Muscle Fatigue (C23.888.592.612.612)NCT07790016
Photobiomodulation on NMES-Induced Muscle Fatigue and Damage
A study testing Photobiomodulation Therapy (PBMT) in people with Muscle Fatigue (C23.888.592.612.612) and Delayed Onset Muscle Soreness (DOMS), run by Federal University of Rio Grande do Sul at 1 site in Brazil.
Trial summary
Neuromuscular electrical stimulation (NMES) is effective for strength training and rehabilitation, but non-selective motor unit recruitment often induces rapid fatigue, discomfort, and muscle damage. Read more about this study
- Who is it for?
- Ages 18 to 40 yearsHealthy volunteers can take part
- Conditions the study is for
- Muscle Fatigue (C23.888.592.612.612), Delayed Onset Muscle Soreness (DOMS), Muscle Damage
- What is being tested?
- Photobiomodulation Therapy (PBMT)
- Type of treatment
- Medical device
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 12 participants
- Where
- 1 siteBrazil
- Study dates
- 1 Nov 2022to 1 Dec 2023
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 40 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Healthy male and female adults aged between 18 and 40 years.
- Engaging in regular physical activity (minimum of twice a week).
- No history of hospitalization for COVID-19 in the past 12 months.
- Demonstrated ability to tolerate neuromuscular electrical stimulation (NMES).
- Capable of fully understanding and complying with the experimental protocol and procedures.
Who cannot join
- Presence of any sensory impairments or neurological alterations.
- Ingestion of caffeine, coffee, energy drinks, or other stimulants in the 12 hours preceding the testing sessions.
- Body Mass Index (BMI) greater than 30 kg/m².
- Any medical contraindication to performing maximal physical exertion or presenting an abnormal cardiovascular/blood pressure response after maximal effort.
Trial locations and contacts
1 site in 1 country.
Brazil1 site
Laboratório de Pesquisa do Exercício
Porto Alegre, Rio Grande do Sul, 90690200
About this study
Official title: Effects of Photobiomodulation and Stimulation Sites on Muscle Fatigue and Damage Induced by Neuromuscular Electrical Stimulation in Healthy Individuals
Neuromuscular electrical stimulation (NMES) is effective for strength training and rehabilitation, but non-selective motor unit recruitment often induces rapid fatigue, discomfort, and muscle damage. Photobiomodulation therapy (PBMT) has been proposed to attenuate muscle fatigue and accelerate recovery, yet evidence regarding its acute prophylactic effects against NMES-induced fatigue remains limited. This randomized, single-blind, sham-controlled crossover pilot trial evaluates the acute effects of pre-exercise PBMT on knee extensor neuromuscular fatigability, muscle damage, discomfort, and functional recovery following a standardized NMES fatigue protocol in healthy adults.
Read the detailed description
This study utilizes a randomized, single-blind, sham-controlled crossover design to evaluate the acute effects of photobiomodulation therapy (PBMT) on neuromuscular electrical stimulation (NMES)-induced fatigue in healthy individuals.
Participants undergo testing across two intervention blocks separated by a 7-day washout period between limbs:
Intervention Phase: Five minutes prior to an electrically evoked fatigue protocol, participants receive either active PBMT (multi-diode GaAlAs laser cluster; 810 nm; 200 mW per diode; 30 J per point across 8 quadriceps sites; total energy dose: 240 J) or sham PBMT (identical positioning with the device inactive and acoustic blinding).
NMES Fatigue Protocol: The protocol is performed on an isokinetic dynamometer with the knee fixed at 90° flexion. Rectangular biphasic symmetrical pulses (100 Hz; 1 ms pulse width; 5 s on, 10 s off) are delivered over 20 minutes to evoke 60 isometric contractions adjusted to an initial torque of 20% maximal voluntary isometric contraction (MVIC).
Evaluation Timeline: Neuromuscular and functional assessments are conducted at Baseline, Immediately Post-Fatigue, and at 24, 48, and 72 hours post-protocol. Tests include maximal voluntary isometric torque, resting supramaximal evoked twitches, transverse ultrasound echointensity of the rectus femoris and vastus lateralis, pressure pain thresholds via algometry, Visual Analog Scales for discomfort, and horizontal Single Hop Test performance.
