Photobiomodulation Effects on Fatigue and Muscle Damage Induced by NMES

NCT07602933 | Not Yet Recruiting DMC

• 1 other identifier: 5.309.992(1)
• Study Type: interventional
• Target: 36
• Locations: 1 country
• Sites: 1

Brief Summary

Neuromuscular electrical stimulation (NMES) is widely used to improve muscle strength and mitigate atrophy. However, its clinical efficacy is often limited by early neuromuscular fatigue, muscle damage, and discomfort, which reduce patient tolerance and contraction time. Photobiomodulation (PBM) has emerged as a potential therapy to enhance muscle performance and accelerate recovery by minimizing fatigue and damage. Despite its potential, few studies have investigated the effects of PBM applied specifically before an NMES-evoked fatigue protocol. This randomized, double-blind, placebo-controlled trial aims to evaluate the acute effects of PBM on neuromuscular fatigue, muscle damage, and functional outcomes in healthy young subjects. Participants will receive either active PBM (cluster probe: 5 lasers 810nm/200mW; 4 LEDs 660nm/10mW; Total Energy: 249.6 J per limb) or sham treatment 5 minutes before a fatiguing NMES protocol (80 contractions at 20% MVIC, 80 Hz, 1ms pulse width) applied to the quadriceps muscle. Assessments will be performed at baseline, immediately post-intervention, and at 24h, 48h, and 72h post-intervention. Primary outcomes include maximum and evoked isometric strength, mechanical work, and electrical muscle activity. Secondary outcomes include muscle damage (ultrasound echo-intensity), delayed onset muscle soreness (DOMS), functional performance (unilateral vertical jump), and clinical discomfort. The study seeks to determine if PBM can effectively modulate NMES-induced fatigue and muscle damage, potentially optimizing its clinical application.

Conditions

Photobiomodulation; Fatigue; Discomfort; Electrical Stimulation; Muscle Damage

Keywords

Photobiomodulation; Fatigue; Discomfort; Muscle Damage; Electrical stimulation

Outcome Measures

Primary Outcomes (2)

• Maximal voluntary isometric contraction (MVIC)

  Largest knee extensor torque generated isometrically and voluntarily on an isokinetic dynamometer. Unit of Measure: Newton-meters (N.m)

  Baseline (pre-intervention) on Day 1; immediately after the fatigue protocol on Day 1; and at 24, 48, and 72 hours after the fatigue protocol (on Days 2, 3, and 4, respectively).

• Evoked fatigue

  Fall in the evoked torque during the fatigue protocol. Unit of Measure: Newton-meters (N.m)

  Continuously during the 20-minute fatigue protocol.

Secondary Outcomes (8)

• Muscle Echo Intensity

  Baseline (pre-intervention) on Day 1; immediately after the fatigue protocol on Day 1; and at 24, 48, and 72 hours after the fatigue protocol (on Days 2, 3, and 4, respectively).

• Pressure Pain Threshold

  Baseline (pre-intervention) on Day 1; immediately after the fatigue protocol on Day 1; and at 24, 48, and 72 hours after the fatigue protocol (on Days 2, 3, and 4, respectively).

• Quadriceps Muscle Thickness

  Baseline (pre-intervention) on Day 1; immediately after the fatigue protocol on Day 1; and at 24, 48, and 72 hours after the fatigue protocol (on Days 2, 3, and 4, respectively).

• Countermovement Jump (CMJ) Height

  Baseline (pre-intervention) on Day 1; immediately after the fatigue protocol on Day 1; and at 24, 48, and 72 hours after the fatigue protocol (on Days 2, 3, and 4, respectively).

• Lower Limb Joint Kinematics During Jump

  Baseline (pre-intervention) on Day 1; immediately after the fatigue protocol on Day 1; and at 24, 48, and 72 hours after the fatigue protocol (on Days 2, 3, and 4, respectively).

Other Outcomes (2)

• Vastus Lateralis Pennation Angle

  Continuously during the 20-minute fatigue protocol on Day 1.

