We all know dehydration in any percentage is BAD mkay for athletes. The body doesn't function properly when not fully hydrated. That's common knowledge. The blood thickens, metabolic function is impaired, the body slows down. Nasty things happen when the body seriously dehydrates, culminating in cognitive dysfunction, physical collapse, muscular damage, and ultimately death. But what is actually going on?
Here is something to think about: I came across it in another blog post on reasonings behind why drinking water helps weight loss. Dr Briffa notes: "It has been found that cells that are dehydrated do not take up glucose very efficiently  – something that could cause the metabolism to stall. Also, studies show that when the blood is made more dilute, fatty breakdown in the body (lipolysis) is enhanced [2,3]." He is making this case in reference to weight loss, but think about the energy sources the body uses during sub-max endurance efforts: fats.Glucose is also required as a metabolic process. Quite simply, the body's metabolism cannot work, because glucose is not taken up, when the body is dehydrated.
Here are the citations Dr Briffa uses:
1. Thornton SN, et al. Hydration increases cell metabolism. International Journal of Obesity [epub ahead of print publication 20 January 2009] Int J Obes (Lond) 2009;33(3):385
2. Mathai ML, et al. Selective reduction in body fat mass and plasma leptin induced by angiotensin-converting enzyme inhibition in rats. Int J Obes (Lond) 2008;32:1576″1584.
3. Schliess F, et al. Cell hydration and mTOR-dependent signalling. Acta Physiol (Oxf) 2006;187: 223-229.
3 hours ago