7 Studies Showing Red Light Therapy Speeds Injury Healing

7 Studies Showing Red Light Therapy Helps with Soft Tissue Injuries

Red light therapy is becoming the unfair advantage that can’t be banned from amateur or professional sports play. Here are 7 more studies showing how this therapy keeps athletes on the field.

Studies show that red light therapy helps athletes with injuries:

  1. reduces ankle sprain pain after one session
  2. reduces ankle sprain pain after two sessions
  3. reduces ankle sprain edema
  4. returns athletes from injury to play up to 71% faster
  5. reduces shoulder teninitis pain faster than naproxen sodium
  6. improves Achilles tendinitis healing time faster when prefaced with ice therapy
  7. speeds eccentric exercise tendinitis physical therapy

To see more studies showing how red light therapy helps injured athletes, see my article: 7 MORE Studies Show Red Light Therapy Helps Injured Athletes.

Don’t remember the difference between a sprain and a strain? See my article: Soft Tissue Injury & Muscle Pain that Prevent Athletic Play

Can Red Light Therapy Help with Sprained Muscles?

Several studies show that red light therapy can help heal sprained muscles.

Using the light reduces bruising, edema, and pain.

Study #1 Red Light Therapy Reduces Ankle Sprain Pain by 30.81%

Red light therapy helps with the pain and bruising of ankle sprains, according to a 2018 study published in Lasers in Medicine and Science.

This study showed that red light therapy can reduce ankle sprain pain by as much as 30.81%.

Red light therapy reduced ankle sprain pain by 30.06% and 30.81%, based on improvements in the McGill and Visualized Analog scale (VAS) pain assessment tests[1].

This study used 10 joules/cm^2 of  627 nm red light on 40 volunteers who had acute ankle sprains.

Person's hands holding red, inflamed ankle
Red light therapy helps with achilles heel tendonitis

All volunteers received protection, rest, ice, compression and elevation.

Then twenty received red light therapy, and 20 received a sham treatment for the next 6 days.

In addition to the perception of pain reducing about 31%, there was also significantly less bruising in the treatment group after 6 days of red light therapy.


[1] de Moraes Prianti B, Novello GF, de Souza Moreira Prianti T, Costa DR, Pessoa DR, Nicolau RA. Evaluation of the therapeutic effects of led (λ627 ± 10 nm) on the initial phase of ankle sprain treatment: a randomised placebo-controlled clinical trial. Lasers Med Sci. 2018 Jul;33(5):1031-1038. doi: 10.1007/s10103-018-2460-6. Epub 2018 Feb 8. PMID: 29423840.

Study #2 Multiple Red Light Therapy Sessions Reduce Ankle Sprain Pain

Red light therapy reduces pain in moderately severe ankle sprains, according to a 2019 study published in the American Journal of Physical Medicine and Rehabilitation[2].

Authors tested an unusual protocol in this study, one that worked despite prior indications that it would not.

The “biphasic dose response” of red light therapy says that too much light is counter productive.

Soccer player with blue socks kicking soccer ball
Red light therapy helps with muscle sprain healing and pain relief

Here, the subjects received two doses of red light in one session, and the results were still positive.

Both groups had moderately severe ankle sprains.

Group 1 received a red light therapy session, then a second session after a 30 minute break.

Their ankles received two sessions of 635 nm red light for three days, for a total of 6 treatment sessions.

Group 2 received rest, ice, compression and elevation therapy.

Researchers then tested the subjects’ recovery at 10 days and at 6 weeks after treatment.

Those with sprained ankles in the treatment group experienced significantly less pain at 10 days, but not at 6 weeks.

One would not expect a pain reduction from 3 days of treatment a month and a half earlier.


[2] Calin MA, Badila A, Hristea A, Manea D, Savastru R, Nica AS. Fractionated Irradiation in Photobiomodulation Therapy of Ankle Sprain. Am J Phys Med Rehabil. 2019 Aug;98(8):692-698. doi: 10.1097/PHM.0000000000001178. PMID: 31318750.

Study #3 Red Light Therapy reduces Ankle Sprain Edema

Red light therapy reduces the edema associated with ankle sprains, according to a study posted to the Journal of Clinical Laser Medicine & Surgery[3].

Ankle sprains often cause edema, which is a swelling from trapped fluid.

The swelling adds to the pain sensation of a sprained ankle.

Researchers tested reducing edema with these treatment combinations:

  • 16 subjects: rest, ice, compression, elevation
  • 16 subjects: rest, ice, compression, elevation, placebo red light therapy
  • 15 subjects: red light therapy
Soccer player chasing ball with opponent running behind him
Red light therapy helps with chronic inflammation reduction

They studied these protcols on soccer players.

The red light therapy was 820 nm infrared pulsed at 16 Hz.

They found that red light therapy reduced edema significantly more than traditional treatment, or traditional treatment plus placebo light therapy.


[3] Stergioulas A. Low-level laser treatment can reduce edema in second degree ankle sprains. J Clin Laser Med Surg. 2004 Apr;22(2):125-8. doi: 10.1089/104454704774076181. PMID: 15165387./span>

Can Red Light Therapy Help with Muscle Strains?

Red light therapy helps with muscle strains, according to the studies on intercostal, abdominal, and shoulder muscle strains.

Study #4 Post Injury Return-to-Play 71% Faster with Red Light Therapy

A 2016 study showed that red light therapy helped with reducing healing time in knee sprains, hamstring sprains, achilles tendinitis, intercostal strains (muscle strains), shoulder strains, and foot fractures.

In a study of 395 university athletes with sports-related injuries, red light therapy cut recovery time by half, according to a 2016 study published in Laser Therapy[4].