• Adipose Tissue Thickness

  Baseline

Study Arms (2)

Photobiomodulation (PBM)

EXPERIMENTAL

Participants in this arm will receive active photobiomodulation therapy.

Device: Active Photobiomodulation; Other: NMES-evoked fatigue protocol

Sham PBM

SHAM COMPARATOR

Participants in this arm will receive an inactive (placebo) photobiomodulation treatment.

Device: Placebo Photobiomodulation; Other: NMES-evoked fatigue protocol

Interventions

Active Photobiomodulation DEVICE

Application of PBMT using a cluster probe (Thor-DD2; 5 laser diodes: 810nm, 200mW; 4 LEDs: 660nm, 10mW). The treatment involves 8 points on the quadriceps (2 on vastus medialis, 3 on vastus lateralis, and 3 on rectus femoris). Each point is irradiated for 30 seconds in continuous mode with direct contact and slight pressure. Total energy: 31.2 J per point and 249.6 J per limb. Both therapist and participant will wear protective goggles.

Photobiomodulation (PBM)

Placebo Photobiomodulation DEVICE

The procedure is identical to the active PBMT (8 points, 30 seconds per point, same pressure and positioning), but the device will be turned off. To ensure blinding, participants will wear protective goggles and a blindfold to prevent visual perception of the light.

Sham PBM

NMES-evoked fatigue protocol OTHER

Neuromuscular Electrical Stimulation (Myomed 932) applied to the quadriceps. Parameters: 80 Hz frequency, 1 ms pulse width (biphasic rectangular pulse), 5s:10s ON:OFF ratio with 1s ramp-up/down. The protocol lasts 20 minutes, totaling 80 evoked isometric contractions. Current intensity is adjusted to generate an initial torque of 20% of the baseline Maximum Voluntary Isometric Contraction (MVIC).

Photobiomodulation (PBM); Sham PBM

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy male and female volunteers.
• Age between 18 and 45 years.
• Practice physical activity regularly
• No history of musculoskeletal injuries in the lower limbs in the last 6 months
• Ability to tolerate NMES

You may not qualify if:

• Have sensory intolerable changes due to NMES
• Consumed coffee or another stimulant in the last 12 hours
• Have a body mass index (BMI) greater than 30 kg/m2 (grade I obesity)
• Present any contraindication for the performance of maximum effort
• Abnormal increase in blood pressure after maximal exertion

Sponsors & Collaborators

• Federal University of Rio Grande do Sul: lead
• Conselho Nacional de Desenvolvimento Científico e Tecnológico: collaborator

Study Sites (1)

Laboratório de Pesquisa do Exercício

Porto Alegre, Rio Grande do Sul, 90690200, Brazil

Location

MeSH Terms

Conditions

Fatigue

Condition Hierarchy (Ancestors)

Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Study Officials

• Marco A Vaz, PhD

  Federal University of Rio Grande do Sul

  STUDY CHAIR

• Marco A Vaz, PhD

  Federal University of Rio Grande do Sul

  STUDY DIRECTOR

• Marco A Vaz, PhD

  Federal University of Rio Grande do Sul

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Marco A Vaz, PhD

CONTACT

+555133085853; marco.vaz@ufrgs.br

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Masking Details: Participants and outcome assessors will be blinded to the intervention groups. The investigator responsible for data analysis will also be blinded. Due to the nature of the equipment operation, the individual administering the treatment (care provider) will not be blinded.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Full Professor

Model Details: Design Model: Parallel Assignment. Number of Arms: 2 (Arm 1: PBM; Arm 2: Sham). Timeline: Assessments will be performed at baseline, followed by the NMES-evoked fatigue protocol. Subsequent evaluations will be conducted post-intervention immediately, and at 24, 48, and 72 hours post-intervention.

Study Record Dates

• First Submitted: April 27, 2026
• First Posted: May 22, 2026
• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): August 30, 2026
• Study Completion (Estimated): September 30, 2026
• Last Updated: May 22, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will not share

Locations

BR (1)