Bone: An Acute Buffer of Plasma Sodium during Exhaustive Exercise?

Both hyponatremia and osteopenia separately have been well documented in endurance athletes. Although bone has been shown to act as a “sodium reservoir” to buffer severe plasma sodium derangements in animals, recent data have suggested a similar function in humans. We aimed to explore if acute changes in bone mineral content were associated with changes in plasma sodium concentration in runners participating in a 161 km mountain footrace. Eighteen runners were recruited. Runners were tested immediately preand post-race for the following main outcome measures: bone mineral content (BMC) and density (BMD) via dual-energy Xray absorptiometry (DEXA); plasma sodium concentration ([Na+]p), plasma arginine vasopressin ([AVP]p), serum aldosterone concentration ([aldosterone]s), and total sodium intake. Six subjects finished the race in a mean time of 27.0±2.3 h. All subjects started and finished the race with [Na+]p within the normal range (137.7±2.3 and 136.7±1.6 mEq/l, preand post-race, respectively). Positive correlations were noted between change (Δ; post-race minus pre-race) in total BMC (grams) and [Na+]p (mEq/l) (r=0.99; p Required Publisher's Statement Original version is available from the publisher at: https://www.thieme-connect.com/DOI/DOI?10.1055/ s-0033-1347263 This article is available at The Cupola: Scholarship at Gettysburg College: http://cupola.gettysburg.edu/healthfac/52