<clinical_study>
  <!-- This xml conforms to an XML Schema at:
    https://clinicaltrials.gov/ct2/html/images/info/public.xsd -->
  <required_header>
    <download_date>ClinicalTrials.gov processed this data on September 20, 2023</download_date>
    <link_text>Link to the current ClinicalTrials.gov record.</link_text>
    <url>https://clinicaltrials.gov/ct2/show/NCT03796117</url>
  </required_header>
  <id_info>
    <org_study_id>3.064.351</org_study_id>
    <nct_id>NCT03796117</nct_id>
  </id_info>
  <brief_title>Pulsed Current Versus Russian Current Effects in Healthy Young Subjects.</brief_title>
  <official_title>Neuromuscular Parameters, Current Intensity and Discomfort Level Between Pulsed Current and Russian Current in Healthy Young Subjects.</official_title>
  <sponsors>
    <lead_sponsor>
      <agency>Federal University of Rio Grande do Sul</agency>
      <agency_class>Other</agency_class>
    </lead_sponsor>
  </sponsors>
  <source>Federal University of Rio Grande do Sul</source>
  <oversight_info>
    <is_fda_regulated_drug>No</is_fda_regulated_drug>
    <is_fda_regulated_device>No</is_fda_regulated_device>
  </oversight_info>
  <brief_summary>
    <textblock>
      Low frequency pulsed current (PC) and medium frequency alternating current (Russian current -&#xD;
      RC, 2.5 kHz) have been largely studied due to their clinical use. However, it is not clear&#xD;
      which current is the most efficient due to the existente literature conflicts.Therefore, the&#xD;
      purpose of this study is to compare the neuromuscular efficiency, evoked torque, current&#xD;
      intensity, fatigability and level of discomfort between the PC and the RC in healthy young.&#xD;
      The current types will be tested in the same participant by the intervention sequences&#xD;
      randomization. On the first, second, third and fourth days, the maximum voluntary isometric&#xD;
      contraction (MVIC), the current intensity level, discomfort level, evoked torque, and&#xD;
      clinical and neuromuscular efficiency of each current will be evaluated. Anthropometric&#xD;
      measurements will also be assessed on the first day. In addition, the current intensity&#xD;
      required to produce a torque level of 20% of the MVIC, the current intensity required to&#xD;
      generate a torque of 40 Nm and the maximum intensity tolerated by the participant will be&#xD;
      evaluated. Three contractions will be recorded in each condition, and the level of discomfort&#xD;
      will be assessed during the evoked contractions. Evoked torque will be evaluated at the&#xD;
      maximum tolerated intensity level using the isokinetic dynamometer. Clinical and&#xD;
      neuromuscular efficiency will be evaluated (1) at the current intensity necessary to evoke&#xD;
      20% MVIC, (2) at the current intensity necessary to generate 40 Nm, and (3) at the maximum&#xD;
      tolerated current intensity. On the fifth and sixth days, muscle fatigue induced by the&#xD;
      diferente current types will be evaluated. Fatigue will be evaluated with sufficient current&#xD;
      intensity to generate 20% of the MVIC. MVIC will be performed before and after the fatigue&#xD;
      protocol, and the fatigue will be determined by the relative variation of the MVIC before and&#xD;
      after the fatigue protocol. Fatigue will also be evaluated through the evoked torque&#xD;
      variation between the first and the last minute of the fatigue protocol, as well as by the&#xD;
      total work generated in each protocol. Neuromuscular efficiency will be evaluated before and&#xD;
      immediately after the protocol through (1) the ratio between input NMES current intensity and&#xD;
      output evoked torque, (2) total work (area under the evoked force by time curves) generated&#xD;
      during the fatigue protocol, and (3) by the changes in muscle architecture from rest to&#xD;
      evoked contraction at the maximal current intensity.&#xD;
    </textblock>
  </brief_summary>
  <detailed_description>
    <textblock>
      This study is characterized by a quantitative approach, with a randomized crossover clinical&#xD;
      study design, blinded to evaluators and participants. The objective is to compare the&#xD;
      neuromuscular and clinical efficiency, evoked torque, current intensity, fatigue and&#xD;
      discomfort level between the low frequency biphasic pulsed current (PC) and the median&#xD;
      frequency sinusoidal alternating Russian current (RC) in healthy young participants. The&#xD;
      effect of the two neuromuscular electrical stimulation (NMES) current types on the cited&#xD;
      variables will be evaluated in the same participant, by means of the randomization of the&#xD;
      interventions sequences for each participant. The evaluation protocols will be performed by 2&#xD;
      blinded raters for the current type and for the outcome variables. A blinded evaluator to the&#xD;
      study will randomize the current type, which will be applied on the different evaluation&#xD;
      days, through a lottery using opaque envelopes. A researcher blinded to the study groups will&#xD;
