By far, the most important electrolyte to replace during long tennis sessions in the hot sun is sodium - not potassium.
’s Role in Hydration and Rehydration for Tennis
The importance of the addition of sodium to fluid consumed during, and especially
after training or competition has been shown to be vital for improved rehydration.
The need for sodium replacement is due in part from sodium’s role as the major ion
in the extracellular fluid, and to replace the obligatory losses in sweat.
"Many athletes do not consume enough sodium in their regular diet to support strenuous physical activity, especially in early stages of training and in hot and/or humid environments.
Having recovery drinks and food that contain sufficient levels of sodium is helpful for a number of purposes:
- Replaces the sodium that is lost in sweat
- Stimulates glucose (energy) absorption by
- Increases the athletes drive to drink
- May reduce the symptoms of exertional heat cramps, exertional heat exhaustions and exertional hyponatremia
During multi-day tournaments or practice, it is common for players to experience a subtle but gradual sodium deficit and this can result in heat and hydration related problems (exhaustion, cramping etc) towards the later
rounds of tournament."
"As sodium has important other benefits such as increasing drive to drink Heat and Hydration Recovery in Tennis USTA Recovery Project 187 and replacing sodium losses that are large in sweat, it appears from the literature that no added benefit is gained by adding potassium to recovery drinks
. Potassium rich foods or supplements have not typically been shown to provide additional benefit
Muscle cramping during and after tennis play is an unwarranted aspect of
high-level competitive tennis. Cramps typically occur with slight muscle
fasciculations 75 or “twitches” that the athlete only notices between points or at the changeover. These subtle signals alert the athlete (and coach) that s/he may only have 20-30 minutes before severe cramps may occur, which would severely hinder the athletes ability to perform at a competitive level. These cramps are often experienced post-play during recovery, between matches and between days during training and competition. With respect to exercise-related muscle cramping, there are typically two forms of cramping that tennis players are most often confronted with:
1) Overworked muscle fibers
2) Muscle cramps related to extensive sweat losses and a sodium deficit,
known as exertional heat cramps