Specific Populations - Youth

Question 1

Maximal Oxygen Uptake/VO2 Max

Answer 1

Represents the maximum amount of oxygen that can be extracted from the atmosphere, transported to the working muscle, and taken up and utilized by the exercising tissue. 1

Question 2

What is VO2 maxed measured in? For Kids & Adults? Why?

Answer 2

Measured in

Absolute: L.min-1

Ratio scaled (divide by body mass): ml.kg-1.min-1

In children and young people, allometric scaling: ml.kg-0.67.min-

Question 3

Why is VO2 max a physiological characteristic of interest

Answer 3

Sets the limit for ATP generation using oxygen dependent (‘aerobic’) metabolic pathways; therefore has an important influence of performance

Maximal oxygen uptake seems to be linked to markers of health independent of other risk factors e.g. ‘fit but fat’

Question 4

Maximal Oxygen Uptake vs. ‘Peak’

Answer 4

Plateau’s: only a minority of children and young people attain – and hence use of the term ‘peak’ oxygen uptake in the paediatric literature

Question 5

Maximal / Peak Oxygen Uptake: Criteria

HR with adults to younger people

Answer 5

Heart rate will be higher than adults

The RER will be lower as a result of lactate not being produced in higher volumes compared to adults

Question 6

How does “peak” oxygen uptake change with age, and are there differences between males and females ? (Age)

Answer 6

More muscle mass as you age = higher VO2

Males will also have a higher VO2 levels as a result of having testosterone levels compared to women

Body mass in this context isnt takwen into account

Question 7

How does “peak” oxygen uptake change with age, and are there differences between males and females ? (Gender)

Answer 7

Some girls can have puberty at the age of 9

Lower VO2 for girls as a result of also more fat development

Question 8

Peak oxygen uptake and age summary

Peak VO2 & Gender. What are the values

Answer 8

Peak VO 2 gradually increases in males (0.25 L.min-1 per year)

Peak VO 2 gradually increases in females (0.125 L.min-1 per year) but perhaps levels off, even falls at 13-15 years

Male values higher than females (10 years: 2-10%; 14 years: 27-31%; 16 years: 37%)

women half then men along with a decrease

Question 9

What are the reasons for these differences between males and females?

MM, Hae, BM & PA

Answer 9

Boys have greater muscle mass resulting in:
* Facilitates the utilisation of oxygen (more muscle, more places)
* Peripheral muscle pump helps with venous return to heart, boosting Stroke Volum (SV)

Increases in Haemoglobin (Hb) concentration during late teens
* more muscles = higher haemoglobin concetration

Biological maturation
* Independent of chronological age, body size, muscle mass and Hb concentration
* Older males > Older females

Physical activity
* males are more active

Question 10

Peak Oxygen Uptake & Fat Free mass (Armstrong, 2001)

Answer 10

• The initial model revealed mass, stature and age as significant explanatory variables of VO2, peak with an additional positive effect for stage of maturity.
• Girls’ values were significantly lower than those of boys and a significant age-by-sex interaction described a progressive divergence in boys’ and girls’ VO2, peak.

Fat-free mass was the dominant influence on the growth of VO2, peak but the multilevel regression models demonstrated that, with body size and fatness allowed for, VO2, peak increased with age and maturation in both sexes

Fat = less VO2

Question 11

Differences in stroke volume

VO2 peak & MSI

Answer 11

VO, peak
boys, 47.2 $ 6.1; girls, 40.4 $ 5.8 mL/kg/min - 16.8% difference

Maximal stroke index
boys, 62 + 9; girls 55 + 9 mL/m - 12.7% difference

Conclusions:
SV and body composition contribute to sex-related variations in VO2, max
* Unclear if due to sex differences in relative heart size or dynamic factors influencing ventricular preload and contractility during exercise

Question 12

Differences in stroke volume: Size

Boys Vs Girls

LBM = Lean Body Mass

Answer 12

VO, peak
Boys 47.9 mL/kg/min
Girls 40.9 mL/kg/min
Boys 19.0 mL/kg LBM(1.33)/min Girls 18.9 mL/kg LBM(1.33)/min
normalized (allometric equation) the difference totally disappeared

Maximal SV was significantly higher in boys than in girls - but when expressed relative to LBM, the difference was no longer significant.

Conclusions:
* Contrary to adults, lower SV max was the sole limiting factor of VO, max that distinguished boys from girls
* This difference disappeared when normalised for LBM

Question 13

Muscle O2 Extraction Dynamics for gender

Answer 13

Girls required a greater fractional O2 extraction to increase work rate and O2 extra tian compared it laya in
during ramp exercise

more muscle = more oxygen uptake

Conclusions:
To 10-y-f children is in part, in 9-
related to sex-specific changes in muscle O2, extraction dynamics during incremental exercise

Question 14

Comparing untrained to trained

How does training increase peak oxygen uptake within in young people? WHY?

