Determinants of Exercise Performance Flashcards
What determines performance over a set distance?
The ability of the athlete to produce and sustain the highest power output possible throughout a race
Determinates of average race pace?
Rate of aerobic energy expenditure
Economy
How is running economy measured?
VO2/speed
What influences aerobic energy expenditure?
VO2 max
Fractional utilisation (% VO2max)
Aerobic and anaerobic contribution
What influences VO2max?
Blood volume
Cardiac output
What influences anaerobic and aerobic contribution?
VO2 kinetics
How is marathon running speed measured?
VO2max x %VO2max@LT x economy
LT = lactate threshold
What influences performance VO2 (aerobic)?
Lactate threshold VO2
Muscle capillary density
What influences lactate threshold VO2?
Maximal oxygen consumption
Aerobic enzyme activity
Distribution of power output
What influences maximal oxygen consumption?
Muscle capillary density Stroke volume Maximal heart rate Haemoglobin content Aerobic enzyme activity
What influences performance O2deficit (anaerobic)?
Total buffering capacity
Distribution of power output
What influences gross mechanical efficiency?
% slow-twitch (Type 1) muscle fibres
Anthropometry
Elasticity
How is performance velocity/power determined?
(Performance VO2 (aerobic) + performance O2deficit (anaerobic) x gross mechanical efficiency
Define maximal oxygen uptake?
The maximal rate at which ATP can be re-synthesised aerobically
Relationship between VO2max and performance?
There are strong correlations between VO2max and performance in heterogeneous groups
What’s the average VO2max value for elite male and female runners?
Male - 70-85ml/kg/min
Female - 60-75ml/kg/min
In terms of running the economy what is best in runners?
A lower running economy is better
Define running economy?
The oxygen cost of running at sub-maximal speeds?
What are the units for running economy?
ml/kg/min
ml/kg/km
What influences running economy?
Anthropometric factors
Physiological factors
Biomechanical factors
Technical factors
How to measure running economy? (Jones & Doust 1996)
Range of speeds typically used in training
Constant gradient of 1%
Corrected fro air resistance in outdoor training
What is vVO2max?
The velocity (running speed) at VO2max
What is velocity at VO2max (vVO2max)?
The interaction of VO2max and running economy
Provides a ‘functional expression’ of VO2max
How is velocity at VO2max (vVO2max) useful?
Helps enable differences in performance in athletes with similar VO2max
Enables accurate prediction of 16km race performance
What is %VO2max?
Fractional utilisation of VO2max?
What is fractional utilisation of VO2max (%VO2max) associated with?
The accumulation of lactate in the blood
The changes in gas exchange
Perception of effort
Calculate the running speed for 10km?
- VO2max = 70ml/kg/min
- Sustain 85% VO2max over 10km
- Running economy = 190ml/kg/min
VO2 = 70 x 0.85 = 59.5ml/kg/min VO2 (ml/kg/h) = VO2 x 60 RS = (VO2 x 60) / E RS = (59.5 x 60) / 190 RS = 18.789km/h = 18.789 / 1.8789 = 10km = 60min / 1.8789 = 31.93min = 31min56sec
Haemoglobin and Vo2max? (Schmidt & Prommer 2010)
Haemoglobin concentration is a poor predictor of VO2max
Haemoglobin mass is more predictive of VO2max
How to estimate total blood haemoglobin mass?
Pre-blood sample = %HbCO
Breaking in a known quantity of CO for 10min
Post-blood sample = %HbCO
%HbCO increase allows you to calculate the total Hb mass
What is blood lactate?
The balance between lactate production and clearance
Predictors of performance? (Joyner & Coyle 2008)
Protocol -> time to exhaustion
Time to fatigue is very predictive of %VO2max at lactate threshold
Capillary density is also a predictor of performance (related to running economy)
What is oxygen uptake kinetics?
The rate at which oxygen uptake rises to meet the ‘steady-state’ exercise requirement
Faster adaptation increases the ‘oxygen deficit’
How can oxygen uptake kinetics be measured?
Breath-by-breath gas analyser
Oxygen uptake kinetics? (Burnley & Jones 2007)
Steady-state is achieved in ~1min in endurance-trained athletes
What are the mechanisms of respiration regulation?
Central chemoreceptors
Peripheral chemoreceptors
Properties of central chemoreceptors?
Stimulated by CO2 increase in cerebrospinal fluid
Rate and depth of breathing increases
Removes excess CO2 from the body
Properties of peripheral chemoreceptors?
In aortic and carotid bodies
Sensitive to blood PO2, PCO2, and H+
How is pulmonary ventilation regulated?
The body must maintain a homeostatic balance between blood PO2, PCO2, and pH
Requires coordination between respiratory and cardiovascular systems
Coordination occurs via involuntary regulation of pulmonary ventilation
What is HCO3-?
Bicarbonate
What is the main buffer in Acid-based balance in the body?
