Why is it important to understand how different body systems interact when developing a training plan?

Because some people cant handle as much as other peopl.

Explanation:

You could overrun somebody by pushing them to hard. But you would'nt know if they had asthma in their lungs that just happened. Or if the person had an unknow health complicagtion.

it's diluted or concentrated

in a diluted solution, you can add a lot more solute but in concentrated only a little more can be added