When you are doing everything “right” in the gym, hitting your protein targets, and still feel stuck, it is natural to look for tools that might move the needle. Red light therapy is one of the most talked‑about options right now for recovery, performance, and even muscle growth.
As a red light therapy wellness specialist and health advocate, I want to help you separate what the science actually shows from marketing hype, and then translate that into practical, at‑home strategies that respect your time, money, and health.
This article focuses specifically on how red light therapy may influence muscle protein synthesis and growth, what the evidence says, and how to integrate it realistically into a muscle‑building plan.
Muscle Protein Synthesis: Why It Matters for Your Results
Muscle protein synthesis is the process of building new muscle proteins. When it outpaces muscle protein breakdown over time, muscle size and strength increase. Heavy resistance training, adequate protein intake, and high‑quality sleep are the cornerstones of this process.
Every hard workout creates microscopic damage in muscle fibers. Your body responds by repairing that damage and, ideally, making the muscle slightly bigger and stronger. That repair work depends on cellular energy, blood flow, inflammation control, hormone balance, and sleep quality.
Red light therapy does not replace training or nutrition. Instead, it aims to support the conditions under which muscle protein synthesis happens: better cellular energy production, improved circulation, more favorable gene expression in muscle tissue, and lower excessive inflammation.
What Red Light Therapy Is—and What It Is Not
Red light therapy, often called photobiomodulation or low‑level laser therapy, uses specific wavelengths of red and near‑infrared light to influence biological processes without heating or damaging tissue.
Multiple sources describe similar wavelength ranges. Fitness and clinical articles typically reference red light around 620–670 nanometers and near‑infrared light around 800–850 nanometers, sometimes extending up to roughly 900–950 nanometers for certain devices. An NSCA coaching article explains that this light is used to stimulate, heal, or regenerate tissue and increase antioxidants in the body, while a sports physical therapy clinic notes that athletic applications commonly use wavelengths between about 660 and 850 nanometers.
Mechanistically, several evidence summaries converge on the same idea. Red and near‑infrared light is absorbed by structures inside mitochondria, particularly cytochrome c oxidase. A narrative review of 46 human studies on photobiomodulation in muscle tissue describes how this absorption boosts mitochondrial respiration, increases ATP (the cell’s energy currency), modulates oxidative stress, and influences gene expression. Other clinical pieces describe increased nitric oxide, which widens blood vessels and improves circulation, as well as reductions in inflammatory markers.
Red light therapy is not a tanning bed, and it is not a high‑heat treatment. Clinicians from University of Utah Health emphasize that devices are designed not to get hot in the way a tanning bed does. It is also not a magic cure‑all. Stanford dermatology experts highlight that while red light is well supported for some skin and hair indications, claims about athletic performance and recovery remain exploratory rather than firmly established.
How Red Light Therapy Could Support Muscle Protein Synthesis
If you think of muscle protein synthesis as a construction project, red light therapy is not the bricks or the blueprint. It is more like improving the power supply and local road access so the work crews can perform efficiently.
Mitochondrial energy and muscle‑building signals
In a randomized, placebo‑controlled trial of red and near‑infrared LED therapy combined with strength training, researchers found greater gains in muscle size and strength compared to training with sham light. Muscle biopsies showed that light therapy upregulated myogenic and hypertrophy‑related genes and downregulated genes tied to atrophy and inflammation. That pattern strongly suggests a more anabolic environment in the muscle, which is precisely what you want for robust muscle protein synthesis.
A broader narrative review on photobiomodulation in human muscle tissue reports similar mechanistic themes. Studies consistently show that pre‑exercise light exposure can increase ATP production, support antioxidant defenses such as superoxide dismutase, and reduce markers of muscle damage like creatine kinase. All of these changes reduce the “cost” of each workout on your tissues, potentially allowing more frequent or harder training without tipping into overtraining.
