Photobiomodulation as Medicine: Low-Level Laser Therapy (LLLT) for Acute Tissue Injury or Sport Performance Recovery

Abstract

Background/Objectives: Low-level laser therapy (LLLT) has gained traction in sports and exercise medicine as a non-invasive therapeutic for preconditioning the body, exertion recovery, repair and injury rehabilitation. LLLT is hypothesized to modulate cellular metabolism, tissue microenvironment(s) and to decrease inflammation while posing few adverse risks. This review critically examines the evidence-base for LLLT effectiveness focusing on immediate care settings and acute/subacute applications (<6 months post-injury). Methods: A comprehensive literature search was conducted, prioritizing systematic reviews, meta-analyses and their primary research papers. Results: Findings are relevant to trainers and athletes as they manage a wide range of issues from superficial abrasions to deeper tissue concerns. LLLT parameters in the research literature include wide ranges. For body surface structures, studies show that LLLT holds promise in accelerating wound healing. In sport performance studies, LLLT is typically delivered pre-exercise and reveals beneficial effects on exertion recovery, improvements in muscle strength, endurance and reduced fatigue. Evidence is less convincing for acute, deep tissue injury models, where most studies do not report significant benefits for functional outcomes over conventional therapeutic modalities. Conclusions: Variability in LLLT delivery parameters and findings across studies underscores a need for clear treatment guidelines for the profession. Technical properties of laser light delivery to the body also differ materially from LED devices. Sport physiotherapists, team physicians, trainers and athletes should understand limitations in the current evidence-base informing photobiomodulation use in high-performance sport settings and weigh potential benefits versus shortcomings of LLLT use in the mentioned therapeutic contexts.

Keywords: acute tissue injury; low-level laser therapy; photobiomodulation; sport performance; wound healing.

Figure 1

Low-level laser therapy (LLLT) and light-emitting diode therapy (LEDT) are both forms of red-light therapy used for various medical purposes, including the treatment of superficial wounds and sore or injured connective tissues. Not to scale; for illustrative purposes only.

Figure 2

Comparison of favorable and inconclusive research studies of LLLT for sports-related models [17,18,19,20,21,22,23,24,25,26,27,28]. Research findings are considered favorable based on the conclusions drawn from the authors of LLLT use in sport performance settings (i.e., number of repetitions, time on field), or recovery (i.e., delayed onset of muscle soreness (DOMS)).

Figure 3

Comparison of favorable and inconclusive results when applying LLLT (Class IIIb) for acute or subacute (<6 month onset) injuries. Research findings are considered favorable based on the conclusions drawn from the authors [93,94,95,96,97]. Our interest was in studies emphasizing functional outcomes versus studies focusing primarily on subjective measures or pain management.

Figure 4

Delivery of red or infrared light to body structures may involve an interplay of biological processes that lead to decreased inflammation and accelerated recovery of strained or damaged tissues [12].