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Therapeutic Photobiomodulation Before Strenuous Exercise Attenuates Shoulder Muscle Fatigue
Joshua A Crow1, John W Stauffer1,2, David Levine3
1Pain Research and Intervention Center of Excellence, Department of Community Dentistry and Behavioral Science, College of Dentistry, University of Florida, Gainesville.
Context:
Photobiomodulation therapy (PBMT) applied as a preconditioning treatment before exercise has been shown to attenuate fatigue and improve skeletal muscle contractile function during high-intensity resistance exercise. Practical implications for preconditioning muscles with PBMT before fatiguing exercise include a safe and noninvasive means to enhance performance and reduce the risk of musculoskeletal injury.
Objective:
To examine the muscle fatigue-attenuating effects of PBMT on performance of the shoulder external-rotator muscle group when applied as a preconditioning treatment before high-intensity, high-volume resistance exercise.
Design:
Sham-controlled, crossover design.
Setting:
Laboratory.
Patients Or Other Participants:
Twenty healthy men (n = 8) and women (n = 12) between the ages of 18 and 30 years.
Intervention(S):
Photobiomodulation therapy was administered using a near-infrared laser (λ = 810/980 N·m, 1.8 W/cm2, treatment area = 80-120 cm2) to the shoulder external-rotator muscles at a radiant exposure of 10 J/cm2. Participants performed 12 sets of isokinetic shoulder exercise. Each set consisted of 21 concentric contractions of internal and external rotation at 60°/s. The sets were subdivided into 3 blocks of exercise (block 1: sets 1-4; block 2: sets 5-8; block 3: sets 9-12).
Main Outcome Measure(S):
Normalized peak torque (N·m/kg), average peak torque (N·m), total work (N·m), and average power (W).
Results:
During the last block of exercise (sets 9-12), all performance measures for the active PBMT condition were 6.2% to 10% greater than the sham PBMT values (P < .02 to P < .001).
Conclusions:
Photobiomodulation therapy attenuated fatigue and improved muscular performance of the shoulder external rotators in the latter stages of strenuous resistance exercise.