Blood flow, nutrient delivery, and connective tissue
Several athletic recovery articles describe another key effect: improved circulation. A sports physical therapy clinic notes that red light therapy increases nitric oxide, widens blood vessels, and enhances oxygen and nutrient delivery to working muscles. City‑based gym articles similarly emphasize vasodilation and increased blood flow as central to both recovery and performance.
Other sources, including dermatology‑focused reviews, show that red light can increase collagen and elastin synthesis. For muscle growth, collagen may not sound exciting, but healthy tendons and connective tissue are what let you keep loading heavy without chronic pain. Supporting those structures indirectly supports consistent progressive overload, which is a major driver of muscle protein synthesis over months and years.
Inflammation, soreness, and training volume
Inflammation after training is normal, but when it becomes excessive or lingers, it can limit how often and how hard you can train. Multiple sources, from clinical reviews to gym‑based reports, converge on anti‑inflammatory effects. The NSCA coaching article describes how red light therapy in animal models enhanced defenses against oxidative stress, inhibited inflammation, and reduced creatine kinase activity. Human trials summarized in sports performance reviews report lower blood markers of muscle damage and oxidative stress in some protocols.
Function‑oriented clinics and wellness centers note practical outcomes like up to roughly 50 percent reductions in delayed onset muscle soreness in some studies and faster return of strength between sessions. A 2015 meta‑analysis in Lasers in Medical Science reviewed randomized, placebo‑controlled trials and concluded that phototherapy applied before exercise improved muscular performance and accelerated recovery, with many studies showing significant improvements in time to exhaustion, repetitions, and other performance measures.
Less soreness and faster recovery do not directly equal higher muscle protein synthesis, but they make it more realistic to sustain the training volume and intensity that drive hypertrophy.
Sleep, hormones, and systemic recovery
Recovery is not only a local muscle phenomenon. Sleep and hormones matter just as much for building muscle.
An NSCA article points to research suggesting that photobiomodulation can improve sleep, a critical factor for preventing overtraining. City‑based fitness content also highlights improved sleep, including better circadian rhythm regulation when red light is used consistently in the evening. Another gym article notes potential modulation of hormones such as testosterone and cortisol, though this area is still early and not standardized.
Medical centers like Mass General Brigham describe red‑light based photobiomodulation as one of several recovery tools alongside rest, nutrition, and float tanks. Reported benefits include more exercise energy, faster recovery, better sleep, and reduced inflammation. Better sleep and more favorable stress hormone patterns are exactly the systemic conditions in which muscle protein synthesis tends to thrive.
What the Research Shows for Muscle Size, Strength, and Endurance
When we zoom in on muscle growth and performance outcomes, the evidence is promising but not uniform. It helps to think in terms of patterns rather than one‑size‑fits‑all rules.
Trials showing enhanced hypertrophy and strength
The LED therapy study mentioned earlier is a central piece of evidence. In that trial, participants performed resistance training with or without red and near‑infrared light applied to the trained muscles. The group receiving light therapy had greater muscle hypertrophy, larger improvements in strength and power, less increase in blood markers of muscle damage, and lower delayed onset muscle soreness. Gene expression data supported a shift toward muscle‑building and away from muscle‑breakdown pathways.
An applied physiology study in the European Journal of Applied Physiology, cited by performance‑oriented wellness authors, compared two groups of athletes. Both groups trained, but only one received red light therapy. The light‑treated group achieved more than 50 percent greater increases in muscle thickness and strength than the training‑only group. Ultrasound imaging and isokinetic dynamometry confirmed these differences.
Other controlled trials in healthy young men found that combining strength training with light therapy significantly increased maximal torque in leg extension and leg press compared with training alone. In one study, leg‑press performance improved 55 percent more in the light group than in the non‑therapy group.
Smaller, localized studies show similar patterns. A placebo‑controlled crossover trial found that red light therapy increased maximum repetitions in hand and grip exercises by about 52 percent compared with sham light.
