Hydration for Athletes for Competition
To add another layer of complexity to the issue, human sweat contains far more than just water. Electrolytes (electrically charged ions such as sodium, potassium, calcium, and magnesium) are also lost and must be replaced along with the fluid. While many electrolytes can be obtained from the food we eat, there may be advantages to replacing them during exercise as well; most notably sodium, which may be considered the most important electrolyte to replace during periods of heavy sweating.
The importance of proper hydration and electrolyte balance to performance cannot be underestimated, and these materials can be thought of as the foundation upon which everything else is built.
Devil is in the detail: There are numerous variables to consider, the most important of which are the quality of the water and the balance and quality of electrolyte replacement.
When undergoing a rigorous training programme or competing, there is a significant drain on body stores of vital electrolytes to ensure that the level of resistance can be maintained for as long as possible.
The metabolic waste products will be expelled through perspiration, breathing, urination, and defecation, resulting in thirst - the need to replenish the water and electrolytes used in energy creation.
Dehydration compromises cardiovascular function by decreasing blood flow to muscles and cardiac output. The resulting increase in heart rate causes a decrease in stroke volume. Hypovolemia hampers an athlete’s thermoregulation. The more hyperthermic an athlete is, the greater their work capacity decreases.
Low blood volume, from dehydration, also thwarts oxygen and glucose transport to muscle cells. At just a 2% loss in body fluids, an athlete’s performance is impaired. Fatigue and performance impairment caused by dehydration can cause athletes to compromise their physical mechanics. Therefore, not only does dehydration impair performance, it indirectly raises an athlete’s risk of injury and directly raises their risk for heat-related illnesses.
Hyperhydration: Equally important to performance and hydration is ensuring an athlete does not drink more than their fluid and electrolyte losses. When serum sodium levels are diluted to less than 130 mEq/L, intracellular swelling occurs and alters central nervous system function.
This is labelled symptomatic hyponatremia and can occur when athletes drink in excess of their fluid losses, deplete their extracellular fluid sodium by heavy sweat loss, or a combination of high fluid intake and excessive sweating. Hyperhydration has no beneficial exercise performance effects.
Symptomatic hyponatremia and dehydration are negatively associated with exercise performance.
Psychological Role of Electrolytes:
- Modulators of Energy Production
- Modulators of Energy Storage
- Modulators of Energy Use (i.e. metabolism)
- Regulators of Total Body Fluid Levels
Most Important Electrolytes:
- Sodium is found outside the cell and is primarily responsible for fluid balance.
- Potassium is found inside the cell and regulates metabolism.
- Magnesium regulates levels of other electrolytes and muscle relaxation.
- Calcium regulates muscle contraction and heart rhythm.
These electrolytes are mostly bound to chloride, bicarbonate, sulphate and phosphate ions.
What is The Correct Physiological Balance of Electrolytes?
-> Balance is unique to the person in question. Despite significant physiological similarities, we are all biochemically unique.
Some athletes will require more electrolytes than others.
Recognising that electrolytes play distinct physiological and psychological roles at the cellular level has led many sports nutritionists to advise athletes to pay close attention to their diets and consume as wide a variety of fresh fruit, vegetables, naturally grown grains, and reared meats and fish as possible.
Safe Hydration Strategies:
1) Before Training or Competitions
Drinking in excess before exercise can have the opposite effect desired: gastrointestinal issues and impaired performance 1.
Choosing liquid fuel reduces gastric emptying time and residual intestinal load, which may be advantageous for nervous athletes or athletes who need to "make weight" before the competition 1.
2) During Training or Competitions
Maintaining proper hydration by drinking during exercising has the greatest beneficial impact on the performance of any single nutritional intervention 1.
- Start drinking water early and at regular intervals
- Replace sodium electrolytes during periods of heavy sweating
It may be sufficient to use bodyweight change data to identify athletes with exceptionally high sweat volume losses and to monitor them during longer, hotter, or more intense training sessions and competitions. These athletes may benefit from having access to more fluids than other athletes.
Precaution: Telling athletes with higher sweat loss how much to drink or forcing them to replace their losses as quickly as those with lower sweat rates may cause more harm than good, especially if their losses exceed the stomach's gastric emptying rate.
3) After Training or Competitions,
Making sure athletes refuel their depleted energy, fluid, and electrolyte stores after competition or practice is part of ensuring they are properly fueled for their next practice or competition. This may take up to 24 hours. Rapid muscle glycogen repletion is especially important after exercise if an athlete must exercise more than once in 24 hours. The body recovers best when an athlete begins refuelling as soon as they finish exercise 1.
Despite their efforts to replace fluids, athletes are frequently mildly dehydrated after exercise. This can impair subsequent exercise performance 1.
Although an exact sodium recommendation has not been developed, the evidence is clear regarding sodium's role in encouraging plasma and total body rehydration through increased sodium intake 1.
It may be beneficial to select fluids with flavour and sodium. This encourages athletes to consume more fluids.
- After exercise, chilled beverages are also more commonly consumed and are beneficial.
- Athletes should be warned that drinking beverages with more than 4% alcohol content may cause delayed physical recovery from exercise.
- Calories consumed in the form of alcohol or fat may deplete needed carbohydrates, which are a priority for proper muscle glycogen synthesis.
Learning what works for your own body and exercise habits, using a combination of scientific knowledge, recognising thirst sensations, and good old-fashioned trial and error, are probably the best ways to discover what works for you or the athletes you work with.
"Some athletes have been measured as loosing as little as 2.3 grams of sodium during a 4.5 hour training session, with others losing 30 grams during the same time period."