Work

Light transmission and thermal impact of different photobiomodulation therapy devices on the Achilles tendon of human volunteers: A comparative study

Year: 2025

Type: article

Abstract: BACKGROUND: The relationship between light transmission and thermal effects of different photobiomodulation therapy devices on deeper tissues remains unclear. AIM: To compare light transmission and thermal effects of three photobiomodulation therapy devices on the in situ Achilles tendon of healthy adults. METHODS: A clinical exploratory study was conducted. Eighteen male volunteers (n = 36 tendons) underwent irradiation with three photobiomodulation therapy devices: a high-powered single-wavelength (HPSW, 9,000 mW), a low-powered single-wavelength (LPsW, 100 mW), and a low-powered multi-wavelength (LPmW, 450 mW). Tissue thickness, transmitted power, skin temperature, and thermal discomfort were assessed. RESULTS: Achilles tendon thickness did not differ across conditions (p > 0.05). The LPmW device exhibited the highest transmitted power (141.1 μW ± 33.5) compared with the HPSW (39.7 μW ± 27.0) and LPsW (23.9 μW ± 10.5) devices (p < 0.0001), as well as the lowest increase in skin temperature (p > 0.05). The HPSW device induced the greatest thermal discomfort (p < 0.0001). CONCLUSION: These findings suggest that the LPmW device delivers greater transmitted power while causing a smaller increase in skin temperature compared with the LPsW and HPSW devices in the resting human Achilles tendon, making it a potentially safer and more efficient option for deeper tissue treatment.

Source: Photodiagnosis and Photodynamic Therapy

DOI: 10.1016/j.pdpdt.2025.105234