What is the best way for athletes to carbohydrate load and what sort of athletes should consider using it?

Good - Carbohydrate loading has been demonstrated to improve endurance exercise because athletes can exercise at their optimal intensity for a longer time. Three to four days of exercise tapering while following a high-carbohydrate diet (7 to 10 grams per kilogram of body weight) is sufficient to elevate muscle glycogen levels prior to a game or competition. Performers involved in sustained activities would benefit from carbohydrate loading.

Better – Carbohydrate loading is a strategy involving changes to training and nutrition that can maximise muscle glycogen stores prior to endurance activities.It involves 1-4 days of exercise taper while following a high carbohydrate diet (7-12g/kg body weight) in an effort to elevate muscle glycogen levels. Carbohydrate loading enables muscle glycogen levels to be increased by about 50-70% and this extra amount allows endurance athletes to exercise at their optimal pace for a longer time. Anyone exercising continuously at a moderate to high intensity for 90 minutes or longer is likely to benefit from carbohydrate loading..

Comment: The better answers qualifies that endurance activities lasting longer than 90 mins benefit from carb loading rather than simply stating “sustained activities” as in the other answer. The longer the activity/competition goes for and the longer the exercise taper needs to be and the higher the amount of carbs taken in.

What is the glycemic index and does it really matter to athletes?

Good - Theglycaemic indexranks foodson a scale of 0 to 100,according to how muchthey raise blood sugarover a two-hour period, compared to pure glucose. It is important because it informs us about best food options before and after competition.

Better - The glycemic index is a measure of the effects of carbohydrates on blood sugar levels. Carbohydrates that break down quickly and release glucose rapidly into the bloodstream are high GI; carbohydrates that break down more slowly, releasing glucose more gradually into the bloodstream are low GI.

Low-GI foods release glucose slowly and steadily and have proven to be ideal pre-exercise inclusions in diets. High-GI foods cause a more rapid rise in blood glucose levels and are more suitable for fuel restoration after endurance activities (usually lasing longer than 90 mins)

Comments: The better response understands what the GI actually is and provides examples of when to take in low GI and high GI foods in relation to exercise. The better response also states an exercise duration time after which high GI foods should be considered to assist recovery.

What’s the difference between hypertonic, hypotonic and isotonic drinks - I keep picking up sports drink bottles from the supermarket fridge and am confused about their labels.

Good –

  • Hypotonic drinks haveless than 8% concentration of carbohydrate and minerals compared to normal human body fluids. These drinks are absorbed rapidly from the intestine, and are good for rapid fluid replacement during and after exercise.
  • Isotonic sports drinks generally contain carbohydrates and electrolytes at 6-8% concentration which is similar to that of most normal fluids in the human body. Isotonic concentration allows for relatively rapid absorption of the ingested fluid from the stomach and small intestines. This allows for rehydration during exercise, and supplies fuel and electrolytes to keep the athlete functioning at peak levels during endurance events.
  • Hypertonic drinks are best used after long endurance events to replenish glycogen stores, or for “carbohydrate loading” in the days prior to an endurance event. Hypertonic fluids are absorbed more slowly than isotonic or hypotonic drinks - water is drawn into the intestine to dilute hypertonic drinks prior absorption.

Better –

Isotonic drinks

Isotonic drinks have the same osmolality as the body’s own fluids, containing comparable

amounts of carbohydrate and electrolytes. Of the three types of sports drinks, isotonics are

usually preferred by athletes for their balance of refuelling and rehydration.

Hypotonic drinks

Hypotonic drinks have a low osmolality, containing lower concentrations of carbohydrate and

electrolyte particles and are therefore absorbed at a faster rate than isotonic drinks. Hypotonic drinks quickly replace fluids lost by sweating and are suitable for athletes who need fluid without the added boost of electrolytes or energy from carbohydrates.

Hypertonic drinks

Hypertonic drinks have a higher osmolality than the body’s own fluids and are absorbed more slowly than isotonic drinks. Relatively high in carbohydrate, hypertonic drinks can be used to supplement daily carbohydrate intake and are typically used after exercise to top up muscle glycogen stores. In ultra-distance events, high levels of energy are required and hypertonic drinks can be used to meet the energy requirements. If consumed during exercise, hypertonic drinks need to be used in conjunction with isotonic drinks to replace fluids.

Comment: The better answer shows a thorough understanding of what is in each of the sports drinks and when they are best consumed to assist both performance and recovery. Both answers show a high level of understanding of sport drink make up and applications.

Intravenous hydration is better than oral hydration because it allows hydration to occur quicker - do you agree with this statement.

Good – Yes - IV hydration allows for quicker absorption of water by the body’s cells than oral hydration which results in water needing to be absorbed by the gut before it can hydrate.

Better – Research actually shows very little difference between Iv and oral hydration and IV should only be used in extreme cases when performers cannot consume water orally such as when they are unconscious, about to receive medical treatment or suffering from head injuries. Evidence indicates that when equal volumes of the same concentration of fluid are used for rehydration intravenously or orally, no performance or physiological advantage exists to justify the use of IV rehydration. IV treatment is invasive, requires trained medical staff, must be given off the field, and increases risk of infection and bruising. Thus, an oral rehydration protocol usually provides a more effective and safe hydration approach.

Comment: The better response shows a deep understanding of the two forms of hydration and provides a strong argument supporting oral hydration and extreme cases under which IV hydration might be considered. It should be noted that WADA added infusions as a prohibited ergogenic method in 2006!

What sort of supplementation would athletes consider and what benefits are they seeking? (caffeine, creatine and protein)

Good – Athletes might consider creatine and protein supplementation because this increases the PC stores and also rebuilds damaged muscles quicker. Protein is a low efficiency fuel source and not often used.

Better - Caffeine is used as a central nervous system stimulant and circulatory and respiratory stimulant. Caffeine intensifies muscle contractions and even speeds up the use of the muscles’ short-term fuel stores. Caffeine is thought to improve performance by increasing the utilisation of fat as an exercise fuel and ‘sparing’ the use of the limited muscle stores of glycogen (glycogen sparing) but only in first 15–20 minutes of sub-maximal performance.

Creatine salts, in contrast with creatine monohydrate, are more easily soluble and stable in solution and thus sometimes added to sports drinks or gels. Rapid loading may be achieved by five days of repeated doses. Once the muscle creatine content has been saturated it takes about four weeks to return to resting levels. A daily dose (maintenance dose)of 3–5 g will allow elevated levels to be maintained These protocols will increase creatine muscle stores by 20 to 50%.

Most beneficial for athletes:

involved in repeated short maximal efforts with brief recovery periods

engaged in short interval training

undertaking high intensity resistance training seeking to increase protein synthesis

Protein supplementation is mainly used by athletes calling upon power and strength, such as body builders and weight lifters, as a means of developing and maintain skeletal muscle, and it:

  • promotes glycogen resyhtesis
  • provides the raw material for both muscle construction and repair
  • plays an important role in the immune system
  • is critical to the endocrine (hormone production) system
  • facilitates the transmission of nerve impulses throughout the nervous system
  • prevent sports anemiaby promoting an increased synthesis of haemoglobin, myoglobin, oxidative enzymes

The better answer looks at the benefits of each type of supplementation as well as comparing and contrasting the different practices with each other