Lab 2 Lactate threshold, lactate turnpoint and maximum oxygen uptake (V̇ O2max) using cycle ergometry or treadmill running. Flashcards
Health & Saftey Proccedures for VO2 max testing
Prepare and PPE
All participants must complete an appropriate warm-up and warm-down.
Participants may feel light-headed or sick on completing the test; someone in the group is responsible for the participant throughout the procedure.
All participants must complete a pre-exercise questionnaire before starting exercise.
The person collecting the expired gas samples MUST wear full protective equipment and gloves when handling the mouthpiece and nose-clip, as well as when taking capillary blood samples.
The physiology tutors will train you how to take samples safely.
Please ensure that a tutor observes your first blood sample (this will be performed at rest).
Preparation for VO2 Max Proceedure
Consent, Measure, HR, Evaccuate, Record, Allow
- Complete an informed consent form and general health screening form before starting the experiment.
- Measure body mass to the nearest 0.1 kg and stature to the nearest 0.01 m.
- Fit a HR monitor to the participant and check that the heart rate is displayed.
- Evacuate eight Douglas bags and attach a mouthpiece and tubing to the first bag.
- Record the ambient (room) temperature (°C) and pressure (mmHg) and record this in
- Allow time for familiarisation with the mouthpiece and nose-clip prior to the start of the test, at least 30 seconds.
How do you do a VO2 Max test on a:
Cycle Ergometer
Adjust, Press, Perform, Begin, Increase, Continute, Completing
- Adjust the seat height on a Wattbike so that the participant can cycle comfortably with a knee angle of ~ 160-170 degrees with the pedal in the down stroke.
- Press ‘Quick Ride’ on the screen, select ‘ERGO’ mode at bottom and adjust the load using the arrows on the bottom left box.
- Perform a light warm-up at 60 RPM at 60W for 5 minutes.
- Begin Stage 1 with a load of 90W (men) or 60W (women) with the participant cycling at a cadence of 60 - 80 rpm (try to keep this consistent throughout the test) and cycle for three minutes.
- Increase the resistance by adding 30W every 3 minutes.
- Continue increasing the resistance every 3 minutes, until the participants indicate that they can only manage one more minute*
- On completing the exercise protocol reduce the applied load to 60 - 100W depending on how the participant feels and ask the participant to cycle for at least 5 minutes before a period of seated rest.
How do you do a VO2 Max test on a:
Treadmill
Familiarse, Perform, Set, Begin, Increase, Completing
- Familiarise the participant with the treadmill, including how to mount and dismount while the treadmill belt is moving.
- Perform a light warm-up at 7km.h-‘ for 5 minutes.
- Set the treadmill gradient to 1% (Jones and Doust, 1996) and leave it at this gradient for the entire test.
- Begin stage 1 at 7.5 km.h-‘
- Increase the treadmill speed by 1.5 km.h-‘ every 3 minutes, until the participant indicates that they can only manage one more minute.
- On completing the exercise protocol and collecting the final blood sample, reduce the treadmill speed to 7km.h-1 (or a speed at which the participant is very comfortable) in order to complete a 5-minute cool down before a period of seated rest.
For a VO2 max test
Measurements: Final Minute of each Stage
- Expired gas (first stage and at least last 2 stages)
- HR every 10 s in the final 30 s
- RPE in the final 15 s
- Blood lactate in the final 15 s of cycling.
For the treadmill running test, at the end of each three-minute stage the participant should place their hands on the guard-rails, straddle the running belt and the blood sample should be taken whilst they are standing in this position
The treadmill is then set to the new speed and the participant should match their cadence with the treadmill belt before resuming running for the next 3-minute stage.Participants must give a verbal or hand signal when they feel that they can only
manage one more minute.
For expired gas collections, during the early / easy stages, hand the participant the nose clip and mouthpiece at 1 min 30 sec and take it back from them following the collection at minute 3.
However, once the RPE is ≥17, the participant should keep the mouthpiece in and nose clip on.
RER Equation
VCO2 ÷ VO2
Maximum oxygen uptake: Plateau and secondary criteria
Although the participant purportedly completed a maximum exertion cycling test, you need to verify that the measurements recorded are a valid indication of the participant’s maximum ability to consume oxygen.
