1
Q
Marathon World Record
A
- dropping almost 4x faster than preceding decades
- current record = 2:01:09 Eluid Kipchoge, Berlin, 2022
2
Q
Pillars to Sub-2 Hour Marathon Success
A
- athlete selection (human physiology and genes)
- course and environment
- training (coaching, exercise physiology)
- nutrition / hydration
- equipment
3
Q
Acute Effects to Aerobic Exercise - Brain
A
- neural activity = increase or decrease
- blood flow = no change
- blood distribution = increase
- metabolism = increase or decrease
4
Q
Acute Effects to Aerobic Exercise - Lungs
A
- ventilation and gas exchange = increase
- blood flow = increase
- blood distribution = increase
5
Q
Acute Effects to Aerobic Exercise - Heart
A
- cardiac output = increase
- coronary blood flow = increase
- oxygen consumption = increase
- blood flow distribution = increase
6
Q
Acute Effects to Aerobic Exercise - Blood Cells
A
- haemoconcentration (red blood cell movement increase) = increase
- oxygen content = increase
- levels of energy substances = no change / increase
7
Q
Acute Effects to Aerobic Exercise - Muscle Fibres
A
- metabolism and blood flow = increase
- oxygen extraction and consumption = increase
- mechanical strains = increase
8
Q
Acute Effects to Aerobic Exercise - Capillaries
A
- arterial dilation = increase
- capillary pressure and energy substrate exchange = increase
- venoconstriction = increase
9
Q
Acute Effects to Aerobic Exercise - Pancreas, Gut & Kidneys
A
- blood flow = decrease
- metabolism = increase
10
Q
Acute Effects to Aerobic Exercise - Bone Marrow
A
- blood flow = no change / increase
- mechanical strain = increase
- release of stem cells = increase
11
Q
Acute Effects to Aerobic Exercise - Liver
A
- blood flow = decrease
- metabolism = increase
12
Q
Acute Effects to Aerobic Exercise - Adipose Tissue
A
- blood flow = increase / no change / decrease
- metabolism = increase
13
Q
Acute Effects to Aerobic Exercise - Skin
A
- blood flow = increase / no change / decrease
- metabolism = ?
14
Q
Endurance Definition
A
‘The act of sustaining prolonged stressful effort’. It is limited by the capacity of the C-R system (heart, blood vessels, blood, lungs) to deliver O2 and excrete CO2 and in the ability of muscle to metabolise fuels aerobically
15
Q
Determinants of Endurance Performance
A
- maximum rate a subject can exercise at (VO2max)
- the highest % of this rate of the subject can exercise at for a sustained period of time (% of VO2max)
- economy of subject carrying out repetitive muscular actions (O2 cost per unit speed)
- choice of energy pathways that are employed to power exercise at the optimal achievable %VO2max (i.e., anaerobic glycolysis vs oxidative phosphorylation
16
Q
Factors Determining Pace
A
- rate of anaerobic energy expenditure (VO2max, %of VO2max that can be sustained, anaerobic threshold)
- economy (VO2 unit per speed)
17
Q
Physiological Factors Determining Success in Cycling
A
- VO2max
- %VO2max
- choice of fuel (fat: CHO; CHO-oxid: non-oxid combustion
- O2 economy
18
Q
Cycling Endurance (VO2 equation)
A
- VO2 = Q x a-vO2 difference
- Q (cardiac output) = HR (heart rate) x SV (stroke volume)
19
Q
Aerobic Ability - Ball et al., 2017
A
Chris Froome:
VO2 peak = 5.91 L/min-1 (84ml/kg/min)
PPO = 525W
Gross Efficiency = 23.3% (average values 22%)
20
Q
Factors Determining Aerobic Performance
A
- blood volume, SNS + PNS, Mitochondrial & capillary density, respiratory capacity
- venous return, speed of O2 use
- max HR, max SV, Hb conc, O2 extraction of muscle
- cardiac output, a-vO2 difference
- genetics + training
21
Q
VO2max Definition
A
‘the maximum rate of oxygen uptake under normal conditions of ambient temperature and pressure for a subject utilising the majority of muscle mass in a dynamic exercise activity’
22
Q
Criteria to use VO2peak instead of VO2max
A
- plateau in VO2 when plotted against work intensity
