Red Light Therapy & Muscle Endurance: The Evidence

About the author

Evelyn Reed, M.S.

Health Science EducatorCertified Wellness Coach

Evelyn Reed, M.S., is a Health Science Educator and Certified Wellness Coach specializing in evidence-based, at-home wellness solutions. With a Master's degree in Health Science, she focuses on translating complex scientific research on cellular health and light therapy into practical, accessible protocols. Evelyn is dedicated to empowering individuals to manage pain, improve sleep, and enhance skin vitality. Her science-first, empathetic approach makes her a trusted advocate for achieving long-term health goals.

As a red light therapy wellness specialist, I see the same pattern over and over: driven runners, cyclists, lifters, and weekend warriors show up asking whether red light can give them a safe, legal edge in endurance and recovery. They have often seen impressive marketing claims, but they also want evidence, not hype. In this article I will walk you through what the science actually says about red light therapy for muscle endurance, where the evidence is promising, where it is weak, and how to think about practical, at-home use in a realistic, health-first way.

What Red Light Therapy Is (and What It Is Not)

Red light therapy, often called photobiomodulation or low-level light therapy, uses low-intensity red and near-infrared light to influence cellular function. Clinical and sports sources consistently describe it as noninvasive and non-thermal at the doses used for therapy. Instead of heating tissues like some infrared saunas, it delivers light energy that certain cellular structures can absorb.

In practice, red light therapy is delivered by LEDs or low-level lasers. In sports and wellness settings, devices usually emit light in the visible red range and just beyond it in the near-infrared range. Panels, flexible pads, full-body beds, and targeted clusters for individual muscles are all common formats. At home, people typically use panels or wraps aimed at the legs, glutes, back, or shoulders while they sit or stand comfortably.

It is important to be clear about what red light therapy is not. It is not a replacement for training, nutrition, sleep, or rehabilitation. Stanford Medicine emphasizes that while there is solid evidence for red light therapy in some dermatologic uses such as certain hair and skin applications, claims about athletic performance and muscle recovery are not yet strongly supported by robust clinical data. That tension between promising mechanisms and incomplete evidence is the backdrop for everything that follows.

How Red Light Could Influence Muscle Endurance

Cellular Energy and Mitochondria

Across scientific reviews and clinical explanations, one mechanism shows up repeatedly. Red and near-infrared light is absorbed by a mitochondrial enzyme called cytochrome c oxidase. When this enzyme absorbs photons, it can become more efficient at driving the electron transport chain, which is where cells make ATP, the main energy currency.

A major narrative review of photobiomodulation in human muscle reported that this mitochondrial stimulation increases ATP production, enhances muscle fiber excitability, and modulates gene expression related to repair and antioxidant defenses. Animal experiments where skeletal muscle was exposed to red light before intense exercise showed dose-dependent reductions in markers of muscle damage and oxidative stress, and improved antioxidant enzyme activity. All of this provides a plausible biological basis for improved endurance and recovery.

Blood Flow, Nitric Oxide, and Inflammation

Several sports-focused clinics and physical therapy centers highlight another important piece of the puzzle: nitric oxide and circulation. Red and near-infrared light exposure appears to promote vasodilation, widening blood vessels so that more oxygen and nutrients reach working muscles. One performance clinic describes increased nitric oxide release, better blood flow, and reduced inflammatory markers as key benefits.

By improving circulation and modulating inflammation, red light therapy could help muscles clear metabolic byproducts more efficiently and shift from fatigue and damage toward repair. A physical therapy center that uses red light for athletic recovery describes how it can reduce pro-inflammatory cytokines, increase anti-inflammatory pathways, and decrease swelling and stiffness around joints and tendons. For endurance, that could mean less lingering discomfort and an easier time repeating workouts.

Red light therapy activating cellular energy pathways in a blood vessel for muscle endurance.

Muscle Contraction, Calcium, and Fatigue

Some sports medicine sources note that photobiomodulation may influence how muscle cells handle calcium ions. Better regulation of calcium inside muscle fibers supports more efficient contraction and relaxation cycles and may delay the onset of fatigue. A clinic working extensively with athletes describes how pre-conditioning muscles with red and near-infrared light improved stamina and mechanical performance in subsequent workouts, partly through more efficient calcium handling and higher ATP availability.

