An abundant and continual supply of atp is necessary for all living cells. active muscle cells require an extraordinary amount of atp to permit strenuous exercise for prolonged periods. toxins, reduced blood flow, and a compromised respiratory system can interfere with the transport of oxygen to active cells. a runner in a marathon faces multiple obstacles to continue to produce sufficient atp to remain competitive. when oxygen delivery becomes insufficient to support a runner's aerobic metabolism, cells switch to an emergency mode in which

Explained.

Explanation:

When oxygen delivery becomes insufficient to support a runner's aerobic metabolism, cells switch to an emergency mode in which ATP is insufficiently produced and is lactic acid is produced as by product. Thus the runner finds difficult to remain competitive in the race because of lack energy.

To overcome this state the runner needs to increase his/her oxygen in take. This why it is advised to breath deeply.

from my research i have to the conclusion that decomposers, such as fungi, bacteria and invertebrates, play a critical role in nutrient cycling and without them the earth's ecosystem may not support life as we know it. elements such as carbon, nitrogen and phosphorus exist in limited amounts on earth, although huge amounts of carbon are being released into the atmosphere from underground sources now by humans. it is still extremely important that other nutrients be retained by the process of re-use. decomposers are organisms that are able to chemically break down dead material and make these elements available for use by other organisms. without this breakdown of dead material, dead bodies would pile up. so decomposers also play a role in clean up also. without them, life might not continue as we know it and dead material would overwhelm the earth.