redlight.store

Reviewed August 31, 2026

Red Light Therapy Before or After a Workout?

Most people use a panel after training, because recovery is how these devices get sold. The one trial designed to answer the timing question directly found the opposite, and the size of the gap is hard to ignore.

The trial that actually asked the question

Vanin and colleagues published a randomized, double-blinded, placebo-controlled trial in Lasers in Medical Science in 2016. Forty-eight men trained for 12 weeks on leg press and leg extension, five sets of ten at 80 percent of one-rep max, split into four groups of twelve:

  • Light before and light after each session
  • Light before, placebo after
  • Placebo before, light after
  • Placebo before and placebo after

Light came from cluster probes held in skin contact at six sites on each thigh, combining 905nm super-pulsed laser, 875nm infrared LEDs and 640nm red LEDs. The dose was 30 joules per site, 180 joules per muscle group, applied 5 to 10 minutes either side of the session.

The result

Peak torque in maximum voluntary contraction rose over 12 weeks by:

  • 39 to 46 percent in the light-before group
  • 20 to 21 percent in the light-after group
  • 12 to 19 percent in the before-and-after group
  • 14 to 15 percent in the placebo group

Read that list twice. Light before training roughly tripled the placebo group's gain. Light before and after did no better than placebo.

One-rep max followed the same shape. Leg press rose 169 to 176 percent in the light-before group against 86 to 120 percent in placebo. Leg extension rose 95 to 100 percent against roughly 49 percent. The before-only group separated significantly from every other group by week eight and stayed there.

The authors' conclusion was direct: phototherapy yields enhanced strength gains when applied before exercise.

Why doing both might be worse than doing one

The authors flagged the tension before they ran the study. Exercise-induced muscle damage and the inflammatory response that follows are part of how muscle adapts. Light applied afterwards may dampen that signalling, including satellite cell activation, which is the machinery you want running after a hard session.

That is a hypothesis rather than a settled finding, and it comes from a single trial with twelve people per group. But it fits the data, and it echoes a wider pattern in recovery research where blunting the inflammatory response can blunt the adaptation you were training for.

Preconditioning is the plausible mechanism

Ferraresi, Huang and Hamblin reviewed 46 human muscle studies covering 1,045 participants in the Journal of Biophotonics in 2016. Their framing is preconditioning. Light applied before exercise appears to raise the muscle's capacity to handle the session rather than repairing it afterwards.

They also raised something under-discussed. Five minutes before exercise may not be the ideal window. They cite work where performance effects were far larger when light was applied several hours ahead rather than immediately before.

Nobody has replicated that at home-device scale, so treat it as an open question rather than a protocol.

Dose ranges from the review

Ferraresi and colleagues summarized total energy across the studies they covered:

  • Biceps: 20 to 80 joules
  • Quadriceps: 56 to 315 joules
  • Treadmill work across the whole body: 360 to 510 joules

Wavelengths clustered in red at 630 to 660nm and near-infrared at 808 to 950nm. Wavelengths covers which of those a given device actually emits, and why near-infrared matters more than red for anything below the skin.

Those are total energies delivered to a muscle group rather than irradiance figures. Converting between them needs your device's real output, which is rarely the number on the box. Dosage has the arithmetic.

The caveat if you already train

Machado and colleagues published a randomized placebo-controlled trial in the Brazilian Journal of Physical Therapy in 2022, adding photobiomodulation to a six-week sprint and squat program in already-trained individuals. It produced no additional benefit over placebo or over training alone.

Their reading was blunt: people already adapted to a training stimulus did not benefit.

That is an important limit on the 2016 result, which recruited men doing less than one exercise session a week. If you have been lifting seriously for years, the honest expectation is smaller, possibly nothing.

What about soreness?

Post-exercise use still has a case for delayed onset muscle soreness and markers of muscle damage, which is a different goal from strength adaptation.

Vanin's later systematic review and meta-analysis in Lasers in Medical Science in 2018 found effects on soreness and damage markers more consistent than effects on raw output. Ferraresi and colleagues made a similar point, noting that post-exercise application looks most useful alongside regular training over weeks rather than as a one-off.

If you want to feel less wrecked tomorrow, after training is a reasonable time to use it. Just do not assume you get both benefits from the same session.

The gap between the trials and your panel

Every number above came from cluster probes pressed against the skin at six marked sites per thigh, running 228 seconds per site.

Standing in front of a wall panel is not that. Irradiance falls off sharply with distance and the light spreads over a much larger area, so the joules landing on your quadriceps are a fraction of the protocol figure, and coverage is uneven across the muscle.

Why irradiance numbers are usually wrong explains why the figure on the box makes this harder to estimate than it should be. Contact devices and wraps map far more closely onto what these trials did, which panel, mask, wrap or cap goes through.

A defensible protocol

If you want to follow the evidence rather than the marketing:

Use it before training if strength adaptation is the goal. Target the muscle group you are about to work, in contact or as close as the device allows. Allow five to ten minutes before you start, which is what the trial did.

Keep distance and duration consistent so the dose is repeatable across weeks. Then judge it at eight to twelve weeks, not eight days. The groups in the 2016 trial only separated clearly from week four onward. How long before results show covers why nothing in this category reads quickly.

FAQ

Can I use it before and after? The one trial that tested this found the both-groups did no better than placebo. That is a single result with twelve people per arm and should not be treated as settled, but there is currently no evidence that doubling up helps and one reason to think it may not.

Does it help on rest days? Nothing in the timing literature addresses rest-day use for performance. If you are using it for soreness or joint discomfort, rest days are fine. If you are using it to support strength adaptation, the evidence attaches to the training session itself.

Is near-infrared better than red for muscle? For anything below the skin, yes. Visible red does not reach muscle bellies or joint capsules in useful quantity. The trials used near-infrared, usually paired with red. Wavelengths explains the depth question.

How close does the device need to be? As close as you can manage. The trials used direct contact. A panel at arm's length delivers a small fraction of the same dose, which is the most common reason home use fails to reproduce trial results.

Sources

Keep reading