Biathlon

To sustain a fast running and swimming speed over prolonged periods of time as well as transition from one to the other. The key physiological attributes required to do this, are:  A high capacity to utilise oxygen (VO2 Max)  An ability to run a relatively fast speeds without accumulating high concentrations of lactic acid in the muscles  An ability to swim and run fluently and economically  Seamlessly transition from one discipline to the other

 The body has a choice of three systems to provide energy for muscular work and exercise, including two anaerobic and one aerobic.  Understanding how these energy systems contribute to energy production and their limitations is an important aspect of improving physical performance.  Which of the energy systems is used depends on the intensity and duration of the activity.

 Muscles require energy to contract or perform muscular work  This energy is produced by the breakdown of a molecule known as adenosine triphosphate (ATP).  There are three energy systems that the human body uses to provide the energy for the production of ATP.  These are: the creatine phosphate system, the lactic acid system and the aerobic system.

 ATP is found in all cells  Needed to perform almost every function in the body  ATP is adenosine and three phosphate groups.  When energy is required for muscular work – like when we exercise – a chemical reaction takes place in which ATP is split at the third phosphate molecule and energy is released.

 There is only a short supply of ATP in the muscle cell, therefore our bodies need to continually remake or resynthesise ATP to sustain the exercise or muscular work needed for daily activities.  Once the ATP molecule is split and energy is released, the ATP must be reformed using another source of energy if the muscular work is to continue.  This energy to resynthesise ATP is obtained from one of three energy systems (that we mentioned earlier)

 We have three ways to recharge the high energy stores so they can continue muscular work or be ready to work again at a later stage.  Two of these systems depend on the food we eat, the other depends on another high energy compound found in the cells called creatine phosphate.

 Creatine phosphate is readily available in muscle cells and rapidly produces ATP.  Like ATP, CP is only available in short supply in the muscles, therefore it can only provide limited amounts of ATP to the muscles so it can keep working.  Fortunately the body can also use the energy from food sources such as carbs, fats and proteins to provide energy to resynthesise ATP

 Carbohydrates are the primary source of ATP production.  Obtained from foods such as bread, grains, pasta, fruits and vegetables and are known as complex carbohydrates  Carbs are converted into glucose which is transported to the muscles via the bloodstream from the intestine.

 These sources of glucose can become depleted quickly during prolonged, intense exercise and so carbohydrates must be replenished daily through a balanced diet.  You will need to think about your carbohydrate intake before undertaking exercise lasting longer than 1hr. Many endurance athletes utilise carbohydrate loading to increase muscle glycogen stores and therefore delay the onset of fatigue.

 What could happen if we do not balance energy input with energy expenditure?

 Fats can produce large amounts of ATP  Obtained from foods such as dairy products, nuts, fatty meats and oils.  Fats are the body’s preferred energy source when at rest or performing low-intensity activities such as walking.  Aerobic training increases fatty acid breakdown during exercise of mild to moderate intensity, which in turn spares glycogen stores and allows the trained individual to exercise more for longer, before tiring.

 Proteins contain amino acids which are the building blocks of our body and are essential for growth and repair  Obtained from foods such as meat, fish, eggs and dairy products.  In extreme cases, amino acids can be used to provide energy to resynthesise ATP.

1. Refer to the “Sports and nutrition” fact sheets on the Australian Institute of Sport website at Read the fact sheets on ‘Competition and training’ and select a protocol that is most relevant for your type of training 3. Prepare a daily meal planner (for one meal or for the whole day) based on the recommendations. You may wish to conduct further research using the Australian Healthy Eating Guidleines or other fact sheets on the website, to assist and inform your plan and understanding of the food fuels (carbs, fats and proteins).