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Three Part Question

IN [adults with delayed onset muscle soreness/exercise induced muscle injury] IS [therapeutic laser beneficial] AT [decreasing pain, improving function and reducing recovery time].

Clinical Scenario

A 25 year old football player patient presents with a 24 hour history of delayed onset muscle soreness affecting his gluteal and hamstring region following an intense gym weight training session which included loaded squats, deadlifts, stiff leg deadlift and lunge exercises.
He is due to train today and tomorrow before a game in three days’ time, although he feels he is too sore and stiff to be able to participate in training.

You have heard from a colleague who works in sports medicine that application of localised laser therapy can help improve pain, function and the reduce recovery time, and therefore wonder if it should form part of your management plan to enable the player to return to training as soon as possible.

Search Strategy

The MEDLINE (1966-05/2015 ), CINAHL (1982-05/2015), AMED (1985 – 05/2015) and SPORTDiscus (1830 – 05/2015) and EMBASE (1996 – 05/2015) databases were searched using the OVID interface.
The Cochrane Library was also searched using the strategy:
(Laser therapy OR therapeutic laser) AND (delayed onset muscle soreness OR exercise induced muscle injury).
All searches were limited to human AND English language.
The following search strategy was used:

1. Delayed onset muscle soreness.mp.
2. EXERCISE INDUCED MUSCLE SORENESS.mp.
3. Exercise induced muscle injury.mp.
4. 1 or 2 or 3
5. Laser Therapy/
6. Lasers/
7. Laser Therapy, Low-Level/
8. Phototherapy/
9. therapeutic laser.mp.
10. high powered laser.mp
11. 5 or 6 or 7 or 8 or 9 or 10
12. 4 and 11.

Search Outcome

The search yielded six papers though three were excluded; one study was excluded as it exclusively investigated the use of phototherapy rather than laser therapy. Another study was excluded as it referred to a protocol of a double blind placebo controlled RCT investigating prophylactic laser dosage on DOMS, although the results have not been published as yet. A further study was also excluded as this investigated prophylactic low level laser therapy application before induction of DOMS.

