To the point, at least in this study, where the authors questioned, in effect, whether it was an unfair advantage.
I have photobiomodulation units (a fancy word, in this case, for what is commonly known as Red Light Therapy) from Amazon, for under $40 dollars. Good for DJD as well. And macular degeneration/vision issues/hypothyroidism, per research.
The Infrared at around 850 nm will penetrate further, both frequencies can be used simultaneously.