ENERGY
ENERGY
Exercise and Sports Physiology
ENERGY: the ability to perform work or put mass into motion
(joules).
WORK: the ability to apply force over a distance (work = force
(N) x distance moved (m)) (joules or newtons).
POWER: the rate at which we can work/work (FxD) divided by time
(w).
KINETIC ENERGY: energy is the form of muscle contraction/joint
movement.
ATP (adenosine triphosphate): a chemical energy stored as a high
energy compound in the body – an immediate source of energy.
EXOTHERMIC: a chemical reaction that releases energy.
ENDOTHERMIC: a chemical reaction that requires energy.
COUPLED REACTIONS: when the products from one reaction are then
used in another.
SACROPLASM: fluid-like gelatine that fills the spaces within the
muscle cells and is a store of glycogen, fat, proteins, enzymes and
myoglobin.
MATRIX: intracellular fluid within the mitochondria where
oxidation takes place.
MITOCHONDRIA: small sub-unit sites of a muscle cell where
aerobic respiration takes place.
CRISTAE: internal membrane like structure within the
mitochondria.
ATP/PC SYSTEM
ATP is an anaerobic reaction which sites in the muscle cell
sarcoplasm. The controlling enzymes are ATPase and Creatine Kinase.
It’s net total of ATP is 1.
Structure of ATP
Advantages:
· Doesn’t require oxygen.
· PC stored in the muscle cell is readily available energy
source.
· Simple/small compound; very quick reaction and
resynthesis.
· Provides energy for explosive high-intensity exercise and
movements.
· No fatiguing by-products.
Disadvantages:
· Only small amounts of ATP and PC stored in the muscle
cells.
· 1 PC resynthesizes 1 ATP.
· Only provides energy to resynthesise ATP for up to 8-10
seconds.
ATP Resynthesis
This is a reversible endothermic reaction which require energy
from 1 of the 3 systems to resynthesise ADP back to ATP. The 3
energy systems work together to supply energy to do this via
coupled reactions.
LACTIC ACID SYSTEM
CHO stored in the muscle/liver as glycogen is converted to
glucose by the glycogen phosphorylase enzyme. The glucose then goes
through anaerobic glycolysis by PFK, which converts it into pyruvic
acid. Due to the lack of oxygen (because it’s anaerobic), the
pyruvic acid is converted to lactic acid by the LDH.
Advantantages: large about of glycogen in our bodies; therefore
it can provide more ATP than PC. Few chemical reactions therefore
it is quick for high intensity activities. No delay – no
oxygen.
Disadvantages: there is a by-product; lactic acid which inhibits
enzyme action.
3. ELECTRON TRANSPORT CHAIN (ETC)
The hydrogen atoms combine with the coenzymes NAD and FAD to
form NADH, which is carried down the ETC where the hydrogen is
split into H+ and E-. this provides sufficient energy to
resynthesise 34 ATP. The H+ ion combines with O2 to form H20.
Overall the aerobic system produces 38 ATP (aerobic glycolysis 2,
kreb’s cycle 2 and ETC 34).
Advantages: large glycogen and FFA stores available as efficient
energy fuels, large ATP resynthesis (38), provides energy for
low/moderate intensity high duration exercise and no fatiguing
by-products.
Disadvantages: slowest rate of ATP, requires more O2, more
complex series of reactions and limited energy for high intensity
work.
2. AEROBIC ENERGY SYSTEM
The Acetyl CoA from stage 1 combines with oxaloacetic acid to
form citric acid, which is then further broke down within the
matrix of mitochondria. Four actions take place here:
1. CO2 is produced and removed via the lungs.
2. Hydrogen atoms are removed through oxidation.
3. Energy is produced to resynthesise 2 ATP molecules.
4. Oxaloacetic acid is regenerated.
1. AEROBIC GLYOLYSIS
Aerobic glycolysis is the same process as anaerobic glycolysis,
expect that because oxygen is present it inhibits the accumulation
of lactic acid by diverting pyruvic acid. The pyruvic acid combines
with coenzyme A to form Acetyl CoA.
AEROBIC ENERGY SYSTEM
There are three stages to aerobic system, which involves
breaking down glycogen, glucose and fats to provide energy via
coupled reactions, which is then used to resynthesise ADP to ATP.
This system use oxygen to break down one glucose mole into H20 and
CO2 in three complex stages; aerobic glycolysis, Kreb’s cycle and
electron transport chain (ETC).
Fats
Triglycerides (fats) are broken down by enzymes termed lipases
into FFA and glycerol. They are a fuel used with the aerobic
system. FFAs are broken down into Acetyl CoA which broken down by
the Krebs cycle. FFAs produce more Acetyl CoA than glycogen,
however, they require 15% more O2.