Red Light Therapy: Should You Use It Before or After Exercise?

Red light therapy (RLT) – also known as photobiomodulation (PBM) – has gained popularity among athletes and fitness enthusiasts. It involves exposing tissues to red or near-infrared light, which can penetrate skin and stimulate cellular processes. Research shows RLT can boost muscle energy, reduce inflammation, and speed recovery. The big question is when to use it: before exercise to boost performance, or after exercise to aid recovery? In this article we analyze the latest medical studies to answer this, focusing on real scientific evidence. We’ll compare pre-workout and post-workout RLT effects on strength, endurance, fatigue, and recovery.

How Red Light Therapy Works

Red light (typically 630–660 nm) and near-infrared light (800–850 nm) are absorbed by mitochondria – the energy factories of cells – especially by the enzyme cytochrome c oxidasepmc.ncbi.nlm.nih.gov. When this light is absorbed, it may dissociate inhibitory nitric oxide from the enzyme and restore electron transport in the mitochondrial chainpmc.ncbi.nlm.nih.gov. This leads to increased mitochondrial membrane potential, more ATP (cellular energy), and changes in reactive oxygen species signalingpmc.ncbi.nlm.nih.gov. In practical terms, RLT “lights up” muscle cells, giving them more energy to work and recover. Studies confirm RLT increases muscle cell oxygen usage and markers of metabolic activitypmc.ncbi.nlm.nih.gov. As a result, research has found that RLT can reduce fatigue, increase endurance, and decrease markers of muscle damage (like creatine kinase) in exercised musclespubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov.

Benefits of RLT Before Exercise

Performance Preconditioning. Using RLT before a workout is often called pre-conditioning. Several trials show pre-workout RLT can enhance strength and endurance. For example, one randomized trial on volleyball players gave a cluster of 810 nm laser diodes to the biceps before elbow flexion tests. Compared to placebo, active RLT increased repetitions by ~14.5% and extended time-to-exhaustion by ~8%pubmed.ncbi.nlm.nih.gov. Post-exercise measurements also showed lower blood lactate, lower creatine kinase (CK), and lower C-reactive protein when RLT was used pre-exercisepubmed.ncbi.nlm.nih.gov. In other words, muscles pre-treated with RLT performed longer and recovered faster than untreated muscles.

A comprehensive meta-analysis likewise found the most consistent performance gains occur when RLT is applied before exercise. In 13 high-quality trials, 10 showed significant performance improvements with pre-exercise RLT. On average, RLT before exercise significantly increased time-to-exhaustion (by ~4 seconds) and increased maximum repetitions (by ~5 reps) versus placebopubmed.ncbi.nlm.nih.gov. These gains were statistically significant (p<0.005 for exhaustion time, p<0.0006 for repetitions)pubmed.ncbi.nlm.nih.gov. The meta-study concluded that muscle performance improved mainly with RLT before workoutspubmed.ncbi.nlm.nih.gov. Practically, this means doing RLT as a warm-up can let you lift more, run longer, or delay fatigue in training.

• Example: In the sports science literature, pre-workout RLT typically involves shining the light on target muscles for 3–5 minutes before exercisephysio-pedia.com. The beneficial effects of that light can last for several hours (typically 3–6 hours) during the subsequent exercisephysio-pedia.com. This window of enhanced energy helps muscles work harder.

• Key studies:

  • Leal-Junior et al. (2010) showed that 810 nm laser applied pre-exercise to the biceps brachii increased repetitions and time to exhaustion, and resulted in significantly lower post-exercise lactate, CK, and CRP in athletespubmed.ncbi.nlm.nih.gov.

  • Oliveira et al. (2017) tested 810 nm LED therapy before exercise at different power settings. They found 100 mW per diode (500 mW total) before exercise gave the best outcomes: greater maximal voluntary contraction (strength) and lower muscle soreness and damage markers after exercisepubmed.ncbi.nlm.nih.gov. Higher power was less effectivepubmed.ncbi.nlm.nih.gov. This underscores using the right dose.