- final RER >1.10
- heart rate within 10 beats.min
23
Q
Criteria to use VO2peak instead of VO2max
A
- plateau in VO2 when plotted against work intensity
- final RER >1.10
- heart rate within 10 beats.min-1 of age predicted max
- final lactate value of >10mmol.L-1 (this is variable)
24
Q
VO2 max and Marathon Times - Farrell et al., 1979
A
- VO2max is correlated with marathon times
- time = 2.17-3.49
- r value = 0.91
- still large unaccounted for variations in people with same VO2max
25
Billat et al., 1994
- velocity at VO2max helps determine race pace
- athletes with the same VO2max run at different speeds so velocity at VO2max (vVO2max) is an important determinant of performance
- time spent at VO2max (tlimvVO2max) determines performance
26
Endurance performance determinants
- anaerobic metabolism also determines performance
- lactate threshold shows strong relationship to performance
- determining maximum lactate steady state (MLSS) can determine optimal race pace
27
Morgan et al., 1989
- athletes running at same sub-max speed show differing O2 cost
- amongst athletes of similar ability VO2max is poor indicator of performance
- performance time is related to VO2max, AT and RE showing link between state of physical training and predicted performance time
- appropriate increased measured training volume mostly leads to decreased performance times
28
Endurance Training Definition - ACMS Position Stand, 1998
'when exercise involving large muscle groups is performed 3-5d/wk at an intensity between 40/50-80% VO2max for 20-60+ mins over several weeks it leads to functional changes that improve the rate of energy supply to demand, essential to perform endurance sports at a high level'
29
Endurance Training - Non-Cardiovascular Effects - Skeletal Muscle
- oxidative phosphorylation = increase
- muscle hypertrophy
- calcium handling = increase
30
Endurance Training - Non-Cardiovascular Effects - Ventilation
- vital capacity = increase
- tidal volume = increase
- max inspiratory and expiratory factor = increase
31
Endurance Training - Non-Cardiovascular Effects - Hemorrheology
- blood viscosity = decrease
- coagulability = decrease
- oxygen transport capacity = increase
32
Endurance Training - Cardiac Effects - Normal LV function
- I/R protection
- prevention of age-related diastolic dysfunction
- physiologic hypertrophy to training
33
Endurance Training - Cardiac Effects - Systolic Heart Failure
- reverse LV-remodelling
- LV ejection fraction = increase
- improved neurohormonal activation
- arrhythmia prevention
34
Endurance Training - Cardiac Effects - Diastolic Heart Failure
- prevention of diastolic function
- improvement of LV relaxation and compliance in HFNEF
35
Endurance Training - Cardiac Effects - Cardiac Values
- prevention of value degeneration
- prevention of calcification
36
Endurance Training - Vascular Effects - Aorta
- aortic stiffness = decrease
- aortic compliance = increase
37
Endurance Training - Vascular Effects - Conduit Vessel
- endothelial vasodilation = increase
- NO production = increase
- oxidative stress = decrease
38
Endurance Training - Vascular Effects - Resistance Vessel and Microcirculation
- vasculogenesis by EPCs sensitivty to adenosine = increase
39
Endurance Training - Vascular Effects - Capillary Bed
- capillary vessel formation = increase
40
Endurance Training - Vascular Effects - Venous Circulation
- venular capillaries = increase
41
Endurance Training - Vascular Effects - Pulmonary Artery
- endothelial function = increase
- pulmonary artery pressure = decrease
- in chronic heart failure
42
Endurance Training -Neurohormonal and Autonomic Effects
- sympathetic tone = decrease
- parasympathetic tone = increase
43
Endurance Training -Neurohormonal and Autonomic Effects - In CHF
- norepinephrine
- angiotensin II
- ANP, BNP
44
