[HNF 126] - Topic V

• Hydration


  The more client sweats, the more care they should take to avoid dehydration
• Fluid loss


  For every 1 kg decrease in weight represents a loss of approximately 1 L of fluid
• Dehydration


  Impairs performance and has an adverse effect of health
• As blood volume decreases, and body temperature rises


  It places extra strain on the heart, lungs and circulatory system, which means the heart must work harder to pump blood around your body
• Effects of dehydration


  • 1% - Generates thirst sensation
  • 2-3% - Impaired performance and increased body temperature
  • 4% - 2—30% decrease in endurance performance, Symptoms: fatigue, nausea, vomiting and diarrhea
  • 5-6% - Heat cramps, chills, nausea, clammy skin, rapid pulse. Dehydration from this point onwards can be fatal---children and older people are more at-risk
  • 6-10% - Reduced sweat and urine production, weakness, headaches, dizziness, confusion, dry mouth
  • Over 10% - Can be life-threatening heat stroke, hallucinations, unsteady walk, no urine or sweat produced
• Exercise hydration strategies


  The side effects of being dehydrated can range from mild discomfort through reduced sport or exercise performance to death when dramatic loss occur
• The sports drinks market has increased dramatically over the past years. Sport drinks these days make a variety of different claims.
• Determining suitable drink


  Dependent on the type of exercise and state of preferences of that individual
• Dehydration


  Cumulative, which means you can easily become dehydrated over successive days of training or competition if you fail to rehydrate fully between workouts or races
• Symptoms of dehydration


  • sluggishness
  • a general sense of fatigue
  • headaches
  • loss of appetite
  • feeling excessively hot
  • light-headedness
  • nausea
• Urine output color


  A surprisingly accurate way of assessing hydration status. "Very pale yellow" or "pale yellow" indicates that you are within 1% of optimal hydration
• Losing weight through exercise in sweatsuits is not only potentially dangerous but has no effect whatsoever on fat loss!
• Any weight loss will simply be fluid, which will be regained immediately when you next eat or drink
• The exercise may seem harder because you will be sweating more, but this will not affect the body's rate of fat breakdown
• If anything, you are likely to lose less fat, because you cannot exercise as hard or for as long when you wear a sweatsuit
• Timing of hydration: Pre-training

  ACMS: 5 to 7 ml of fluid per kg/BW slowly between 4 and 2 hrs. before exercise or training
• 110 to 250ml 5 to 10 minutes before exercise is not a bad idea as this will be available to replace sweat losses immediately
• The IOC cautions against over-drinking before and during exercise, because of the risk of water intoxication
• Timing of hydration: during exercise

  Significant fluid losses will result in a drop in performance for most (non-elite) athletes, so experts advise limiting dehydration to less than 2% of your body weight
• In cold environments, dehydration greater than 2% is likely to be better tolerated
• Dehydration of up to 3% has little effect on strength, power and sprint exercise
• Studies have shown that you can maintain optimal performance if you replace at least 80% of your sweat loss during exercise
• Appropriate Drinks Per Activity Type

  • Exercise lasting than 30 minutes - Nothing or water if thirsty
  • Low –moderate intensity exercise lasting less than 1 hr - water
  • High-intensity exercise lasting less than 1 hr - Hypotonic or isotonic sports drink
  • High-intensity exercise lasting more than 1 hr - Hypotonic or isotonic sports drink, or glucose polymer drink
• Fluid loading (hyperhydration)


  Glycerol is a hyperhydrating agent, which through its strong osmotic activity, drags water into both extracellular and intracellular fluid. This results in an increase in total body fluid.
• Studies at the Australian institute of sports found that by doing this, athletes retained an extra 600 ml of fluid and improved performance in a time trial by 2.4%
• The potential performance benefits should be weighed up against the possible side effects, which include gastrointestinal upsets and headaches
• Practical hydration tips


  • ACSM recommends cool drinks (15 to 22 degrees centigrade)
  • You will also be inclined to drink more if the drink is palatable and in a container that makes it easy to drink
  • Studies have shown that during exercise, athletes voluntarily drink more of a flavored sweetened drinks than water, be it a sports drink o, diluted fruit juice or fruit squash
• Practical drinking tips


  • Bottles with sport caps are probably the most popular containers
  • It is also important to make drinks really accessible" for example, for swim training have drinks bottle at the poolside for games played on a pitch or court (football, hockey, rugby, netball, tennis) have the bottle available adjacent to the pitch or court
• Sports drink or water?

  • During low or moderate intensity activities such as easy pace swimming, cycling, or power walking carried out for LESS than 1 hour, fluid losses are likely to be relatively small and can be replaced fast enough with plain water
  • During high intensity exercise lasting LESS than 1 hour, drinking a sports drink containing up to 8g sugar per 100mL rather than water may benefit your performance
  • During high intensity exercise lasting LONGER than 1 hour, you require rapid fluid replacement as well as fuel replacement. A sports drink would help prevent this
• Carbohydrates in Drinks


  • Less than 45 min - None
  • 45 to 75 min - Mouth rinse/very small amounts
  • 1 to 2 hr - Up to 30 g/hr
  • 2 to 3 hr - Up to 60 g/hr
  • 3 hrs - Up to 90 g/hr
• Drinking too much water

  • Water intoxication and hyponatremia sometimes happens in long distance runners or triathletes who consume a lot of water and lose a lot of salt through sweat
  • Consequently, the amount of salt available to body tissues decreases, which can lead to problems with brain, heart and muscle functions
• An advisory statement in marathons on fluid replacements written for the international marathon medical directors association and USA track and field advises endurance runners not to drink as much as possible but to drink ad libitum no more than 400-800 mL per hour
• Timing of hydration: after exercise

  • Both water and sodium need to be replaced to restore normal fluid balance after exercise
  • Ideally, your client should drink approximately 1.2-1.5 times the weight of the fluid loss during exercise
• Its not advisable to drink the whole amount straightaway, as a rapid increase in blood volume promotes urination and increases the risk of water intoxication
• Sports drink vs water for recovery

  Sports drink maybe better than water at speeding recovery after exercise, particularly when fluid losses are high or for those athletes who train and compete twice a day
• Best post-exercise drink


  • Skimmed milk may be even better option at promoting post-exercise rehydration
  • Consuming a drink containing CHO with small amounts of protein improves fluid retention after exercise
• Water intake on non-exercising day

  • The quantity of water need to ensure optimum health is often quoted as around 8 glasses of water, which equates to about 2-2.5L per day
  • Fluid intake should be continuous throughout the day and can be taken in many ways, not only through the liquids taken on board, as for many people most of the fluid they consume each day is within the food they eat