  • Larkin-Kaiser et al. (2015) applied near-infrared (NIR) therapy to muscles before strenuous resistance exercise. The treated muscles had significantly less strength loss immediately after exercise compared to sham (p=0.05)pubmed.ncbi.nlm.nih.gov, meaning RLT helped preserve muscle strength.

In summary, multiple trials find pre-exercise RLT boosts acute muscle output and endurance. Athletes often report they can push slightly harder or longer. The exact protocols vary, but common features include using red/NIR LEDs or lasers on the working muscles for a few minutes in advance, delivering on the order of 5–6 joules per spotpubmed.ncbi.nlm.nih.gov.

Benefits of RLT After Exercise

Using RLT after exercise targets the recovery phase. Post-workout RLT does not improve that workout’s performance (since it’s applied after), but it can reduce damage and soreness from the workout. Recent studies show improved recovery metrics when RLT is applied immediately following exercise, especially if the exercise caused muscle damage. Key findings include:

• Reduced soreness and strength loss. In one double-blind trial, subjects performed a damaging eccentric exercise (30 reps at 100% max strength). Immediately afterward, one group got 630 nm LED therapy (20.4 J/cm²) on the muscle, while the placebo group got inactive “sham” treatment. Over the next 4 days, the RLT group had significantly less muscle soreness, less loss of strength, and better range of motion than placebopubmed.ncbi.nlm.nih.gov. In fact, a single LED session after exercise dramatically attenuated the usual damage symptoms up to 96 hours post-exercisepubmed.ncbi.nlm.nih.gov.

• Lower muscle damage markers. Another study had soccer players do repeated Wingate cycling tests. A cluster of LEDs (810 nm and 660 nm) was applied either pre-exercise or during rest periods. The group receiving post-exercise LED therapy had a significant reduction in blood lactate and lower CK levels than placebo or pre-exercise treatmentpubmed.ncbi.nlm.nih.gov. Similarly, in hamstring soreness after competition, daily post-match LEDT on volleyball players curtailed the rise in CK.

• Shorter recovery time. Research suggests that RLT after training (especially over days/weeks) can enhance muscle tissue repair. By bolstering antioxidant defenses and reducing inflammation, post-workout RLT may help solidify training gains. A systematic review noted that RLT after workouts was generally effective at speeding recovery when combined with a training programphysio-pedia.comphysio-pedia.com (though it noted more work is needed).

In practice, doing RLT right after a workout (or competition) gives muscles a boost in repair. For instance, professional volleyball players receiving LED therapy after competition saw far smaller increases in CK than those without lightpubmed.ncbi.nlm.nih.gov (see below). In the gym, the athlete would simply apply the light panel or laser to the exercised muscles immediately post-exercise. Effects such as reduced DOMS (delayed onset muscle soreness) can be noticeable during the next hours/days.

Pre-Workout vs. Post-Workout: What Does Research Say?

Should you prioritize RLT before or after exercise? The scientific evidence suggests both timings offer benefits, but in different ways:

• Pre-Workout (Performance Boost): The strongest, most consistent evidence is for using RLT before exercise to enhance performance. Multiple controlled trials found that pre-exercise RLT increases repetitions, power, and time to fatigue compared to no lightpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov. Meta-analyses confirm that average performance (like endurance runs or lifting reps) improves significantly with pre-conditioning RLTpubmed.ncbi.nlm.nih.gov. The meta-review found gains particularly when RLT was applied before workouts (power 50–200 mW, 5–6 J per spot)pubmed.ncbi.nlm.nih.gov. In other words, if your goal is to squeeze maximum performance out of a workout (lifting heavier, running further), using RLT pre-workout is generally most effective.

