Sodium intake does not influence bioimpedance-derived extracellular volume loss in head-down rest.

Introduction: There is disagreement regarding the impact of dietary sodium on alterations in extracellular volume during head-down bed rest (HDBR). The primary purpose of this study was to assess the effects of salt intake on extracellular volume (ECV) during HDBR.

Methods: We performed whole-body bioimpedance spectroscopy with controlled sodium intake during 4 d of ambulation and 8 d of -6 degrees HDBR in 10 normotensive men.