2.  In high intensity exercise longer than 2 seconds ATP is resynthesized using PC (stored in muscles) CP High energy bond PC stores are limited so ATP can only be resynthesized in this way for upto 10 seconds

3.  This process involves 2 immediate reactions which take place within the muscle cell sarcoplasm.  When PC is broken down energy is released: CP Energy

4. CP Same energy is then used to resynthesize ATP Energy ADPATPP PC => P + C + Energy (Exothermic Reaction) Energy + ADP + P => ATP (Endothermic Reaction) Enzyme responsible for the breakdown of PC is Creatine Kinase

5.  When energy produced by one reaction is used in another reaction it is known as a COUPLED REACTION.  Therefore the resynthesis of ATP using PC is a COUPLED REACTION  The breakdown of PC is ANAEROBIC.

6.  Which of the following activities use the ATP- PC system? (you must be able to justify your choice(s))

7.  Correct Answers:  Why? – because they all last less than 10 seconds  Wrong Answers:  Why ? – Because they last longer than 10 seconds

8.  No Oxygen is used and no lactic acid is formed in this system – therefore it is also called the Alactic Anaerobic System  The main advantage of the ATP-PC system = it is a very immediate source of energy

9.  When hard exercise is longer than 10seconds (beyond ATP-PC threshold) and all PC is used up, ATP then has to be resynthesized by a different system – LACTIC ACID SYSTEM  Therefore the point at which we switch from the ATP-PC System to the Lactic Acid System is known as the ALACTIC-LACTIC THRESHOLD

10.  Speed endurance and power athletes use anaerobic work in order to delay the onset of the Alactic-Lactic Threshold.  Anaerobic work causes biological adaptations that allow muscle cell sarcoplasm to contain more ATP and creatine so ATP-PC system provides energy for longer at the highest possible rate.  Some athletes use daily Creatine supplements to increase the total muscle creatine.

11.  Complete the Homework sheet for next lesson.