Nutritional Strategies to enhance performance

Carbohydrates

The body uses glycogen for periods of high intensity short duration activity as well as those of lower intensity and longer duration. Therefore it is vital for many activities that nutritional strategies are put in place to maximise the amount of glycogen available for ATP production.

Glycaemic Index (GI)

Is the rate at which carbohydrates are absorbed into the bloodstream.This varies depending on the type of sugars present in the food. Foods are given a ranking out of 0-100 that gives an indication of the speed at which they raise glucose levels within the blood. An example of foods with high GI would be lollies whilst foods like porridge have a much lower GI as they release sugars slower into the blood stream.

Pre-event Carbohydrate(CHO) intake

  • (aimed to maximise glycogen stores and availability of glucose)
  • 3-4 hours prior to the event a light meal with moderately high GI should be eaten.
  • 1-2 hours prior to the event: A small snack with high GI should be eaten.
  • less than 1 hour prior to exercise: sports drinks and lollies should be consumed with high GI.

During the event

High GI foods can be eaten as these top up glycogen stores and can prevent fatigue cause by running out of glycogen. A popular alternative to foods during the event may be CHO gels which are concentrated fluids with high GI content they are often taken with water to not upset the stomach but they allow for a large amount of quick and ready to use glucose.

Post-event Carbohydrate intake

  • (aimed to replenish glycogen stores.)
  • Best done in the time frame of 30-60 minutes post exercise as this is when the body is looking to uptake glucose to replenish stores.
  • The food or drink should be high GI and low in fibre.

Strategies used to increase and preserve glycogen stores

Glycogen sparing

Is a result of aerobic training that can be used in long distance endurance events where the athlete has a highly developed aerobic system so that instead of using glycogen stores they can oxidize fats to provide ATP for exercise this enables them to spare oxygen without decreasing intensity. This allows the athlete to work at a higher intensity for longer before glycogen stores run out.

Carbohydrate loading

Is where the athlete consumes  larger amounts of carbohydrates in their diet prior to an event so that their glycogen stores are full. This will ensure that they do not experience fatigue as a result of glycogen depletion.

Protein supplements

Protein is needed to help repair and build muscle. Therefore it is important that athletes have a sufficient amount of protein in their diets.

Post-exercise protein consumption

Protein is often consumed in conjunction with carbohydrates  after exercise as the protein helps with the intake and storage of carbohydrates allowing the athlete to replenish their glycogen stores quicker.

Fats

  • Fats are important as they are the predominant fuel used at sub-maximal intensities .
  • At rest as fats provide high amounts of energy.
  • Athletes that are highly trained are able to use fats over glucose at the beginning of exercise in order to preserve glycogen stores.

Creatine supplementation

Creatine can be made by the body and is obtained from the diet. It may be beneficial for athletes participating in explosive high intensity activities to take these supplements in order to increase creatine phosphate stores and therefore delay fatigue caused by the depletion of this fuel. However data suggests the improvement in stores caused by this type of supplementation is limited.

Possible side-effects may include

  • Nausea
  • Cramps
  • Diarrhoea

Caffeine supplements

Caffeine is a stimulant it works to increase performance by

  • Increasing alertness and stimulation of the nervous system (this would be useful for power athletes taking part in explosive power movements eg. shot put)
  • Increasing fat usage (this would be beneficial for long distance athletes at it would help hem glycogen spare by using fats before using glycogen to supply energy)
  • Decreasing perceived exertion this would be useful to all athletes as they would feel like they are working at a lower intensity then they actually are in reality.

Possible side effects include

  • Muscle tension
  • Anxiety
  • Acts as a diuretic and can cause dehydration as adequate fluid is not taken in to compensate for this.