Muscle Fatigue Caused by Repetitive Muscle Exercise
Conditions
Keywords
Running Biomechanics, Inertial Measurement Units, Low-Level Laser Therapy, Photobiomodulation Therapy, Recreational Runners
Brief summary
This randomized, sham-controlled, two-period crossover study evaluated the effects of portable 808-nm low-level laser therapy (LLLT) on acute recovery and running biomechanics following a quadriceps-dominant fatiguing task in recreational runners. Twenty male recreational runners completed both active LLLT and sham conditions, separated by a 2-week washout period. After the fatiguing task, participants received 10 minutes of bilateral quadriceps LLLT or sham treatment, followed by treadmill running at the same fixed self-selected speed. Quadriceps soreness, heart rate, running spatiotemporal parameters, and kinematic responses were assessed using a verbal numerical rating scale, heart-rate monitoring, two-dimensional video analysis, and inertial measurement units.
Detailed description
Each participant completed two experimental visits in randomized order, with one active LLLT condition and one sham condition separated by a 2-week washout period. At each visit, participants completed a 5-minute treadmill warm-up followed by a 3-minute pre-fatigue running trial at a fixed self-selected running speed. They then performed a repeated stand-sit-stand task designed to produce quadriceps-dominant lower-limb fatigue. Immediately after the fatiguing task, participants received either active portable 808-nm LLLT or sham treatment for 10 minutes over the bilateral rectus femoris, vastus lateralis, and vastus medialis muscles. A 3-minute post-intervention treadmill running trial was then performed at the same running speed used before the fatiguing task. Quadriceps soreness was assessed using a 0-10 verbal numerical rating scale. Heart rate was monitored using a chest-strap heart-rate monitor. Running spatiotemporal and kinematic variables were assessed using high-frame-rate two-dimensional video analysis and three inertial measurement units positioned over the bilateral distal tibiae and sacral region.
Interventions
DEVICELLLT
Portable 808-nm low-level laser therapy applied bilaterally to the rectus femoris, vastus lateralis, and vastus medialis for 10 minutes.
DEVICESham
Sham device applied to the same bilateral quadriceps sites for 10 minutes, matching the LLLT condition in device appearance, placement, duration, and fixation.
Sponsors
Chia Nan University of Pharmacy ＆ Science
Lasinmed Medical Electronics Co., Ltd.
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Masking description
The LLLT and sham devices were pre-coded as Conditions A and B by the manufacturer. Only the manufacturer retained the code linking each condition to the actual intervention. Participants, intervention personnel, investigators, and outcome assessors remained unaware of condition identity until completion of data analysis. The devices were covered during application to prevent visual identification of the assigned intervention.
Intervention model description
Randomized, two-period crossover design. Participants were assigned to one of two intervention sequences (LLLT followed by sham, or sham followed by LLLT), with a 2-week washout period between experimental visits.
Eligibility
Sex/Gender
MALE
Age
18 Years to 40 Years
Healthy volunteers
Yes
Inclusion criteria
1. Male recreational runners aged 18-40 years. 2. Recreational running status determined using the World Masters Athletics (WMA) age-graded performance score, with an age-graded score below 60%. 3. Previous experience with treadmill running. 4. Rearfoot-strike running pattern. 5. No running-related lower-limb injury during the preceding 6 months
Exclusion criteria
1. WMA age-graded performance score of 60% or higher. 2. Non-rearfoot-strike running pattern. 3. Leg-length discrepancy greater than 3 cm. 4. Use of an orthosis, brace, or other lower-limb medical device that could influence running gait.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Quadriceps Soreness | Immediately after the 10-minute intervention and before the post-intervention running trial. | Quadriceps soreness was assessed using a 0-10 verbal numerical rating scale (VNRS), where 0 indicated no soreness and 10 indicated the worst imaginable soreness. Decimal responses were permitted. |
| Distal-Tibial Acceleration at Initial Contact | At initial contact during the post-intervention treadmill running trial; events were identified within the 60-120-second analysis interval. | Resultant distal-tibial acceleration was measured using bilateral inertial measurement units and expressed in meters per second squared (m/s²). Values from 10 consecutive steps were averaged for each limb, and the left- and right-limb means were subsequently averaged. |
| Distal-Tibial Angular Velocity at Initial Contact | At initial contact during the post-intervention treadmill running trial; events were identified within the 60-120-second analysis interval. | Resultant distal-tibial angular velocity was measured using bilateral inertial measurement units and expressed in degrees per second (°/s). Values from 10 consecutive steps were averaged for each limb, and the left- and right-limb means were subsequently averaged. |