Taken together, these mechanisms explain why researchers and coaches are interested. If red light therapy can increase ATP, improve blood flow, modulate oxidative stress and inflammation, and support muscle contraction mechanics, there is a reasonable chance it might help you do more work before fatigue sets in and recover faster afterward. The key question is how consistently that promise shows up in actual human studies.

What the Research Shows About Muscle Endurance

Acute Performance: One-Off Sessions Around Exercise

Much of the research on red light therapy for performance and endurance looks at acute effects. Typically, participants receive red or near-infrared light directly on the muscles that will be used, shortly before exercise. The exercise tests range from elbow flexion to cycling or running to exhaustion.

A large narrative review of photobiomodulation in human muscle identified 46 controlled trials with more than 1,000 participants. Many of these trials applied red or near-infrared light as pre-conditioning to upper or lower limb muscles and then measured outcomes like repetitions to failure, time to exhaustion, torque, blood lactate, and markers of muscle damage. Several studies showed that pre-exercise light increased the number of repetitions, prolonged time to exhaustion, or reduced blood lactate and muscle damage markers compared with placebo.

At the same time, not all studies are positive. The same review noted rigorously blinded crossover trials where pre-exercise laser treatment to the biceps did not significantly improve repetitions, lactate reduction, or electromyography-derived fatigue. Examine.com, an independent evidence review resource, points out that many of the encouraging resistance-exercise results come from a single research group working with young male volleyball players. That concentration of data limits confidence and generalizability.

For endurance-type tasks such as cycling or running to exhaustion, some trials report improved performance after pre-exercise red light therapy, while others show no meaningful difference. Overall, the acute performance evidence can be summarized as small, protocol-dependent benefits in certain conditions, rather than a consistent, universal boost.

Long-Term Strength and Endurance Gains with Training

Fewer studies have looked at what happens when you combine red light therapy with weeks of training. This is where questions about muscle hypertrophy and sustained endurance adaptations come into play.

Examine.com notes that only a handful of long-term trials exist. In one study on young men, applying red light before strength training sessions led to greater increases in muscle size and strength compared with training alone. In contrast, a study in older men did not find added benefits of red light on strength or muscle growth, and a trial in older women using red light after strength training showed no improvement in muscle strength, with muscle size not reported. These results suggest that any enhancement may be age- and protocol-specific.

A performance-focused wellness provider summarizes a 2015 systematic review and meta-analysis of randomized, placebo-controlled trials and reports that phototherapy with red and near-infrared light significantly improved key performance measures, including maximum repetitions, speed, endurance, and time to exhaustion when applied before exercise. The same source cites individual strength trials in young men where combining training with pre-exercise red light yielded greater strength gains than training alone, including roughly a 55 percent larger improvement in leg press performance compared with non-therapy groups.

Some endurance-oriented studies, including a triple-blind treadmill trial, have reported that pre-exercise red light therapy increased time to exhaustion and oxygen uptake and that using it both before and after sessions led to endurance gains developing several times faster than with training alone. However, these findings come from a limited number of studies, often with relatively small sample sizes and varied dosing parameters.

A coaching-oriented article from the National Strength and Conditioning Association describes red and near-infrared light therapy as a potentially valuable tool for strength and conditioning professionals, noting evidence that combining strength training with photobiomodulation can outperform strength training alone on some performance outcomes. Yet even in that context, the need for more standardized protocols and higher-quality trials is emphasized.

Muscle Soreness, Recovery, and Training Frequency

For endurance athletes, recovery is just as important as what happens during a single workout. Several clinics and wellness practices assert that red light therapy reduces delayed onset muscle soreness and speeds recovery. One physical therapy center that uses 660 to 850 nanometer light for athletic clients reports that performance studies show up to about a 50 percent reduction in delayed onset muscle soreness, with improved power output and endurance, allowing more frequent, intense training.

At the same time, evidence reviews urge caution. The large narrative review of muscle photobiomodulation includes multiple randomized trials where light applied after eccentric exercise did not significantly reduce soreness or improve strength recovery compared with placebo. Examine.com concludes that, across studies, red light therapy does not reliably lessen muscle soreness in the days after a workout.

