4 mA tDCS, Estrogen, and Leg Muscle Fatigability

NCT04471805 | Completed Results FDA Device

• 1 other identifier: 202005124
• Study Type: interventional
• Target: 10
• Locations: 1 country
• Sites: 1

Brief Summary

The majority of transcranial direct current stimulation (tDCS) studies have failed to consider sex as a modulating factor. This neglect may partly account for the high inter-subject variability bemoaned by many tDCS investigators (e.g., approximately 50% of participants do not respond to tDCS) and has certainly delayed progress in the field. Therefore, research into how sex influences stimulation-related outcomes is vital to fully understand the underlying mechanisms of tDCS, which has shown great inconsistency. Because of the menstrual cycle, the hormonal levels of women fluctuate considerably more than in men. Importantly, these hormonal variations might impact the efficacy of neuromodulatory tools, like tDCS. It is suggested that estrogen, which is high in the second follicular phase, reinforces excitatory mechanisms in the motor cortex. However, because anodal tDCS enhances cortical excitation there is also a possibility of excessive excitability. For instance, anodal tDCS may lead to overexcitation and non-optimal performance when it is applied in the second follicular phase of the menstrual cycle. Currently, there is a lack of knowledge on how the phases of the menstrual cycle affect tDCS performance outcomes in healthy young women because no studies have examined if and how the phases of the menstrual cycle alter tDCS efficacy. This study is critical for determining the optimal time to administer anodal tDCS, and the ideal intensity for that administration, to achieve the most beneficial results. Furthermore, this investigation will emphasize the need for future tDCS studies to test women during the same menstrual cycle phase.

Conditions

Healthy

Keywords

transcranial direct current stimulation; muscle fatigue; brain stimulation

Outcome Measures

Primary Outcomes (2)

• Fatigue Index From the Isokinetic Fatigue Test

  Perform 40 consecutive flexion and extension repetitions of the knee on the dominant leg. After a 10 minute rest, do the same task on the non-dominant leg. The fatigue index was calculated using the greatest torque from the relevant repetitions of the fatigue test as follows: (\[mean of reps 3 through 7-mean of last five reps\]/mean of reps 3 through 7) X 100 and is expressed as a percentage of decline in torque production.

  Completed at each visit, spaced approximately 14 days apart for 2 consecutive months

• Muscle Activity During the Strength and Fatigue Tests

  Collect electromyographic (EMG; muscle activity) information during the fatigue tests. Muscle activity is measured as electrical signals/voltages. The muscle activity of the knee extensors (rectus femoris, vastus medialis, and vastus lateralis) was averaged to represent the cumulative activity of this muscle group. The first two repetitions of the fatigue test were considered adaptation repetitions and were removed. Therefore, the remaining 38 repetitions were used for the average EMG analyses. The subsequent 38 repetitions were also organized into 8 windows. The first seven windows consisted of five consecutive and non-overlapping repetitions (e.g., window 2 = reps 8-12; window 3 = reps 13-17, etc.) while the last (eighth) window was comprised of the final three repetitions.

  Completed at each visit, spaced approximately 14 days apart for 2 consecutive months

Secondary Outcomes (1)

• Estrogen Level

  Completed at each visit, spaced approximately 14 days apart for 2 consecutive months

Study Arms (1)

Eumenorrheic Women

EXPERIMENTAL

Participants will have the anode (active electrode) placed over the brain area that controls their dominant leg and the cathode (return electrode) above the ipsilateral eyebrow. tDCS is administered in the early follicular phase, late follicular phase, and mid-luteal phase of their menstrual cycle. tDCS: Stimulation is ramped up to 4 mA over the first 30 seconds and stays at 4 mA for the remainder of the simulation time. Sham: Stimulation is turned on (4 mA) for 30 seconds at the beginning and the end of the trial but stays at 0 mA in the intervening time.

Device: Sham transcranial direct current stimulation 4 mA; Device: Transcranial direct current stimulation 4 mA

Interventions

Sham transcranial direct current stimulation 4 mA DEVICE

Uses weak electrical current (4 mA intensity) at the beginning and the end of a given stimulation period to control for potential placebo-like effects or participant expectation bias.

Also known as: Sham tDCS 2 mA

Eumenorrheic Women

Transcranial direct current stimulation 4 mA DEVICE

Uses weak electrical current (4 mA intensity) to either increase or decrease brain excitability and improve functional or cognitive outcomes.

Also known as: tDCS 4 mA

Eumenorrheic Women

Eligibility Criteria

• Age: 18 Years - 35 Years
• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Has a regular menstrual cycle
• Young adult (18-35 years)
• Right-side dominant
• At least 30 min of moderate-intensity, physical activity on at least 3 days of the week for at least the last 3 months
• Without chronic neurological, psychiatric, or medical conditions
• Not taking any psychoactive medications.

You may not qualify if:

• Pregnant
• Known holes or fissures in the skull
• Metallic objects or implanted devices in the skull (e.g., metal plate)
• Women on hormonal contraceptives/supplements.

Sponsors & Collaborators

• University of Iowa: lead

Study Sites (1)

University of Iowa

Iowa City, Iowa, 52242, United States

Location

Results Point of Contact

• Title: Thorsten Rudroff, PhD
• Organization: University of Iowa, Department of Health and Human Physiology

thorsten-rudroff@uiowa.edu

(319)467-0363

Study Officials

• Thorsten Rudroff, PhD

  Health and Human Physiology

  PRINCIPAL INVESTIGATOR

Publication Agreements

• PI is Sponsor Employee: No
• Restrictive Agreement: No

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor

Study Record Dates

• First Submitted: July 10, 2020
• First Posted: July 15, 2020
• Study Start: October 1, 2020
• Primary Completion: November 1, 2021
• Study Completion: November 1, 2021
• Last Updated: May 10, 2023
• Results First Posted: May 10, 2023

Record last verified: 2023-04

Locations

US (1)