- Conditions
- Muscle Fatigue (C23.888.592.612.612), Delayed Onset Muscle Soreness (DOMS), Muscle Damage, Photobiomodulation (PBM), Neuromuscular Electrical Stimulation (NMES)
- Being tested
- Photobiomodulation Therapy (PBMT), Sham Photobiomodulation
- Keywords
- Photobiomodulation, Low-Level Laser Therapy, Neuromuscular Electrical Stimulation, Muscle Fatigue, Pilot Study
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Photobiomodulation Therapy (PBMT)Device
Multi-diode cluster probe (GaAlAs laser; 5 diodes; wavelength: 810 nm; power output: 200 mW per diode; continuous mode) applied across 8 points over the quadriceps femoris (3 on rectus femoris, 3 on vastus lateralis, and 2 on vastus medialis) for 30 seconds per point (30 J/point), delivering a total energy dose of 240 J per limb.
Sham PhotobiomodulationDevice
Identical probe positioning over the 8 quadriceps locations for 30 seconds per point with the laser device completely turned off. Auditory headphones are used to blind participants against sound cues.
| Study group | Role | What they receive |
|---|---|---|
| Active PBMT + NMES | Experimental | Participants receive active Photobiomodulation Therapy (PBMT) applied to the knee extensor muscles 5 minutes prior to undergoing a 20-minute neuromuscular electrical stimulation (NMES) fatigue protocol on the randomized lower limb. Receives: Device: Photobiomodulation Therapy (PBMT) |
| Sham PBMT + NMES | Sham comparator | Participants receive sham Photobiomodulation Therapy (device turned off, identical positioning and acoustic blinding) applied to the knee extensor muscles 5 minutes prior to undergoing a 20-minute neuromuscular electrical stimulation (NMES) fatigue protocol on the contralateral lower limb. Receives: Device: Sham Photobiomodulation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Maximal Voluntary Isometric Contraction (MVIC) Torque
Knee extensor peak isometric torque measured on an isokinetic dynamometer (Biodex System 3 Pro) during 5-second maximal isometric contractions with the knee fixed at 90° flexion, expressed in Newton-meters (N.m).
Measured: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Secondary outcomes (9)
Muscle Damage via Ultrasound Echointensity
Quantitative grayscale histogram analysis (0 = black, 255 = white) of transverse ultrasound images (ImageJ software) of the rectus femoris (at 40%, 50%, and 60% of the femur length) and vastus lateralis (at 50% of the femur length) muscles to assess structural muscle damage.
Measured: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Supramaximal Evoked Twitch Torque
Knee extensor evoked torque produced by single supramaximal electrical twitches (1 Hz, 500 µs rectangular biphasic pulses at rest) delivered to the rectus femoris motor point, measured in Newton-meters (N.m) on the isokinetic dynamometer to evaluate peripheral muscle fatigue.
Measured: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Evoked Neuromuscular Efficiency
Ratio between the supramaximal evoked twitch peak torque and the applied current intensity (Nm/mA) during resting single pulses.
Measured: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Sitting Muscle Discomfort
Subjective sensation of discomfort/pain in the quadriceps femoris evaluated while seated at rest using a 10 cm Visual Analog Scale (VAS), where 0 cm represents 'no discomfort' and 10 cm represents 'maximum discomfort'.
Measured: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Pain Pressure Threshold (PPT)
Mechanical pain sensitivity measured using a digital pressure algometer (applied at 90° in kgf/cm²) over the rectus femoris, vastus lateralis, and vastus medialis muscle bellies to identify delayed onset muscle soreness.
Measured: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Single Hop Test (SHT) Functional Performance
Maximal horizontal single-leg hop distance normalized to limb length, calculated as: [Hop Distance (cm) / Limb Length (cm)] * 100.
Measured: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Discomfort During Stair Ascent and Descent
Level of discomfort reported on a 10 cm Visual Analog Scale (VAS) immediately after ascending and descending a 10-step staircase.
Measured: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Total Mechanical Work During Fatigue Protocol
Cumulative mechanical work quantified by the sum of the torque-time integral (TTI) across all 60 evoked contractions during the 20-minute NMES protocol (expressed in N.m.s).
Measured: During the 20-minute NMES fatigue protocol.