Endurance, fatigue resistance, and time to exhaustion
A 2015 systematic review and meta‑analysis in Lasers in Medical Science examined randomized, placebo‑controlled trials using lasers and LEDs in exercise. The majority of trials showed significant improvements in performance measures like maximum repetitions, speed, endurance, and time before exhaustion when light was applied before exercise. The authors concluded that phototherapy improves muscular performance and speeds recovery in these contexts.
Subsequent studies expanded on this. A triple‑blind treadmill study published in 2018 reported that pre‑exercise red light therapy increased time to exhaustion and oxygen uptake and reduced body fat in healthy volunteers compared with placebo. When therapy was applied both before and after endurance sessions, improvements in endurance occurred roughly three times faster than with exercise alone.
In team sports, a randomized, triple‑blinded trial in professional futsal players found that athletes who received red light therapy before matches stayed on the court longer and had better biochemical recovery markers than those receiving placebo light. Competitive cycling trials from the same research group observed increased time to exhaustion and reduced oxygen deficit, suggesting more efficient aerobic metabolism.
Running and sprinting studies also report favorable outcomes. Randomized, double‑blind studies in runners and professional rugby players found that pre‑exercise red light therapy improved running economy, subjective exertion, peak velocity, total time to exhaustion, and average sprint times, while supporting recovery afterward.
Evidence in women and older adults
A six‑month study in postmenopausal women combined near‑infrared light therapy with treadmill training. Compared with treadmill training alone, the light plus exercise group showed greater improvements in maximal exercise tolerance time, metabolic equivalents, and maximal heart rate at a given workload, along with shorter recovery time.
Studies in younger women aged 18 to 30 found that red light therapy increased leg muscle torque and maintained lactate levels during resistance exercise, while another trial in women aged 50 to 60 reported significantly higher quadriceps power and total work and less fatigue in the light‑treated group.
On the other hand, an evidence review from Examine.com notes that only a few long‑term studies have looked at muscle size and strength outcomes, and those show mixed results. One long‑term study in young men reported greater gains in muscle size and strength with pre‑exercise red light therapy, whereas similar trials in older men and older women did not find meaningful strength or hypertrophy benefits. That suggests age, training status, or other factors may influence who responds.
Mixed and null findings
Not all studies show benefits. The 2016 narrative review of 46 human trials on photobiomodulation in muscle tissue highlights considerable heterogeneity. Some early trials on delayed onset muscle soreness in the upper body found no significant differences in pain, range of motion, or peak torque compared with placebo. Other trials using different wavelengths, doses, or application methods found significant soreness reductions.
The same review describes rigorously designed, triple‑blind crossover studies using specific wavelengths over multiple sites on the biceps that failed to improve repetitions, blood lactate, or fatigue indices compared with placebo. Several randomized trials in athletes found no significant changes in aerobic capacity or blood lactate despite using photobiomodulation.
Examine.com’s independent review underscores this inconsistency. Short‑term studies in young male athletes show slight increases in repetitions to failure during eccentric exercises, but many of those data come from a single research group, and replication is limited. Overall, they characterize red light therapy as an experimental ergogenic aid for performance and recovery.
Taken together, the pattern is clear. Under certain conditions—especially when appropriately dosed and timed around exercise—red light therapy can improve performance, reduce markers of muscle damage, and support hypertrophy. However, results are not guaranteed, and benefits appear to be context‑dependent, with some populations and protocols showing no effect.
Recovery, Pain, Sleep, and Hormones: Indirect Pathways to Better Growth
Muscle protein synthesis does not happen in isolation. Pain, sleep, mental stress, and systemic inflammation all modulate how well you adapt to training.
Articles from sports medicine and wellness centers describe clinically meaningful recovery benefits: reduced markers of inflammation and oxidative stress, less delayed onset muscle soreness, and faster restoration of strength after high‑intensity sessions. In some contexts, red‑light‑based photobiomodulation has even outperformed cryotherapy as a recovery modality.
