Download Redistribution of blood and heart rate range

Redistribution of blood
We have a limited amount (4-5 litres) of
blood to transport oxygen
 During exercise – send more blood to
exercising muscles
 Arterioles supplying muscles and other
organs able to open (vasodilation) and
close (vasoconstriction)
 Rings of muscle – pre-capillary sphincters

©Subject Support 2012
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Redistribution of blood
Controlled by sympathetic nerve
impulses from vaso-motor centre in
medulla of brain
 Vasodilation to exercising muscles – need
more oxygen
 Vasodilation to heart muscle – needs
more oxygen
 Vasodilation to skin arterioles – need for
cooling

©Subject Support 2012
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Redistribution of blood
Vasoconstriction to kidneys, liver, guts and
inactive muscles - reduced importance
 Eat before exercise – blood to guts for
digestion – less blood/oxygen for muscles
– performance suffers
 No change in supply to brain - still
working – still needs oxygen

©Subject Support 2012
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Heart rate range
When exercising heart rate increases requires energy/oxygen
 Unfit performer – high resting and
exercising heart rate – 70-150 beats per
minute
 Lots blood/oxygen needed by heart –
less available to muscles – performance
suffers

©Subject Support 2012
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Heart rate range
Training – lower resting heart rate –
bradycardia - benefit?
 Fit performer – lower resting and
exercising heart rate – 60-180
 Less blood/oxygen needed by heart –
more available to muscles – better
performance
 Training – increased heart rate range

©Subject Support 2012
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