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
What is VO2 dependent on?
Central and Peripheral factors
Explain the Fick principle
Fick principle states:
VO2max is equal to our cardiac output multiplied by our arterial-venous oxygen difference
VO2 = CO X (arterial - venous) O2diff
Maximal Vs. Submaximal VO2max testing
Maximal:
Increase level of exercise until they cannot increase any more
Submaximal:
Estimate based on heart rate’s response to exercise
Define cardio output
How much blood the heart pumps out each minute
Cardiac Output (Q) = Heart Rate (HR) X Stroke Volume (SV)
What are the cardiovascular responses to exercise?
- HR, SV and Q increase
- Breathing rate and depth increase
- Blood flow and blood pressure change
- Arterial dilation
All of which result in allowing the body to meet the increased demands placed on it efficiently
What is the resting value for cardiac output?
5.0L/min
but increases directly (linear relationship) with increasing exercise intensity to between 20 to 40 L/min
What happens when exercise intensity exceeds 40% to 60% (of max)?
Cardiac output increases are more of a result of increases in heart rate and stroke volume
Is VO2max the best indicator of endurance ability?

No, it is how much of this maximal rate one can use before lactate accumulates and induces early fatigue.
This is the Anaerobic Threshold (sometimes referred to as the lactate threshold or the ventilatory threshold).
‘Fractional utilisation’
What is maximal heart rate?
Highest heart rate one can achieve in an all-out effort to the point of exhaustion
Maximal heart rate is age dependent and remains constant from day to day but changes slightly from year to year
How is maximal heart rate estimated?
HRmax= 208 - (0.7 X age)
Summarise the typical exercise responses in CV factors
- HR - (linear increase with graded exercise)
• 60 - 90 to age-predicted HRmax (220 – age)
 - SV - (curvilinear increase with graded exercise)
• 60-90 to 100-120 mL.b -1
 - Q - (linear increase with graded exercise)
• 5 to 20 L.min -1
What is endurance performance closely related to?
Endurance performance is closely related to
the capacity of the cardiovascular system to
supply oxygen –> CENTRAL PHYSIOLOGICAL FACTORS
What does FITT stand for and what are the principles of training associated with it?
F. Frequency
I. Intensity
T. Time
T. Type
Overload- progressively in order to adapt
Specificity- specific to sport
Periodisation- Peak at time of certain events
Reversibility- lose adaptions gained if training is stopped
Types of training to increase VO2max
Traditional training methods to increase VO2max
- increase aerobic capacity = increase aerobic training
How can 30second efforts increase endurance capacity?
- increases fitness 2X as much as normal moderate training
Different protocols available, depending on population and goals of training
What is the response of endurance training on the left ventricle?
changes in response to endurance training, aerobic training = eccentric hypertrophy = greater capacity of the left ventricle
vol=mL/beat
stroke volume increases until approximately 60%, capacity then plateaus
What are the central adaptations of endurance training?
! Heartsize ! Strokevolume ! Cardiacoutput ! Heartrate ! Bloodflow ! Bloodpressure ! Plasmavolume
What are the peripheral adaptations of endurance training?
Peripheral adaptations
! Capillarisation
! Improves the delivery of oxygen and removal of by-products
! Mitochondrial density
- The increase in
mitochondrial density allows more fat to be
burned
What are the muscle fibre adaptations to endurance training?
At the muscle, endurance training can also cause a shift from Type IIb to Type IIa fibres (%)
What are the differences in intramuscular substrate stores in endurance athletes?
Endurance athletes also
have larger intramuscular stores of fat

What are the central adaptations of endurance training?
Central adaptations ! Heartsize ! Strokevolume ! Cardiacoutput ! Heartrate ! Bloodflow ! Bloodpressure ! Plasmavolume 
What adaptations will result from sprint training?
! Increased muscle strength
! Strength will increase power
! Increased activity of the glycolytic enzymes
! Increased ‘intramuscular’ buffering capacity will help neutralise the acid build-up and
allow ‘anaerobic’ energy to be generated for a little longer
What are the main responses to training?

• Both VO2max and the anaerobic threshold change in response to endurance training with untrained individuals.
• Only the anaerobic threshold responds to training in well-trained endurance athletes.

