Measurement of Physical Parameters and Development of a Light Emitting Diodes Device for Therapeutic Use

In vivo attenuation profile of 660 nm and 830 nm wavelengths on human elbow skin and calcaneus tendon of different phototypes

Physical factors and tissue characteristics determine the transmission of light through tissues. One of the significant clinical limitations of photobiomodulation is the quantification of fluence delivered at application sites and optical penetration depth in vivo. There is also the difficulty of determining the distances of the application points to cover a uniformly irradiated area. Thus, the aim was to evaluate in vivo the influence of melanin on light transmission of the 660 nm and 830 nm laser wavelengths on skin and tendon. Thirty young individuals of both sexes were recruited, divided into two groups based on melanin index, and submitted to photobiomodulation protocols in the posterior region of the elbow (skin-skin) and the calcaneus tendon (skin-tendon-skin). The irradiation area was evaluated using a homemade linear array of five sensors. We found significant transmission power values for different melanin indexes and wavelengths (p<0.0001). Also, different equipment can generate significant differences in the transmitted power at an 830-nm wavelength. Average scattering values are 14 mm and 21 mm for 660 nm, in higher and lower melanin index, respectively. For 830 nm, values of 20 mm and 26 mm are indicated. Laser light transmission in vivo tissues is related to wavelength, beam diameter, tissue thickness, and composition, as well as melanin index. The 830-nm laser presents higher light transmission on the skin than 660 nm. The distances between the application points can be different, with higher values for 830 nm than 660 nm.

Acute application of photobiomodulation does not bring important gains for the muscular performance and functionality of diabetic individuals

Photobiomodulation therapy (PBMT) has been used to improve the physical performance of individuals with advanced age; however, there are no studies in the literature that support the application of light-emitting diode (LED) therapy for the muscular performance of individuals with diabetes mellitus who show a decline in functionality. The aim of the study was to analyze the acute effects of PBMT on strength and functional performance in type 2 diabetic individuals. Sixty-three volunteers were recruited and randomized into five groups: control (C), sham (S), red LED (R), infrared LED (IR), and red LED + infrared LED (R + IR). On the first day, the volunteers were evaluated using the time up and go (TUG), the 6-min walk test (6MWT), and isokinetic dynamometer of the ankle. In the following 3 days, groups R, IR, R + IR, and S returned for application of PBMT bilaterally, with 180 J of energy on each leg. On the fifth day, a reassessment was performed. There was no statistical difference between groups for the variables of the isokinetic dynamometer, TUG, and 6MWT. Analysis of the size of the clinical effect for the isokinetic variables showed that there was no pattern among the effects observed. There is a moderate effect in favor of R, IR, and R + IR in relation to C for the TUG and a moderate effect of R + IR in relation to C for the 6MWT. The PBMT applied for a short period does not bring important gains for the muscular performance and functionality of diabetic individuals.