To do this you must analyse your last two Douglas bags for oxygen uptake (VOz), to identify if a plateau in VO occurred. You may also use your RER, HR and blood lactate data as secondary criteria to determine if VOmax was achieved (Table ).
What does it mean if there is a VO2 plateau
In the presence of a plateau in VOz, a “true” VOmax has been achieved.
However, in some cases no plateau will be evident despite a maximum effort. If this occurs, we cannot be sure whether the Ozmax has been reached. In this instance it is best to refer to the term VOzpeak rather than VOmax.
Lactate threshold and lactate turnpoint
bLa indicates what
Blood lactate accumulation during incremental exercise tests can be used as an indicator of endurance performance and efficacy of training.
Lactate threshold (green dotted line)
Increase, concrentration in moles
first increase of blood lactate concentration above resting levels (0.5 mmol L’).
For example, if the lactate resting concentration is 0.8 mmol-L’, the lactate threshold is found at 1.3 mmol L- (N.B. the threshold does not have to coincide with an actual data point)
Lactate turnpoint (red dotted line):
ending
Dmod method: Connect the lactate threshold (as defined above with the lactate value at cessation of exercise © in figure below). Then find the value on the lactate curve that is furthest away from this line (* in figure below).
When will the primary collection begin, within a VO2 max test
Whats the RER Mean and how do you calculate Target HR
Primary collection will be within the last 2 douglass bag collections if not it will be a VO2 Peak test and hard to predict when you have a minute left
RER = 0.7 then it will most likely be a case of it using fats
needs to be above 1 to say that anaerobic glycolysis is being used
220 - age * 0.9
What are the contexts behind
Why we measure VO2 max and lactate thresholds
Research Environment
Team Sports
Clinical/Health Environment
Endurance Sport
Why do we measure VO2 max and lactate thresholds
Research Environment
good for texting the maximal fitness of both the circulatory, respiratory and muscular systems
a low VO2 max = greater risk of cardiovascular disease
some might though not be able to do it maximally so instead submaximal tests can be done
Why do we measure VO2 max and lactate thresholds
Team Sports
Doing research into any endurance intervention studies
Begginging of training versus after a training block
used to cateogories people within a study
Unhealthy Vs Healthy VO2 max means
to determine relative exercise intensity to fitness by working at a percentage of their VO2 max
Why do we measure VO2 max and lactate thresholds
Clinical/Health Environment
Yo-yo tests due to the change of direction
done typically for out of season training to set an athletes training intensity
Why do we measure VO2 max and lactate thresholds
Endurance Sport
to tailor their training within a given intensity to improve their endurances
Sub-maximal responses are more sensitive to changes in training status: current fitness.
Lactate, HR, Change
Reduced Lactate or Heart Rate at any sub-maximal running speed or power output indicates an improvement in endurance fitness.
If endurance training is ‘working’, the lactate curve will shift to the right. as demonstrated here
easier to change the lactate threshold compared to changing VO2 Max
VO2 max forms only part of the endurance physiological assessment
Speed, Power, efficiency
what are these assements looking
Speed at lactate threshold is a strong predictor of marathon pace
Speed / power at actate turnpoint can be maintained for approximately 1 hour: therefore a good predictor of 10 mile - half-marathon speed / or 40km TT for Cyclists
Economy / efficiency is also important A lower VOz at a given
sub-maximal speed or power output represents improved economy / efficiency.
Use of lactate thresholds to guide and monitor training intensity
how does it change over time
These zones are based on HR and speed primarily
Done over a number of weeks
Lactate Threshold changes as intensity increases
Lactate Threshold changes as a result of intensity rapidly increasing
Different ways you can measure VO2 max and lactate thresholds.
Protocol type
Equipment Method
Mode of exercise
Different ways you can measure VO2 max and lactate thresholds.
Protocol type
Will be done for the preferred method of exercise
Swimming is awkward to do and other ways to do it can be through a swimming bleep test for sports like water polo as well
Swimming, Running, Rowing or Cycling
Different ways you can measure VO2 max and lactate thresholds.