Medical organizations such as University Hospitals report that red light therapy can lower levels of enzymes linked to muscle damage when used just before activity and may help people return to training with less pain. Reviews on pain management suggest potential benefits across a variety of musculoskeletal conditions and fibromyalgia, although they emphasize that more robust research is still needed.
City‑focused fitness content highlights potential positive effects on hormones like testosterone and cortisol, which are central to muscle building and stress resilience, although these findings are early and not standardized. At the same time, a University of Utah Health podcast team cautions against seeing red light therapy as a shortcut, reminding listeners that “core” health behaviors—nutrition, activity, emotional well‑being, and sleep—carry much stronger evidence.
Clinicians at Mass General Brigham place photobiomodulation alongside other recovery tools such as active rest, nutrition, and float therapy. They note reported benefits like more energy for exercise, faster recovery, improved sleep, and less inflammation. For muscle growth, those systemic improvements can indirectly support higher training quality and better adherence to a long‑term program.
At‑Home Use: Integrating Red Light Therapy into a Muscle‑Gain Plan
If you decide to experiment with red light therapy at home, it should be as a supportive tool layered onto a solid foundation of training, nutrition, and sleep. Research‑based organizations and clinicians consistently stress this point.
Choosing a device thoughtfully
Evidence‑oriented sources emphasize that device quality and parameters matter. Studies that show benefits generally use medical‑grade lasers or high‑quality LED clusters delivering specific wavelengths and energy doses to the target muscles. Lifehacker’s review notes that many consumer devices may not emit the researched wavelengths or sufficient intensity, making them less likely to replicate clinical results.
University of Utah and other medical organizations point out that devices vary widely in wavelength listings. Some masks or panels include only certain bands, while research on mental health, neurodegenerative conditions, or specific muscle outcomes may use others. That means a device can be high quality for one indication and largely untested for another.
When you evaluate a home device, it is reasonable to look for clear labeling of red and near‑infrared wavelengths in ranges that appear repeatedly in studies, approximate power or irradiance data, and transparent safety testing or regulatory clearance for basic safety. Brands associated with professional athletes in marketing materials can be a signal of popularity, but they are not a substitute for unbiased evidence.
Timing around workouts
The bulk of performance‑oriented research applies light before exercise, sometimes immediately before. Trials in strength training, running, cycling, and team sports typically use pre‑exercise exposure to prime muscle tissue. Some studies, such as the treadmill endurance trial, also apply light after exercise and suggest that combining before‑and‑after protocols may accelerate improvements.
Other practitioners emphasize post‑workout use to focus on recovery and soreness reduction. Weightlifting‑focused content notes that post‑workout sessions have the strongest support for recovery and soreness, while pre‑workout exposure may help with fatigue resistance. A practical approach is to pick a consistent pattern—pre‑, post‑, or both around your key sessions—and monitor how you feel and perform over several weeks rather than changing timing frequently.
Many athletic clinics and recovery studios cite session durations around 10 to 20 minutes per body area, sometimes in full‑body beds for about 20 minutes. Evidence reviews, such as the one from the American Council on Exercise, caution that there are no standardized frequency, intensity, time, and type (FITT) guidelines for red light therapy. This is why professionals often recommend a careful trial‑and‑error approach within reasonable boundaries rather than pushing dose aggressively.
Frequency and progression
In studies that reported clear benefits, photobiomodulation was not a one‑time trick. Endurance and strength trials typically applied light therapy multiple times per week over several weeks, often matching the training schedule. Clinical and wellness reports suggest that initial improvements in soreness or stiffness may be subtle, with more noticeable changes in training capacity and fatigue emerging after two to four weeks of consistent use.
For a lifter training three or four days per week, a reasonable starting pattern might be to use red light on the main muscle groups just before or after each heavy session, then reassess after a month. If sleep quality, soreness, or performance metrics like repetitions and bar speed improve without new joint or tendon issues, the protocol may be worth maintaining.
