The Effects of Cathodal tDCS on Muscle Strength in Healthy Adults

NCT ID: NCT04672122

Last Updated: 2022-06-22

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 48 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2020-11-16
• Study Completion Date: 2022-03-31

Brief Summary

To investigate the effects of different intensity of cathodal tDCS on muscle strength in healthy adults.

Detailed Description

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that can modulate cortical excitability. In 2000, Nitsche and Paulus reported the polarity-dependent effect of tDCS in humans, i.e., anodal tDCS facilitates cortical excitability while cathodal tDCS decreases it. (Nitsche & Paulus, 2000). TDCS studies have been replicated by many researchers and reported similar effects of tDCS in humans when using anodal and cathodal tDCS with an intensity of 1 mA. The linear effect of tDCS also has been reported by various studies, i.e., when increase intensity, the polarity-dependent effect of tDCS also enhances. However, conflicting results of cathodal tDCS efficacy have been reported.

Cortical excitability has been used to represent the efficacy of tDCS on neuroplasticity. The linear effect of cathodal tDCS on cortical excitability have been reported by researchers when using intensities at 1, 2, and 3 mA stimulated at the primary motor cortex in healthy participants (Batsikadze et al., 2013; Jamil et al., 2017; Kuo et al., 2013; Mosayebi Samani et al., 2019; Nitsche et al., 2003). Nevertheless, some studies showed the non-linear effects of cathodal tDCS (i.e., when increases intensity, cathodal tDCS enhances the cortical excitability) when using intensities at 1.5 and 2 mA in healthy participants (Batsikadze et al., 2013; Jamil et al., 2017; Mosayebi Samani et al., 2019). Hence, cathodal tDCS efficacy on cortical excitability is still controversy.

Muscle performance is an outcome that represents clinical change induced by tDCS. Previous studies reported the tendency of cathodal tDCS efficacy in decreasing muscle performance of both upper and lower extremities in healthy participants (Cogiamanian et al., 2007; Tanaka et al., 2009). However, previous studies used a single intensity of tDCS in each study. Hence, there was no direct comparison between different intensities of cathodal tDCS on muscle performance in healthy participants.

In our study, we aim to investigate the effect of different intensities of cathodal tDCS on muscle strength in healthy participants.

Conditions

Healthy Participants

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: FACTORIAL
• Primary Study Purpose: OTHER
• Blinding Strategy: DOUBLE

Study Groups

Sham tDCS

Sham transcranial direct current stimulation (tDCS) will be applied for 20 mins. Cathode on the primary motor area (M1) and Anode on the supraorbital area of contralateral side. Current intensity will be at 2 mA (sham mode). The scope of intervention is to investigate effect of sham tDCS on muscle strength.

Group Type: SHAM_COMPARATOR

Transcranial direct current stimulation

Intervention Type: DEVICE

Cathodal tDCS will be applied for 20 mins.

Cathodal-tDCS 1 mA

Cathodal transcranial direct current stimulation (tDCS) will be applied for 20 mins. Cathode on the primary motor area (M1) and Anode on the supraorbital area of contralateral side. Current intensity is fixed at 1 mA and current will flow continuously. The scope of intervention is to investigate effect of cathodal tDCS on muscle strength.

Group Type: EXPERIMENTAL

Transcranial direct current stimulation

Intervention Type: DEVICE

Cathodal tDCS will be applied for 20 mins.

Cathodal-tDCS 1.5 mA

Cathodal transcranial direct current stimulation (tDCS) will be applied for 20 mins. Cathode on the primary motor area (M1) and Anode on the supraorbital area of contralateral side. Current intensity is fixed at 1.5 mA and current will flow continuously. The scope of intervention is to investigate effect of cathodal tDCS on muscle strength.

Group Type: EXPERIMENTAL

Transcranial direct current stimulation

Intervention Type: DEVICE

Cathodal tDCS will be applied for 20 mins.

Cathodal-tDCS 2 mA

Cathodal transcranial direct current stimulation (tDCS) will be applied for 20 mins. Cathode on the primary motor area (M1) and Anode on the supraorbital area of contralateral side. Current intensity is fixed at 2 mA and current will flow continuously. The scope of intervention is to investigate effect of cathodal tDCS on muscle strength.

Group Type: EXPERIMENTAL

Transcranial direct current stimulation

Intervention Type: DEVICE

Cathodal tDCS will be applied for 20 mins.

Interventions

Transcranial direct current stimulation

Cathodal tDCS will be applied for 20 mins.

Intervention Type: DEVICE

Eligibility Criteria

Inclusion Criteria

1. Male and female healthy adults

2. Age range between 18 - 60 years old

3. Right-handed dominant identified by the Edinburg Handedness Inventory

4. No recent muscle injuries of both limbs for a past 6-months

Exclusion Criteria

1. Consumed caffeine within 24 hours prior the experiment

2. History of neurological symptoms i.e. seizures, weakness, loss of sensation or unclear history of pass illness

3. Presence of metal implantation, intracranial shunt, cochlear implantation or cardiac pacemakers

4. Presence of opened wound or infectious wound around scalp

5. Presence of pain in evaluating muscle groups

6. History of surgery in evaluating limbs

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 60 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Mahidol University

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Wanalee Klomjai, PhD

Role: STUDY_DIRECTOR

MU

Locations

Faculty of Physical Therapy, Mahidol University

Salaya, Changwat Nakhon Pathom, Thailand

Countries

Thailand

References

Vimolratana O, Lackmy-Vallee A, Aneksan B, Hiengkaew V, Klomjai W. Non-linear dose response effect of cathodal transcranial direct current stimulation on muscle strength in young healthy adults: a randomized controlled study. BMC Sports Sci Med Rehabil. 2023 Jan 30;15(1):10. doi: 10.1186/s13102-023-00621-7.

Reference Type: DERIVED

PMID: 36717894 (View on PubMed)

Other Identifiers

MU-CIRB2020/314.0210

Identifier Type: -

Identifier Source: org_study_id