Moderation in all things is a simple, consistent guideline to most things in life including hydrating in summer endurance events. Get your fluid and electrolyte balance right  and you can underwrite a performance, get it wrong and drink water to excess and you can potentially be facing up to catastrophic ill health. In the worst case scenario,  you can overwhelm your sodium levels in your plasma with excess water and  be battling hyponatremia.

Hyponatremia is a disturbance in the fluid-electrolyte balance, causing an abnormally low plasma sodium concentration (less than 135 millimoles per liter). The normal range of plasma sodium concentration is 136 to 142 millimoles per liter. An ongoing decrease in plasma sodium concentration upsets the osmotic balance across the blood-brain barrier and can trigger a rapid entry of water into the brain.

A reduction in plasma sodium concentration to 130 to 134 millimoles per liter generally causes no apparent symptoms. Early signs and symptoms of hyponatremia tend to develop when the plasma sodium concentration falls below 130 millimoles per liter and include bloating, “puffiness,” nausea, vomiting, and headache.

There are many potential causes of hyponatremia, but most often it is simple over-hydration. Exercise-associated hyponatremia is primarily caused by drinking an amount of fluid that exceeds sweat and urinary water losses. The most likely explanation for exercise-associated hyponatremia is that excessive drinking reduces the plasma sodium concentration. During exercise, urine output decreases and sets the stage for hyponatremia if too much fluid is ingested or
retained.

In general, an athlete who drinks too much during exercise lasting more than four hours in hot, humid climates is at risk of developing hyponatremia. Smaller and slower athletes who go over the top with fluid intake are at high risk. While large athletes are not ‘immune’ to hyponatremia, the fact is small athletes require less fluid to dilute their extracellular fluid. Slower-paced endurance athletes have more time and more chance to consume too much fluid.

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It is now common to find extensive studies that support the claims that altitude training can improve speed, strength, endurance, and recovery as part of your overall training program.

Why is this so?

You may well ask.

According to the physical sciences, as barometric pressure decreases with increasing elevation, the number of molecules in a given volume of air decreases proportionately. The result, on an absolute basis, is that there are fewer oxygen molecules present in air at higher elevations. What is changing is the actual number of air molecules in a given volume of air, or the air density. This in turn means that there are fewer oxygen molecules available to be transferred to the bloodstream in the lungs. The absolute number of nitrogen molecules also decreases at the same rate, so that the relative proportions of oxygen molecules in the air remains constant at 21% even though there are less molecules of oxygen in the air at high altitudes.

This changed environment elicits concomitant adaptation responses from the body.Exercising or living at altitude reduces the partial pressure of oxygen available; the body responds by increasing the production of erythropoietin (EPO) from the kidneys that in turn increase the number of red blood cells. In theory when you return from altitude you will retain the increased number of red blood cells for a period of time which will thus increase your performance at sea level. Other benefits of altitude training include increased muscle capillary density as well as increased cellular enzymatic capacity.

Certainly, the better the body is at transporting and circulating oxygen the higher the intensity and the longer the duration of work that you will be able to carry out. Since the O2 carrying capacity relies on the number and efficiency of red blood cells, then the greater the number of red blood cells the greater the oxygen carrying capacity.

Similar adaptations can be gained without having to go atop a high mountain.This can be done by using chambers and tents with altered air composition or by interval hypoxic training (IHT). During IHT the athlete is exposed to sharp, strong altitude stimulus using such devices as a hypoxicator and the Altolab. IHT also allows the athlete to continue to train at high intensity at sea level without the negative effects on training intensity and performance that occur whilst training at altitude.
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