      analyze the data. Participants will be blinded to the current type will be receiving. The&#xD;
      evaluations will be performed in six days, and a minimum interval of 7 days will be observed&#xD;
      between the evaluation days. On the first, second, third and fourth days, characterized as&#xD;
      Stage 1, the currents' intensity levels, discomfort level, evoked torque, and neuromuscular&#xD;
      and clinical efficiency of each randomized current will be evaluated. On the fifth and sixth&#xD;
      days, characterized as Stage 2, the muscle fatigue level induced by the two electrical&#xD;
      currents will be evaluated. The first evaluation day will be divided into two phases. Phase 1&#xD;
      corresponds to the initial evaluation, anthropometric data collection and physical activity&#xD;
      level evaluation. In Phase 2, the quadriceps femoris motor point will be located with a&#xD;
      pen-shaped electrode and a neuromuscular electrical stimulation unit, and the subcutaneous&#xD;
      adipose layer thickness covering the motor point will be evaluated by means of&#xD;
      ultrasonography. Subsequently, the ultrasound probe will be maintained on the vastus&#xD;
      lateralis muscle (VL) to obtain muscle architecture data at rest, during the maximal&#xD;
      voluntary isometric contractions (MVICs) and during the evoked contractions. Next, a warming&#xD;
      up protocol will be performed and the participants will perform three MVICs at the knee joint&#xD;
      angles of 60° and 90° of knee flexion (0° = full knee extension) on the isokinetic&#xD;
      dynamometer. Subsequently, the investigators will evaluate (1) the current intensity required&#xD;
      to produce a torque equivalent to 20% MVIC, (2) the current intensity required to produce a&#xD;
      40 Nm torque, the maximum current intensity (mA) tolerated by the subject (3) at an angle of&#xD;
      60° of knee flexion, and (4) at 90° of knee flexion. From these evaluations, the&#xD;
      investigators will analyze the neuromuscular efficiency (ratio between current intensity and&#xD;
      evoked torque). After each NMES test, participants will indicate, on the visual-analog scale,&#xD;
      the discomfort level perceived with each NMES current type. Clinical efficiency will be&#xD;
      evaluated by the ratio between the discomfort level and the evoked torque in the&#xD;
      above-described situations. On the second, third and fourth evaluation day, participants will&#xD;
      perform all the evaluations described in Phase 2 of the first evaluation day, but with&#xD;
      different configurations of the type of current randomized being applied. On the fifth day,&#xD;
      the fatigue protocol will be applied with appropriated parameters according to the randomized&#xD;
      current type, and sufficient current intensity to generate 20% of the MVIC. The discomfort&#xD;
      level during the fatigue protocol will be recorded immediately after the end of the fatigue&#xD;
      test. Participants will conduct three pre- and post-fatigue protocol MVICs in order to assess&#xD;
      the fatigue level. For the sixth evaluation day, the same evaluations reported for the fifth&#xD;
      day will be carried out, but with the second randomized current.&#xD;
    </textblock>
  </detailed_description>
  <overall_status>Completed</overall_status>
  <start_date type="Actual">January 8, 2019</start_date>
  <completion_date type="Actual">August 30, 2019</completion_date>
  <primary_completion_date type="Actual">June 30, 2019</primary_completion_date>
  <phase>N/A</phase>
  <study_type>Interventional</study_type>
  <has_expanded_access>No</has_expanded_access>
  <study_design_info>
    <allocation>Randomized</allocation>
    <intervention_model>Crossover Assignment</intervention_model>
    <primary_purpose>Other</primary_purpose>
    <masking>Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)</masking>
  </study_design_info>
  <primary_outcome>
    <measure>Maximum voluntary isometric contraction of the knee extensors</measure>
    <time_frame>14 minutes</time_frame>
    <description>is an expression of the muscular strength, and will be evaluated by dynamometry.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Knee extensors evoked torque during the tests at submaximal current intensity levels</measure>
    <time_frame>During 90 seconds of electrical stimulation</time_frame>
    <description>is an expression describing the muscular strength generated by electrical stimulation, and will be assessed by dynamometry.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Knee extensors evoked torque during the tests at maximal current intensity levels</measure>
    <time_frame>During 90 seconds of electrical stimulation</time_frame>
    <description>is an expression describing the muscular strength generated by electrical stimulation, and will be assessed by dynamometry.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Knee extensors evoked torque during the fatigue protocol</measure>
    <time_frame>During 20 minutes of electrical stimulation</time_frame>