| Distal-Tibial Angular Velocity at Toe-Off | At toe-off during the post-intervention treadmill running trial; events were identified within the 60-120-second analysis interval. | Resultant distal-tibial angular velocity was measured using bilateral inertial measurement units and expressed in degrees per second (°/s). Values from 10 consecutive steps were averaged for each limb, and the left- and right-limb means were subsequently averaged. |
| Distal-Tibial Acceleration at Toe-Off | At toe-off during the post-intervention treadmill running trial; events were identified within the 60-120-second analysis interval. | Resultant distal-tibial acceleration was measured using bilateral inertial measurement units and expressed in meters per second squared (m/s²). Values from 10 consecutive steps were averaged for each limb, and the left- and right-limb means were subsequently averaged. |
| Step Width During Running | During the 3-minute post-intervention treadmill running trial; 10 consecutive steps were analyzed from 60 to 120 seconds after the start of running. | Step width was measured from posterior-view two-dimensional video analysis and expressed in centimeters. Ten consecutive steps were analyzed and averaged for each participant and condition. |
| Sacral Acceleration at Initial Contact | At initial contact during the post-intervention treadmill running trial; events were identified within the 60-120-second analysis interval. | Resultant sacral acceleration was measured using an inertial measurement unit positioned over the S2 region and expressed in meters per second squared (m/s²). Values from 10 consecutive steps were averaged for each participant and condition. |
| Sacral Acceleration at Toe-Off | At toe-off during the post-intervention treadmill running trial; events were identified within the 60-120-second analysis interval. | Resultant sacral acceleration was measured using an inertial measurement unit positioned over the S2 region and expressed in meters per second squared (m/s²). Values from 10 consecutive steps were averaged for each participant and condition. |
| Sacral Angular Velocity at Initial Contact | At initial contact during the post-intervention treadmill running trial; events were identified within the 60-120-second analysis interval. | Resultant sacral angular velocity was measured using an inertial measurement unit positioned over the S2 region and expressed in degrees per second (°/s). Values from 10 consecutive steps were averaged for each participant and condition. |
| Sacral Angular Velocity at Toe-Off | At toe-off during the post-intervention treadmill running trial; events were identified within the 60-120-second analysis interval. | Resultant sacral angular velocity was measured using an inertial measurement unit positioned over the S2 region and expressed in degrees per second (°/s). Values from 10 consecutive steps were averaged for each participant and condition. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Heart Rate at the End of the Intervention | During the final 10 seconds of the 10-minute intervention. | Heart rate was recorded using a Polar H10 chest-strap heart-rate monitor and averaged over the final 10 seconds of the 10-minute intervention. Heart rate was expressed in beats per minute (beats/min). |
| Sagittal Trunk Inclination Angle at Initial Contact | At initial contact during the post-intervention treadmill running trial; 10 consecutive steps were analyzed from 60 to 120 seconds after the start of running. | Sagittal trunk inclination angle was measured from lateral-view two-dimensional video analysis and expressed in degrees. Positive values indicated trunk flexion and negative values indicated trunk extension. Ten consecutive steps were analyzed and averaged for each participant and condition. |
| Sagittal Trunk Inclination Angle at Toe-Off | At toe-off during the post-intervention treadmill running trial; 10 consecutive steps were analyzed from 60 to 120 seconds after the start of running. | Sagittal trunk inclination angle was measured from lateral-view two-dimensional video analysis and expressed in degrees. Positive values indicated trunk flexion and negative values indicated trunk extension. Ten consecutive steps were analyzed and averaged for each participant and condition. |
| Knee-Flexion Angle at Initial Contact | At initial contact during the post-intervention treadmill running trial; 10 consecutive steps were analyzed from 60 to 120 seconds after the start of running. | Knee-flexion angle was measured from lateral-view two-dimensional video analysis and expressed in degrees. Smaller values represented a more extended knee position. Ten consecutive steps were analyzed and averaged for each participant and condition. |
| Knee-Flexion Angle at Toe-Off | At toe-off during the post-intervention treadmill running trial; 10 consecutive steps were analyzed from 60 to 120 seconds after the start of running. | Knee-flexion angle was measured from lateral-view two-dimensional video analysis and expressed in degrees. Smaller values represented a more extended knee position. Ten consecutive steps were analyzed and averaged for each participant and condition. |
Countries
Taiwan
Outcome results
None listed