Equipment Method
Incremental vs RAMP
Incremental vs Ramp Exercise protocol
Incremental:
Good if also interested in sub-maximal, steady-state VOz, heart rate and blood lactate profile Can’t use ramp test with Douglas bag system.
Power increases by 30 watts every 3 minutes
Ramp
Good if breath by breath (constant measurement)
system is available. Reach VO2 max more quickly. Can be used to determine ventilatory thresholds.
Power increases by 30 watts per minute
1 watt every 2 minutes
cant do sub-vo2 basesd testing
reaches VO2 max quickly
can find sub ventilatory thresholds
Different ways you can measure VO2 max and lactate thresholds.
Mode of exercise
Metabolic Cart vs the Douglass bag
Douglass bag shows where those numbers might come from
Pros & Cons of Cylce Ergometer for VO2 max testing
Pros
Lower Body Focus: It provides a controlled environment for cycling, which is excellent for cyclists or for sports where cycling is an integral part.
Safety: Lower risk of falls or injuries since the participant is seated, making it suitable for those with balance issues or who are less comfortable with running.
Less Intimidating: Participants may find it less daunting to exert themselves on a bike, especially if they have joint issues or are overweight.
Ease of Measurement: It’s easier to connect participants to measurement devices (like ECG or blood pressure cuffs) as they remain relatively stationary.
Cons
Lower VO2 max Values: Typically, VO2 max values are slightly lower on a cycle ergometer compared to a treadmill, due to the engagement of less total muscle mass.
Specificity: May not be as relevant for assessing individuals whose primary activities are not cycling-related.
Skill and Comfort Level: Some people may not be regular cyclists, which can affect their performance and comfort during the test.
Pros & Cons of a treadmill for VO2 max testing
Treadmill
Pros
Natural Movement: Running on a treadmill more closely mimics natural running and walking activities, making it ideal for runners and those involved in sports requiring running.
Greater VO2 max Achievement: Generally, higher VO2 max values are achieved on treadmills because running engages more muscle mass than cycling, demanding more oxygen.
Adaptability: Easier for participants to perform without requiring much skill or adaptation, as most people are accustomed to walking or running.
Cons
Risk of Injury: Treadmills can pose a higher risk of falls and injuries, especially as exhaustion sets in towards the peak of the test.
Intimidation: Some individuals may find running at high speeds intimidating, especially at steep inclines, which could affect their performance.
Cost and Space: Treadmills can be more expensive and require more space than cycle ergometers.
What is the importance of lactate threshold/turnpoint for performance prediction?
Current Aerobic Capacity
Adaptation Evaluation
Race Pacing and Strategy
Progress tracking
What are the ethical implications and methodological limitations of using direct measurements of maximal oxygen uptake on participants who are not well accustomed to strenuous exercise?
Ethical: Risk of injury, Understanding of being able to withdraw at anytime
Methodological: Participant Motivation and Experience, Physiological Responses, Test Validity
What causes the abrupt increase in blood lactate, indicated by the lactate threshold and lactate turnpoint found during exercise in an incremental test (4 marks)?
The use of anaeroic metabolism over aerobic metablomism as a result of an increase in exercise intensity resulting in higher demands.
This increases blood lactate within the blood and overtime as anaerobic production dominates, results in a longer amount of time to reduce blood lactate.
What are the primary criteria for VOmax?
Plateau of Oxygen Consumption: The most definitive criterion for VO₂max is a plateau or leveling off of oxygen consumption despite an increase in exercise intensity. This indicates that the maximum capacity for oxygen use has been reached.
Respiratory Exchange Ratio (RER): An RER greater than 1.1 during exercise suggests that a significant amount of energy is being produced anaerobically, a condition often met at or near VO₂max.
Heart Rate: Approaching maximum heart rate (calculated as 220 minus the person’s age) can also indicate that VO₂max has been reached, as it suggests the cardiovascular system is working at its maximum capacity.
What are the Secondary criteria for VOmax?
Blood Lactate: An elevated blood lactate level, typically more than 8-10 mmol/L, indicates a high level of anaerobic metabolism, supporting the achievement of VO₂max.
Perceived Exertion: High levels of perceived exertion, often measured by scales like the Borg Scale where the individual feels they cannot continue physically, can be a secondary indicator of reaching VO₂max.
