Ashwaganda caught my attention a couple of years back as well. I've tried it shortly.

Although I aim and advise to keep supplementation to a bare minimum, I do consider ashwaganda, creatine and whey protein, one of the few (and there are really not as much as many think.) usefull supplements.

Perhaps for a race, a tip, if I may:

Beetroot is a great natural endurance enhancer (I don't know if it's allowed in comepetive sports) But you need to implement quite a a high amount into your diet.

(A rough guidenline would be drinking about 500ml per day for about two weeks prior at least for a 70kg person, you want to
Make sure thay includes the fibers as well.)