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.
Study Type
OBSERVATIONAL
Enrollment
102
UT Southwestern Medical Center
Dallas, Texas, United States
Changes in Short-interval Intracortical Inhibition (SICI) During the Follicular Phase
The conditioned motor evoked potential (MEP) at each inter-stimulus interval (ISI) was normalized to MEP obtained from unconditioned stimulation. Change was evaluated by regressing the normalized conditioned motor evoked potential amplitude at each ISI with estradiol concentration. Average and standard deviation for each ISI reported.
Time frame: day 1 menses up to day with highest estradiol concentration
Change in Stretch Reflex at Relaxed State
Muscle stretch reflex (MSR) was calculated by dividing the root mean squared (RMS) value of the electromyogram (EMG) response with the RMS of the muscle's EMG during maximal voluntary contraction and the force of the tapper used to elicit the reflex. Change was evaluated by regressing the ratio simultaneously on estradiol and progesterone concentrations, and estradiol x progesterone interaction. Average and standard deviation for each menstrual phase is reported.
Time frame: Follicular, Luteal
Change in Spinal Motor Neuron Excitability in Non Oral Contraceptive User
The spinal motor neuron excitability was measured by calculating the ratio between the maximum peak-to-peak value of H reflex and the maximum peak-to-peak value of M wave. Change was evaluated by regressing the ratio simultaneously on estradiol and progesterone concentrations, and estradiol x progesterone interaction. Average and standard deviation for each menstrual phase is reported.
Time frame: Follicular, Luteal
Normalized Conditioned Motor Evoked Potential in Male and Female
The conditioned motor evoked potential (MEP) at each inter-stimulus interval (ISI) was normalized to MEP obtained from unconditioned stimulation. The difference between male and female groups was evaluated using a 2 (male vs. female) x 7 (ISI) repeated measures ANOVA. Average and standard deviation for each ISI reported.
Time frame: menses period for female, day 1 for male
Change in Spinal Motor Neuron Excitability in Oral Contraceptive User
The spinal motor neuron excitability was measured by calculating the ratio between the maximum peak-to-peak value of H reflex and the maximum peak-to-peak value of M wave. Change was evaluated by regressing the ratio simultaneously on estradiol and progesterone concentrations, and estradiol x progesterone interaction. Average and standard deviation for active and inactive pill phase are reported.
Time frame: Active pill, Inactive pill
Changes in Intracortical Facilitation (ICF) During the Follicular Phase
The conditioned motor evoked potential (MEP) at each inter-stimulus interval (ISI) was normalized to MEP obtained from unconditioned stimulation. Change was evaluated by regressing the normalized conditioned motor evoked potential amplitude at each ISI with estradiol concentration. Average and standard deviation for each ISI reported.
Time frame: day 1 menses up to day with highest estradiol concentration
Change in Stretch Reflex at Active State
Muscle stretch reflex (MSR) was calculated by dividing the root mean squared (RMS) value of the electromyogram (EMG) response with the RMS of the muscle's EMG during maximal voluntary contraction and the force of the tapper used to elicit the reflex. Change was evaluated by regressing the ratio simultaneously on estradiol and progesterone concentrations, and estradiol x progesterone interaction. Average and standard deviation for each menstrual phase is reported.
Time frame: Follicular, Luteal
Change in Steadiness of Isometric Force Production at 20% of Maximum Voluntary Contraction in Non Oral Contraceptive User
Steadiness of the exerted force is quantified using coefficient of variation. Change was evaluated by regressing the steadiness simultaneously on estradiol and progesterone concentrations, and estradiol x progesterone interaction. The analyses was performed during (1) follicular phase, and (2) luteal phase. Average and standard deviation for each phase is reported.
Time frame: Follicular, Luteal
Change in Flexion Reflex Root Mean Squared Value in Non Oral Contraceptive User
The root mean squared (RMS) value were calculated and averaged for each testing visit. Change was evaluated by regressing the RMS simultaneously on estradiol and progesterone concentrations, and estradiol x progesterone interaction. The analyses was performed during (1) follicular phase, and (2) luteal phase. Average and standard deviation for each phase is reported.
Time frame: Follicular, Luteal
Change in Flexion Reflex Duration in Non Oral Contraceptive User
The duration were calculated and averaged for each testing visit. Change was evaluated by regressing the duration simultaneously on estradiol and progesterone concentrations, and estradiol x progesterone interaction. The analyses was performed during (1) follicular phase, and (2) luteal phase. Average and standard deviation for each phase is reported.
Time frame: Follicular, Luteal
Change in Flexion Reflex Latency in Non Oral Contraceptive User
The latency measured from the onset of the stimulus were calculated and averaged for each testing visit. Change was evaluated by regressing the latency simultaneously on estradiol and progesterone concentrations, and estradiol x progesterone interaction. The analyses was performed during (1) follicular phase, and (2) luteal phase. Average and standard deviation for each phase is reported.
Time frame: Follicular, Luteal
Change in Flexion Reflex Root Mean Squared Value in Oral Contraceptive User
The root mean squared (RMS) value were calculated and averaged for each testing visit. Change was evaluated by regressing the RMS simultaneously on estradiol and progesterone concentrations, and estradiol x progesterone interaction. The analyses was performed during (1) active pill, and (2) inactive pill. Average and standard deviation for each phase is reported.
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Time frame: Active pill, Inactive pill
Change in Flexion Reflex Duration in Oral Contraceptive User
The duration were calculated and averaged for each testing visit. Change was evaluated by regressing the duration simultaneously on estradiol and progesterone concentrations, and estradiol x progesterone interaction. The analyses was performed during (1) active pill, and (2) inactive pill. Average and standard deviation for each phase is reported.
Time frame: Active pill, Inactive pill
Change in Flexion Reflex Latency in Oral Contraceptive User
The latency measured from the onset of the stimulus were calculated and averaged for each testing visit. Change was evaluated by regressing the latency simultaneously on estradiol and progesterone concentrations, and estradiol x progesterone interaction. The analyses was performed during (1) active pill, and (2) inactive pill. Average and standard deviation for each phase is reported.
Time frame: Active pill, Inactive pill
Change in Steadiness of Isometric Force Production at 20% of Maximum Voluntary Contraction in Oral Contraceptive User
Steadiness of the exerted force is quantified using coefficient of variation. Change was evaluated by regressing the steadiness simultaneously on estradiol and progesterone concentrations, and estradiol x progesterone interaction. The analyses was performed during (1) active pill, and (2) inactive pill. Average and standard deviation for each phase is reported.
Time frame: Active pill, Inactive pill