Always an adjunct to fundamentals
Multiple independent sources stress that red light therapy cannot compensate for poor training design, inadequate protein intake, insufficient calories, or chronic sleep deprivation. The University of Utah podcast and Lifehacker’s science review both highlight that investing in basics often provides a better return than expensive gadgets.
Some gym‑based guidance even pairs red light therapy explicitly with a high‑protein diet and proper hydration to maximize muscle growth and recovery efficiency. In that spirit, think of red light therapy as one more lever to fine‑tune once your program, nutrition, and sleep are already dialed in—not as the first thing to fix.
Pros and Cons for Muscle Growth–Focused Athletes
From a muscle protein synthesis and growth perspective, the case for red light therapy is neither “snake oil” nor “miracle.” It is nuanced.
On the positive side, randomized trials and meta‑analyses show that, under certain conditions, red and near‑infrared light can amplify strength and hypertrophy gains from resistance training, extend time to exhaustion, reduce markers of muscle damage, and lessen soreness. Some studies in young and middle‑aged adults show very large relative differences in strength and muscle thickness when light is added to training, although these trials are often small. An NSCA coaching article, multiple sports performance reviews, and fitness‑education organizations all frame photobiomodulation as a promising adjunct.
Red light therapy is also generally low risk when used appropriately. Consumer health resources and hospital systems describe a favorable safety profile, with rare side effects such as transient redness or, at very high doses, blistering. They emphasize the importance of avoiding direct eye exposure and using protective goggles when indicated. Some devices carry regulatory clearance for safety, but that is not the same as proof of effectiveness for performance or muscle growth.
On the negative side, the evidence base has clear limitations. Many trials involve small samples, narrow populations (for example, young male athletes), and single research groups. Independent reviews such as Examine.com’s analysis highlight that long‑term data on muscle size and strength are sparse and inconsistent, especially in older adults. Meta‑analyses and narrative reviews describe substantial heterogeneity in wavelengths, doses, timing, and outcome measures, which makes it difficult to define an optimal protocol or predict who will respond.
Cost is another real downside. University health systems report that facial masks can start under about one hundred dollars, while larger panels or full‑body systems run into the hundreds or thousands. Some full‑body beds used in clinics can cost much more than that. None of this is typically covered by insurance when used for performance or general wellness. That money might otherwise go toward higher‑quality food, coaching, sleep optimization, or physical therapy—investments with far more certain returns.
Given this mix, red light therapy for muscle growth is best seen as a low‑risk, potentially helpful experiment for people who already have their fundamentals in place and are comfortable with the financial cost.
Evidence Snapshot
The table below summarizes recurring themes from the research discussed above.
Area of interest |
What the research suggests |
Key nuance |
Hypertrophy and strength |
Trials combining red or near‑infrared light with resistance training show greater muscle size and strength gains than training alone in some young and middle‑aged adults, with one study reporting more than 50 percent greater increases in muscle thickness and strength. |
Effects are strongest in small, well‑controlled studies; evidence in older adults is mixed, with some long‑term trials showing no additional benefit. |
Time to exhaustion and endurance |
Meta‑analytic data and multiple RCTs show longer time to exhaustion and improved running and cycling performance when light is applied before exercise. |
Not all trials replicate these findings; some endurance and intermittent tests show no meaningful difference from placebo. |
Muscle damage and soreness |
Several studies find lower creatine kinase, reduced oxidative stress, and less delayed onset muscle soreness, especially when light is used before or around high‑intensity sessions. |
Early DOMS trials and some athlete studies report no pain or function differences, underscoring that parameters and populations matter. |
Recovery and sleep |
Clinical reports and athletic articles describe better perceived recovery, improved sleep, and faster readiness for the next session with consistent use over weeks. |
There are no standardized dosing guidelines, and improvements often emerge gradually rather than overnight. |
Safety, Medical Considerations, and Realistic Expectations
Most clinical and consumer health sources agree that low‑level red light is generally safe when used correctly. Reported adverse effects in studies are rare and usually mild, such as temporary skin redness or warmth. Eye safety is a consistent caution; experts recommend avoiding direct eye exposure and using appropriate protection, especially with higher‑intensity panels or full‑body beds.