• Post-Workout (Faster Recovery): Applying RLT after exercise is aimed at recovery. Studies show that post-exercise RLT reduces muscle damage and soreness more than no treatment. For example, immediate post-exercise LEDT significantly blunted rises in muscle damage markers (CK) and lessened strength loss for days afterwardpubmed.ncbi.nlm.nih.gov. One controlled trial directly compared pre- vs post-exercise RLT and found both reduced blood lactate and CK after fatigue, but the effect was more pronounced in the post-exercise grouppubmed.ncbi.nlm.nih.gov. This indicates that while pre-workout RLT helps during the workout, using RLT after exercise may be even better at clearing out fatigue metabolites and inflammatory markers.

• Combined Approach: Some experts suggest a combined strategy. Athletes might use a short RLT session before a workout to maximize performance and another session after to accelerate recovery. However, practicality and time may limit this double dosing. The key is that RLT is not a replacement for rest or proper training – it is a supplement that can modestly tip the scales.

• When Not to Use: It’s worth noting that RLT during exercise is not practical or advised. All research targets pre- or post-exercise use. There is no evidence that shining red light on muscles during a workout has any benefit, and it would be cumbersome. In fact, experts recommend not using RLT mid-exercise.

In summary, if you want an acute boost in strength or endurance for the next training session, do RLT before training. If your goal is to reduce soreness and recover faster, apply RLT immediately after training. Many athletes use RLT both before and after on different days or as part of a routine.

Recommended Protocols and Tips

Based on the current evidence, here are some practical guidelines for using RLT with exercise:

• Choose the right device and wavelength. Studies used lasers or LEDs at red (600–660 nm) and/or near-infrared (800–850 nm) wavelengths. Both can work, often in combination. For home use, full-body panels or targeted LED pads can be used on specific muscles. Ensure the device delivers at least a few tens of milliwatts per diode (e.g. 100 mW) so that total energy per muscle is in the range of several joules.

• Dosage matters. The meta-analysis noted best results with power outputs 50–200 mW per diode and doses about 5–6 J per application pointpubmed.ncbi.nlm.nih.gov. Overdosing (too high power or too long) can lessen the effect due to a biphasic dose responsepubmed.ncbi.nlm.nih.gov. For example, one study found that 100 mW diodes gave better results than higher power, which had diminishing returnspubmed.ncbi.nlm.nih.gov. A practical tip is to use moderate power and irradiate each muscle area for 30–60 seconds, moving slowly to cover the region. Many studies delivered tens to hundreds of joules per muscle group (for example, 210–315 J per muscle before competitionpubmed.ncbi.nlm.nih.gov). This typically means multiple diodes or clusters are used.

• Timing:

  • Pre-Workout: Aim to finish RLT 10–20 minutes before exercise. This allows the light to do its preconditioning without delaying your workout. The effects can last for a few hours, so training soon after is fine. Some research suggests the benefits remain for up to 3–6 hours post-lightphysio-pedia.com.

  • Post-Workout: Apply RLT immediately after finishing exercise (or as soon as possible). For maximum recovery benefit, treat the muscles that worked hardest. For example, if you did leg day, shine the red/IR light on your quads, hamstrings, calves.

• Duration and Frequency: Typical RLT sessions around exercise are 3–5 minutes on each muscle groupphysio-pedia.com. Some studies used longer protocols (even up to 40–60 seconds per point, repeated over multiple pointspubmed.ncbi.nlm.nih.gov). Athletes in studies often did RLT once or twice a week with workouts; overtraining on the light is not usually needed. A practical routine could be 1–2 times per week per muscle group (before or after key workouts).

• Safety: RLT is generally safe and non-invasive. Wavelengths in the red/NIR range do not heat tissue (unlike infrared saunas) and have minimal side effects. Still, it’s wise to wear eye protection if using strong light sources. Avoid shining bright LEDs directly in your eyes.

