fitness training increases the concentration of lactic acid the runners can build up muscles before pain stops them running. what is a consequence of this increase

more energy is needed from muscles

Explanation:

hormones in blood stream

image: dtc.ucsf.edu

endocrine glands secrete hormones into the blood stream near them; the hormones then travel in our bloodstream until it reaches its destination, called a target cell, in distance parts of the body. in the target tissue, hormones lock onto the target’s plasma membrane, called the receptor site.