    <description>is an expression describing the muscular strength generated by electrical stimulation, and will be assessed by dynamometry.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Muscular architecture during the knee extensors maximum voluntary isometric contraction tests</measure>
    <time_frame>14 minutes</time_frame>
    <description>is an expression used to describe the muscle fibers arrangement within the muscle, and is evaluated by determining the muscle thickness, fascicle pennation angle and fascicle length, which will be assessed by ultrasonography.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Muscular architecture during knee extensors evoked torque tests at submaximal current intensity levels</measure>
    <time_frame>During 90 seconds of electrical stimulation</time_frame>
    <description>is an expression used to describe the muscle fibers arrangement within the muscle, and is evaluated by determining the muscle thickness, fascicle pennation angle and fascicle length, which will be assessed by ultrasonography.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Muscular architecture during knee extensors evoked torque tests at maximal current intensity levels</measure>
    <time_frame>During 90 seconds of electrical stimulation</time_frame>
    <description>is an expression used to describe the muscle fibers arrangement within the muscle, and is evaluated by determining the muscle thickness, fascicle pennation angle and fascicle length, which will be assessed by ultrasonography.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Muscular architecture during the fatigue protocol</measure>
    <time_frame>During 20 minutes of electrical stimulation</time_frame>
    <description>is an expression used to describe the muscle fibers arrangement within the muscle, and is evaluated by determining the muscle thickness, fascicle pennation angle and fascicle length, which will be assessed by ultrasonography.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Discomfort level generated by electrical stimulation during evoked torque tests at submaximal current intensity levels</measure>
    <time_frame>During 90 seconds of electrical stimulation</time_frame>
    <description>Discomfort will be measured with a Visual Analogue Scale (0-100mm), where 0 and 100 mm corresponded to no discomfort and worst perceived discomfort, respectively.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Discomfort level generated by electrical stimulation during evoked torque tests at maximal current intensity levels</measure>
    <time_frame>During 90 seconds of electrical stimulation</time_frame>
    <description>Discomfort will be measured with a Visual Analogue Scale (0-100mm), where 0 and 100 mm corresponded to no discomfort and worst perceived discomfort, respectively.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Discomfort level generated by electrical stimulation during the fatigue protocol</measure>
    <time_frame>During 20 minutes of electrical stimulation</time_frame>
    <description>Discomfort will be measured with a Visual Analogue Scale (0-100mm), where 0 and 100 mm corresponded to no discomfort and worst perceived discomfort, respectively.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Current intensity required to evoke knee extensors submaximal torque</measure>
    <time_frame>During 90 seconds of electrical stimulation</time_frame>
    <description>Current intensity is defined as the amount or amplitude of electrical current (in milliamperes - mA) required to achieve a specific force, and will be evaluated in the electrical stimulation device.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Current intensity required to evoke knee extensors maximal torque</measure>
    <time_frame>During 90 seconds of electrical stimulation</time_frame>
    <description>Current intensity is defined as the amount or amplitude of electrical current (in milliamperes - mA) required to achieve a specific force, and will be evaluated in the electrical stimulation device.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Neuromuscular efficiency during knee extensors submaximal evoked torque tests</measure>
    <time_frame>During 90 seconds of electrical stimulation</time_frame>
    <description>Neuromuscular efficiency of the electrical currents will be evaluated by calculating the current intensity (input parameter or input) by the evoked torque (output parameter) ratio.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Neuromuscular efficiency during knee extensors maximal evoked torque tests</measure>
    <time_frame>During 90 seconds of electrical stimulation</time_frame>
    <description>Neuromuscular efficiency of the electrical currents will be evaluated by calculating the current intensity (input parameter or input) by the evoked torque (output parameter) ratio.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Neuromuscular efficiency during the fatigue protocol</measure>
    <time_frame>During 20 minutes of electrical stimulation</time_frame>
