Body Mass, Serum Sodium Concentrations & Prolonged Exercise

Study Title: Changes in body mass alone explain almost all of the variance in the serum sodium concentrations during prolonged exercise. Has commercial influence impeded scientific endeavour?
Authors: T. Noakes
Journal: British Journal of Sports Medicine
Date: November 2011

Summary:

• Here's a recent article published in BJSM and shared to me by my graduate co-supervisor, Joe Baker. Rather than being a randomized control trial, this is a highly opinionated and perhaps controversial paper expressing his feelings towards the American College of Sports Medicine outlining the significance of the omission of his previous findings on exercise-associated hyponatremia (EAH) during prolonged exercise. Specifically, based on research that does not include his previous studies in 1985 and 1991, it was promoted by the ACSM that athletes should consume, during exercise, as much fluid as tolerable. On the contrary, it was proposed by Noakes and colleagues that exercise-associated hyponatremia "appears to be (related to) voluntary hyperhydration with hypotonic solutions combined with moderate sweat sodium chloride losses". As an aside, it is not uncommon to witness typical EAH symptoms of vomiting, nausea, dizziness, altered mental status in less skilled (aka "slower") endurance athletes. While the principle argument for this paper was to suggest that very low levels of postexercisue serum sodium concentrations in athletes suffereing from EAH result from body weight gain secondary to fluid retention irrespective of volitional electrolyte (i.e. sodium) consumption, the main "takeaway" from this paper was that his research may be largely ignored due to commercial influence. What Noakes does suggest however, is that increasing sodium ingestion with increasing duration of exercise may not provide any biologically significant effect to countering EAH. So should we really still be drinking our Gatosauce or should we be paying more specific attention to our water consumption levels if we're less gifted and toward the "back of the pack".

Noakes, T. (2011) Changes in body mass alone explain almost all of the variance in the serum sodium concentrations during prolonged exercise. Has commercial influence impeded scientific endeavour? British Journal of Sports Medicine.

For those of you interested in another summary of this paper, please take a look at Alex Hutchinson's blog.