A sports science article from Athletic Lab highlights this tension. It notes one study where pre-exercise light therapy reduced markers and functional impact of muscle damage, but also references a systematic review of 15 studies covering more than 300 participants that judged the evidence for delayed onset muscle soreness reduction as insufficient. The verdict is that recovery benefits are mixed and protocol-dependent, and that the overall evidence quality for soreness reduction remains incomplete.

Clinical sources such as University Hospitals add another layer: red light therapy may help with pain from some musculoskeletal conditions and fibromyalgia and may support recovery from superficial, inflammatory problems and certain strains, but it is not expected to repair mechanical problems such as ligament tears or advanced arthritis.

How Strong Is the Evidence? A Snapshot

To put all of this into perspective, it helps to step back and look at outcomes side by side.

Outcome or claim	Pattern in studies and reviews	Confidence today
Acute strength or endurance boost	Some small trials show more reps or longer time to exhaustion with pre-exercise light; others show no effect; results often limited to specific groups such as young male athletes.	Modest and population-specific, not universal.
Long-term strength and muscle size	One study in young men found extra gains with pre-exercise red light; studies in older adults did not show added benefit.	Mixed and age-dependent; overall low to moderate.
Endurance adaptations (running or cycling)	A few studies report increased time to exhaustion and faster endurance gains; many protocols differ in dose and timing.	Promising but limited; needs more high-quality data.
Muscle soreness and delayed onset muscle soreness	Some individual protocols report less soreness; assessments pooling many trials find inconsistent effects and insufficient evidence.	Weak for soreness relief alone.
General training recovery and readiness	Some markers of damage and oxidative stress improve; subjective recovery is inconsistent; sleep and mood benefits are plausible but not fully established.	Early-stage; supportive rather than definitive.

It is also worth noting that red light therapy as a whole is well studied, even if the endurance-specific subset is still developing. One rehabilitation and wellness article reports roughly 550 randomized controlled trials, 5,000 laboratory studies, and dozens of new papers per month across all photobiomodulation applications. Most of that work is not about sports performance, but it does contribute to the safety profile and mechanistic understanding.

How Mainstream Medicine Views Performance Claims

Dermatology and academic medical centers offer a helpful counterweight to performance marketing. A detailed Stanford Medicine overview of red light therapy traces its roots in dermatology and hair research and concludes that credible evidence supports certain uses, particularly hair growth and aspects of skin rejuvenation, when dosing and device quality are appropriate.

When it comes to athletic performance, muscle recovery, and sleep, that same article is cautious. It notes that while mechanisms for these uses exist in theory, robust clinical data are lacking, and current knowledge does not justify viewing red light therapy as a universal remedy for diverse health conditions. More speculative applications, such as for chronic pain syndromes or neurologic diseases, are described as unproven and in need of rigorous trials.

University Hospitals similarly describes red light therapy as a low-risk, noninvasive option that shows early promise for muscle performance and recovery, especially when combined with exercise, but emphasizes that it is unlikely to reverse structural damage and that cost and access remain practical limitations.

As someone who works with at-home users, I find that aligning personal expectations with this mainstream medical perspective leads to healthier decisions. Red light therapy can be a supportive tool for endurance and recovery, not a guaranteed upgrade, and certainly not a substitute for strategic training, nutrition, and sleep.

Practical, Evidence-Informed Use for Muscle Endurance

Choosing a Device for At-Home Use

At-home devices range from small pads that cover a single knee to large panels and full-body beds. Hospital and dermatology sources note that clinic-based devices are typically more powerful, with better-controlled dosing, than many consumer products, yet home panels can still deliver useful energy if used correctly.

For endurance applications, it is generally more important to cover the large muscles you use most than to chase a specific brand name. Runners and cyclists often focus on quads, hamstrings, and calves; lifters may target quads, hamstrings, glutes, and back muscles. Look for a device designed for therapeutic use that emits both red and near-infrared light in ranges commonly used in photobiomodulation, and choose a size that can comfortably cover key muscle groups from a reasonable distance.

Because power density and distance matter, device instructions and manufacturer guidance are crucial. Clinical sources repeatedly note that timing and dose are important and that professional-grade devices help ensure consistent delivery. At home, replicating clinical precision is unrealistic, so the practical strategy is to stay within conservative, commonly used ranges and avoid excessive exposure.

