N/A
N=102
Exploring the Modulatory Role of Sex Hormones Along the Neuromechanical Axis in Females
Role of Sex Hormones Along the Neuromechanical Axis
Bottom Line
View on ClinicalTrials.gov: NCT03947684 ↗Enrolled (actual)
102
Serious AEs
0.0%
Results posted
Oct 2025
Primary outcome: Primary: Changes in Short-interval Intracortical Inhibition (SICI) During the Follicular Phase — 0.78; 0.83; 0.93; 1.03 ratio to the unconditioned stimulus MEP — p=>0.05
Study Design & Population
- Study type
- Observational
- Phase
- N/A
- Interventions
- —
- Age
- Adult · 18+ yrs
- Sex
- All
- Sponsor
- University of Texas Southwestern Medical Center
- Primary completion
- Apr 2024
Outcome Measures
| Outcome | Result | p-value |
|---|---|---|
| PRIMARY Changes in Short-interval Intracortical Inhibition (SICI) During the Follicular Phase |
0.78; 0.83; 0.93; 1.03; 1.08; 1.11 | >0.05 |
| PRIMARY Change in Stretch Reflex at Relaxed State |
0.0164; 0.0138 | >0.05 |
| PRIMARY Change in Spinal Motor Neuron Excitability in Non Oral Contraceptive User |
0.6; 0.61 | >0.05 |
| PRIMARY Normalized Conditioned Motor Evoked Potential in Male and Female |
0.75; 1.02; 1.06; 1.17; 1.3; 1.35 | >0.05 |
| PRIMARY Change in Spinal Motor Neuron Excitability in Oral Contraceptive User |
0.67; 0.67 | >0.05 |
| PRIMARY Changes in Intracortical Facilitation (ICF) During the Follicular Phase |
1.32; 1.54; 1.46; 1.37; 1.28 | >0.05 |
| PRIMARY Change in Stretch Reflex at Active State |
0.0106; 0.0111 | >0.05 |
| SECONDARY Change in Steadiness of Isometric Force Production at 20% of Maximum Voluntary Contraction in Non Oral Contraceptive User |
2.2; 2.2 | >0.05 |
| SECONDARY Change in Flexion Reflex Root Mean Squared Value in Non Oral Contraceptive User |
0.093; 0.111 | >0.05 |
| SECONDARY Change in Flexion Reflex Duration in Non Oral Contraceptive User |
36.58; 35.60 | >0.05 |
| SECONDARY Change in Flexion Reflex Latency in Non Oral Contraceptive User |
81.96; 80.73 | >0.05 |
| SECONDARY Change in Flexion Reflex Root Mean Squared Value in Oral Contraceptive User |
0.107; 0.083 | >0.05 |
| SECONDARY Change in Flexion Reflex Duration in Oral Contraceptive User |
30; 28.2 | >0.05 |
| SECONDARY Change in Flexion Reflex Latency in Oral Contraceptive User |
77.7; 76.4 | <0.05 sig |
| SECONDARY Change in Steadiness of Isometric Force Production at 20% of Maximum Voluntary Contraction in Oral Contraceptive User |
1.9; 1.9 | <0.05 sig |
Summary
The goal of this project is to test our central hypothesis that changes in sex hormone concentration result in changes to the basic elements of motor control - at multiple levels, from the musculotendinous unit to motor control circuitry. Under Aim 1 the investigator will determine the influence of sex hormone fluctuations on the muscle stretch reflex during active and passive states, and the time lag between hormone concentration changes and the reflex response. The investigator will use a technically simple assessment that could be implemented in the field. Under Aim 2 the investigator will determine the influence of sex hormone fluctuations on spinal motor neuron excitability using H-reflex as a probe and the simultaneous change in the muscle mechanics using muscle twitch response. Aims 1 & 2 will include a focus on the differential role of oral contraceptives. In Aim 3 the investigator will use paired-pulse transcranial magnetic stimulation during active contraction to determine the influence of sex hormone fluctuation.
Eligibility Criteria
Inclusion Criteria
- Females: ages 18-39 years, who are eumenorrheic (regular monthly cycles of 24-35 days) or on a stable hormonal contraceptive regimen for 6 months (oral, transdermal or vaginal), no history of pregnancy, moderately active (less than 7 hours of vigorous physical activity per week)
- Males: Ages 18-39
Exclusion Criteria
- History of musculoskeletal or orthopedic injury of the spine, hip, knee, ankle or foot, history of neurological injury of the peripheral or central nervous system, current smoker, history of disordered eating, history of stress fracture in the lower limb, history of a connective tissue disorder (Marfan's syndrome, Ehlers-Danlos disease).
- For female participants only: Point of care screening for anemia will be completed, and individuals with hemoglobin levels <11.6 g/dl will be excluded from participating in the study.
- Specific exclusion criteria for TMS (male and female): pacemaker, metal implants in the head region, history of epilepsy or seizures, skull fractures or skull deficits, concussion within the last 6 months, unexplained recurring headaches, medications that lower seizure threshold, and pregnancy.
- Additional exclusion criteria for female participants: History of menstrual dysfunction (primary or secondary amenorrhea, oligomenorrhea, anovulatory cycles, polycystic ovarian disease), current or past pregnancy, started or stopped taking oral contraceptives within the previous 6 months, exercise vigorously more than 7 hours per week or currently participating in competitive level sports. The reason for excluding highly active or competitive athletes is due to the high rate of undiagnosed menstrual dysfunction in females of this population.
- This study will not include: adults unable to consent, Individuals who are not yet adults (infants, children, teenagers), pregnant women or prisoners.
Data sourced from ClinicalTrials.gov (NCT03947684). Outcome figures and adverse-event rates are extracted automatically from the registry's posted results and are provided for clinician reference, not as a substitute for the primary publication.