Week 7 Flashcards
Why do we care about VO2max?
- Predicts performance
- Within elite athletes where VO2max is very high other variables determine performance
o But high VO2max is required to be an elite athlete
LT1 work rate and HR
250 W
140 bpm
LT2 work rate and HR
305 W
151 bpm
CP work rate and HR
385 W
170 bpm
Zone 1 work rate and HR
HR=<120bpm, WR= <175W
Zone 2 work rate and HR
120-140bpm, WR= 175-250 W
Zone 3 work rate and HR
HR= 140-151 bpm, WR= 250-305 W
Zone 4 work rate and HR
HR= 151-170bpm, WR=305-385 W
Zone 5 work rate and HR
HR= > 170bpm, WR= >385 W
What is LT1?
Upper limit of moderate intensity domain
Blood lactate typically rises to 2.0mmol/L
What is LT2?
Onset of blood lactate accumulation (OBLA)
Closely associated with CP
Blood lactate levels rise to 4.0 mmol/L
How can you estimate LT1?
-MOD- monoexponential (constant O2 consumption per work rate (W) (efficiency))
-HVY- slow component
-SVR- no steady state
When does the slow component occur?
During heavy and severe constant load exercise
Starts later in exercise (time delay of about 120-180 seconds)
How does the slow component work?
- The slow component of VO2 represents an increased O2 cost of locomotion when exercise is performed more than 3 min at a constant workload above LT
- When exercise is performed btwn LT and CP (heavy), the slow component reaches steady state
- When effort rises above CP (severe) a steady state is not achievable
What is the emergence of the slow component in the heavy intensity domain due to?
Metabolic shift bwtn aerobic and anaerobic systems
How can we use the slow component to identify the HVY intensity domain?
It is where there is an additional increase in O2 cost/consumption
What happens to the slow component as intensity increases?
The magnitude of the slow component increases the further above LT1 you get
During what type of protocol are diff VO2 responses not visible?
Incremental/ramp protocols
What happens to the slow component during constant load exercise?
Slow component is visible during HVY and steady state is not achieved during SVR
Purpose of the Fatmax test
Incremental step test designed to assess maximal fat oxidation (MFO) rate and the intensity at MFO (Fatmax) using indirect calorimetry
Why was the Fatmax test developed?
To define the relationship between whole-body fat
oxidation rates and exercise intensity
What does the Fatmax tell us?
Allows us to estimate the maximal rates of fat oxidation and therefore allows us to see where the slow component starts to estimate LT1
VO2 and VCO2 are used to estimate substrate utilization and MFO (g/min)
Test can be used to determine LT1 and CP
What would ideal data look like from the Fatmax test?
Increasing intensity and increasing fat oxidation up until a point at which carb oxidation takes over and fat oxidation decreases
Duration of steps in Fatmax test
6 min to ensure steady state is reached
What else does the Fatmax test protocol allow us to examine?
VO2/WR
VCO2/VO2
VE/VO2
RER/VO2
Can be then used to estimate LT and CP
What are characteristics of individuals with low aerobic power?
Increased blood lactate levels (lactatemia) at the same absolute submaximal exercise intensities and decreased mitochondrial oxidative capacity
What are patients with metabolic syndrome characterized by?
Decreased capacity to oxidize lipids and early transition from fat to carbohydrate oxidation
Elevated blood lactate concentration as exercise power output increases (metabolic inflexibility)
What is blood lactate correlated with?
Negatively correlated with FATox and positively correlated with CHOox during exercise
Characteristic of elite professional endurance athletes
Increased muscle mitochondrial mass
What is high fat oxidation and low blood lactate accumulation associated with?
Metabolic flexibility and oxidative capacity
What is critical power?
Concept describing the highest sustainable intensity that doesn’t
result in a progressive increase in fatigue.
Threshold separating the heavy- and severe-intensity domains and is the highest intensity where oxidative metabolism can fully meet energy demands
What is CP also termed?
Maximal metabolic steady state (MMSS) or maximal lactate steady state (MLSS)
MLSS (MMSS/CP)
The highest running speed/cycling power at which blood lactate does not rise by more than 1 mM from 10-30 min
How can the CP and work capacity above CP be determined?
Determined using a series of constant power output trials performed to limit of tolerance within the severe intensity domain (>CP)
Critical power calculation
The Critical Power (CP) is determined by calculating the
average power output (Watts) during the final 30 seconds of the 3-minute test
Anaerobic Work Capacity (AWC) Calculation
The AWC is calculated as the integral
of the power vs. time relationship above CP (i.e., the area under the curve where
power exceeds CP)
What test is used to test CP?
3 min all out test
3 min CP test
Either cycling as fast as possible against a fixed resistance (4.5% of body weight) or running on a track
Used to estimate CP and AWC
Equation for fat oxidation
Fat Oxidation (g/min) = 1.695 × VO2 − 1.701 × VCO2
Equation for carbohydrate oxidation
Carbohydrate Oxidation (g/min) = 4.585 × VCO2 − 3.226 × VO2
What does a high fat max mean for athletes?
Better endurance performance
Original fat max protocol
5 min, 35 watt step increments on a cycle ergometer, performed after an overnight fast, until the respiratory exchange ratio reached 1
Results from the original fatmax test
No sig diff when well-trained participants performed longer (35min) or shorter (3min) step tests
Can a Fatmax be determined from a treadmill test?
Yes
Which variables are constantly being monitored during the Fatmax test?
Oxygen consumption (VO2)
Carbon dioxide production (VCO2)
RER
What Watt increase occurred on Fatmax for individuals with WRmax of less than 250W?
40 W
What Watt increase occurred on Fatmax for individuals with WRmax of greater than 250W?
50W
Conventional model of determining CP
Models the intensity of CP from a series of severe intensity prediction trials performed to the limit of tolerance at diff speeds or power outputs
What is another way to determine CP?
Series of 30 min rides of increasing intensity with the CP (MLSS) being defined as the last intensity where steady state lactate is achieved
What has been unsuccessful in predicting MFO and Fatmax?
HR
Power
Estimated VO2max
What can the Fatmax protocol also be used to estimate?
Individual intensity domain thresholds
How is Fatmax determined?
Identifying the stage (WR) at which fat oxidation (g/min) is the highest
When does Fatmax typically occur?
Btwn 50-70% of VO2max in trained individuals
What is not evident in RAMP protocols?
The contribution of the V̇O2 slow component to the V̇O2 versus exercise-intensity relationship
Pattern of the slow component based on the graph
Max value is achieved right after CP, then the slow component decreases at higher work rates bc VO2max represents the upper limit for its expression
When are the equations for fatmax valid?
Only during steady-state exercise
Sex and MFO
Absolute MFO is greater in males then females
MFO relative to FFM is greater in non-obese females than non-obese males
Sex and Fatmax
Greater in females
Exercise modality and fat ox
Greater fat oxidation and reduced carb oxidation in running vs cycling
When should a Fatmax protocol end? (amaro-gahete)
Reduce RER from 1.0 to 0.95
Relationship btwn fat ox and carb ox
Strong inverse
Is MLSS the same as CP?
No
MLSS vs CP
MLSS underestimates actual MMSS
CP represents boundary separating exercise in which physiological homeostasis is met from exercise in which it is not
What is the gold standard for determining MMSS?
CP