The remaining three papers included in the BET were of a randomised controlled trial design and investigated a total of 60, 36 and 60 subjects respectively.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Craig et al 1996 UK	N=60 volunteer male subjects with induced DOMS affecting elbow flexor muscles. Subjects randomised into the following groups: 1. Control 2. Placebo 3. 2.5Hz Combined phototherapy/Low-intensity Laser (CLILT) 4. 5Hz CLILT 5. 20Hz CLIIT	RCT (Evidence level 2b)	1: ROM- elbow flexion, extension and resting angles.	1: No significant differences.	Only male subjects recruited therefore limits external validity. Limited subject inclusion and exclusion criteria stated. Did not state whether random subject allocation was concealed. Unclear if groups were comparable at baseline measures of characteristics and outcome measures. Did not state whether assessors who measured outcomes were blinded. Did not state how many subjects were included in data analysis and dropout rate not reported. Did not state point measures to quantify treatment effect or measures of variability for data obtained.
			2: Mechanical pain threshold/tenderness of 8 points of the biceps brachii.	2: No significant differences.
			3: Pain assessment using Visual analogue scale (VAS).	3: No significant differences.
			4: Pain assessment using McGill Pain Questionnaire.	4: No significant differences.
Craig et al 1999 UK	N=36 volunteer (18 male, 18 female) subjects with induced DOMS affecting elbow flexor muscles. Subjects randomised into the following groups: 1. Control group 2.CLILT group (73Hz pulsed dose) 3.Placebo	RCT (Evidence level 2b)	1: ROM- elbow flexion, extension and resting angles.	1: No significant differences between groups of elbow flexion angle, elbow extension angle Elbow resting angle demonstrated significant differences between the control group, and placebo and CLILT groups; level of significance not stated and direction of differences not stated.	Limited subject inclusion and exclusion criteria stated. Did not state whether random subject allocation was concealed. Unclear if groups were comparable at baseline measures of characteristics and outcome measures. Did not state whether therapists who administered treatment were blinded. Did not state how many subjects were included in data analysis and dropout rate not reported. Did not state point measures to quantify treatment effect or measures of variability for data obtained. Graphs used to depict changes in outcome measures for all groups during experiment but no key provided therefore unable to interpret which data set belonged to each group.
			2: Mechanical pain threshold/tenderness of 8 points of the biceps brachii.	2: No significant differences.
			3: Pain assessment using VAS.	3: No significant differences, although on day 4 subjects receiving CLILT reported a non significant increase in pain compared to control and placebo groups.
			4: Pain assessment using McGill Pain Questionnaire.	4: No significant differences between groups for McGill Pain Questionnaire scores, although on day 3 subjects receiving CLILT reported an increase in pain compared to control and placebo groups.
Parr et al 2010 USA	N=60 volunteer subjects (15 male, 15 female) with induced DOMS affecting elbow flexor muscles. Subjects randomised into the following groups: 1. 2 sessions of high powered laser (HPL) at 3 watts and 5Hz. First dose immediately after DOMS induction (4 mins duration) and second dose on day 2 (90 sec duration). 2. 1 session of HPL as above, but received sham dose on day 2. 3. Control/Placebo received sham doses on both days.	RCT (Evidence level 2b)	1: ROM- total range of elbow ROM and elbow resting angle.	1: No significant differences between groups for total ROM. Group 2 and 3 experienced a significant (p <.05) reduction in resting arm angle from baseline to day 2 and this returned to baseline by day 4 for both groups. Group 1 but not demonstrate reduction in resting angle on any follow up days.	Limited subject inclusion and exclusion criteria stated. Did not state whether random subject allocation was concealed. Did not state how many subjects were included in data analysis and dropout rate not reported. Therapists who administered the treatment were not blinded.
			2: Muscular point tenderness using VAS of the most tender point of the biceps brachii.	2: No significant differences.
			3: Self-reported function using QuickDASH questionnaire.	3: No significant differences.
			4: Maximal voluntary isometric force using computerised isokinetic dynamometer.	4: No significant differences.

Comment(s)

There is a paucity of high quality trials investigating the use of laser therapy in the management of DOMS. Although all included studies were of randomised controlled trial design, all suffered from serious methodological flaws which significantly increased the risk of bias; any results should therefore be interpreted with caution. Only one study by Parr et al (2010) investigated the use of high powered laser in isolation on measures of DOMS. No significant differences were found between experimental and control groups for any dependent variable. Both studies by Craig et al (1996, 1999) evaluated the effect of low intensity laser therapy combined with phototherapy/monochromatic light (CLILT) in a single treatment modality on measures of DOMS. There were no significant differences evident between experimental and control groups for any dependent variable.

Clinical Bottom Line

The current available literature suggests that application of either high powered laser therapy or combined low intensity laser and phototherapy at the dosage used in these studies is ineffective in decreasing pain, improving function and reducing recovery time in patients with DOMS.

References

1. Craig, J.A., Barlas, P., Baxter, G.D., Walsh, D.M. and Allen, J.M. Delayed onset muscle soreness: Lack of effect of combined phototherapy/low intensity laser therapy at low pulse repetition rates Journal of Clinical Laser Medicine and Surgery 1996 14 (6); pp.375-380
2. Craig, J.A., Barron, J., Walsh, D.M. and Baxter, G.D. Lack of effect of combined low intensity laser therapy/phototherapy (CLILT) on delayed onset muscle soreness in humans Lasers in Surgery and Medicine 1999 24; pp.223-230.
3. Parr, J.J., Larkin, K.A. and Borsa, P.A. Effects of class IV laser therapy on exercise induced muscle injury Athletic Training and Sports Health Care 2012 2 (6); pp.267-276