• VO2max is closely related to the function of the cardiovascular system, while the AnT (LT, VT) are more closely related to muscle function.
CENTRAL ADAPTATIONS VS. PERIPHERAL ADAPTATIONS


Several effects of endurance training on the cardiovascular system
= CENTRAL ADAPTATIONS

Several effects of endurance training on muscle
characteristics
= PERIPHERAL ADAPTATIONS
What’s the best indicator or endurance
performance?
While VO2max is a good measure of cardiovascular fitness, Lactate threshold is a better indicator of endurance
performance
Explain the concept of different Heart Sizes?
Heart size doesn't necessarily change, however the left-ventricle size does change. with aerobic (endurance) training Eccentric hypertrophy- larger volume, greater capacity to fill and pump more blood out with each beat.
- Stroke volume increases
- Cardio output increases
- Heart rate decreases
Resistance training: thickening of heart wall, due to increase of blood pressure with each lift,
At what ages do boys and girls undergo puberty?
Girls: 10-14
Boys: 12-16
Boys with a chronological age of 13-14, what is the range of their biological age?
From 9-16 years old
At what ages do both boys and girls reach 98% of their final height
Girls: 16.5
Boys: approx. 17.75
Early Vs. Late growth spurt
The earlier the growth spurt, the more intense the rate of growth.
Late maturers tend to be taller
In boys, early maturers tend to be:
More muscular, have shorter legs and broader hips
What are the hormonal alterations at puberty?
Testosterone:
- protein synthesis
- bone growth
Oestrogen:
- bone growth
- fat deposition- especially in thighs and hips
Changes in muscle strength in boys and girls from onset of puberty
Muscle strength in boys increases from onset of puberty while muscle strength in girls decreases from the same point in time
Explain anaerobic power (increased anaerobic power in response to exercise)
Anaerobic power - maximal rate at which energy can be produced or work can be done without relying on any significant contribution of aerobic energy production
In response to exercise, what is the result of decreased glycolytic capacity?
Lower blood lactate- (lower PFK)
Explain the principles of training
- Specificity
- adaptations will occur that are specific to the training
- training should stimulate the speed. force and timing of the sport - Progressive Overload/ Recovery
- a continual and gradual increase in training workload
- performance = fitness - fatigue = training + rest - Individualisation
- tailoring the training to suit the individual athlete - Reversibility
- use it or lose it
What can you manipulate in strength training?
Sets, repetitions, rest periods, speed of contraction, type of exercise
Define Strength
The maximal force that a muscle group can generate
Define Power
Force times velocity
- The ability to exert force at higher speeds
(sometimes referred to as “speed strength”)
What are the types of contractions?
- Static –> the muscle generates force but doesn’t change length
- Isometric contractions - Dynamic –> the muscle length changes while it generates force
- concentric: muscle generates force while shortening
- eccentric: muscle generates force while lengthening
Iso-inertial contractions and isokinetic contractions
Explain isometric contractions
contracting a muscle at a fixed angle against an immovable object
- helps stabilise joints
- used frequently in rehabilitation programs
Explain Iso-inertial (isotonic) and isokinetic contractions
Iso-inertial:
training is performed against a constant resistance
E.g. lifting a barbell, dumbbell or pin-loaded machine
- increased injury risk
Isokinetic:
Training is performed at a constant speed of movement with variable resistance
Used mostly in research and rehabilitation
- low risk but expensive
What are the two components to strength adaptations?
- Neutral
2. Myogenic/ structural
What are the neutral adaptations to strength training?
- Increased synchronisation of motor units
- Increased co-contraction of synergistic muscles
- Decreased inhibition
- Reduced activity of antagonist muscles
- Occur generally in the first 6 weeks of training
What are the myogenic adaptations to strength training?
- An increase in muscle protein
- Hypertrophy: increase in the size of the trained muscle fibres
- Hyperplasia: increase in the number of muscle fibres
Explain Hypertrophy
- -> Hypertrophy can change your body shape
- -> It is dependent on:
- intensity
- duration of program
- training status
- -> Increase in both type I and II fibres
- -> Greater relative hypertrophy in type II fibres
- -> Increase oxidative capacity and capillary number
- -> Increase fatigue resistance
Explain Hyperplasia
- -> By birth or shortly after, the total muscle fibre number is fully established
- -> Postnatal muscle growth is a result of an increase in fibre area and length
Delayed Onset Muscle Soreness
D.O.M.S
- More severe after eccentric exercise
- Mot related to lactic acid accumulation
- Most likely cause:
Damage to individual muscle fibres and connective tissue
influx of inflammatory cells –> swelling –> pain