Endurance Training -Neurohormonal and Autonomic Effects - Antiarrythmic Effects
- normalisation of heart rate variability
- shortened action potential duration
- hyperpolarization
- attenuated automacity
45
Systemic Effects of Endurance Training - Skeletal Muscle
- hypertrophy
- hyperplasia
- fibre type switching
46
Systemic Effects of Endurance Training - Vascular
- increased flow
- increased vasoreactivity
- increased angiogenesis
47
Systemic Effects of Endurance Training - Metabolism
- increased insulin sensitivity
- increased oxidative phosphorylation
- increased mitochondrial biogenesis
- increased adipose 'browning'
48
Central Adaptation to Endurance Training - Blood Volume
- plamsa volume and Hb increase
49
Central Adaptation to Endurance Training - Stroke Volume
- greater ventricular volume alongside greater myocardial contractility
50
Central Adaptation to Endurance Training - Heart Rate
- decrease at rest and sub-max-ex, no change in MHR
51
Central Adaptation to Endurance Training - Cardiac Output
- greater SV leads to greater max Q
52
Central Adaptation to Endurance Training - Blood flow and Distribution
- increase in total muscle blood flow during max-ex but decrease during sub-max-ex
53
Central Adaptation to Endurance Training - Oxygen Extraction
- increase extraction of O2 and a-VO2 difference
54
Central Adaptation to Endurance Training - Arterial Blood Pressure
- decrease in SBP and DBP at rest and submax
55
Central Adaptation to Endurance Training - Ventilation
- greater tidal volume and breathing frequency leads to greater overall ventilation during max-ex, but decreases during sub-max-ex
56
Central Adaptations to Endurance Training
- myocardial changes
- hypervolemia
- angiogenesis
- respiration
57
Trained Heart - Scharharg et al., 2002
- the max pumping rate of the heart determines VO2max
58
Trained Heart - Ekbom, 1968
- endurance in trained athletes increase Q from 5 - 40L/min (Untrained increase from 5 - 20L/min)
- increased cardiac performance during ex is related to eccentric left ventricular cardiac hypertrophy
59
Benefits of Exercise to Endothelium
- shear stress
- cyclin strain
- myokines (e.g., IL-6)
- adipokines (e.g. adiponectin)
- insulin
60
Tesch et al., 1984 - aerobic exercise
- regular aerobic exercise stimulates new capillary growth
- allows a slower passage pf Hb facilitating better O2 extraction
61
Chronic Microvascular Adaptations - Direct Exercise
- blood vessels supplying active skeletal muscle (O2, glucose and O2 in; CO2, H+and CO2 out
- increased vasodilator signalling
- increased capillary density
- increased insulin/PI3K signalling
62
Chronic Microvascular Adaptations - Indirect Exercise
- decreased HbA1c, decreased insulin secretion and decreased micro complications
63
Hypervolemia (Increase in Blood Volume) - Convertino et al., 1980
- 8% increase in blood volume accounted for by 12% increase in plasma volume following 8 consecutive days training
- pv in first days of training account for bv increase
- rbc can take > 4 weeks to increase in response to training
- increased bv is due to initial protein and fluid shifts from extra- to intra-vascular space followed by increase in total body water
64
Plasma Volume Expansion - Convertino et al., 1991
- every 1% increae in PV leads to a similar % decrease in HR with endurance training
- alters the frank-starling mechanism
- hypervolemia leads to greater central venous pressure leads to end diastolic volume (cardiac preload) leads to greater stroke volume
- hypervolemia increases Qmax and increased VO2max
65
Pulmonary Adaptations to Endurance Training
- reduce respiratort work at a given ex-intensity, lends more O2 to non-respiratory active skeletal musculature
- max-ex: as Ve= Fb x TV, increase in VO2 max raises O2 requirement and elimination of CO2 via greater alveolar ventilation rate
