W8 - Aerobic Fitness Flashcards
- Why is there interest in measuring VO2 max in children and adolescents?
To understand developmental changes
Link to health outcomes i.e current + future CV disease risk
Training purposes
Disease prognosis in paediatric groups
What is the primary criteria typically used to verify VO2 max in young people.
plateau on oxygen uptake
What are the secondary criteria typically used to verify VO2 max in young people.
Different thresholds based on RER, HR, BLa + subjective signs of intense effort etc.
What are the potential limitations of using plateau on oxygen uptake as the primary criteria typically used to verify VO2 max in young people.
Only observed in a minority of cases (~10-30%), leading to why secondary criteria are often used.
What are the potential limitations of using the secondary criteria typically used to verify VO2 max in young people.
People don’t reach VO2max at a fixed RER, HR or BLa.
Meaning people can obtain a VO2max without reaching the RER + HR criteria, or if the criteria are reached, they occur at a sub-maximal VO2. The less stringent the criteria (e.g. 85 vs. 90% age predicted HR max), the greater the under estimation of VO2max.
What is the difference between VO2 max + VO2 peak?
VO2 max is used when an O2 uptake plateau is evident.
Although secondary criteria have been used to give confidence of a ‘maximal effort’ the term VO2peak is used in this instance.
What is the purpose of supra-maximal testing when measuring VO2 max?
To verify peak VO2 obtained from a ramp test to exhaustion is a ‘true’ maximum.
To do this, we increase the power output to 105% peak power in the supramaximal test, and examine whether a further increase in peak VO2 is obtained.
If not, we have demonstrated a plateau over the 2 tests, as power output has increased but the peak VO2 over both tests is similar.
What have the paediatric studies shown us regarding the use of supra-maximal exercise to validate VO2 max?
Children can tolerate well the ramp + supra-maximal protocol.
This improves the incidence of a ‘true’ VO2max.
Studies indicate that ~ 80-90% of children obtain a VO2max measure using this protocol, regardless of age, sex and health status.
What does growth relates increases in peak VO2 appear to be dominated by?
Increases in the blood O2 carrying capacity + SV, hence CO
What are sex-related differences in body mass adjusted peak VO2 largely related to?
Difference in cardiac factors (SV) which reflect sex differences in lean body mass.
What may contribute to sex differences in peak vo2
Females potentially experiencing reduced muscle bf at max exercise
What are the progressive treadmill or cycle protocols typically used in paediatrics?
Continuous/discontinuous
Step or ramp
Fast or slow increments
What is the criterion measure for observing a VO2 max?
A plateau
What does supra-maximal testing in children allow?
For a plateau to be obtained in VO2
Is supramax testing impacted by age, sex, body size or fitness level?
No
What is the gold stantard criterion for VO2?
A plateau in O2 uptake.
What guidelines should be used to verity a VO2 max achieved in children if a plateau is absent?
Peak RER > 1.00
Peak HR > 85-90% age predicted max or 195 beat/min for cycling and 200 beats/min for treadmill
Subjective sings of fatigue + intense effort
Blood lactate conc > 6mM
Data suggests that once body size is accounted for using allometric models, what factors have an impact of the development of peak VO2?
Age - Increase in peak VO2
Sex (M - increase, females - decrease)
Body fatness - decrease
Absolute peak VO2
Age in boys and girls
Absolute peak VO2 increases linearly with age in both boys and girls
Sex differences widen at ~!4 yrs
Absolute peak vO2 increases with…
Age and is largely driven by body size
What is the dominant factor for augmenting peak VO2
Increase in FFM
What is the indirect estimation of aerobic fitness?
VO2max
What has VO2 max /maximal O2 uptake been used to study?
Changes in aerobic fitness during G&M
Efficacy of exercise training programme
Impact of disease on aerobic capacity
Relationship between physical activity, fitness + health
Expressing vO2 max relative to an estimation of ….. is more appropriate in young people
FFM
What can dual-energy x-ray absorptiometry do in regard to the estimation of FFM to express VO2 max?
Can partition out lower body FFM
- Can offer advantage over total FFM when scaling VO2max in younger people.
Recommendations for assessing VO2max in the lab
A combined incremental + supra maximal test protocol should be used to obtain a valid measurement of VO2max in young people both in health + disease.
Why shouldn’t secondary criteria such as HR + RER be used to verify the attainment of VO2 max in young people?
They result in a ‘sub-maximal’ peak VO2.
Why should VO2 max be adjusted for using FFM over body mass in young people?
Because body mass doesn’t account for differences in body composition
What is a major determinant of the rise in peak vO2 during growth + maturation?
SV
