Exercise Physiology Flashcards
What is ATP and why do we need it?
ATP = adenosine triphosphate is the body’s energy currency
- Stored in muscle cells in small amounts
- Needs continual resynthesis from substrates such as creatine phosphate, glucose, glycogen, fat and amino acids
What is the equation for ATP breakdown and energy release?
ATP —-(ATPase)—-> ADP + Pi + Energy
ADP = adenosine diphosphate Pi = inorganic phospate
What is the equation for ADP rephosphorylation?
ADP + Pi + Energy ——–> ATP
How does storage of ATP occur?
ATP stores are limited thus food sources need to be continuously catabolised (broken down) and transferred to the cells for storage as ATP
Which main bodily processes use ATP?
- Myosin ATPase (develop muscle force and contraction)
- Na+/K+ ATPase (restore resting membrane potential)
- Ca+ ATPase (calcium release from cytoplasmic reticulum)
What are the three energy systems?
- Creatine Phosphate System
- Anaerobic
- Rapid response to exercise - Glycolytic/ Lactic Acid System
- Anaerobic
- Slower yet still rapid response - Oxidative/ Aerobic System
- Relatively slow reaction to onset of exercise but increases as time continues
Explain the Creatine Phosphate System/
ATP-PCr (Anaerobic)
PCr + ADP Cr + ATP
PCr= Phosphocreatine
Larger amounts of Creatin stored in muscles than ATP (around 5X)
Rapid response to exercise, predominant energy source for short/ rapid exercise (e.g. 100m sprints, 3-15 seconds) with the rate of energy transfer being 4-8 X that of aerobic metabolism.
Immediate activation yet rapid depletion, replenishes within minutes of ceasing exercise
Explain the Glycolytic/ Lactic Acid System
- A chemical pathway which uses glucose or glycogen as fuel
- Anaerobic and aerobic components
- Glycogen is a very important fuel for intense exercise (can be broken down in absence of oxygen)
- Intense effort for 1-2 minutes
E.g. 400m sprints, 100-200m swim - 5 minutes to fully activate system
Breakdown of glucose to form pyruvic acid and lactic acid
What are the two main processes involved in the Glycolytic/ lactic acid system?
- Glycogenolysis:
glycogen –> glucose - Glycolysis:
glucose –> ATP
End product is lactic acid
When and how can lactate be used in the body?
At lower exercise intensities, the production of lactate is usually met by the clearance of lactate through its use (via the blood) in:
- Other muscle cells to be used as fuel
- Liver to make new glucose
- Muscle and Brain
What is the equation for the anaerobic glycolytic system? *****
Glucose —> Pyruvic Acid —> Lactic Acid
C6H12O6 + 2(ADP + Pi) —> 2 lactate + 2H+ + 2ATP
Produces lactate, hydrogen and ATP
Explain Oxidative or Aerobic Metabolism
Predominant fuel for sustained activity (beyond 2-3 minutes)
Prolonged submaximal endurance-type activities E.g. marathons
Oxidation or breakdown product of glucose of fatty acid catabolism to form AcetylCoA
- Occurs in the mitochondria and involves TCA (crebs cycle) and ETC (electron transport chain and oxidative phosphorylation)
- Minimal accumulation of lactate
- lactate produced by anaerobic side of glycolysis will be cleared at the rate at which it is produced
- maximal oxygen uptake (VO2Max)
What is the relationship between fuels and exercise intensity?
As exercise intensity increases the reliance on fat as a fuel decreases and the reliance on on carbohydrates increases
What are the three types of skeletal muscle fibres?
- Type I
- Type IIa
- Type IIb
Type of muscle fibre is genetically determined
How do muscle fibre types differ?
They differ by both contractile and metabolic characteristics
How are muscle fibre types classified?
They are classified by:
- The way they predominantly produce energy
- Fibres that anaerobic glycolysis- Called Glycotic
- Fibres that aerobic means called Oxidative - Speed of contraction
Giving rise to:
- Fast-twitch glycolytic
- Fast-twitch oxidative glycolytic
- Slow-twitch oxidative
Explain Type I muscle fibres
Type I muscle fibres
Slow-twitch oxidative fibre
Large amounts found in marathon runners
highly fatigue resistant with slow contraction speed
High myoglobin content, high mitochondrial content (mitochondria oxidative phosphorylation takes place- aerobic metabolism takes place)
Explain Type IIb muscle fibres
Fast-twitch glycotic
Rapid contraction speed
Highly fatiguable
E.g. Sprinters
Explain Type IIa muscle fibres
Combination of Type I and Type IIb
What occurs during prolonged sub-maximal exercise?
Glycogen depletion which results in fatigue
When/where is glycogen used?
Glycogen is used only in active muscles.
When glycogen stored are depleted then glucose (from the blood), fat and protein are used
Along with glycogen depletion, what are other contributors to fatigue?
- Hypoglycaemia
- Dehydration
- Lack of Oxygen (inadequate blood flow)
- Failure of the fibres contractile mechanisms
- Nervous system
- peripheral
- central - Accumulation of metabolic by-prodcts
What are some strategies of delaying fatigue?
Nutritional strategies to delay onset of fatigue during prolonged sub maximal exercise
- Carbohydrate intake before and during exercise
- Fluid intake before and during exercise (after for enhanced recovery)
What causes Fatigue during HIT?
Fatigue during High Intensity Training (HIT) has been associated with:
Acidosis
- disturbance in Calcium homeostasis
- loss of potassium from muscles
What are some strategies for delaying HIT fatigue?
Nutritional Strategies
- Alkalising agents
- Creatine supplementation
What is the role of Creatine?
PCr + ADP broken down to produce Cr + ATP
Increase stores in Phosphocreatine within muscle using supplementation.
Creatine- obtained in meat
has a role in short-term energy production
What are the 4 roles of the cardiovascular system?
- Delivery of O2 and nutrients
- removal of CO2 and H2O (and end products)
- Delivery of hormones
- Heat distribution (approx. 25% efficiency)
What is the general (unbalanced) formula for fuel oxidisation?
Carbon fuel + Oxygen –> CO2 + H2O + energy
Explain VO2max
VO2max, also referred to as maximal aerobic power, maximal oxygen consumption or VO2 peak, is defined as:
‘the maximal rate at which oxygen can be taken up, delivered and used by tissues
Explain Absolute Vs. Relative VO2max
Relative: ml/kg/mil = ml per Kg per minute
= VO2 (L/min) X 1000 (ml) / body weight (kg)
Absolute: L/min = Litres per minute
What factors affect VO2 max?
- Sex
- Bosy size
- Age
- Mode
- Level of training