Glycerol to Ensure hydration
Exercise performed for more than an hour in hot, humid environments can cause excess fluid loss of 3 liters. In these conditions, where else is there to ensure hydration, but we must go further: very prolonged and intense physical activity or people who tend to excessive sweating should also be factors to take into account not only the environment.
Warm atmosphere + moisture = fatigue dehydration
With hot and humid environments we do not refer only to Seville, summer, 14h. 40 and the shade; It can be a gym with very crowded at rush hour. Well, in these environments, fatigue is not associated with both the depletion of glycogen stores (cold, yes) and dehydration.
To prevent hyperthermia and reduce heat stress, it is important fluid intake and also affects the degradation rate of muscle glycogen (= dehydration faster depletion of glycogen stores, especially in resistance).
It is a hyperhydrating agent whose use constitutes a special strategy to avoid dehydration in the heat. Glycerol is an alcohol three carbon that is released from the triglycerides in the process of lipolysis.
When consumed orally (glycerin) is slowly metabolized in the liver and kidneys, and combined with fluid, the osmotic pressure is increased thereby enhancing fluid retention.
Glycerol, as polyalcohol is not produced high insulin response (low glycemic index), however if it can be transformed into glycogen, the body providing a source of valuable energy. Is attributed similar to that of any carbohydrate (4 Kcal./g) caloric density, however, polyalcohols studies have shown that this energy density could be much lower (2 – 3.5 Kcal./g) depending on the polyalcohols and different situations.
Evidence in humans
- It has been used successfully to compete in sports by weight categories in which dehydration in order to achieve a certain weight is used. After weighing, glycerol supplementation is done just before the competition.
- Work under stress cyclists compete in heat allowed improving endurance time after glycerol ingestion versus placebo.
- The yield of 40-km is enhanced with glycerol rehydration similar to if rehydration is carried off without glycerol intravenously manner.
How do I manage it?
Supplementation doses should be small (1-1.2 ml / kg.) With large volumes of fluid (25-35ml / kg) in the hour before exercise. During exercise, can be ingested at a rate of 1 ml / kg of a 20% solution of glycerol in water.
You can also go to the protocol used by Montner et al (1996)., but may assume too much fluid for non-professional athlete. It started with glycerol ingestion 2.5 hours before exercise as follows:
- Drinking 5 ml / kg of a 20% glycerol
- Wait 30 minutes and drink 5 ml / kg of water
- Wait 15 minutes and drink 5 ml / kg of water
- Wait 15 minutes and drink 1 ml / kg of a 20% glycerol and 5 ml / kg of water
- Wait 30 minutes, then drink 5 ml / kg of water
- Begin exercise an hour later.
Although it is especially suitable for endurance sports performance and explosive strength training also it depends on proper cellular hydration. The combination of glycerol and creatine ensure proper hydration and will valuable for those wishing to increase muscle mass mixture.
Possible side effects
It must be particularly cautious because fluid retention is an increase of weight which could be negative for certain sports and presents certain risks or side effects that may not appear and different degree (nausea, gastrointestinal disorders, headache due to increased intracranial pressure, etc …). In any case, we must adjust supplementation protocols to avoid side effects and monitor supplementation before the competition by health care.