Thanks for this great link.
I have copied the areas below because many don't download links, and this information is too important to miss.
(I have also sent a copy of this report as part of an inquiry to the USTA Sports Science group - I am not aware that this is well known in tennis circles.)
"However, recent research indicates that some athletes need even more care in this area than others. They’re called “salty sweaters
,” and when the heat strikes, they are more likely than other athletes to suffer from heat-related illnesses.
AT GREATER RISK
As the name implies, the biggest difference between salty sweaters and other athletes is that salty sweaters lose more sodium when they sweat—in some cases, a lot more. Consider this: In a study of 10 football players, sodium losses during a two-hour practice ranged from 0.8g to 8.5g. In another study of top male tennis players
during matches on a hot, humid day, average sodium loss was 2.7g per hour, but one player lost 12g of salt in an hour.
"IDENTIFYING SALTY SWEATERS
How do you know if an athlete is a salty sweater? The most scientific test is to use absorbent patches to collect sweat and employ specialized analyses to determine exact electrolyte losses. This is the method used by researchers. However, for athletic departments, this isn’t very practical. Fortunately, simpler methods are available.
At Florida State, we start by using our pre-participation physical exam. Since salty sweaters appear to get muscle cramps more easily, we use our questionnaire to identify athletes with a history of cramping. We also ask our athletes if they have noticed more salt loss themselves. Two simple questions can be sufficient to help identify athletes potentially at risk
How often have you experienced muscle cramps during practice or games?
When you sweat, does your sweat often sting your eyes or taste salty?
• Tastes Salty
• Stings Eyes
"At Florida State, I would estimate that 10 to 15 percent of our athletes could accurately be classified as salty sweaters. Generally speaking, of the 100-plus athletes on our football rosters, between 10 and 15 are identified as salty sweaters at risk for muscle cramps.
"We use a pre-made product containing a combination of sodium and potassium. The powder is mixed with either water or a carbohydrate/fluid replacement. It is important to note that the electrolytes need to be consumed in combination with high fluid volumes
When supplementing, each athlete should be treated individually. Initially, sodium supplementation should be done conservatively, with 1,500 to 3,000 mg
. If the salty sweater continues to suffer from muscle cramps, the amount of supplementation can be increased.
As mentioned, research has found that in very rare cases, an athlete can lose more than 10g of sodium per hour, and in these cases, up to 6,000mg of sodium supplementation is certainly warranted.
Another idea is sodium loading prior to competition. This is a relatively new concept, but early studies have produced positive results. Most research has utilized acute sodium loading protocols in an attempt to increase plasma volume, thereby improving heat tolerance and performance. Recent studies conducted in New Zealand have found sodium loading to increase plasma volume in both men and women. It has also been shown to reduce physiological strain, reduce perceived strain, and increase exercise capacity."
can be another time when salty sweaters need extra help. It’s important to make sure they pay particular attention to their pre-competition sodium intake to help prevent them from cramping during competition. At Florida State, we begin supplementing our salty sweaters two to three days prior to a competition, increasing their daily sodium consumption by 1,500 to 3,000mg via dietary means or supplementation. This protocol is most common amongst football players, but it may also be warranted for other athletes who have a history of late-game muscle cramps.