TRIATHLON NEW ZEALAND – TRI SCHOOLS Energy Systems

ENERGY SOURCES Carbohydrates: FOOD FOR WINNING ENERGY SOURCES Carbohydrates: Main fuel source for both mental and physical activity. Broken down into Glucose- Stored primarily in the muscle as Glycogen. Fats: Primary fuel source used at rest and at lower intensity exercise. Broken down into Lipids and Fatty Acids- Stored in the body as adipose tissue. Protein: Use to repair/build muscles Used as energy (only 5-10%) with intense training or if CHO intake is inadequate Broken down into Amino Acids

PLANNING THE TRAINING Muscle Contraction In the mitochondria, ATP (adenosine tri-phosphate) is broken down which releases energy which in turn causes the muscle fibres to contract the muscle.

PLANNING THE TRAINING Muscle Contraction

The ATP Molecule Adenosine Tri-phosphate (ATP) P Adenosine P P b. The breakdown of ATP into ADP + P: P Adenosine P P Energy Energy for cellular function to contract working muscle

PLANNING THE TRAINING The ATP Molecule Unfortunately there is only enough ATP in the muscles to last for 2 seconds. The body has 3 other systems to replenish ATP to ensure we can keep exercising.

ATP Production at Rest ATP replenish with the use of Oxygen (Aerobic) PLANNING THE TRAINING ATP Production at Rest ATP replenish with the use of Oxygen (Aerobic) Uses 75% Fats (lipids) and 25% CHO (glycogen) Wastes products and expired and breathed out

ATP Production during Exercise PLANNING THE TRAINING ATP Production during Exercise ATP-CP System Anaerobic (Lactic Acid) Glycolysis Aerobic Glycolysis

Energy System Interplay PLANNING THE TRAINING Energy System Interplay The interplay of energy systems refers to the dominant energy system at any given time during an event. All energy systems make ATP from the start of physical activity. However, one is more dominant than the others at particular times, depending on the intensity & duration of the activity.

Energy System Interplay PLANNING THE TRAINING Energy System Interplay The following graph shows the energy supply when cycling for 200 seconds to exhaustion.

PLANNING THE TRAINING ATP-CP Energy System Replenishes ATP rapidly by breaking down Creatine Phosphate releasing energy to reform ATP Short duration (<10 secs) Active at the beginning of all forms of activities Especially important in high intensity exercises like weight lifting that require short bursts of energy. Only a small quantity of PC can be stored. Athletes do try to load up with supplements

Anaerobic (Lactic Acid) Glycolysis PLANNING THE TRAINING Anaerobic (Lactic Acid) Glycolysis Breakdown of carbohydrates (glycolysis) for fuel when without oxygen eg beginning of exercise or high intensity workout >85% of HRmax Results in formation of lactic acid, which causes muscle fatigue Last for 10 seconds to 2 minutes 1 molecule- 3 ATP molecule

Aerobic Glycolysis Replenishes ATP with the use of oxygen PLANNING THE TRAINING Aerobic Glycolysis Replenishes ATP with the use of oxygen Efficient- 1 molecule- 36 ATP molecule System works at rest and during very low intensity exercise This form of energy primarily utilizes fats (75%) and carbohydrates (25%) as fuel sources, but as intensity is increased there is a switch from fats (25%) to carbohydrates (75%)

PLANNING THE TRAINING Anaerobic Threshold The AT, also known as the lactate threshold, is the point where lactate (lactic acid) begins to accumulate in the bloodstream. Body moves from predominately using the Aerobic to Anaerobic system. Untrained individuals have a low AT (approximately 55 % of VO2 max), and elite endurance athletes, a high AT (approx. 80 - 90% of VO2 max).

Oxygen Uptake Increases sharply at onset PLANNING THE TRAINING Oxygen Uptake Increases sharply at onset Levels off within a few minutes if pace is constant (steady state)

Maximal Oxygen Uptake (VO2 max) PLANNING THE TRAINING Maximal Oxygen Uptake (VO2 max) VO2 is the amount of oxygen taken in, distributed and utilized by the body to produce energy. VO2 maximum is the maximal amount of O2 the body can take up & use in 1 minute for every kilogram of body weight. VO2MAX, together with LT (Lactate Threshold) are the most accurate measure of aerobic fitness. VO2MAX can be calculated in a maximal laboratory test. The intensity progressively increases until a pace is reached or the power output required is so high that the athlete is exhausted. Expired air is collected through a mouthpiece and analysed by a computer. The respiratory exchange ratio (RER) is a ratio of carbon dioxide production compared to oxygen consumption.