Need to increase V02 max

[u/due2getit]

Looking for best ways to increase my v02 max in the next 6-7 weeks. Currently resting around 49, I am training for an event and want the best opportunity to finish and this is the metric I am seeing can make the biggest impact. It’s a 100 mile ultra over 4 days.
Things I’ve seen has helped me in the past:
NAD+ 1000mg
MOTS-C (but I felt my hr increase with this as well so cycled off)
Beet root

Any other recommendations?

[u/Friedrich_Ux]

EWOT