    <description>Neuromuscular efficiency of the electrical currents will be evaluated by calculating the current intensity (input parameter or input) by the evoked torque (output parameter) ratio.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Clinical efficiency during knee extensors submaximal evoked torque tests</measure>
    <time_frame>During 90 seconds of electrical stimulation</time_frame>
    <description>Clinical efficiency of the two electrical currents will be evaluated by calculating the ratio between the evoked torque (output parameter) and the level of discomfort generated.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Clinical efficiency during knee extensors maximal evoked torque tests</measure>
    <time_frame>During 90 seconds of electrical stimulation</time_frame>
    <description>Clinical efficiency of the two electrical currents will be evaluated by calculating the ratio between the evoked torque (output parameter) and the level of discomfort generated.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Clinical efficiency during the fatigue protocol</measure>
    <time_frame>During 20 minutes of electrical stimulation</time_frame>
    <description>Clinical efficiency of the two electrical currents will be evaluated by calculating the ratio between the evoked torque (output parameter) and the level of discomfort generated.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Muscle Fatigue Index</measure>
    <time_frame>During 20 minutes of electrical stimulation</time_frame>
    <description>Characterized by the force decrease after the fatigue protocol, it will be evaluated by dynamometry.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Fatigue Index from Evoked Torque</measure>
    <time_frame>During 20 minutes of electrical stimulation</time_frame>
    <description>Characterized by the decrease of the evoked torque during the fatigue protocol, the fatigue index from evoked torque will be evaluated by dynamometry, and obtained by the analysis of evoked torque curves.</description>
  </primary_outcome>
  <primary_outcome>
    <measure>Total work generated during the fatigue protocol</measure>
    <time_frame>During 20 minutes of electrical stimulation</time_frame>
    <description>The torque-time integral of the evoked torque curves during the fatigue protocol will be evaluated. The sum of the torque curve integral of all evoked contractions during the fatigue protocol will be calculated to determine the total work evoked by each current during the fatigue protocol.</description>
  </primary_outcome>
  <secondary_outcome>
    <measure>Thickness of the subcutaneous fat layer on the motor point</measure>
    <time_frame>It will be evaluated during the first evaluation day.</time_frame>
    <description>Corresponds to the amount of subcutaneous adipose tissue and will be evaluated by ultrasonography.</description>
  </secondary_outcome>
  <secondary_outcome>
    <measure>Level of physical activity</measure>
    <time_frame>8 minutes. It will be evaluated during the first evaluation day</time_frame>
    <description>The level of physical activity (PA) of each subject will be assessed by the International Physical Activity Questionnaire (IPAQ).The scores will be assessed by calculating the metabolic equivalents (MET) for each activity level. Walking score will be achieved by the multiplication of 3.3 METs with the total walking duration in minutes in a week. Moderate physical activity scores will be achieved by the multiplication of 4.0 METs with the total moderate physical activity duration in minutes in a week. Vigorous physical activity scores will be achieved by the multiplication of 8.0 METs with the total vigorous physical activity duration in minutes in a week. Total physical activity MET-minutes/week will be obtained through sum of walking, moderate and vigorous MET minutes/week scores. Categorical Score will be classified into three levels of physical activity: low, moderate and high.</description>
  </secondary_outcome>
  <number_of_arms>2</number_of_arms>
  <enrollment type="Actual">30</enrollment>
  <condition>Healthy Young</condition>
  <condition>Electric Stimulation Therapy</condition>
  <arm_group>
    <arm_group_label>Experimental Group 1: healthy young</arm_group_label>
    <arm_group_type>Experimental</arm_group_type>
    <description>Participants receive two interventions (Pulsed Current - PC, or Russian Current - RC) in a specific order, according to randomization. Evoked torque, discomfort level, current intensity, neuromuscular efficiency, clinical efficiency and fatigability level will be evaluated.</description>
  </arm_group>
  <arm_group>
    <arm_group_label>Experimental Group 2: healthy young</arm_group_label>
    <arm_group_type>Experimental</arm_group_type>
    <description>Participants receive two interventions (Pulsed Current - PC, or Russian Current - RC) in a specific order, according to randomization. Evoked torque, discomfort level, current intensity, neuromuscular efficiency, clinical efficiency and fatigability level will be evaluated.</description>
  </arm_group>
  <intervention>
    <intervention_type>Device</intervention_type>
    <intervention_name>Pulsed current</intervention_name>
