KINE 2P84 Lecture Notes - Lecture 14: Ductus Arteriosus, Hematocrit, Ductus Venosus
8 May 2018
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KINE 2P84 Growth and Development
Muscle Strength
Structure
- Mass & strength increase as we grow
- Specific strength is per body size
Number of fibres
- Is determined around birth and everyone is equal
- Increase in muscle mass is not due to hyperplasia (# of fibres)
- The cross-sectional area (width) is increased in volume and mass and in adolescence
men > women
- The fibre length is increased due to increase in contractile proteins
Strength
- Absolute strength vs relative strength (relative to body mass)
- Strength increases with age, boys > girls, and girls increase mostly in lower extremities
- Have to take into account the change in proportions
Maturity
- For boys early maturers are stronger at all ages, whereas girls, early maturers are
stronger before puberty but not after. Late maturers catch up.
Relative to body size
- For boys early maturers are stronger but the difference is not apparent. For girls early
maturers have lower strength as the peak rate of strength occurs after the peak rate of
height
Differences between individuals
- Muscle is characterized by size, composition and function which is characterized by
coordination and activation pattern
Interpolated twitch technique
- Maximal contraction is then furthered by electrical stimulation
- Children have overall lower activation of motor units as they do not utilize their higher-
threshold type II motor units
Rate of torque/force development (explosive force)
- Childre’s is loer relatie to a stregth or od size
- Threshold occurs at a lower intensity in men/women than boys/girls (EMG)
Resistance Training
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Child Adolescence
- Increase strength due to growth and furthermore on top due to training, in isotonic,
isokinetic and isometric contractions
- Equal across gender
- Boys increase 2x as much as men in %
Effect
- Muscle strength, performance & rehabilitation increased, where sports injuries
decreased
Safety
- Very low injury rate, dependant on gradual progression, proper technique, proper
equipment, and supervision
- Need to consider maturity level, technical proficiency and existing strength level
Cardiorespiratory Changes and Aerobic Performance
Fetal Circulation
- At 3 weeks cells are contracting to make beats in heart tissue, at 6 there is a definitive
form, at 8 the main blood vessels are formed and there is a full heart
- Oge to the lood oes fro the other’s ateral irulatio, ot the lood
- The placenta is the interchange between mother and fetus, it is busy with blood vessels.
Connected to the fetus through the umbilical cord, one vein (oxygenated blood) and
two arteries (deoxygenated, to mother). There is less oxygen because it went through
the mother first
Shunts
- Detours in the fetus, not in postnatal life
- Consists of the foramen ovale, which is an opening between the right and left atrium so
that some blood goes through, shunts the lungs, bypassing as it is not necessary. Next
the ductus arteriosus, which is a small vessel that connects the pulmonary arteries and
aorta, also bypassing lungs. Lastly the ductus venosus, which connects the vena cava
with inferior vein for the same purpose.
Adjustments at birth
- The lungs inflate and blood flow to them increases, the umbilical cord constricts and
dries up, and the three shunts will close.
Changes in cardiovascular function
- Heart rate decreases with growth, and blood pressure increases with growth (systolic –
contraction, diastolic – vascular resistance)
Changes in blood features
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Document Summary
Mass & strength increase as we grow. Is determined around birth and everyone is equal. Increase in muscle mass is not due to hyperplasia (# of fibres) The cross-sectional area (width) is increased in volume and mass and in adolescence men > women. The fibre length is increased due to increase in contractile proteins. Absolute strength vs relative strength (relative to body mass) Strength increases with age, boys > girls, and girls increase mostly in lower extremities. Have to take into account the change in proportions. For boys early maturers are stronger at all ages, whereas girls, early maturers are stronger before puberty but not after. For boys early maturers are stronger but the difference is not apparent. For girls early maturers have lower strength as the peak rate of strength occurs after the peak rate of height. Muscle is characterized by size, composition and function which is characterized by coordination and activation pattern.
