-scale questionnaire designed to assess physical, psychological, and behavioral symptoms associated with the menstrual cycle. The questionnaire provides a total score ranging from 22 to 110 points, with higher scores indicating greater menstrual-related distress and symptom severity.
• Change in Cardiac Autonomic Regulation [Baseline and 8 weeks]: Assessment of heart rate variability (HRV) through the root mean square of successive differences between adjacent R-R intervals recorded via a heart rate monitor at rest.The following variables were obtained: mean R-R interval (RR, ms) and the root mean square of successive differences between adjacent R-R intervals (RMSSD, ms), to assess autonomic nervous system activity and cardiac autonomic modulation.

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

Inclusion Criteria:

* General Profile: Active women aged 18 to 35 years.
* FHA Group: Clinical diagnosis of Functional Hypothalamic Amenorrhea, defined as the absence of menstruation for at least three consecutive months not attributable to other endocrine disorders.
* Control Group (EU): Eumenorrheic women with regular ovulatory cycles lasting between 24 and 35 days during the previous six months.
* Commitment: Agreement to participate in a supervised 8-week resistance training program and provision of medical documentation confirming menstrual status.

Exclusion Criteria:

* Hormonal Status: Current use of any hormonal contraceptives.
* Medical Conditions: Diagnosed endocrine disorders such as Polycystic Ovary Syndrome (PCOS), hyperandrogenism, or thyroid dysfunction.

Pregnancy: Current pregnancy.

* Physical Activity History: Engagement in any structured resistance training program during the three months prior to the start of the intervention.
* General Health: Any medical condition that could interfere with the study protocol or the ability to perform physical exercise.

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