Answer: Thank you for your question -
a tricky one in its present form as there are so many variables
involved. We have approached a number of our associates about
this and opinion is divided.
However, a suggested answer
Given that the person
has no abnormalities in muscle or heart or blood supplies, then,
as the vessel (the aorta) that conducts fresh oxygenated blood
supplies to both sides of the body, does so at the same time,
there should be no difference in which arm shows fatigue first.
One idea is that when a muscle is forced to contract where the
oxygen supply is insufficient, lactic acid builds up and eventually
stops the muscle from contracting, so fatigue sets in, until
the lactic acid has been dispersed. Some people seem to think
that the side of the body that is furthest away from the fresh
oxygenated blood will tire first. Ironically, if you are right
handed and the muscles are more developed on this side, then
you will need more oxygen to keep fatigue away and so this side
will show fatigue first.
We contend that this is not so, as more regular exercise can
lead to better blood supplies to the muscles, which makes them
more efficient and so the aerobic respiration lasts longer and
waste products are removed more efficiently; hence the non-preferred
arm would tire more quickly, as the muscles in the preferred
arm are stronger and therefore more efficient.
Given all this, it seems that as the causes of fatigue are uncertain,
that your best course of action would be to establish that all
variables are cancelled out and then to conclude that there should
be no difference in fatigue in either arm based on blood supply