by Gabrielle Herman, PT, DPT, CMPT
Introduction
Photobiomodulation therapy (PBMT) or low-level laser therapy (LLLT) is the application of laser light to a pathologic tissue or condition by a means of a low-powered laser and/or light emitting diodes. PBMT causes a photochemical effect in which light is absorbed and induces chemical changes in tissues. PBMT is used to promote tissue regeneration, reduce inflammation and swelling, and relieve pain. The aim of this study was to determine effectiveness of PBMT and cryotherapy both isolated and combined following muscle fatigue from high-intensity exercise.
Methods
- Forty volunteers, average age of 25.30 years old, were randomly divided into five groups: (1) placebo group (PG); (2) PBMT group (PBMT); (3) cryotherapy group (CG); (4) cryotherapy-PBMT group (CPG); and (5) PBMT-cryotherapy group (PCG)
- Volunteers subjected to a muscle fatigue-inducing protocol on the elbow flexors of their dominant upper extremity for four sessions
- Measures:
- Maximal Voluntary Contractions (MVC) – measured prior to exercise, immediately post exercise, and at 24, 48, and 72 hours
- Blood collection– was performed at initial session at the following intervals: pre-exercise, 5 min post exercise, and 60 min post exercise
- In the remaining sessions performed 24, 48, and 72 h later, blood collection and isometric evaluation of MVC were repeated
- PBMT application: cluster of 69 LEDs held in direct contact with skin on muscle belly of biceps receiving a phototherapy with 41.7-J dose (30 s of irradiation) or 0 J for placebo group
- Cryotherapy application: thermal bags containing ice cubes fixed to biceps with compression in supine position for 20 minutes
Results
- Maximal Voluntary Contractions
- Exercise led to significant decrease in production of MVC after fatigue protocol in all groups
- After treatment (72 hours), significant increases in MVC capacity and decrease in DOMS of volunteers who received treatment with PBMT, CPG, and PCG, compared with the PG and CG group
- CG showed no differences compared to PG
- Blood Collections Concentrations
- Biochemical marker of oxidative damage to lipids (TBARS nmol/ml):
- Significant decrease in TBARS concentrations in PBMT, CPG, and PCG, compared with the PG
- In CG there was a significant decrease in TBARS concentrations at 1, 48, 72 h after treatment
- Biochemical marker of oxidative damage to proteins (Carbonylated proteins; CP):
- Significant decrease in PC concentrations in the PBMT, CG and PCG, compared with the PG
- In the CPG, a significant decrease in PC concentrations in 24 to 72 h after treatment
- Muscle damage (Creatine Kinase; CK)
- 1-72 hours after treatment, significant decrease in CK shown PBMT compared with PG
- PCG and CPG groups with significant decrease in CK 48 and 72 h after treatment respectively
- Biochemical marker of oxidative damage to lipids (TBARS nmol/ml):
Discussion
- PBMT has considerable potential for prevention of muscle fatigue and damage caused by high-intensity exercise
- PBMT can improve performance when applied post-exercise for goal of muscle recovery
- Cryotherapy demonstrates some effect in reduction of markers of oxidative damage to lipids and proteins
- Cryotherapy has no influence on maintain MVC capacity
- Cryotherapy alone had no effect on muscle damage marker (CK), only in the group along with PBMT
- PBMT application exhibited significant improvement in MVC after 60 min after the application of the muscle recovery protocol
PTF Take Aways
- Cryotherapy associated with PBMT does not improve effects of PBMT, isolated application of PBMT seems to be the best option to improve muscle recovery in the long term and short term
- Cryotherapy in isolation is unable to provide muscle recovery
Does photobiomodulation therapy do better than cryotherapy in muscle recovery after a high-intensity exercise?A randomized, double-blind, placebo-controlled clinical trial. Lasers Med Sci (2017) 32:429–437.