Medical Investigation

On hyponatremia

GENERAL INFORMATION ABOUT THE RESEARCH PROJECT (FHIAE08IL)

PROJECT NAME: LANZAROTE MARATHON-2008 EXERCISE ASSOCIATED HYPONATREMIA PATHOPHYSIOLOGY: FHIAE-08-IL.

RESEARCHERS: UNIDAD DOCENTE DEL ÁREA DE SALUD DE LANZAROTE (Teaching Unit of the Lanzarote Health Area – Canary Health Service, of the Spanish Public Health System).

CONTACT: fhiae08il@gmail.com

WHAT DO WE RESEARCH ON?

Large amounts of water and mineral salts are lost during prolonged exercise. Endurance sportsmen and women know it well. They eat and drink during competition to avoid the consequences of these losses. In some cases, body water proportion is rapidly increased relatively to sodium –the main blood salt. This problem is called hyponatremia syndrome (from hypo= low, natrium= sodium and emia= blood) and sometimes turn into a severe health problem for long distance athletes.

This has been studied in other famous races -New Zealand and South Africa ironman triathlons, and Houston or Boston marathons. Thanks to the help of more than 60 triathletes -who kindly consent to participate- we were able to carry out a complex research study about “hyponatremia” during the XVII Ironman Lanzarote 2007. The results confirm the importance of weight changes during the race course. Besides that –and this is certainly a new finding-, we detected that sweat composition could have some importance for this health problem. We research on the exact role of the sweat for this syndrome.

HOW WILL WE DO IT?

If you voluntarily consent to participate in the study, we will weigh you three times and analyse your urine (twice), sweat (twice) and blood (once). We will also measure your body fat and do a small survey.

On November 27 and 28, at the registration, we will weigh you and measure your body fat percentage. After doing this, you will be given a small bottle. When you wake up on November 29 -the Marathon day- you put a sample of your urine (50-100 millilitres) into it. Before we begin the studies, we make sure that you understand everything and you must sign an authorisation (consent form) that allows us to include you in the studies.

The research staff will be placed at the entrance of the athletes area on race day, between 8:00 and 9:50, close to the chip control point, to take your urine bottle and weigh you again. We will then also put up a sticker on your skin to get a sweat sample. You will have to keep it on until the finish.

Once you finish the race, we will weigh you again and measure your body fat (last time). We also extract a blood sample of 20 millilitres from a forearm vein with a needle. This is a familiar procedure, the same used for common blood analysis. We recover the sticker to get the sweat sample, and give you another bottle for the last urine sample. Last we will do a small survey about medication taken, possible medical problems occurred during the race and fluids consumed during the marathon.

POSSIBLE BENEFITS FOR THE PARTICIPATING RUNNER.

We will give you a summary of your personal tests, mailed to you before March 2009. These results might be useful for training plans or when choosing the best fluid composition in accordance to your blood and sweat chemistry. Remember that sweat tests is not a commonly used procedure, and it is not available in many clinical laboratories.

Furthermore, your unselfish help will contribute to a better understanding of medical problems affecting endurance sports participants, which might mean a better prevention and treatment.

POSSIBLE INCONVENIENCES FOR THE PARTICIPATING RUNNER.

Weigh you and get your written consent at the registration takes about 10 minutes. Before the race starts, we will need about a minute to weigh you and take your urine bottle and put up the sticker. Once you finish the mrathon, we need about twenty minutes for surveying and taking the urine, sweat and blood samples. Needle jabs are disturbing and slightly painful. The amount of blood drawn after finishing is quite small (20 millilitres).

CONFIDENTIALITY AND SPECIAL CONSIDERATIONS.

In no case and under no circumstances can these samples be used as a doping control or any other related issue. That is not our goal, and samples are not compliant with the mandatory legal conditions. The data obtained in the study will only be used for scientific purposes, always in line with the legal requirements regarding personal data. The data may be published in scientific journals but without revealing your name or any identifiable references to you.

WHAT DO I HAVE TO DO IF I WISH TO PARTICIPATE?

If you have read and understood this information, and you are interested in participating in the study, please click on the following link to find a form to fill out and send to the medical team. In October, we will send you more detailed information and an example of the "consent form" to be signed upon the registration between 27 and 28 November, once at Lanzarote.

Thank you in advance!