Energy systems

Energy systems

1. Energy = capacity to do work

   • Potential or kinetic
   • 1kcal = 4.2kJ
   • LAW OF THERMODYNAMICS = energy cannot be created or destroyed/ net heat heat supplied is equal to work done

2. FREE ATP

   • small ATP store in muscle = 8mmol/kg wet weight of muscle
   • power exercise for 2s
   • energy from phosphate bonds

3. PHOSPHAGEN SYSTEM

   • = ATP/PCr system
   • delivers most ATP for up to 6s
   • explosive, short activities
   • phosphocreatine split into creatine and a free phosphate by action of enzyme creatine kinase >> releases energy
   • Creatine supplementation
     • can't increase creatine stores in muscle and liver
       • upper limit of 150-160mmol/kg dried muscle
     • can increase recovery of phosphocreatine if person has low levels of creatine

4. GLYCOLYSIS

   • >> breaks glucose into 2 pyruvate and produces net 2 ATP
   • Key enzyme = phosphofructokinase
   • Pyruvate destination
     • Lactic acid
       • dissociates into lactate and H+
         • why lactate rises
           • increase in sympathetic activity and adrenaline release during exercise increases PFK activity
           • increase in ADP and Pi from dephosphorylation
           • increase in fast twitch muscle fibre recruitment
     • Krebs cycle

5. AEROBIC SYSTEM

   • Pyruvate oxidised to form acetyle coA which enters Krebs cycle
     • catalysed by pyruvate dehydrogenase complex
   • Krebs cycle
     • = catabolic energy transfer
     • acetyl coA substrate broken down to form H+ and CO2
     • net 2 ATP f4rom 1 molecule of glucose
   • Chemiosmosis
     • redox reaction generate enough energy to pump hydrogen ions into space between inner and outer mitochondrial membrane
       • hydrogen ions build up and then flood back into inner membrane
         • generates energy - used to join ADP and Pi >> ATP
           • 1 molecule of glucose >> 34 ATP
             • final reaction = hydrogen and oxygen combine >> H2O