    <description>For stage 1 of the study, which corresponds to analysis of the evoked torque, evaluation of the discomfort level, current intensity, analysis of neuromuscular efficiency and clinical efficiency, 2 configurations (PC1 and PC2) will be used.&#xD;
PC1, will be set at a frequency of 100 Hz, phase duration of 1000 microseconds, ON-OFF time of 5s:10s.&#xD;
PC2, will be set at a frequency of 100 Hz, phase duration of 200 microseconds ON-OFF time of 5s:10s.&#xD;
For stage 2 of the study, which corresponds to the analysis of the fatigability level, only the PC1 configuration will be used.</description>
    <arm_group_label>Experimental Group 1: healthy young</arm_group_label>
    <arm_group_label>Experimental Group 2: healthy young</arm_group_label>
  </intervention>
  <intervention>
    <intervention_type>Device</intervention_type>
    <intervention_name>Russian Current</intervention_name>
    <description>For stage 1 of the study, which corresponds to analysis of the evoked torque, discomfort level, current intensity, neuromuscular efficiency and clinical efficiency, 2 configurations (RC1 and RC2) will be used.&#xD;
RC1, will be set to a frequency of 100 Hz, burst duty cycle of 20%, ON-OFF time of 5s:10s.&#xD;
RC2, will be set at a frequency of 100 Hz, burst duty cycle of 50%, ON-OFF time of 5s:10s.&#xD;
For stage 2 of the study, which corresponds to the analysis of the fatigability level, only the RC2 configuration will be used.</description>
    <arm_group_label>Experimental Group 1: healthy young</arm_group_label>
    <arm_group_label>Experimental Group 2: healthy young</arm_group_label>
  </intervention>
  <eligibility>
    <criteria>
      <textblock>
        Inclusion Criteria:&#xD;
&#xD;
          -  Young male&#xD;
&#xD;
          -  Age between 18 and 35 years&#xD;
&#xD;
          -  Physically active,&#xD;
&#xD;
          -  Normal knee function and range of motion&#xD;
&#xD;
          -  No pain complaints&#xD;
&#xD;
          -  No presence of lower limb pathology at the dominant limb.&#xD;
&#xD;
        Exclusion Criteria:&#xD;
&#xD;
          -  Health problems (neurological, musculoskeletal impairment),&#xD;
&#xD;
          -  Contraindication to maximal exercise,&#xD;
&#xD;
          -  Having been treated with NMES in the last 3 months in the lower limb&#xD;
&#xD;
          -  Not meeting the inclusion criteria.&#xD;
      </textblock>
    </criteria>
    <gender>Male</gender>
    <minimum_age>18 Years</minimum_age>
    <maximum_age>35 Years</maximum_age>
    <healthy_volunteers>Accepts Healthy Volunteers</healthy_volunteers>
  </eligibility>
  <overall_official>
    <last_name>Marco A Vaz, PhD</last_name>
    <role>Principal Investigator</role>
    <affiliation>Federal University of Rio Grande do Sul</affiliation>
  </overall_official>
  <location>
    <facility>
      <name>Exercise Research Laboratory, School of Physical Education, Federal University of Rio Grande do Sul</name>
      <address>
        <city>Porto Alegre</city>
        <state>Rio Grande Do Sul</state>
        <zip>90690-200</zip>
        <country>Brazil</country>
      </address>
    </facility>
  </location>
  <location_countries>
    <country>Brazil</country>
  </location_countries>
  <verification_date>June 2021</verification_date>
  <study_first_submitted>December 24, 2018</study_first_submitted>
  <study_first_submitted_qc>January 3, 2019</study_first_submitted_qc>
  <study_first_posted type="Actual">January 8, 2019</study_first_posted>
  <last_update_submitted>June 8, 2021</last_update_submitted>
  <last_update_submitted_qc>June 8, 2021</last_update_submitted_qc>
  <last_update_posted type="Actual">June 10, 2021</last_update_posted>
  <responsible_party>
    <responsible_party_type>Principal Investigator</responsible_party_type>
    <investigator_affiliation>Federal University of Rio Grande do Sul</investigator_affiliation>
    <investigator_full_name>Marco Aurélio Vaz, PhD</investigator_full_name>
    <investigator_title>Principal Investigator</investigator_title>
  </responsible_party>
  <keyword>Muscle Strength</keyword>
  <keyword>Fatigue</keyword>
  <keyword>Neuromuscular efficiency</keyword>
  <keyword>Discomfort level</keyword>
  <keyword>Electric Stimulation</keyword>
  <patient_data>
    <sharing_ipd>No</sharing_ipd>
  </patient_data>
  <!-- Results have not yet been posted for this study                                          -->
</clinical_study>


download date: ClinicalTrials.gov processed this data on September 20, 2023
link text: Link to the current ClinicalTrials.gov record.
url: https://clinicaltrials.gov/ct2/show/NCT03796117
org study id: 3.064.351
nct id: NCT03796117
lead sponsor: 
is fda regulated drug: No
is fda regulated device: No
Low frequency pulsed current (PC) and medium frequency alternating current (Russian current -
      RC, 2.5 kHz) have been largely studied due to their clinical use. However, it is not clear
      which current is the most efficient due to the existente literature conflicts.Therefore, the
      purpose of this study is to compare the neuromuscular efficiency, evoked torque, current
      intensity, fatigability and level of discomfort between the PC and the RC in healthy young.
