Photobiomodulation Effects on Fatigue and Muscle Damage Induced by NMES
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18-45
SponsorFederal University of Rio Grande do Sul
About this trial
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.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
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
Disqualifiers
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
Trial design
Design model
Parallel
Treatments tested in this trial
Active Photobiomodulation
DeviceApplication 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.
Placebo Photobiomodulation
DeviceThe 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.
NMES-evoked fatigue protocol
Other interventionNeuromuscular 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).
Treatment groups
36 Participants
are divided into 2 treatment groupsGroup A: Photobiomodulation (PBM)Experimental treatment 2 interventions
Group B: Sham PBMSham comparator 2 interventions
Trial outcomes
Primary outcomes
1
Maximal voluntary isometric contraction (MVIC)
Largest knee extensor torque generated isometrically and voluntarily on an isokinetic dynamometer. Unit of Measure: Newton-meters (N.m)
Time frame
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).2
Evoked fatigue
Fall in the evoked torque during the fatigue protocol. Unit of Measure: Newton-meters (N.m)
Time frame
Continuously during the 20-minute fatigue protocol.Secondary outcomes
1
Muscle Echo Intensity
Quantitative analysis of muscle ultrasound images to assess changes in echo intensity, reflecting acute edema and changes in muscle quality. Analysis will be performed specifically on the Rectus Femoris (RF), Vastus Medialis (VM), and Vastus Lateralis (VL). Unit of Measure: Arbitrary Units (au) on a 0-255 grayscale
Time frame
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).2
Pressure Pain Threshold
The minimum pressure at which a subject perceives a stimulus as painful, measured via pressure algometry on the quadriceps muscle bellies to quantify delayed onset muscle soreness (DOMS). Unit of Measure: Newtons (N)
Time frame
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).3
Quadriceps Muscle Thickness
Ultrasound assessment of structural changes in the quadriceps muscle group, for the Rectus Femoris (RF), Vastus Medialis (VM), and Vastus Lateralis (VL). This variable evaluates acute morphological changes or edema-induced swelling following the NMES protocol. Unit of Measure: Millimeters (mm)
Time frame
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).4
Countermovement Jump (CMJ) Height
Measure Description: Maximum jump height achieved during a vertical countermovement jump on a force platform to assess dynamic muscle power. Unit of Measure: Centimeters (cm)
Time frame
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
1
Vastus Lateralis Pennation Angle
Measure Description: Assessment of real-time changes in the pennation angle of the Vastus Lateralis muscle during the fatigue protocol using continuous ultrasound imaging. Unit of Measure: Degrees (°)
Time frame
Continuously during the 20-minute fatigue protocol on Day 1.2
Adipose Tissue Thickness
Measurement of the fat layer thickness overlying the Rectus Femoris, Vastus Medialis, and Vastus Lateralis using ultrasound imaging. This measure is used to characterize the sample's morphology and will serve as a covariate to adjust the delivered PBM dose and NMES current penetration analysis. Unit of Measure: Millimeters (mm)
Time frame
BaselineSponsors and contacts
Click on the lead sponsor to view all of their trials.
Federal University of Rio Grande do Sul
Lead sponsor
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Collaborator
Source ClinicalTrials.gov