Ad libitum water consumption off-sets the thermal and cardiovascular strain exacerbated by dehydration during a 3-h simulated heatwave.

4 °C or 20 °C ad libitum water ingestion prevented dehydration levels that exacerbate thermal/cardiovascular strain, despite blunted fluid intake with 4 °C water. Higher core temperatures with NOFR are attributed to impaired internal heat distribution secondary to a lower FBF.