EXS 510
Case Study Essay Question #1: Cardiorespiratory System
No matter how the race ends, it must first start. Although we may be looking at three different
athletes, competing in three different races. They must all go through the same phase at the beginning
of each of their prospective events. The first phase I’m talking about is the Rest-To-Exercise Transition.
Research has shown that “when measuring O2 consumption during the transition from rest to light or
moderate exercise, O2 consumption increases rapidly and reaches a steady state within 1-4 minutes.”
(Powers, et al 2020) The fact that O2 consumption doesn’t instantly increase to a steady state value
signifies that the body is depending on the use of anaerobic energy sources in some capacity to produce
ATP at the start of exercise. There is significant evidence that would show that “at the onset of exercise,
the ATP-PC system is the first active bioenergetic pathway, followed by glycolysis, and finally aerobic
energy production.” (Powers, et al 2020). To me, the previous statement shows that there is never a
single bioenergetic pathway in use, but rather there is a layering or transition from pathway to pathway
as these events increase in length.
The first athlete we’ll discuss is the 100m sprinter. This athlete can run 100m in :10 seconds flat!
According to the USATF, an Olympic qualifying time for the Men’s 100m sprint is a 10.05! It is important
to point this out, as a way to better describe the level of intensity of this particular sprinter and his time.
For a race like this, within the time constraints this athlete will use a combination of ATP-PC and
glycolysis as bioenergetic pathways. This sprint calling for a predominantly anaerobic metabolic pathway,
the ATP-PC system will be the primary supplier of all the ATP needed for exercise lasting :1-:5 seconds.
High intensity exercises lasting longer than :5 seconds will begin to utilize the ATP producing capability of
glycolysis. So as our sprinter is running, after about :5 seconds he will begin to transfer from the ATP-PC
system over to the glycolysis system.
Our next athlete is an 800m runner, finishing this race in 2 minutes flat. Sadly enough, our
sprinter still has some more training to do, hopefully he hasn’t hit his ceiling because an Olympic
qualifying time in the Men’s 800m is 1:46.25. None-the-less a 2-minute 800m is still quite the feat.
Referencing back to my opening statement, when you consider the rest-to-exercise transition you will
see that this sprinter will utilize the ATP-PC system at the start of the race, but will soon transfer over to
a 50%/50% anaerobic to aerobic energy contribution. Generally speaking, very heavy exercise lasting
roughly 60 seconds would call for a ratio of 70%/30% anaerobic to aerobic energy production. However
heavy exercises such as the race that our sprinter is competing in, lasting 2 minutes will utilize an equal
50%/50% split of anaerobic and aerobic pathways in order to supply the needed ATP.
Our third and final athlete is a 10,000m distance runner. Completing this race in 30 minutes,
considering that this time is only 2 minutes off of an Olympic qualifying time, I’d say that this sprinter is
on his was to some world class times. Once again referencing back to my opening paragraph, when we
consider the rest-to-exercise transition we will see that our distance runner must first use the ATP-PC
system to create enough movement to start the race. This race will predominantly call for the use of
aerobic metabolism. Because the athlete will be operating at a submaximal, moderate intensity for a
time greater than 10 minutes it will be possible for our sprinter to maintain a steady state oxygen uptake
for the race’s duration. This is assuming that our athlete is racing in fair weather, or on an indoor track.
In conclusion, I think when one considers the rest-to-exercise transition. It is easy to see that all
three events discussed use a combination of bioenergetic systems to power each and every muscle
contraction for our perspective athletes.
References
Powers, S. K. (2020). Exercise Physiology: Theory and Application to Fitness and Performance (11th
Edition). McGraw-Hill Higher Education (US). https://mbsdirect.vitalsource.com/books/9781260813562
EXS 510
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