energy systems in exercise and physical activity

Question 1

energy systems

Answer 1

all energy released by body is created by splitting of a chemical bond from the substance adenosine triphosphate (ATP)
ATP = energy currency ~ carbs, protein and fats converted into before used as energy
all potential energy stored between the adenosine molecule and the 3 attached phosphates
energy is released from ATP as one of phosphate groups splits ~ this converts ATP to ADP (adenosine diphosphate)
ADP cannot be used as energy so needs to be converted back to ATP
the body stores only very small amounts of ATP at any given time, so the three energy systems are concerned with how the body obtains ATP (from nutrients), or how ADP is reconverted back into ATP

Question 2

creatine phosphate system (CP)

Answer 2

CP system is the body’s fastest method of replenishing ATP ~ reconverts ADP back to ATP
creatine found naturally in body and stored in muscles in small quantities
required to shuttle a phosphate molecule towards ADP in immediate demand for energy
when phosphate bonds with ADP becomes ATP again
anaerobic process because no oxygen requires
this system is able to fuel maximal muscular activity for up to 10 secs before muscle CP stores become depleted

Question 3

the lactic acid system

Answer 3

also activated during high intensity exercise (not maximal) lasting between 2-3 mins
also referred to as ‘anaerobic glycolytic system’ ~ breakdown of stored forms of carbohydrates to release ATP
when glycogen broken down into glucose and then ATP, large volumes of lactic acid are produced as a consequence
lactic acid is a metabolic by product that has potential to interfere with muscles ability to contract ~ because energy releasing reactions are dependent on a stable chemical environment and lactic acid disrupts this
must be removed to continue - rest or lower intensity
when lactic acid is removed from muscles by the circulatory system it is transported to the liver where can be converted back to glucose
lactic acid is not a waste product but a by-product of anaerobic energy production from carbs

Question 4

aerobic pathway

Answer 4

aerobic energy system is body’s most efficient energy system ~ can use a variety of nutrients in order to release ATP (anaerobic cannot)
wholly dependent on oxygen = not able to respond as quickly as the anaerobic pathways
before energy can be released cardiovascular system must transport oxygen to muscles
not only used to fuel prolonged modes of exercise ~ most dominant at rest and low intensity
largely takes place in slow twitch muscle fibres rich in mitochondria
mitochondria can burn oxygen and other nutrients to produce ATP

Question 5

the energy system continuum

Answer 5

1-4 seconds ~ anaerobic ~ stored ATP in muscles
4-20 seconds ~ anaerobic ~ ATP and CP
20-45 seconds ~ anaerobic ~ ATP, CP and glycogen
45-120 seconds ~ anaerobic ~ Muscle glycogen
120-240 seconds ~ aerobic and anaerobic ~ muscle glycogen and lactic acid
240-600 seconds ~ aerobic ~ muscle glycogen and fatty acids