The main adaptations are related to your bodies ability to regulate heat, and increased plasma volume:
Here is the article: https://www.researchgate.net/publication/275954405_Adaptations_and_mechanisms_of_human_heat_acclimation_Applications_for_competitive_athletes_and_sports
the muscle metabolism stuff is at bottom of page 25 and top of page 26. My read - at best there are minimal adaptations related to substrate utilization. Someone else may get more out of it.