The use of a heart rate monitor can be helpful,
although finding an individuals threshold limit requires testing and will vary considerably
from person to person, an averagely fit person
may find this limit is 140-1530 beats per minute,
whilst a top athlete may be able to raise their
heart rate up to 180 before working anaerobically.
A simpler way to tell, which is relatively
accurate, is that if you are running aerobically
then you should be able to have a
conversation. If you are too out of breath to
talk then you should slow a little.
The thing to remember with these sessions is
that you are trying to run hard, without being
limited by the amount of oxygen you can take in.
These runs will be important for any distance
runner for building fitness and should be hard
work, but you should not be running so hard that
you start to feel that you need to stop because
you are completely out of breath. One way of
thinking about it is that you should run hard,
but know that if you needed to produce a sprint
finish you could.