Fatigue Index (% Work Decline)
Percentage reduction in work performed between the first 5 evoked contractions and the last 5 evoked contractions of the NMES fatigue protocol, calculated as: [(Initial Work - Final Work) / Initial Work] * 100.
Measured: During the 20-minute NMES fatigue protocol.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted27 Aug 2026
- Study start1 Nov 2022
- Primary completion1 Aug 2023
- Study completion1 Dec 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Muscle Fatigue (C23.888.592.612.612)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 12 participants (actual)
Sponsor and investigators
- Lead sponsor
- Federal University of Rio Grande do Sul
- Sponsor type
- University, hospital or other
- Collaborators
- Conselho Nacional de Desenvolvimento Científico e Tecnológico
- Responsible party
- Principal investigator, Marco Aurélio Vaz, PhD, Federal University of Rio Grande do Sul
- Investigators
- Marco A Vaz, PhD, Study chair, Federal University of Rio Grande do SulMarco A Vaz, PhD, Principal investigator, Federal University of Rio Grande do Sul
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07790016
- Sponsor's protocol ID
- 56181622.4.0000.5347
- Status last verified
- Aug 2026
- First submitted
- 24 Aug 2026
- Last updated
- 31 Aug 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: Individual participant data will not be publicly shared to protect participant confidentiality in accordance with the local ethics committee approval.
Study at a glance
From the registry record, last updated by the sponsor on 31 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Photobiomodulation and Stimulation Sites on Muscle Fatigue and Damage Induced by Neuromuscular Electrical Stimulation in Healthy Individuals
- ClinicalTrials.gov ID
- NCT07790016
- Acronym / sponsor ID
- 56181622.4.0000.5347
- Conditions
- Muscle Fatigue (C23.888.592.612.612), Delayed Onset Muscle Soreness (DOMS), Muscle Damage, Photobiomodulation (PBM), Neuromuscular Electrical Stimulation (NMES)
- Keywords
- Photobiomodulation, Low-Level Laser Therapy, Neuromuscular Electrical Stimulation, Muscle Fatigue, Pilot Study
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 12 participants (actual)
- Lead sponsor
- Federal University of Rio Grande do SulUniversity, hospital or other
- Collaborators
- Conselho Nacional de Desenvolvimento Científico e Tecnológico
- Study start
- 1 Nov 2022 (actual)
- Primary completion
- 1 Aug 2023 (actual)
- Study completion
- 1 Dec 2023 (actual)
- First posted
- 27 Aug 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Neuromuscular electrical stimulation (NMES) is effective for strength training and rehabilitation, but non-selective motor unit recruitment often induces rapid fatigue, discomfort, and muscle damage. Photobiomodulation therapy (PBMT) has been proposed to attenuate muscle fatigue and accelerate recovery, yet evidence regarding its acute prophylactic effects against NMES-induced fatigue remains limited. This randomized, single-blind, sham-controlled crossover pilot trial evaluates the acute effects of pre-exercise PBMT on knee extensor neuromuscular fatigability, muscle damage, discomfort, and functional recovery following a standardized NMES fatigue protocol in healthy adults.
Detailed description
This study utilizes a randomized, single-blind, sham-controlled crossover design to evaluate the acute effects of photobiomodulation therapy (PBMT) on neuromuscular electrical stimulation (NMES)-induced fatigue in healthy individuals.
Participants undergo testing across two intervention blocks separated by a 7-day washout period between limbs:
Intervention Phase: Five minutes prior to an electrically evoked fatigue protocol, participants receive either active PBMT (multi-diode GaAlAs laser cluster; 810 nm; 200 mW per diode; 30 J per point across 8 quadriceps sites; total energy dose: 240 J) or sham PBMT (identical positioning with the device inactive and acoustic blinding).
NMES Fatigue Protocol: The protocol is performed on an isokinetic dynamometer with the knee fixed at 90° flexion. Rectangular biphasic symmetrical pulses (100 Hz; 1 ms pulse width; 5 s on, 10 s off) are delivered over 20 minutes to evoke 60 isometric contractions adjusted to an initial torque of 20% maximal voluntary isometric contraction (MVIC).
