Photobiomodulation

Photobiomodulation applies low-power red or near-infrared light to tissue, at a level that does not heat it, using lasers, light-emitting diodes or lamps.

What it is

Photobiomodulation (PBM), the application of red or near-infrared light to tissue, uses lasers, light-emitting diodes (LEDs) or broadband lamps at a power that does not heat the tissue [1][2]. It is also known as low-level laser therapy (LLLT) or low-level light therapy [1]. In consumer use it is often called cold laser or red light therapy. Researchers agreed on the name at a consensus meeting in 2014, and it has been indexed as a medical subject heading in the biomedical literature since 2015 [1]. Photobiomodulation is a generic scientific term rather than the name of a proprietary or trademarked method [1].

Most devices used for muscle and joint conditions emit wavelengths between about 600 and 1,100 nanometres, in the red and near-infrared range [3][4]. A session usually involves holding a probe or panel on or near the skin for around a minute per site, although protocols vary widely [4][5].

How it is proposed to work

The mechanism is not fully understood. The leading hypothesis is that red and near-infrared light is absorbed by cytochrome c oxidase, an enzyme in mitochondria, the energy-producing structures inside cells. On that hypothesis, the absorbed light releases nitric oxide from the enzyme, which would increase electron transport and the production of adenosine triphosphate (ATP), the cell's energy currency. A brief rise in reactive oxygen species, molecules formed as a normal by-product of cell metabolism, is also proposed to switch on signalling pathways that alter gene expression, cell survival and cell movement. A second suggested route is that near-infrared light opens light-sensitive ion channels in the cell membrane, letting calcium into the cell. Through these routes, light is proposed to lower inflammatory signalling within tissue.

Dose is thought to matter in both directions: low doses are proposed to stimulate cell activity, while higher doses are expected to produce no effect or to inhibit it, a pattern described as a biphasic dose response. Researchers have not agreed on standard parameters, and wavelength, power density, energy dose, pulsing and timing are each thought to change what happens. These are hypotheses, not descriptions of what has been established in people.

What it is used for

Photobiomodulation is used mainly by physiotherapists, sports-medicine practitioners and pain clinicians [4]. They apply it to muscles, joints and tendons that are painful or recovering, usually alongside exercise, manual therapy or other care rather than on its own [4]. Equipment ranges from a hand-held probe held over a single point to panels that cover a larger area, and the light is delivered on or close to the skin [3][4]. In sport it is used around training, as part of a recovery routine. Devices of this kind are made for use alongside other care for pain rather than for a named disease [2]. Practitioners work to a protocol that sets the wavelength, the power and the time spent on each site, and these protocols vary widely from one device to another [5]. This page describes where and why the therapy is used; what it achieves is a separate question, and the section below explains how we intend to answer it.

Our own trials

Most of the therapies and technologies we work with are young as subjects of scientific study, and the published work on them changes from year to year. Rather than point to studies that may already be out of date, HarmoniQ Tech intends to evaluate each therapy in its own trials, to record what we find, and to adjust our methods and our own algorithms to those findings. Our trials have not yet begun. Until they have, we describe what each therapy is, how it is proposed to work and how we intend to use it, and we make no claim about what it achieves.

Safety and who should take care

Direct eye exposure is the main hazard: devices can exceed safe eye exposure limits, and device guidance and practitioner consensus both advise safety eyewear for everyone present [2][4]. Practitioner consensus advises against treating over a developing fetus, over a known tumour, and with low-frequency pulsed visible light in people with photosensitive epilepsy [4]. Device labelling guidance carries the same cautions for pregnancy and for use over or near a cancerous lesion [2]. Extra care is advised over skin with reduced sensation, in photosensitivity disorders or with photosensitising medicines, and with higher-output devices or masks that can warm tissue if used too long [2]. Because the proposed mechanism is dose-dependent, a session follows a set dose protocol rather than a longer or stronger exposure. Speak to a clinician before starting, especially during pregnancy, with a cancer history, photosensitivity, epilepsy or an acute injury.

How HarmoniQ Tech uses this

Photobiomodulation is intended to be a scheduled intervention. We are developing a step-by-step programme of lifestyle change that combines PBM with biofeedback, in which sensors show a person a bodily signal so they can learn to influence it, and a proprioceptive vibration therapy. Within that programme, PBM is intended for recovery phases after injury, applied according to a protocol we are developing, with the aim of supporting tissue recovery and easing pain. It is not designed to replace medical care, and we do not offer it for any specific disease. Each session is designed to log dose, site, duration and the person's own report of the response. The HarmoniQ guidance system (in development), which we are developing to turn sensor data into step-by-step lifestyle guidance, will aim to read these logs alongside biofeedback signals and posture and movement measurements. It will then suggest when a recovery plan might include a PBM session. It will not diagnose, prescribe or treat. Our aim is that the three therapies together support recovery from injury and, over time, strength, posture and overall health.