What is the primary therapeutic effect of low-level laser therapy (LLLT) in soft tissue injuries?

• A. Thermal heating to increase tissue elasticity.
• B. Photobiomodulation that reduces inflammation, accelerates tissue repair, and decreases pain.
• C. Electrical stimulation to contract muscles.
• D. Mechanical vibration to stimulate proprioception.

Answer: (B)

LLLT works through photobiomodulation: low-level light triggers cellular responses that reduce inflammation, speed tissue repair, and lower pain. The light interacts with mitochondrial chromophores, increasing ATP production and modulating reactive oxygen species and signaling pathways, which promotes collagen synthesis, angiogenesis, and overall healing with less nociception. This is a non-thermal effect, so it isn’t about heating tissue to change elasticity. The other options describe electrical stimulation or mechanical vibration, which are different modalities that achieve their effects through muscle activation or proprioceptive input rather than light-induced cellular changes.