Evaluation Timeline: Neuromuscular and functional assessments are conducted at Baseline, Immediately Post-Fatigue, and at 24, 48, and 72 hours post-protocol. Tests include maximal voluntary isometric torque, resting supramaximal evoked twitches, transverse ultrasound echointensity of the rectus femoris and vastus lateralis, pressure pain thresholds via algometry, Visual Analog Scales for discomfort, and horizontal Single Hop Test performance.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (participant)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Active PBMT + NMES | Experimental | Device: Photobiomodulation Therapy (PBMT)Participants receive active Photobiomodulation Therapy (PBMT) applied to the knee extensor muscles 5 minutes prior to undergoing a 20-minute neuromuscular electrical stimulation (NMES) fatigue protocol on the randomized lower limb. |
| Sham PBMT + NMES | Sham comparator | Device: Sham PhotobiomodulationParticipants receive sham Photobiomodulation Therapy (device turned off, identical positioning and acoustic blinding) applied to the knee extensor muscles 5 minutes prior to undergoing a 20-minute neuromuscular electrical stimulation (NMES) fatigue protocol on the contralateral lower limb. |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Healthy male and female adults aged between 18 and 40 years.
- Engaging in regular physical activity (minimum of twice a week).
- No history of hospitalization for COVID-19 in the past 12 months.
- Demonstrated ability to tolerate neuromuscular electrical stimulation (NMES).
- Capable of fully understanding and complying with the experimental protocol and procedures.
Key exclusion criteria (4 listed)
- Presence of any sensory impairments or neurological alterations.
- Ingestion of caffeine, coffee, energy drinks, or other stimulants in the 12 hours preceding the testing sessions.
- Body Mass Index (BMI) greater than 30 kg/m².
- Any medical contraindication to performing maximal physical exertion or presenting an abnormal cardiovascular/blood pressure response after maximal effort.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Photobiomodulation Therapy (PBMT)Multi-diode cluster probe (GaAlAs laser; 5 diodes; wavelength: 810 nm; power output: 200 mW per diode; continuous mode) applied across 8 points over the quadriceps femoris (3 on rectus femoris, 3 on vastus lateralis, and 2 on vastus medialis) for 30 seconds per point (30 J/point), delivering a total energy dose of 240 J per limb. | Device | Active PBMT + NMES |
| Sham PhotobiomodulationIdentical probe positioning over the 8 quadriceps locations for 30 seconds per point with the laser device completely turned off. Auditory headphones are used to blind participants against sound cues. | Device | Sham PBMT + NMES |
Primary outcome
Maximal Voluntary Isometric Contraction (MVIC) Torque
Time frame: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Knee extensor peak isometric torque measured on an isokinetic dynamometer (Biodex System 3 Pro) during 5-second maximal isometric contractions with the knee fixed at 90° flexion, expressed in Newton-meters (N.m).
9 secondary outcomes
Muscle Damage via Ultrasound Echointensity
Time frame: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Supramaximal Evoked Twitch Torque
Time frame: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Evoked Neuromuscular Efficiency
Time frame: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Sitting Muscle Discomfort
Time frame: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Pain Pressure Threshold (PPT)
Time frame: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Single Hop Test (SHT) Functional Performance
Time frame: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Discomfort During Stair Ascent and Descent
Time frame: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.
Total Mechanical Work During Fatigue Protocol
Time frame: During the 20-minute NMES fatigue protocol.
Fatigue Index (% Work Decline)
Time frame: During the 20-minute NMES fatigue protocol.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 31 Aug 2026.
- Individual participant dataSharing planned: Undecided. Individual participant data will not be publicly shared to protect participant confidentiality in accordance with the local ethics committee approval.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Marco A Vaz, PhD study chair
Federal University of Rio Grande do Sul
Marco A Vaz, PhD principal investigator
Federal University of Rio Grande do Sul
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Photobiomodulation Therapy (PBMT) in people with Muscle Fatigue (C23.888.592.612.612) and Delayed Onset Muscle Soreness (DOMS), run by Federal University of Rio Grande do Sul at 1 site in Brazil.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 31 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Brazil. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Maximal Voluntary Isometric Contraction (MVIC) Torque (time frame: Baseline, Immediately post-fatigue protocol, 24 hours, 48 hours, and 72 hours post-fatigue.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 31 Aug 2026.