1. Metabolic Rate & the Evaluation of Physical Performance in Children

2. HEAT BALANCE & TEMPERATURE REGULATION
METABOLISM:
CHEMICAL REACTIONS: HEAT & ENERGY
HEAT LOSS:
RADIATION, CONDUCTION, CONV ECT ION 70%
EVAPORATION (skin & lungs) 27%
WARMING INSPIRED Al R 2%
URINE & FAECES 1%
CONTROL:
H Y P OT H A LAM U S
PERIPHERAL RECEPTORS
Comparison of core and peripheral temperatures

3. CONTROL IN NEWBORNS
Mechanisms of shivering & sweating are poorly developed
Sweat glands immature
Large S.A./ Wt ratio
Thin subcutaneous adipose tissue layer
LEADS TO INSTABILITY OF BODY TEMPERATURE

4. Average body temperature drops with age
SD also drops, indicating better control

5. Vasoconstriction well developed Crying increases metabolic rate
CONTROL IN NEWBORNS
Vasoconstriction well developed
Crying increases metabolic rate
Restlessness & increased movements
Brown fat

6. Vulnerability of the Adolescent Athlete
There have been several deaths of adolescent athletes
Intense prolonged activity
High ambient temperature & humidity
Athletic equipment
Big (small S.A. /Weight ratio)
Lack of water

7. HEAT STROKE Sweating (Sweat is hypotonic)
Water leaves cells to hypertonic exterior
Water leaves blood, decrease in blood volume
High concentration of electrolytes in blood
Excessive water loss, sweating is shut-off
Temperature rises rapidly (>40ºC)
Heart failure

8. Metabolic Rate Chemical reactions of the body
Reactions = Energy + Heat
Direct Calorimetry
sealed chamber where all inputs and outputs are monitored

9. Indirect Calorimetry Determination of oxygen uptake
Spirometer for oxygen uptake
OK for low levels of oxygen uptake
Collection and analysis of expired gases
Used as indicator of aerobic fitness

10. Respiratory Quotient

11. Respiratory Quotient (R.Q.)
Carbohydrate
C6H12O6 + 6O2 --> 6CO2 + 6H2O
R = 6CO2 / 6O2 = 1.0
Fat
C16H32O2 + 23O2 --> 16CO2 + 16H2O
R = 16CO2 / 23O2 = 0.70

13. Maximum Oxygen Uptake

14. VO2max testing Treadmill Cycle ergometer (15% less) Criteria of max.
Heart rate above 190
Subjects report
VO2 plateaus
Blood Lactate
R greater than 1.1

15. Reliability of VO2max (ml.kg-1.min-1) in Children and Adolescents
Source
Sample
Test Type
Reliability Coefficient
Boileau et al. (1977)
21 M, y
Walk
r = .87
Cunningham et al. (1977)
66 M, 10 y
Walk/Run
r = .56
Cureton (1976)
27 M & F, 7-12 y
r = .88
Paterson et al. (1981)
8 M, y
Jog
Run
R = .47
R = .87
R = .95
Note. r = interclass reliability; R = intraclass reliability
(Fitnessgram Reference Guide)
Typical R values for Height (0.99) and Skinfold (0.96) measurements