Adaptation: Lecture 2
Effects of Training Intensity
Exercise intensity and duration effect on Kreb’s Cycle
Slow twitch: as intensity increases, right away cytochrome C enzyme increases until about 83%
VO2 max where it plateaus and begins to decrease.
Once intensity increases, duration will decrease.
Red vastus (fast oxidative glycolytic) peaks at 83% as well but is maintained afterwards
White vastus (fast glycolytic) begins to adapt at 83% (this is where they begin to be recruited)
Stroke Volume Adaptation to Aerobic Training
Change in SV PostTraining
Stroke Volume is greater in aerobic trained at all levels of
• This is a result of increased EDV, decreased ESV and increased EF
• In the untrained (moderate intensity) stroke volume stabilizes – they do not get same
linear increase as trained.
EDV changes in SV posttraining
Pre-training: increases with intensity to moderate, after this point there is no
• As intensity increases, O2 uptake will increase and CO will
increase but these are not happening because of an increase in EDV
(happens because of an increased HR)
Post-training: has higher EDV at rest. Increases a bit with first intensity increase and again at
final stage going to VO2 max it increases again.
• Increase stroke volume instead of HR
Maximum heart rate, whether trained or untrained will not change much.
ESV changes in SV posttraining
Post-training: more left in the heart after training AT REST
• The SV will still be much greater because the EDV is so much
Even though you lose some of the change in ESV because you are
filling it to a much greater degree it translates into greater SV at rest.
Closer to maximum work rates, you pump more blood out with training. There is less volume
remaining in heart during maximum intensity.
EF changes in SV posttraining
Of total SV how much is being ejected at each beat • At rest it is similar. Even though fraction is similar though, the numbers are different – SV
is higher post training but you are still ejecting same percentage
Untrained: EF either decreases or stays the same
Post-training: EF continues to increase. Increase in filling, less volume remaining in heart.
Heart rate changes in SV posttraining
Post-training: Heart rate is reduced with aerobic training at rest and
during submaximal exercise
Maximal HR is about the same or very slightly reduced in trained (but
they can deliver more O2)
• The same amount of oxygen is needed b