- sub-max-ex: endurance training reduces ventilatory equivalent for O2 (Ve/VO2) during sub-max-ex and lowers % of total O2 cost of breathing
- decrease in O2 cost of breathing by ventilatory muscle enhances endurance by reducing fatigue and the non-used O2 by respiratory muscles is available elsewhere
66
Babcock et al., 1998 - Endurance Training Benefits Ventilatory Muscles
- inspiratory muscle fatigue occurs during prolonged intense exercise
- enhances ability to sustain high levels of sub-max ventilation. training causes less disruption in whole-body hormonal and acid base balance that could negatively effect muscle function
- increases inspiratory muscle capacity to generate force and sustain a given level of inspiratory pressure
- performance is benefitted by reduced energy demand due to less respiratory work, reduced lactate production by ventilatory muscles and improve how ventilatory muscles metabolise as fuel
- anaerobic threshold can be determined by ventilatory threshold, related to performance
67
Muscle Adaptations to Endurance Training
- hypertrophy
- fuel storage
- mitochondria
68
Costill et al., 1976 - Hypertrophy of Type 1 Muscle Fibres
- gastrocnemius muscle type 1 fibres; elite endurance runners 79%, non-elite middle distance runners 62%, and untrained 58%
- fibre size in elite runners 30% bigger
- genetic predisposition in determining muscle fibre response to ex shown through small magnitude of change with training
69
Andersen and Henriksson, 1977 - Skeletal Muscle Adaptations to Regular Aerobic Exercise
- 8 weeks of endurance training led to a conversion of type 11b to 11a
70
Maughan et al., 1997 - Fuel Storage and Endurance Training
- muscle glycogen storage is increased (due to increased sensitivity of muscle insulin receptors)
- insulin promotes glucose uptake via GLUT4 transporters (25% higher in endurance trained muscle)
71
Fuel Storage and Endurance
- glycolytic enzymes are increased
- training increases capacity for glycogen provided adequate time has elapsed and sufficient CHO is consumed
72
Hurley et al., 1986 - Fuel Storage and Endurance
- muscle TG concentrations significantly increase with endurance training and are used more
- aerobic training reduces muscle glycogen use and plasma glucose oxidation during ex but increases the use of fat during ex
73
Mendenhall et al., - Fuel Storage and Endurance
- lower RER and muscular RQ
- smaller rise in plasma FFA concentration
- lower rate of use of blood glucose by muscle
- reduced accumulation of muscle lactate
- increased oxidation of lipid relative to CHO
-
74
Mitochondrial Size and Density
- mitochondria don't limit VO2max but influence performance by selection of energy used
- greater mitochondrial (conc and size) means greater pyruvate oxidation and less lactate in cytosol at any given exercise intensity
- greater mitochondria improves efficient ATP resynthesis via oxidation (more than 30mol ATP from OP, 3mol ATP produced by glycolysis)
- more mitochondria improves fat oxidation
- increased mitochondria number and size improves aerobic ATP production
75
Kiessling et al., 1971 - Muscle Mitochondria Density and Enzyme Activity
- mitochondria size is increased (~14-40%) in trained muscle
- mitochondrial number increased (120%) in human vastus lateralis of trained men following 28 weeks training
76
Holloszy et al., 1970 - Muscle Mitochondria Density and Enzyme Activity
- trained muscle mitochondria increased capacity to generate ATP aerobically via oxidative phosphorylation
- TCA cycle enzymes increased by 34-101% after treadmill training
- isocitrate dehydrogenase increased by 90%
- cytochrome C content increased 102%
77
Gollnick and Saltin, 1983 - Muscle Mitochondria Density and Enzyme Activity
- relationship between VO2max and and SDH (mitochondrial marker)
SR-334
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