HCO3- (bicarbonate)
What is H2CO3?
Carbonic acid
What is the acid-based balance equation?
H+ + HCO3- H2CO3 CO2 + H2O
What is the primary function of pulmonary ventilation?
To remove H+ from the blood
How can increase ventilation aid exercise?
It helps maintain a stable pH by removing H+ formed during exercise
What stimulus stimulates central and peripheral chemoreceptors to increase ventilation?
Excess CO2
The effects of increased ventilation?
CO2 exhalation -> redcued blood PCO2 and H+ concnetration -> pH increases
The effects of decreased ventilation?
CO2 build-up -> increased blood PCO2 and H+ concentration -> pH decrease
Define the ventilatory threshold?
The point during exercise when ventilation increases disproportionately to oxygen consumption
When oxygen demand keeps increasing linearly, whilst there is a break-in point in ventilation
Relationship between ventilation (VE) and VO2?
Curvilinear relationship
What is the ventilatory equivalent for O2 and CO2?
- Ventialtion = 60l/min
- VO2 = 1.6l/min
- VCO2 = 1.7l/min
The ventilatory equivalent
= VE/VO2 = 60/1.6
= VE/VCO2 = 60/1.7
The ventilatory equivalent for VO2 = 37.5
The ventilatory equivalent for VCO2 = 35.3
Relationship between the ventilatory equivalent and the ventilatory threshold?
The ventilatory equivalent remains relatively constant over a wide range of submaximal exercise levels
The ventilatory equivalent increase at the ventilatory threshold
Define maximal lactate steady state (MLSS)?
The highest intensity at which lactate production = lactate removal
At higher intensities, progressive lactate accumulation and H+ accumulation, therefore, enhanced CO2 production
A good predictor of 10km race performance
Define the respiratory compensation point?
The highest exercise intensity at which changes in respiration manage to compensate for the increase in H+
The second breakpoint in the ventilation curve when ventilation further increases
Lactate vs ventilatory thresholds
Lactate threshold coincides with ventilatory threshold -> increase H+ ions, results in an increase in CO2 -> triggers an increase in ventilation due to chemoreceptors
Maximal lactate steady state (MLSS) coincides with respiratory compensation -> further increase in H+ ions, results in a further increase in CO2 -> triggers a greater increase in ventilation
Many names of the ventilatory threshold?
Aerobic ventilatory threshold
Aerobic threshold
Aerobic gas exchange threshold
Ventilatory threshold 1
Many names of the respiratory compensation point?
Anaerobic ventilatory threshold
Anaerobic gas exchange threshold
Ventilatory threshold 2
The aerobic ventilatory threshold is found at approximately the same intensity lactate begins to accumulate in the blood, why?
H+ is formed as lactate is formed, this needs buffering, and the resulting CO2 needs to be removed
Lactate threshold and ventilatory threshold debate proposed by Peronnet & Aguilaniu (2006)
Bicarbonate is not the main buffer in the muuscle
Yet buffering by bicarbonate doesn’t increase CO2 production in the muscle
Is the disproportionate increase in VCO” at the mouth above the ventilatory threshold due to hyperventilation
Training zones based on ventilatory thresholds? (Meyers et al. 2005)
Below ventilatory threshold = regenerative exercise
Between the 2 thresholds = extensive exercise
Above RCP = intervnal/intensive exercise
Training zones based on ventilatory thresholds? (Faude et al. 2009)
Below ventilatory threshold = regenerative/lo-intensity endurance training
Between the 2 thresholds = moderate/high-intensity endurance training
Above RCP = interval training
Advantages of prescribing training using the ventilatory thresholds?
No blood sampling required
Disadvantages of rescribing training using the ventilatory thresholds?
Expensive equipment
mask/mouthpiece required
Effects of training on ventilatory thresholds? (Meyers et al. 2005)
The better trained, the higher the threshold
Therefore, the greater the absolute VO2max and with respect to %VO2max
Threshold occur at higher relative and absolute intensties
The ventilatory threshold to track performance? (Meyer et al. 2005)
Similar to lactate thresholds, a better predictor of performance than VO2max
VO2max may remain constant, whereas the ventilatory threshold and RCP increase during the season
What were the parameters used in Molina (2017) Half-marathon performance predictors?
Weekly training volume, running experience, BMI, and the sum of skinfolds
Peak speed and RCP speed
RCP step rate, RCP step length, and maximal step length
Peak speed, RCP speed, and running experience
Which model best predicted half-marathon performance? (Molina 2017)
RCP speed
Best predictors of marathon running performance? (Scheer et al. 2018)
Oxygen uptake corresponding to lactate threshold
Age
Best predictors of train running performance? (Scheer et al. 2018)
Step test variables (the speed at individual anaerobic threshold)
Running economy
Another name for maximal lactate steady state (MLSS)?
The lactate turn-point (LTP)
