In our latest study published in Sports Medicine on the 3rd April 2021 led by Dr Mark Waldron (Swansea University), we meta-analysed 28 studies to explore how heat acclimation or acclimatisation can modify maximal oxygen consumption. This is an area of some heated discussion in the literature (see for example the point-counterpoint in J.Physiol here).
To summarise our findings, we found that heat acclimation can enhance VO2max adaptation in thermoneutral or hot environments by at least a small and up to a moderate–large amounts, with larger improvements occurring in the heat.
The article can be found here: 10.1007/s40279-021-01445-6