Answered: part 1 A young athlete has trained over…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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part 1 A young athlete has trained over several months to participate in a duathlon sprint. They are doing this with their good friend, and it’s just for fun. They anticipate (based on their training times) that the total race will take them ~90 minutes to complete. The race will take place on a cool autumn day, and the individual expects to be performing at a steady state of ~50% of their maximal aerobic capacity. What would be happening to the plasma concentrations of the following hormones within the first 30 minutes or so of the race (ie, moving from rest to a steady state): Epinephrine/Norepinephrine Insulin As time passes (ie, duration), what changes will be occurring to energy substrate oxidation (ie, what’s being burned for energy CHO, Protein, or Fat)? What would you expect to be happening to blood lactate concentrations during the race? (ie, between minute 30 and minute 60) What if instead of a cool autumn day competing just for fun, this athlete raced in the middle of a hot summer day and at an intensity of ~85% of their maximal aerobic capacity? What would happen to their oxygen consumption and blood lactate concentrations during this race? Immediately following the race, (ie, right after they cross the finish line and stop running) what happens to the athlete’s oxygen consumption rates, and why? part 2 Imagine an athlete comes to an exercise science lab for an aerobic capacity test. At the lab, the athlete will run on a treadmill while indirect calorimetry and EKG are measured by the exercise physiology students. Before running, the athlete is given a few minutes to warm up. Then, once the test begins, the speed and grade of the treadmill are increased every 2-3 minutes. This continues until the athlete signals that they can no longer continue. At that point the test is concluded, and the athlete is able to cool down and then rest. The whole test only takes 10-15 minutes. 1. Why would the exercise science students wait for 2-3 minutes between each time that they increase the exercise intensity when assessing the aerobic system (ie, aerobic capacity) (based on what you know about exercise metabolism, RER, and oxygen consumption)? (ie, why not increase every 30 or 60 seconds???) 2. As the intensity of the exercise increases, what fuel substrate will the body use more and what will it use less, and how can this be measured as they collect ventilatory gasses (ie, VO2 and VCO2)? 3. What do you think will be happening to plasma concentrations of norepinephrine and epinephrine during this test? 4. At some point, oxygen consumption no longer increases (ie, plateaus) despite an increased workload. What is the term used to describe this phenomenon? 5. At this point (described in #4), is the electron transport chain still producing ATP (ie, is aerobic metabolism still going)? part 3 An athlete is training for track season as a competitive sprinter. They are performing sprints along level ground at maximal effort/speed. They can only sprint for about 30-90 seconds at this intensity before they must stop and recover. 1. This effort (taking 30-90sec.) is predominantly anaerobic. What would the primary energy substrate for this activity be, and from where will it be derived (what storage)? 2. After that single (first) sprint, would muscle glycogen be completely/mostly depleted (why or why not)? 3. What is regulating the rate of muscle glycogenolysis? 4. As the athlete continues performing repeated sprints with little rest between, what will happen to blood lactate concentrations, AND how does this impact (interact) with the hormonal regulation/mobilization of energy substrates? 5. In the initial 5-10 seconds of each sprint, what is the energy source that the athlete can use to quickly generate ATP? Can this system/source be used for subsequent sprints (why or why not)?

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