Cardiovascular and VO2 Max In Children Flashcards
Brake: Activity of the left and right cardiac vagus nerves decreases what?
Heart rate
Accelerator: Activity of the right sympathetic nerves increases what?
Heart rate
Reducing the brake?
Speeds the heart
Reducing the accelerator?
slows the heart
Heart rate is increased by?
decreasing parasympathetic activity (vagal withdrawal) and increasing sympathetic vagal activity
At low heart rates (<100BPM)…
Heart rate is varied by altering vagal activity
Beyond 100BPM heart rate is controlled by
adjusting sympathetic activity
Body surface area (BSA) relates to two size dependent cardiac variables?
Stroke volume and cardiac output
Resting metabolic rate is often linked with?
body heat loss
According to dimensions theory, heart mass or volume should relate to BSA by?
Exponent 1.5
As children grow, resting cardiac output progressively…
Decreases relative to body mass
Stroke volume increases in direct proportion to?
Body mass
During rest, the heart rate is?
inversely related to mass and age in children (decreases as they get bigger and older)
During maximal exercise, their maximal heart rate is?
Independent of body size between ages of 6 and 16 years
Is heart rate recovery in children slower or faster than adults?
Faster
Gender differences may be explained by?
Lower haemoglobin levels in girls
Heart rate recovery might be related to?
Lower acidic levels, quicker post-exercise removal of metabolites
How much is stroke volume attenuated in children?
Nearly double the stroke volume in from rest to maximal exercise.
Cardiac output in children compared to adults is?
Lower (although, rate of increase is similar)
How is lower cardiac output compensated by?
Having a higher Arteriovenous oxygen tension difference
What is the Fick equation and O2 uptake concept?
That arterial flow of oxygen (first term) venous flow of oxygen (second term) flow of oxygen leaving or entering the circulation
Heart rate and total peripheral resistance is … in children
Higher
Stroke volume in children is often?
Lower
Children, for a given muscle mass, have higher cardiac output and lower total peripheral resistance at a given VO2, what does this indicate?
Higher muscle blood flow.
The inconsistency between lower cardiac output and a higher muscle blood flow can be explained by?
Having a smaller absolute amount of muscle mass performing exercise
What are the effects of smaller absolute muscle mass?
When performing an ‘X’ amount of work, would be stressed to a greater extent. Generating more metabolic by-products and heat per unit of muscle.
What is the results of small absolute muscle mass?
There are 3 (too long)
Between the ages of 6 and 12, a boys VO2max more than doubles from what?
1.2L/min to 2.7L/min
During puberty, VO2max rise ____ in males and ____ in females?
Accelerates, Plateus
Ontogenetic improvements in VO2max can be determined by two factors
Increases in size of exercising tissue (skeletal muscle), and changes in functional capacity of its energy systems (aerobic enzyme capacity)
As children grow, maximal rate of cellular aerobic metabolism becomes?
Relatively slow
three factors that influence left ventricular size
Blood volume, heart rate (vagal tone) and hormonal effect on the heart