      The current types will be tested in the same participant by the intervention sequences
      randomization. On the first, second, third and fourth days, the maximum voluntary isometric
      contraction (MVIC), the current intensity level, discomfort level, evoked torque, and
      clinical and neuromuscular efficiency of each current will be evaluated. Anthropometric
      measurements will also be assessed on the first day. In addition, the current intensity
      required to produce a torque level of 20% of the MVIC, the current intensity required to
      generate a torque of 40 Nm and the maximum intensity tolerated by the participant will be
      evaluated. Three contractions will be recorded in each condition, and the level of discomfort
      will be assessed during the evoked contractions. Evoked torque will be evaluated at the
      maximum tolerated intensity level using the isokinetic dynamometer. Clinical and
      neuromuscular efficiency will be evaluated (1) at the current intensity necessary to evoke
      20% MVIC, (2) at the current intensity necessary to generate 40 Nm, and (3) at the maximum
      tolerated current intensity. On the fifth and sixth days, muscle fatigue induced by the
      diferente current types will be evaluated. Fatigue will be evaluated with sufficient current
      intensity to generate 20% of the MVIC. MVIC will be performed before and after the fatigue
      protocol, and the fatigue will be determined by the relative variation of the MVIC before and
      after the fatigue protocol. Fatigue will also be evaluated through the evoked torque
      variation between the first and the last minute of the fatigue protocol, as well as by the
      total work generated in each protocol. Neuromuscular efficiency will be evaluated before and
      immediately after the protocol through (1) the ratio between input NMES current intensity and
      output evoked torque, (2) total work (area under the evoked force by time curves) generated
      during the fatigue protocol, and (3) by the changes in muscle architecture from rest to
      evoked contraction at the maximal current intensity.
This study is characterized by a quantitative approach, with a randomized crossover clinical
      study design, blinded to evaluators and participants. The objective is to compare the
      neuromuscular and clinical efficiency, evoked torque, current intensity, fatigue and
      discomfort level between the low frequency biphasic pulsed current (PC) and the median
      frequency sinusoidal alternating Russian current (RC) in healthy young participants. The
      effect of the two neuromuscular electrical stimulation (NMES) current types on the cited
      variables will be evaluated in the same participant, by means of the randomization of the
      interventions sequences for each participant. The evaluation protocols will be performed by 2
      blinded raters for the current type and for the outcome variables. A blinded evaluator to the
      study will randomize the current type, which will be applied on the different evaluation
      days, through a lottery using opaque envelopes. A researcher blinded to the study groups will
      analyze the data. Participants will be blinded to the current type will be receiving. The
      evaluations will be performed in six days, and a minimum interval of 7 days will be observed
      between the evaluation days. On the first, second, third and fourth days, characterized as
      Stage 1, the currents' intensity levels, discomfort level, evoked torque, and neuromuscular
      and clinical efficiency of each randomized current will be evaluated. On the fifth and sixth
      days, characterized as Stage 2, the muscle fatigue level induced by the two electrical
      currents will be evaluated. The first evaluation day will be divided into two phases. Phase 1
      corresponds to the initial evaluation, anthropometric data collection and physical activity
      level evaluation. In Phase 2, the quadriceps femoris motor point will be located with a
      pen-shaped electrode and a neuromuscular electrical stimulation unit, and the subcutaneous
      adipose layer thickness covering the motor point will be evaluated by means of
      ultrasonography. Subsequently, the ultrasound probe will be maintained on the vastus
      lateralis muscle (VL) to obtain muscle architecture data at rest, during the maximal
      voluntary isometric contractions (MVICs) and during the evoked contractions. Next, a warming
      up protocol will be performed and the participants will perform three MVICs at the knee joint
      angles of 60° and 90° of knee flexion (0° = full knee extension) on the isokinetic
      dynamometer. Subsequently, the investigators will evaluate (1) the current intensity required
      to produce a torque equivalent to 20% MVIC, (2) the current intensity required to produce a
      40 Nm torque, the maximum current intensity (mA) tolerated by the subject (3) at an angle of
      60° of knee flexion, and (4) at 90° of knee flexion. From these evaluations, the
      investigators will analyze the neuromuscular efficiency (ratio between current intensity and
      evoked torque). After each NMES test, participants will indicate, on the visual-analog scale,
      the discomfort level perceived with each NMES current type. Clinical efficiency will be
      evaluated by the ratio between the discomfort level and the evoked torque in the
      above-described situations. On the second, third and fourth evaluation day, participants will
      perform all the evaluations described in Phase 2 of the first evaluation day, but with
      different configurations of the type of current randomized being applied. On the fifth day,
      the fatigue protocol will be applied with appropriated parameters according to the randomized
      current type, and sufficient current intensity to generate 20% of the MVIC. The discomfort
      level during the fatigue protocol will be recorded immediately after the end of the fatigue
      test. Participants will conduct three pre- and post-fatigue protocol MVICs in order to assess
      the fatigue level. For the sixth evaluation day, the same evaluations reported for the fifth
      day will be carried out, but with the second randomized current.
allocation: Randomized
intervention model: Crossover Assignment
primary purpose: Other
masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
measure: Maximum voluntary isometric contraction of the knee extensors
time frame: 14 minutes
description: is an expression of the muscular strength, and will be evaluated by dynamometry.