When to Use Red Light for Endurance

Most sports research and many performance clinics focus on three windows: before exercise, after exercise, and on rest days.

Pre-exercise sessions aim to “pre-condition” muscles by increasing ATP availability, improving blood flow, and lowering metabolic stress during the upcoming workout. Reviews of muscle photobiomodulation and several sports clinics describe pre-exercise exposures as the most common strategy for improving endurance and strength. Some physical therapy practices that work with athletes use combined red and near-infrared light on the primary muscles for roughly 10 to 20 minutes per area before key workouts, with some going up to about 30 minutes depending on device strength and distance.

Post-exercise sessions are oriented toward recovery. Clinics that highlight recovery effects often recommend using red light within a few hours after training to support tissue repair, clear metabolic byproducts, and reduce stiffness. A FunctionSmart physical therapy protocol, for example, uses near-infrared wavelengths in 10 to 20 minute sessions per body area, with timing in the first few hours after intense exercise for recovery applications.

Rest-day sessions can be used to support ongoing recovery and manage chronic tightness or mild joint discomfort. A weightlifting-focused wellness studio describes flexible timing options, including post-workout, pre-workout, and rest-day use, with sessions lasting about 10 to 20 minutes in front of a panel that feels warm but not hot.

Because red light therapy has a dose window where too little energy is ineffective and too much may be counterproductive, more is not always better. A detailed dermatology study of a home-use red LED mask, used twice weekly for 12-minute sessions, emphasized that photobiomodulation effects take days to unfold and that energy beyond an optimal window may lead to diminished returns. While that study focused on skin, the same dose-response concept is widely discussed in photobiomodulation research.

In practical terms, I encourage people to start at the lower end of their device’s recommended exposure time for the distance they plan to use, focus on two to four endurance-related sessions per week rather than daily marathons, and adjust only after several weeks of consistent use.

Integrating Red Light into a Complete Endurance Routine

Red light therapy works best as part of a broader, thoughtful plan. The endurance gains that matter most come from progressively challenging training that your body can adapt to and recover from.

Training structure should remain the foundation. That means well-designed running, cycling, rowing, or resistance programs that build volume and intensity gradually, with appropriate recovery days and deload periods. Red light therapy may help you feel a bit more ready for those key sessions, but it cannot rescue a chronically overloaded or poorly planned program.

Nutrition, hydration, and sleep are equally critical. Multiple sports recovery articles highlight that poor sleep is both a symptom and driver of overtraining. Some red light studies in female basketball players suggest that evening exposure can improve sleep quality and increase nocturnal melatonin secretion, and there is experimental work showing that red light exposure shortly after waking may reduce sleep inertia. Even so, I tell clients to view those potential sleep benefits as a bonus, not a cure for chronic sleep deprivation. You still need enough hours in bed and a consistent schedule.

If you decide to use red light therapy to support endurance, track tangible markers that matter to you. That might be the number of intervals you can complete before your form breaks down, your perceived exertion at a given pace, or how quickly your legs feel normal again after a long run. If you see no meaningful change after four to six weeks of consistent use, it is reasonable to reassess whether it is worth your time and cost.

Safety, Side Effects, and Sensible Precautions

Across dermatology, rehabilitation, and hospital sources, red light therapy has a favorable safety profile when used properly. Devices used for therapeutic purposes generally emit minimal ultraviolet light, and serious side effects are rare. Reported risks mainly involve eye exposure and occasional mild skin irritation.

To use red light therapy safely for endurance:

Avoid shining the light directly into your eyes. Use proper eye protection if you are close to powerful panels, especially full-body beds or high-output clinic devices.

Be cautious if you have photosensitive conditions or take medications that increase light sensitivity. Consult your physician before starting therapy in those situations.

Understand that red light will not repair structural damage. For ligament tears, significant cartilage loss, or advanced degenerative joint disease, red light may ease symptoms but is not known to reverse the underlying mechanical problem.

Pay attention to how you feel during and after sessions. If you notice headaches, skin irritation, or unusual fatigue following sessions, shorten your exposures or pause use and discuss with a healthcare professional.

Pros and Cons for Muscle Endurance

From an evidence-based wellness standpoint, red light therapy for endurance has clear potential upsides and equally clear limitations.

