Staying hydrated while exercising in the heat has been a hot (pun intended) topic as the recent summer heat wave stifles runners across the US. Sometimes, a great source provides interesting new research or highlights new developments on the summer training and hydration conversation, but if I have to read one more basic article on how runners need to drink more in the summer, I’m going to tear my hair out. Instead, this article will provide an advanced hydration technique you can use to stay hydrated and perform better in the heat – hyper-hydration

What is Hyper-hydration

Hyper-hydration is the act of hydrating your body above its normal state before exercise. Research has demonstrated that beginning your run hyper-hydrated will delay or eliminate the onset of dehydration, particularly if you fail to completely replace sweat loss during your run. Given that most runners do not rehydrate enough to replace all their fluid and electrolyte loss, especially for those of us that sweat heavily, hyper-hydration can be a useful strategy.

How to Hyper-hydrate

Hyper-hydration is difficult because excess fluid intake before exercise will usually be quickly excreted through the urine; simply speaking, you’ll pee it out quickly. To combat this, runners can use a product called Glycerol to help them retain fluids and electrolytes. Glycerol is a rapidly absorbed, natural metabolite with osmotic action, which means it is evenly distributed within body fluid compartments, allowing for greater fluid and electrolyte retention. Numerous scientific studies have concluded the glycerol ingestion reduces cardiovascular strain and enhances thermoregulation, which improves exercise performance in the heat.

If you’re interested in trying glycerol on your next long, hot training run, you can purchase it cheaply here (note: glycerol and glycerin are the same product, it’s just not sold under the name glycerol)

To use glycerol in training, you should ingest glycerol at 1.0 g/kg (x) your body weight diluted in 21 ml/kg of water (x) your body weight over a period of 90 minutes to 2 hours prior to exercise. That sounds a little confusing for most of us non math majors, so here is a more simplified explanation.

Step 1. Multiple your weight in kilograms (pounds to kilogram calculator if you need) by 1.0. This number is the total number of glycerol you will need.

Step 2. Multiple your weight in kilograms by 21 milliliters (milliliters to ounces calculator). This is the amount of water you need to drink.

Step 3. Add the amount of glycerol from step 1 to the amount of water in step 2.

Step 4. 90 minutes to 2 hours prior to exercise, drink the glycerol/water solution you mixed in step 3.

Example: A 160 pound runner weighs 72 kilograms. Glycerol amount is 1.0 g/kg x 76 = 76 grams (2.6 oz). Water amount is 72kg x 21ml = 1596 ml (53 oz). So, this runner would add 2.6oz of Glycerol to 53oz of water and drink this 90 minutes to 2 hours before their run.

There is no advantage in increasing the intake above these levels since the extra glycerol and water are excreted in the urine. Likewise, a higher concentration of glycerol in the water may lead to bloating.

What to watch out for

Recently, researchers and scientists have warned runners that over-hydrating is a dangerous side effect to hyper-hydration in runners. While there is certainly a danger in drinking too much water without properly balancing electrolyte levels, it takes an extreme amount of water to experience issues with hyponutremia. The glycerol advocated in this article helps retain electrolytes, as well as water, so hyponutriemia should not be an issue if you include glycerol in your hyper-hydration plans. If you’re still concerned, you can also take an electrolyte replacement tablet with the water, which will ensure you have elevated electrolyte levels.

Finally, in rare cases, glycerol can cause nausea, headaches, blurred vision and bloating. It doesn’t happen to most runners, but you should test out the glycerol on a shorter run before you head out for an important workout, a long run, or a race, just in case.

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Further research studies consulted:

(1) Freund, B.J., Montain, S.J., Young, A.J., Sawka, M.N., DeLuca, J.P., Pandolf, K.B., Valeri, C.R. (1995). Glycerol hyperhydration: hormonal, renal, and vascular fluid responses. Journal of Applied Physiology, 79, 2069-2077.

(2) Koenigsberg, P.S., Martin, K.K., Hlava, H.R., Riedesel, M.L. (1995). Sustained hyperhydration with glycerol ingestion. Life Sciences, 5, 645-653.

(3) Lyons, T.P., Riedesel, M.L., Meuli, L.E., Chick, T.W. (1990). Effects of glycerol-induced hyperhydration prior to exercise in the heat on sweating and core temperature. Medicine and Science in Sports and Exercise, 22, 477-483.

(4) Montner, P., Stark, D.M., Riedesel, M.L., Murata, G., Robergs, R.A., Timms, M., Chick, T.W. (1996). Pre-exercise glycerol hydration improves cycling endurance time. International Journal of Sports Medicine, 17, 27-33.

(5)Murray, R., Eddy, D.E., Paul, G.L., Seifert, J.G., Halaby, G.A. (1991). Physiological responses to glycerol ingestion during exercise. Journal of Applied Physiology, 71, 144-149.

(6) Noakes, T.D. (1993). Fluid replacement during exercise. Exercise Sport Science Review, 21, 297-330.

(7) Riedesel, M.L., Allen, D.Y., Peake, G.T., Al-Qattan, K. (1987). Hyperhydration with glycerol solutions. Journal of Applied Physiology, 63, 2262-2268.