Copeptin concentration pre- and post-fluid prescription calculated utilizing Mann–Whitney U tests (sex differences) and Friedman tests (pre to post and menstrual cycle comparisons). Data presented as median with interquartile range (IQR). *P < 0.05 from pre to post. FDehy, follicular phase dehydrated trial; FEuhy, follicular phase euhydrated trial; LDehy, luteal phase dehydrated trial; LEuhy, luteal phase euhydrated trial; MDehy, men dehydrated trial, MEuhy, men euhydrated trial.