On the positive side, it is noninvasive, generally safe when used correctly, and mechanistically plausible. Multiple controlled trials show that pre-exercise red or near-infrared light can increase repetitions to failure, extend time to exhaustion, or improve certain biochemical markers in specific conditions. Some long-term studies in younger adults suggest that adding red light to training can enhance strength and hypertrophy beyond training alone. Many athletes and active individuals also report subjective benefits, such as feeling less stiff or more “ready” for the next workout, and some research supports possible improvements in sleep and mood, which indirectly support endurance.

On the negative side, evidence is inconsistent, and the effect sizes when present are usually modest. Stronger results often come from small trials or single research groups in specialized populations, which makes it hard to know how well they generalize to everyday runners, cyclists, or recreational lifters. Studies in older adults show little or no added benefit, and systematic reviews have not confirmed a reliable reduction in soreness. Dosing parameters vary widely, and consumer devices range from relatively affordable to very expensive, with no guarantee of results. Perhaps most importantly, there is a real risk that people invest energy and money into light gadgets while neglecting the fundamentals of training progression, sleep, and nutrition that have far stronger evidence.

In my experience, people who get the most from red light therapy for endurance are those who are already committed to sound training and recovery habits and who approach the technology with curiosity and realism rather than urgency or desperation.

Muscle endurance pros: improved stamina, fatigue resistance, functional fitness. Cons: slower muscle growth, overtraining.

A Sample Endurance-Day Routine Using Red Light

To make this more concrete, here is how a typical endurance-focused client might integrate red light therapy into a weekly plan while staying aligned with the research.

On two to four key endurance days per week, they position a red and near-infrared panel so that it covers their main working muscles, such as quads, hamstrings, and calves for a runner or cyclist. About 15 to 30 minutes before the workout, they sit or stand at the manufacturer-recommended distance and use the device for a modest, consistent session length in the 10 to 20 minute range per area, depending on device power. During that time they might hydrate, mentally review the workout, and allow their body to ease into a ready state.

After particularly demanding sessions, such as an interval workout or long run, they may add a shorter post-exercise session within a few hours, again targeting the main muscles with moderate exposure. On rest or easy days, they might skip red light altogether or use it briefly on areas that tend to feel tight or achy, such as calves, hips, or lower back, always paying attention to how they feel and avoiding excessive cumulative exposure.

Throughout, they keep a simple log of workouts, perceived exertion, soreness scores, and any notable changes in sleep or mood. If, after a month or two, they observe that recovery feels smoother, that they can handle slightly higher quality work without extra fatigue, or that sleep has improved, they may decide that the routine is worth continuing. If not, they can step back without having compromised the basics of their program.

Common Questions About Red Light and Endurance

Many people ask whether red light therapy alone can meaningfully increase their VO2 max or race times？

The current evidence suggests that while red light may modestly improve some performance measures in specific conditions, it cannot replace the adaptations you get from consistent, appropriately challenging endurance training. It should be viewed as a supportive modality rather than a primary driver of endurance capacity.

Another common question is how long it takes to notice a difference？

Sports clinics that integrate red light into physical therapy and performance programs often report that subtle benefits such as reduced stiffness or a better recovery sensation may appear within two to four weeks of consistent use. That timeline matches what we know about cellular signaling and tissue adaptation. At the same time, some people do not feel any noticeable change even after several weeks, and the science does not guarantee a response.

People also worry about overdoing red light therapy. Photobiomodulation research, including dermatology studies, emphasizes that there is an optimal dose window. Once mitochondrial and transcriptional pathways are activated, extra energy does not necessarily add benefit and may even be counterproductive. Practically, that means following device instructions, resisting the urge to dramatically exceed recommended session lengths, and paying close attention to how your body responds over time.

In the end, red light therapy for muscle endurance sits in an interesting place: backed by plausible biology and a growing but mixed body of research, embraced by many athletes and clinics, yet viewed cautiously by academic medicine. Used thoughtfully, it can be a compassionate, science-informed addition to an endurance routine, especially for people who already take training, recovery, and sleep seriously. My advice as a wellness advocate is to treat red light therapy as a useful tool in the toolbox, not the toolbox itself, and to let careful self-observation and honest expectations guide whether it deserves a place in your own routine.