Red light therapy, Useful.
Useful as conditioning for the knee: used consistently across the test block, it reduced pain in humid, cold conditions and removed the sudden pain that used to hit on a specific movement at warm-up.
No variability-score or Body Battery shift from a session, red light acts locally on tissue, not on the nervous system. What I track instead: knee pain and stiffness at warm-up. Less pain in humid, cold conditions than before the block, and no more of the sudden pain on a specific movement at warm-up that used to hit without warning.
Certain mornings, at warm-up, the knee is sore. Not a constant ache, a soreness that seems to be waiting to be warmed up, as if the joint needs to get moving again before it accepts the effort.
What red light therapy does physiologically
Red light therapy, the clinical term is photobiomodulation, is simple to describe and easy to oversell. A panel emits light in the red and near-infrared range, roughly 630 to 850 nanometres, and you sit in front of it with the target area exposed. The light penetrates the skin a few millimetres to a couple of centimetres, depending on the wavelength. Red light (around 660 nm) reaches surface tissue. Near-infrared (810 to 850 nm) goes deeper, which is why it is the relevant one for a joint like the knee.
What happens during exposure. The light is absorbed by an enzyme inside your mitochondria, the small structures that produce most of a cell’s energy. Think of the mitochondria as the cell’s power plant. The current view is that the light briefly nudges that power plant to run more efficiently and to ease a bottleneck in energy production. The practical downstream effect studied in athletes is twofold: a modest local anti-inflammatory response, and a small improvement in how muscle handles fatigue when the light is applied before effort.
Three distinct use cases, ranked by how strong the evidence actually is. Do not confuse them.
What happens after. For chronic joint problems, the effect is cumulative rather than instant. The research on tendons and joints uses repeated sessions over weeks, not one dramatic visit. A single session in front of a panel does not resolve an inflamed knee. What the evidence supports is a gradual reduction in pain and stiffness across a block of regular sessions.
What it does NOT do. It does not rebuild cartilage, it does not “heal” a structural injury, and it is not a shortcut around sleep, food, or training load. It does not act on your nervous system the way a sauna or a cold plunge does, so do not expect your watch to light up after a session.
A recovery-centre wall panel is not automatically delivering the energy density used in the trials. Distance, exposure time, and wavelength all change the dose, and most centres do not publish those numbers. Two people sitting in front of the same panel at different distances get two different treatments. This is the single biggest reason a protocol that worked in a study can do nothing in practice. Before you judge the tool, find out what dose you are actually getting.
What the science says
Start with where the evidence is thin, because that is where the marketing is loudest. General post-workout recovery is the weakest case. A 2025 meta-analysis of photobiomodulation for Delayed Onset Muscle Soreness (DOMS, the deep ache that peaks 24 to 72 hours after hard eccentric work) pooled 14 studies but could only quantitatively combine four of them, and reported a moderate reduction in soreness at 72 to 96 hours and an improvement in muscle strength recovery [1]. That is a real signal, but it rests on a small number of trials with varied wavelengths and doses, which is exactly the kind of base that should make you cautious rather than convinced. One supportive meta-analysis is a reason to keep testing, not a verdict.
Where the evidence is more convincing is at the two ends the marketing tends to ignore. Before exercise, photobiomodulation has the most consistent support: a large systematic review found it improved muscular endurance and reduced exercise-induced fatigue, with the effect holding across both laser and LED devices [3]. And for chronic lower-limb joint and tendon pain, a 2022 meta-analysis of randomised trials found that correctly dosed treatment significantly reduced pain (around 12 to 15 mm on a 100 mm scale) and disability in the short and medium term, as an add-on to exercise [2]. The effect is modest, the confidence intervals are wide, and there is no long-term data, so it is help at the margin, not a cure. On funding: the DOMS meta-analysis declared no funding and no conflict of interest, and the joint-pain review reported that none of the included trials were funded by the laser industry, though two of its authors are former office-holders of a laser-therapy research association, which is worth naming plainly.
What changed: in humid, cold conditions, the pain is less present than before. And most notably, I no longer get that sudden pain on a specific movement at warm-up, the one that used to arrive without warning.
Verdict
Useful, as conditioning for the knee.
Used consistently across the test block at Ice Break Uluwatu, red light therapy changed how the knee behaves at warm-up, categorically less reactive than before the block started. The condition that matters: this is ongoing conditioning, built over weeks of regular sessions, not a same-day fix from one visit to the panel.
How to use it
When. Two distinct use cases, do not mix them up. For output and fatigue, apply it before training. For joint inflammation or tendon pain, treat the area on rest days or after sessions, across a block of several weeks.
Distance and duration. Sit at the distance the panel specifies, usually fairly close, for 10 to 20 minutes on the target zone. Closer is not automatically better; the device is designed for a specific working distance.
Wavelength. For a deep joint like the knee, the near-infrared range (810 to 850 nm) is what penetrates far enough to matter. Surface red light (around 660 nm) is aimed at skin and shallow tissue. A panel with both, like the five-wavelength setup at Ice Break, covers both depths.
Consistency. This is not a reactive tool like foam rolling. The joint-pain evidence comes from repeated sessions over weeks. One visit proves nothing. If you cannot commit to a block, you cannot judge it.
Where it sits in the stack. It is an add-on, not a base. Sleep, hydration and food come first (the recovery base). If you are pairing it with cold at a centre like Ice Break, treat the cold plunge and the light as separate tools acting on different systems, not one combined protocol.
FAQ
Is red light therapy the same as an infrared sauna?
No, and the difference matters. An infrared sauna uses infrared to heat your body, the benefit comes from the heat load and the sauna-style stress response. Red light therapy uses specific wavelengths at low heat to act on tissue at the cellular level, not to cook you. If you are sweating, that is a sauna. If you are sitting in front of a cool bright panel, that is photobiomodulation. They are different protocols with different evidence.
Will it actually help a chronically inflamed knee, or is that wishful thinking?
The honest answer is: modestly, and only with consistency. The randomised-trial evidence on lower-limb tendon and joint pain shows a real but small reduction in pain and disability over weeks, and works best as an add-on to your rehab and training, not instead of it [2]. If you are expecting a single session to fix a knee that has been angry for months, you will be disappointed. If you run it as a multi-week block alongside loading the joint properly, it may take the edge off.
Should I use it before or after training?
Depends on your goal. The strongest evidence for output and fatigue is for use before effort [3]. The recovery-and-soreness case for use after is weaker and less consistent [1]. For joint inflammation, timing relative to a session matters less than doing it regularly across weeks. Pick the goal first, then the timing.
How many sessions before I know if it works for me?
Not one, and not three. The joint and tendon studies run over multiple weeks, so give it at least a full training block before you judge. Track one or two concrete things, morning knee stiffness and whether you can load the joint in your next session, rather than a vague sense of feeling better.