energy for exercise

• how is ATP broken down


  ATPase is released which is an exothermic reaction. this releases energy for muscular contraction and leaves ADP + Pi.
• how is ATP resynthesised

  endothermic reaction. energy absorbed rebuilds bond between P and ADP
• characteristics of the ATP-PC system


  after first 2 seconds of intense activity. release of creatine kinase which catalyses breakdown of phosphocreatine. phosphocreatine in broken down anaerobically in the sarcoplasm. bond between ATP and PC is broken, releasing energy. one mole of PC broken down, one mole of ATP is resynthesised. this forms a coupled reaction where breakdown of PC releases free phosphate and energy to resynthesises ATP.
• characteristics of glycolytic system


  10 seconds after intense activity. release of phosphofructokinase which catalyses the breakdown of glucose. glycogen phosphorylase catalyses breakdown of glycogen, converting glycogen into glucose. anaerobic glycolysis is when glucose is broken down in the absence of oxygen, resulting in the production of pyruvic acid. one mole of glucose broken down results in a net production of 2 moles of ATP. lactate hydrogenase is released and catalyses the conversion of pyruvic acid to lactic acid which slows ATP re synthesis.
• characteristics of the aerobic system


  low to moderate exercise as there is sufficient oxygen to enable energy production. aerobic glycolysis occurs in the sarcoplasm and converts glucose into pyruvic acid through the enzyme PFK. this produces 2 moles of ATP. as there is enough energy being produced and enough oxygen, pyruvic acid isn't converted into lactic acid. the Krebs cycle is when acetyl con combines with oxaloacetic acid to form citric acid which is then oxidised. two moles of ATP is released. occurs in the matrix of mitochondria. the electron transport chain - hydrogen atoms are carried along the etc along the crustal of mitochondria by NAD and FAD, splitting into ions and electrons. hydrogen carriers provide enough energy to release 34 moles of atp. the net production of atp from the aerobic system is 38 moles.
• how do free fatty acids provide energy


  triglycerides can be metabolised aerobically as ffa's provide a large fuel store which conserves glycogen and glucose. lipase is released and converts triglycerides into ffas and glycerol. ffas are converted into acetyl coa and go through the Krebs cycle. used in low intensity exercise.
• energy continuum


  intensity is very high - duration is less than 10 seconds, atp-pc system will be predominant contributing up to 99% of energy for atp resynthesis. high intensity - 10s-3 minutes e.g. 400m run, glycolytic system will be predominant, contributing 60-90% of energy for atp resynthesis. low-moderate intensity - over 3 mins e.g. marathon, triathlon etc. the aerobic system would be predominant in this case, contributing up to 99% of energy for atp resynthesis.
• intermittent exercise


  where intensity varies during an activity or training. threshold - the point at which an athletes predominant energy production moves from one energy system to another.
• recovery periods


  atp-pc store - 30s for 50% regeneration, 3 minutes for 100% regeneration. myoglobin stores can be fully replenished in 3 mins. blood lactate levels rise dramatically with prolonged high-intensity. during low-intensity exercise, blood lactate is removed with the right amount of oxygen present. recovery periods also present the opportunity for rehydration and glucose replenishment.
• fitness levels


  athletes with a high aerobic capacity or vo2 max has an efficient process of inspiring, utilising and transporting glucose and oxygen. this increases intensity of and duration of exercise. buffering capacity is increased, limiting effects of lactic acid as it is flushed out by oxygenated blood. more free fatty acids can be broken down as more oxygen is available.
• other factors affecting relative contribution of energy systems to overall energy production


  player's position - e.g. a goalkeeper's predominant energy system would be aerobic system, whereas a midfielder would use different systems as they attack and defend. tactics and strategies - e.g. kicking for a line out to allow some of the ATP-PC store, man on man vs zonal marking. level of competition - in a harder match, the intensity will be higher, increasing contribution from anaerobic energy system. structure of the game - large pitches increase the duration of the game and lowering the intensities of set plays. this increases the contribution of the aerobic energy system.