In this studies the following soft tissue injuries were treated with red light therapy:

  • 96 knee sprains
  • 35 hamstring muscle strains
  • 30 Achilles tendinitis
  • 26 intercostal muscle strains
  • 20 shoulder sprains
  • 20 abdominal muscle strains
  • 17 foot fractures

Injuries from the 395 athletes occurred during a range of sports including:

  • baseball
  • basketball
  • crew
  • cross country
  • field hockey
  • football
  • golf
  • lacrosse
  • soccer
  • softball
  • swimming/diving
  • tennis
  • track & field
  • volleyball
  • wrestling

Researchers treated these injuries with 830 nm infrared light.

Female tennis player wearing white, holding tennis racquet in right hand, and holding right elbow with left hand, and has look of pain on her face
Tendinitis responds well to red light therapy

Treatments reduced inflammation and pain, and there were no side effects.

Sprains were amongst the injuries treated. Those with sprains, as well as those with other injuries, returned to the field in an average of 9.6 days when treated with red light therapy.

Injury Expected Return to Play (Days) Actual Return to Play (Days) Returned to play this much faster with red light therapy
Mild hamstring strain 10-14 7 30-50%
Mild knee sprain 7-10 3.6 49-64%
Severe chostocondral muscle sprain 7-14 5.5 21-61%
Severe hip pointer (contusion) 21-24 7 67-71%
Very severe ankle sprain 28-42 12 57-71%

[4] Foley J, Vasily DB, Bradle J, Rudio C, Calderhead RG. 830 nm light-emitting diode (led) phototherapy significantly reduced return-to-play in injured university athletes: a pilot study. Laser Ther. 2016 Mar 31;25(1):35-42. doi: 10.5978/islsm.16-OR-03. PMID: 27141153; PMCID: PMC4846838.

Can Red Light Therapy Help with Tendinitis?

Several studies show that red light therapy can help with tendinitis.

Studies on shoulder, achilles heel, bicipital, and eccentric exercise tendinitis show that red light therapy reduces inflammation, shortens healing time, and improves range of motion.

Study #5 Red Light Therapy More Effective Than Naproxen Sodium for Shoulder Tendinitis

Red light therapy reduces pain and improves movement better than naproxen sodium, according to a 1989 study in the Scandanavian Journal of Rheumatology[5]

The study tested the effects of 904 nm infrared low level laser therapy on 30 patients with shoulder injuries in the forms of supraspinatus tendinitis or bicipital tendinitis.

Football player flying horizontally over touchdown line
Red light therapy reduces delayed onset muscle soreness

The naproxen sodium and the red light therapy help with the tendinitis healing.

Red light therapy participants had greater pain relief and more range of motion improvements than the drug group.

The placebo group had no improvements. There were no side effects.


[5] England S, Farrell AJ, Coppock JS, Struthers G, Bacon PA. Low power laser therapy of shoulder tendonitis. Scand J Rheumatol. 1989;18(6):427-31. doi: 10.3109/03009748909102106. PMID: 2694356.

Study #6 Icing Skin Improves Red Light Therapy Achilles Tendinitis Results

Red light therapy reduces achilles heel tendinitis inflammation, and those results improve with icing the area first, according to a 2017 study published in Photomedicine and Laser Surgery[6].

Icing for 20 minutes before red light therapy produced better results than red light therapy without icing.

The 54 subjects received red light therapy, ice therapy, then red light therapy again.

man holding red, inflamed knee
Red light therapy helps with acute inflammation

The red light therapy was either  904 nm infrared “superpulsed” or 810 nm infrared continuous mode therapy.

Red light therapy reduced the tendon inflammation.

Researchers extrapolated how far photons reached based on tendon thickness before and then after treatements.

They compared the distance light traveled into the injury before ice treatment and then after ice treatment.

They concluded that ice therapy improved the distance that photons reached into the injury.


[6] Haslerud S, Naterstad IF, Bjordal JM, Lopes-Martins RAB, Magnussen LH, Leonardo PS, Marques RH, Joensen J. Achilles Tendon Penetration for Continuous 810 nm and Superpulsed 904 nm Lasers Before and After Ice Application: An In Situ Study on Healthy Young Adults. Photomed Laser Surg. 2017 Oct;35(10):567-575. doi: 10.1089/pho.2017.4269. Epub 2017 Jun 30. PMID: 28677985.

Study #7 Red Light Therapy Improves Eccentric Exercise Tendinitis Therapy

Red light therapy reduces achilles heel tendinitis healing time, stiffness, crepitation and tenderness, according to a 2008 study published in The American Journal of Sports Medicine[7].

The study was conducted on 52 recreational athletes who were separated into treatment and treatment-placebo groups.

Baseball player in red shirt and white pants running to his left with outstretched baseball glove as ball approaches him
Red light therapy provides more oxygen to the muscles.

Researchers combined eccentric exercise therapy with 820 nm red light therapy or with a red light placebo therapy.

The subjects who received red light therapy along with physical therapy had sigificantly less pain than the physical therapy exercise group.

Red light therapy significantly improved the subjects’ morning stiffness, tenderness, and crepitation (crackling) over the eccentric exercise only group.



[7] Stergioulas A, Stergioula M, Aarskog R, Lopes-Martins RA, Bjordal JM. Effects of low-level laser therapy and eccentric exercises in the treatment of recreational athletes with chronic achilles tendinopathy. Am J Sports Med. 2008 May;36(5):881-7. doi: 10.1177/0363546507312165. Epub 2008 Feb 13. PMID: 18272794.

Caroline Bogart

I research the bloody hell out of everything that interests me, then translate it into blog posts to solidify my knowledge and share the information.

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