Medical organizations note that red light therapy is not designed to repair structural problems like torn ligaments or advanced osteoarthritis. It may help with pain and inflammation, but it does not reverse severe joint degeneration. People with a history of skin cancer, significant eye disease, or those taking photosensitizing medications are advised to speak with a clinician before starting treatment.
Limited research in pregnancy has not flagged clear harm at therapeutic doses, but reputable sources still recommend involving a physician when using any energy‑based device during pregnancy.
The biggest risk for most healthy lifters is not medical; it is opportunity cost and unrealistic expectations. Buying an expensive panel while neglecting training quality, protein intake, calorie sufficiency, or sleep is an easy way to be disappointed. Red light therapy should never become a distraction from the habits that account for the bulk of your muscle protein synthesis and long‑term progress.
A Brief FAQ on Red Light Therapy and Muscle Growth
Can red light therapy replace hard training or high‑protein eating for muscle gain?
No. Every independent review emphasizes that red light therapy is an adjunct. The trials that show improved muscle size and strength all involve structured resistance training programs. Some gym‑based guidance even recommends pairing red light therapy with a high‑protein diet and good hydration to get the most from it. Think of light as a recovery amplifier, not the main driver of growth.
How long might it take to notice any effects?
In reports from physical therapy clinics and gym environments, people sometimes feel subtle improvements in stiffness and soreness after initial sessions, but more measurable changes in performance or training tolerance typically appear after two to four weeks of consistent use. Clinical trials showing hypertrophy or endurance gains usually run for several weeks to months.
Is more light always better?
Not necessarily. The sports performance literature shows that photobiomodulation’s effects depend strongly on wavelength, dose, timing, and where the light is applied. Some well‑designed studies using certain parameters show no benefit, which suggests there is not a simple “more is better” relationship. Since there are no universal dosing guidelines, it is prudent to follow manufacturer instructions, avoid extreme session lengths, and, when possible, work with a clinician or knowledgeable coach.
Who is most likely to benefit?
Based on the patterns in the evidence, red light therapy may be most useful for people who are already training regularly, eating enough protein, and prioritizing sleep, but who still struggle with lingering soreness, limited recovery between sessions, or plateaus in performance. It may also be helpful for older adults or individuals with joint or tendon issues who need to manage inflammation carefully to maintain training volume. However, responses are individual, and some people will notice little change.
In my experience working with athletes and dedicated lifters, red light therapy can be a valuable ally when it is used thoughtfully, layered onto solid fundamentals, and approached with realistic expectations. If you choose to bring a red light panel into your home gym, let it support—not replace—the training, nutrition, and recovery habits that you already know build muscle.
References
- https://lms-dev.api.berkeley.edu/studies-on-red-light-therapy
- https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=7743&context=etd
- https://pmc.ncbi.nlm.nih.gov/articles/PMC5026559/
- https://aichat.physics.ucla.edu/Download_PDFS/publication/YCvxS1/AriWhittenRedLightTherapyRecommendations.pdf
- https://dash.harvard.edu/server/api/core/bitstreams/3c6f36f1-0010-4f64-9675-14686c456953/content
- https://med.stanford.edu/news/insights/2025/02/red-light-therapy-skin-hair-medical-clinics.html
- https://healthcare.utah.edu/the-scope/mens-health/all/2024/06/176-red-light-therapy-just-fad
- https://www.acefitness.org/resources/pros/expert-articles/8857/red-light-therapy-and-post-exercise-recovery-the-physiology-research-and-practical-considerations/?srsltid=AfmBOorI5vRwGm7xlY9Ci-k7v4hJxz3UaghhysrH0lOB2wgDBfk2UvZu
- https://www.massgeneralbrigham.org/en/about/newsroom/articles/recovery-for-athletes
- https://www.uhhospitals.org/blog/articles/2025/06/what-you-should-know-about-red-light-therapy
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