measure: Knee extensors evoked torque during the tests at submaximal current intensity levels
time frame: During 90 seconds of electrical stimulation
description: is an expression describing the muscular strength generated by electrical stimulation, and will be assessed by dynamometry.
measure: Knee extensors evoked torque during the tests at maximal current intensity levels
time frame: During 90 seconds of electrical stimulation
description: is an expression describing the muscular strength generated by electrical stimulation, and will be assessed by dynamometry.
measure: Knee extensors evoked torque during the fatigue protocol
time frame: During 20 minutes of electrical stimulation
description: is an expression describing the muscular strength generated by electrical stimulation, and will be assessed by dynamometry.
measure: Muscular architecture during the knee extensors maximum voluntary isometric contraction tests
time frame: 14 minutes
description: is an expression used to describe the muscle fibers arrangement within the muscle, and is evaluated by determining the muscle thickness, fascicle pennation angle and fascicle length, which will be assessed by ultrasonography.
measure: Muscular architecture during knee extensors evoked torque tests at submaximal current intensity levels
time frame: During 90 seconds of electrical stimulation
description: is an expression used to describe the muscle fibers arrangement within the muscle, and is evaluated by determining the muscle thickness, fascicle pennation angle and fascicle length, which will be assessed by ultrasonography.
measure: Muscular architecture during knee extensors evoked torque tests at maximal current intensity levels
time frame: During 90 seconds of electrical stimulation
description: is an expression used to describe the muscle fibers arrangement within the muscle, and is evaluated by determining the muscle thickness, fascicle pennation angle and fascicle length, which will be assessed by ultrasonography.
measure: Muscular architecture during the fatigue protocol
time frame: During 20 minutes of electrical stimulation
description: is an expression used to describe the muscle fibers arrangement within the muscle, and is evaluated by determining the muscle thickness, fascicle pennation angle and fascicle length, which will be assessed by ultrasonography.
measure: Discomfort level generated by electrical stimulation during evoked torque tests at submaximal current intensity levels
time frame: During 90 seconds of electrical stimulation
description: Discomfort will be measured with a Visual Analogue Scale (0-100mm), where 0 and 100 mm corresponded to no discomfort and worst perceived discomfort, respectively.
measure: Discomfort level generated by electrical stimulation during evoked torque tests at maximal current intensity levels
time frame: During 90 seconds of electrical stimulation
description: Discomfort will be measured with a Visual Analogue Scale (0-100mm), where 0 and 100 mm corresponded to no discomfort and worst perceived discomfort, respectively.
measure: Discomfort level generated by electrical stimulation during the fatigue protocol
time frame: During 20 minutes of electrical stimulation
description: Discomfort will be measured with a Visual Analogue Scale (0-100mm), where 0 and 100 mm corresponded to no discomfort and worst perceived discomfort, respectively.
measure: Current intensity required to evoke knee extensors submaximal torque
time frame: During 90 seconds of electrical stimulation
description: Current intensity is defined as the amount or amplitude of electrical current (in milliamperes - mA) required to achieve a specific force, and will be evaluated in the electrical stimulation device.
measure: Current intensity required to evoke knee extensors maximal torque
time frame: During 90 seconds of electrical stimulation
description: Current intensity is defined as the amount or amplitude of electrical current (in milliamperes - mA) required to achieve a specific force, and will be evaluated in the electrical stimulation device.
measure: Neuromuscular efficiency during knee extensors submaximal evoked torque tests
time frame: During 90 seconds of electrical stimulation
description: Neuromuscular efficiency of the electrical currents will be evaluated by calculating the current intensity (input parameter or input) by the evoked torque (output parameter) ratio.
measure: Neuromuscular efficiency during knee extensors maximal evoked torque tests
time frame: During 90 seconds of electrical stimulation
description: Neuromuscular efficiency of the electrical currents will be evaluated by calculating the current intensity (input parameter or input) by the evoked torque (output parameter) ratio.
measure: Neuromuscular efficiency during the fatigue protocol
time frame: During 20 minutes of electrical stimulation
description: Neuromuscular efficiency of the electrical currents will be evaluated by calculating the current intensity (input parameter or input) by the evoked torque (output parameter) ratio.
measure: Clinical efficiency during knee extensors submaximal evoked torque tests
time frame: During 90 seconds of electrical stimulation
description: Clinical efficiency of the two electrical currents will be evaluated by calculating the ratio between the evoked torque (output parameter) and the level of discomfort generated.
measure: Clinical efficiency during knee extensors maximal evoked torque tests
time frame: During 90 seconds of electrical stimulation
description: Clinical efficiency of the two electrical currents will be evaluated by calculating the ratio between the evoked torque (output parameter) and the level of discomfort generated.