• Regulatory Note: Because RLT can enhance muscle performance, some question whether it might be considered a performance aid. Currently there are no sports bans on PBM, but researchers have even suggested anti-doping agencies might need to consider itpubmed.ncbi.nlm.nih.gov. In practice, using RLT is as legal as using any other recovery tool.

Key Takeaways for Athletes

• Pre-workout RLT is best for performance. Numerous trials show that applying red/NIR light to muscles before exercise can increase strength, endurance, and repetitionspubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov. It also leads to less accumulation of fatigue markers (like lactate) during exercise. If your goal is to improve the workout itself, do RLT beforehand.

• Post-workout RLT is best for recovery. Studies indicate that RLT immediately after exercise lowers muscle soreness, maintains strength, and speeds repairpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov. It can blunt the rise of CK and other damage markers in the blood. If your goal is to recover faster from a hard session, use RLT right after.

• Both can be used. For maximal effect, athletes sometimes combine both timings on separate days or sessions. For example, one could do RLT before an intense workout and again after a competition. However, even one session (pre or post) will provide benefits in its target area (performance or recovery).

• Use the proper dose. Stick to moderate power (e.g. ~100 mW diodes) and a few joules per pointpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov. Avoid extreme over- or under-dosing. Follow the manufacturer’s guidelines and the research protocols if available.

• Realistic expectations. RLT is not a magic bullet. It yields modest enhancements. You won’t suddenly double your max, but you may do a few more reps or recover a bit faster. Combine it with solid training, nutrition, and rest for best results.

Final Thoughts

Red light therapy is backed by a growing body of research as a useful tool for athletes. The consensus of clinical studies is clear: RLT before exercise tends to boost performance and delay fatiguepubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov, while RLT after exercise helps the body recover by reducing muscle damage and sorenesspubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov. Choosing the right timing depends on your primary goal. In practice, many athletes find benefit in both approaches – doing a brief RLT session before critical workouts for a performance edge, and again after tough workouts or games to speed recovery.

Remember: Always follow manufacturer guidelines, use eye protection, and consult a professional if you have medical conditions. Red light therapy is an exciting aid in sports medicine, but it complements – not replaces – disciplined training and proper recovery strategies.

References: The above points are supported by numerous clinical studies and reviewspubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.govpmc.ncbi.nlm.nih.gov.

• Leal-Junior EC et al., Effects of low-level laser therapy on exercise-induced skeletal muscle fatigue and recovery (J Orthop Sports Phys Ther, 2010)pubmed.ncbi.nlm.nih.gov

• Ferraresi C et al., Photobiomodulation in human muscle tissue: advantage in sports performance? (J Biophotonics, 2016)pubmed.ncbi.nlm.nih.gov

• Leal-Junior EC et al., Phototherapy (LLLT and LEDT) on exercise performance: systematic review and meta-analysis (Lasers Med Sci, 2015)pubmed.ncbi.nlm.nih.gov

• Dos Reis FA et al., LLLT before or after exercise on muscle fatigue and recovery (Photomed Laser Surg, 2014)pubmed.ncbi.nlm.nih.gov

• Oliveira AR et al., Pre-exercise PBMT (810 nm) in muscle performance and recovery (Photomed Laser Surg, 2017)pubmed.ncbi.nlm.nih.gov

• Borges LS et al., LED phototherapy improves muscle recovery after damaging exercise (Lasers Med Sci, 2014)pubmed.ncbi.nlm.nih.gov

• Ferraresi C et al., LEDT before matches prevents CK increase in volleyball players (Lasers Med Sci, 2015)pubmed.ncbi.nlm.nih.gov

• Larkin-Kaiser KA et al., NIR light therapy to attenuate strength loss after resistance exercise (J Athl Train, 2015)pubmed.ncbi.nlm.nih.gov

• Hamblin MR et al., Mechanisms and mitochondrial redox signaling in photobiomodulation (Photochem Photobiol, 2018)pmc.ncbi.nlm.nih.gov