CO, B&P volume, SV, MM, L, Bl

Answer 14

Higher maximal cardiac output

Higher blood and plasma volume

Higher haemoglobin concentrations

Higher stroke volume Decreased heart rate

Larger myocardial mass and heart volume?

Increased lung function

Less blood lactate levels compared to adults and untrained youths

Question 15

What effect does age and maturation have on responses to training?

FFM, 8-10 Increase, 11-18 increase

Answer 15

“trigger point” – Katch (1983)

Young people 8 to 10

Average increase in mass related peak oxygen uptake 6.5%

Young people 11 to 18

Average increase in mass related peak oxygen uptake 5.5

to demonstrate a increase due to training is really difficult because you might see changes due to growth & a lot of young people are fit and active anyways

Pre and pubertal children do get benefits from exercise

Question 16

Sex differences in response to training?

Answer 16

At the moment no evidence to suggest a difference as a result of a lack of testing

Problems with this conclusion?
* hasnt been looked at within studies
* theres very few studies for female

Question 17

Arteriovenous oxygen difference between genders

Answer 17

Central factors of heart size and peak cardiac output are proportional to the LBM of the individual and
sex independent.

Sex differences in peripheral factors such as muscle fibre type profile, may affect AVO2 difference and underlie prepubertal boys’ higher peak V O2

How good are you at extracting oxygen from the capilaries

Question 18

What factors at play when giving

Exercise Prescription

Answer 18

Mode, Frequency, Duration, Intensity and Programme length

Mode: The mode of delievery ie intervals

Question 19

EP: Mode

What mode of exercise should young people undertake to
improve peak oxygen uptake?

interval or continous exercise

Answer 19

Both

Question 20

Exercise Prescription: Mode

Answer 20

a variety of exercise modes have been undertaken

• Continuous exercise
• Interval
• Mix of two
• Cycling, running, resistance exercise

Exercise using large muscle groups regardless of mode has the potential to increase peak oxygen uptake

Question 21

Exercise Prescription: Frequency

Answer 21

How often per week sessions occur

Question 22

Exercise Prescription: Duration

Answer 22

How long the sessions will last

Question 23

Exercise Prescription: Intensity

Most likely to come up in an exam

Answer 23

How intense a programme is in terms of heart rate

Question 24

Exercise Prescription: Programme Length

Answer 24

how long the programme is

Question 25

EP: Frequency

What is the minimum frequency of exercise that young people should undertake to improve peak oxygen uptake?

Answer 25

With 2 exceptions frequency was 3 to 4 sessions a week in all studies

Question 26

EP: Duration

What duration of training do young people need to
undertake to improve peak oxygen uptake?

Answer 26

Duration varied from 12 to 90 min, range 20 to 40 min

In general training sessions of 40 to 60 min most
successful

Question 27

EP: Intensity

What intensity of exercise should young people undertake
to improve peak oxygen uptake?

Answer 27

• This appears to be crucial
• Massicotte and Macnab (1974)
• Boys trained for 12 min, 3 times a week, for 6 weeks
• 66 to 72% of heart rate max
• 75 to 80% of heart rate max
• 88 to 93% of heart rate max
• Only group who trained at highest intensity improved peak oxygen uptake

Question 28

EP: Programme lenght

What length of training programme do young people need to undertake to improve peak oxygen uptake?

Answer 28

Programme Length
* Ranged from 6 to 20 weeks
* Stoedefalke and colleagues (2000) trained post menarcheal girls for 20 weeks - no changes
* Massicotte and Macnab 1974 trained boys for 6 weeks -
10.8% increase
* Prudent to recommend proaramme of 1) weeks

Question 29

EP: Intensity

High intensity interval training: Outline

Answer 29

Costigan et al., (2015) High-intensity interval training for
improving health-related fitness in adolescents: a
systematic review and meta-analysis. Br J Sports Med
49(19):1253-61
* examined adolescents(13–18 years)
* examined health-related fitness outcomes;
* involved an intervention of
≥4 weeks in duration;
* included a control or moderate intensity comparison group;
* prescribed high intensity activity (e.g., 85–95% peak heart rate or 80–100% peak work rate)

Question 30

High intensity interval training: results

Answer 30

Results
* Mean difference = 2.6 mLkg−1ꞏ min −1, 95% CI 1.8 to 3.3, p<0.001
* The effects of HIIT on cardiorespiratory fitness were large (d=1.05, 95%
CI 0.36 to 1.75) and body composition were medium
* Study duration was a moderator for the effect of HIIT on body fat percentage

• Intervention effects for waist circumference and muscular fitness were not statistically significant

Conclusions
* HIIT is a feasible and time-efficient approach for improving
cardiorespiratory fitness and body composition in adolescent
populations