measure: Clinical efficiency during the fatigue protocol
time frame: During 20 minutes of electrical stimulation
description: Clinical efficiency of the two electrical currents will be evaluated by calculating the ratio between the evoked torque (output parameter) and the level of discomfort generated.
measure: Muscle Fatigue Index
time frame: During 20 minutes of electrical stimulation
description: Characterized by the force decrease after the fatigue protocol, it will be evaluated by dynamometry.
measure: Fatigue Index from Evoked Torque
time frame: During 20 minutes of electrical stimulation
description: Characterized by the decrease of the evoked torque during the fatigue protocol, the fatigue index from evoked torque will be evaluated by dynamometry, and obtained by the analysis of evoked torque curves.
measure: Total work generated during the fatigue protocol
time frame: During 20 minutes of electrical stimulation
description: The torque-time integral of the evoked torque curves during the fatigue protocol will be evaluated. The sum of the torque curve integral of all evoked contractions during the fatigue protocol will be calculated to determine the total work evoked by each current during the fatigue protocol.
measure: Thickness of the subcutaneous fat layer on the motor point
time frame: It will be evaluated during the first evaluation day.
description: Corresponds to the amount of subcutaneous adipose tissue and will be evaluated by ultrasonography.
measure: Level of physical activity
time frame: 8 minutes. It will be evaluated during the first evaluation day
description: The level of physical activity (PA) of each subject will be assessed by the International Physical Activity Questionnaire (IPAQ).The scores will be assessed by calculating the metabolic equivalents (MET) for each activity level. Walking score will be achieved by the multiplication of 3.3 METs with the total walking duration in minutes in a week. Moderate physical activity scores will be achieved by the multiplication of 4.0 METs with the total moderate physical activity duration in minutes in a week. Vigorous physical activity scores will be achieved by the multiplication of 8.0 METs with the total vigorous physical activity duration in minutes in a week. Total physical activity MET-minutes/week will be obtained through sum of walking, moderate and vigorous MET minutes/week scores. Categorical Score will be classified into three levels of physical activity: low, moderate and high.
arm group label: Experimental Group 1: healthy young
arm group type: Experimental
description: Participants receive two interventions (Pulsed Current - PC, or Russian Current - RC) in a specific order, according to randomization. Evoked torque, discomfort level, current intensity, neuromuscular efficiency, clinical efficiency and fatigability level will be evaluated.
arm group label: Experimental Group 2: healthy young
arm group type: Experimental
description: Participants receive two interventions (Pulsed Current - PC, or Russian Current - RC) in a specific order, according to randomization. Evoked torque, discomfort level, current intensity, neuromuscular efficiency, clinical efficiency and fatigability level will be evaluated.
intervention type: Device
intervention name: Pulsed current
description: For stage 1 of the study, which corresponds to analysis of the evoked torque, evaluation of the discomfort level, current intensity, analysis of neuromuscular efficiency and clinical efficiency, 2 configurations (PC1 and PC2) will be used.
PC1, will be set at a frequency of 100 Hz, phase duration of 1000 microseconds, ON-OFF time of 5s:10s.
PC2, will be set at a frequency of 100 Hz, phase duration of 200 microseconds ON-OFF time of 5s:10s.
For stage 2 of the study, which corresponds to the analysis of the fatigability level, only the PC1 configuration will be used.
arm group label: Experimental Group 1: healthy young
arm group label: Experimental Group 2: healthy young
intervention type: Device
intervention name: Russian Current
description: For stage 1 of the study, which corresponds to analysis of the evoked torque, discomfort level, current intensity, neuromuscular efficiency and clinical efficiency, 2 configurations (RC1 and RC2) will be used.
RC1, will be set to a frequency of 100 Hz, burst duty cycle of 20%, ON-OFF time of 5s:10s.
RC2, will be set at a frequency of 100 Hz, burst duty cycle of 50%, ON-OFF time of 5s:10s.
For stage 2 of the study, which corresponds to the analysis of the fatigability level, only the RC2 configuration will be used.
arm group label: Experimental Group 1: healthy young
arm group label: Experimental Group 2: healthy young
criteria: 
gender: Male
minimum age: 18 Years
maximum age: 35 Years
healthy volunteers: Accepts Healthy Volunteers
last name: Marco A Vaz, PhD
role: Principal Investigator
affiliation: Federal University of Rio Grande do Sul
facility: 
country: Brazil
responsible party type: Principal Investigator
investigator affiliation: Federal University of Rio Grande do Sul
investigator full name: Marco Aurélio Vaz, PhD
investigator title: Principal Investigator
sharing ipd: No