Based on some of the experiences of our athletes this weekend, it seems to me that there is a need for a little more information on which to fine tune the nutritional plan – especially in regard to our sodium intake.
The weekend was obviously a tough training weekend – especially for those who did two loops at wildflower but it was also the first time this year we have had to deal with heat and few of us, if any are particularly well heat acclimated yet. However while the current weather forecast for wild flower seems to indicate temperatures in the mid 70’s it is always a possibility that it is going to be hot again this year so those who are racing need to be prepared.
Without trying to scare you – or overwhelm you with numbers, the difference between “normal” blood concentrations of sodium and what might be considered an “emergency” situation of low sodium can be as little as 500 mg of sodium. So it definitely pays, from a medical perspective, to try and get this done right and obviously from a performance perspective you would not want your training to be compromised due to a nutritional breakdown.
Athletes who are acclimatized to heat typically have lower sweat sodium concentrations in warmer conditions. So if the race you are training for has a history of high temperatures (Wildflower and Auburn are two that spring to mind) then it is important to address the variable you can control – sodium intake – rather than the variable you cannot – the weather. Adult athletes can lose between 1.0-2.5 liters of sweat per hour. In severe heat conditions, this can increase to 3.5 liters per hour. Sweat is mostly water but contains many other compounds including sodium, chloride, potassium, calcium, and a host of other compounds. If you are very disciplined you could bring a scale with you to workouts and weigh yourself before and after, or pay for a sweat test to be done but since most of us are not going to do that, you will need to estimate where you might fit in that category and at least be aware of making sure you are at least replacing the minimum sodium losses.
Research has shown that sweat sodium concentrations can range from 115-2,300 milligrams of sodium lost per liter of sweat. However, the AVERAGE athlete usually falls within the 700mg to 1200mg per liter of sweat. Thus at the minimum sweat rate, the average athlete is losing 700mg per hour.
It might help to see an example;
“Scott knows that he loses about 1 liter of sweat per hour in conditions predicted for his upcoming Ironman. He also knows that his sweat is usually quite concentrated, leaving a lot of salt stains on his clothing. He guesses his sweat contains sodium at the higher end of the normal range, about 1200 mg/liter. So with a sweat rate of 1 liter per hour, under ideal conditions he should replace 1200 mg of sodium per hour. Scott's favorite sports drink contains only 300 mg of sodium per liter. Each gel he is consuming contains 50 mg of sodium, and each bar he consumes contains 100 mg of sodium. The following table summarizes Scott's water and sodium intake per hour:
| Per hour | Water (liters) | Sodium (mg) |
| Sports Drink | 1 | 300 |
| 3 Gels | Negligible | 50 x 3 = 150 |
| 1 Bar | None | 100 |
| Total | 1 liter | 550 |
| Deficit | 0 | 650 |
Based on this basic Ironman diet, Scott ingests enough water every hour, but his sodium intake is far below what he actually needs, about 650 mg per hour short, considering he needs 1200 mg/hour. Multiply this by 12 hours, and you have 7.8 grams of sodium, or 19.5 grams of salt (the human body contains around 40g of total sodium). Most likely, Scott is headed for severe hyponatremia.”
Also bear in mind that in athletes who have high sweat rates can lose sodium amounts approaching 5,000 milligrams per hour.
In addition to what may be lost during competition, a “clean” daily diet can also contribute to the problem. “Clean” eating is characterized by eating more whole foods such as fruits, vegetables, grains and protein and less processed and refined foods. This often leads to a lower overall daily salt intake and while beneficial from a health perspective, it can have a significant impact on sodium levels in the body before a race. Since this method of eating is gaining momentum, it is often recommended to implement a “sodium loading” regimen before a race and follow through with a higher sodium intake during a race. After competition, the athlete returns to the normal “clean” eating daily diet again.
Sodium Loading;
There has been research on sodium loading and the basic premise behind the mechanism is in the expansion of plasma volume, which is important to cardiovascular function and endurance exercise performance. Expanding plasma volume, termed hypervolemia, may reduce cardiovascular and heat strain seen with exercise, thus improving an athlete’s ability to perform. While there are a few ways to increase plasma volume, sodium loading is easy to implement and has shown good results, including in warmer conditions.
Also drinking fluids that provide a higher sodium concentration before exercise can improve exercise tolerance in warmer conditions.
For more details on how to go about Sodium Loading and to read the full text of this article, which I have significantly edited you can join the team first endurance network for free at http://team.firstendurance.com/
http://team.firstendurance.com/page/sodium-loading-2
Sodium Consumption During a Race
The American College of Sports Medicine recommends consuming 500-700 milligrams of sodium per liter of fluid per hour of exercise while other researchers have recommended a higher range of around 1700-2900 milligrams of sodium per liter of fluid per hour. Seebohar recommends a minimum of 800mg per hour. This is a large discrepancy, mostly due to the requirements of individual athletes and varying environmental conditions. However, the general observation has been that most athletes underconsume sodium during training or a race which typically has negative consequences. Sodium loading has been shown to work in a laboratory setting and has been yielding good results for athletes during actual competitions. It is recommended to try this approach during more intense training that mimics similar conditions of which your race will be.
Endurolytes or Salt Stick?
Endurolytes contain 40mg per capsule while salt stick capsules contain 215 mg of sodium. If we use the example of Bob from the previous page he has an hourly deficit of 650mg of salt – in this scenario he would need to take 15 endurolyte capsules an hour in addition to the electrolyte drink, 3 gels and a bar he is currently eating - that seems a lot to manage! Alternatively he could take 3 salt stick capsules an hour and meet his sodium needs.
*** Just as I was about to send this out – another article shows up on the USAT coaching website on this topic! Link below***
http://usatriathlon.org/content/index/6036
Cramping
Here are two links to articles about cramping for those who are prone to this. I was actually a little surprised to realize that electrolyte imbalance was not considered a major contributor to cramping - but rather they pointed to duration and intensity of exercise over which we do have some control. It serves as another reminder about the importance of building an appropriate endurance base and of making sure you don’t go to hard or to fast during your training as the ability to ride at a higher threshold for 80 miles does not automatically translate into the ability to ride at a lower threshold for 112.
http://www.scysa.net/filecabinet/muscle_cramps_info.pdf
http://ezinearticles.com/?Muscle-Cramps-in-Runners&id=1265152
Finally – here is a link to 10 common mistakes for Ironman – I know we have read them before but it does not hurt to do it again – especially with Wildflower having that festival feel, its easy to go “hang out” at the expo in the hot sun for hours at a time the day before your race. Relax, rest, hydrate, get your feet up and stay out of the sun.
http://searchwarp.com/swa58560.htm
Good Luck at Wildflower
Coach John Magee
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