l carnitine is amino acid Nature's Bounty L-Carnitine Supplement, 500 mg30 caplets MY PROTEIN L Carnitine Amino
Description
In such actions as resistance training, cardio, or daily activity

You can find detailed UV spectra of L-Arginine and information about its various lambda maxima by visiting the following link

Dec 2022;82:101766

Plus, muscle pain and fatigue after exercise were reduced, and sleep was improved

As further research emerged over the years, I have added it to a handful of other treatment protocols