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    Exercise Physiology

Bioenergetics: Interaction Among Energy Systems

Great way to get a better understanding of the energy systems.

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Dr. Reiss, I really enjoyed this article. I had to read it a couple times before I truly understood everything it entails.  I feel like this article went more in depth than our course book.  After watching the ATP and... more »Dr. Reiss, I really enjoyed this article. I had to read it a couple times before I truly understood everything it entails.  I feel like this article went more in depth than our course book.  After watching the ATP and Glycolysis tutorials on the other shelves and following it up with this article I feel like I have a better grasp of the overall concept of bioenergetics and the 3 energy supply system our body utilizes.  There were two key points that I focused on: the anaerobic system is actually capable of supporting high muscle force and power outputs immediately where as the aerobic energy system doesn’t respond as fast because of the lower ATP transition speed.   The second point that I found most beneficial was learning more about lactate production.  I always assumed lactate was a negative sign, but after reading this article I realized its actually beneficial to muscle contraction and the ability to remove pyruvate and sustain a high rate of ATP generation. 11-16-2012 4:04am

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Comment by Jessica Amore

Excellent Jessica! I am glad you found these resources helpful.  The energy systems are the foundation to exercise physiology in general and can be somewhat difficult concepts to grasp without a course in biochemistry (and even then they... more »Excellent Jessica! I am glad you found these resources helpful.  The energy systems are the foundation to exercise physiology in general and can be somewhat difficult concepts to grasp without a course in biochemistry (and even then they are not easy concepts)!  You are correct about lactate, it does actually enhance muscle contraction to a point (lactate threshold) and then it can begin to become a detriment to performance. 11-16-2012 6:06am

Good evening Dr. Reiss, Jessica, |  So, this article among many other things is saying that because the production of lactate regenerates NAD+ which can then convert to NADH and NAD+ is needed in the cytosol to promote ATP regeneration,... more »Good evening Dr. Reiss, Jessica, |  So, this article among many other things is saying that because the production of lactate regenerates NAD+ which can then convert to NADH and NAD+ is needed in the cytosol to promote ATP regeneration, lactate is good for the purpose of creating energy for the muscles...right?  And if we reach our lactate threshold...or rather surpass it, it may detriment our performance.  I read that this process is one of oxidation and so I am curious, because the body tends to over-consume oxygen during the period post-exercise and perhaps the muscles being used are still experiencing contractions due to synaptic(?) messages to and fro via the CNS...is that extra oxygen thereby being utilized in a way that creates excess lactate and increasing acute and/or DOM soreness?  If so...would a cool-down help to alleviate this? I realize I may be way off base here...tantamount perhaps to a kid raising his hand and asking a "stupid" question but if I can further my knowledge I am OK with that!   | Jeremy 11-28-2012 2:14pm

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Comment by Jeremy Campbell

Lactate serves to facilitate muscle contraction via NAD+ until it reaches a point (lactate threshold) where production of lactate outpaces removal.  At that point, it begins to accumulate and can interfere with muscle contraction,... more »Lactate serves to facilitate muscle contraction via NAD+ until it reaches a point (lactate threshold) where production of lactate outpaces removal.  At that point, it begins to accumulate and can interfere with muscle contraction, thereby inhibiting movement.   | In general, we "over consume" oxygen post exercise (EPOC) because when we stop exercising, our bodies don't immediately return to baseline.  It takes time for HR to decrease, metabolism to slow down, sweating to stop, etc...so in essence. we still have higher O2 needs post activity than at rest.  Of course, this is all dependent on intensity of activity.  The higher the intensity, the longer it takes the body to return to resting conditions.   | Lactate is generated when the intensity of the activity is such that the working systems need more O2 than we can consume (higher intensity activities).  When not enough O2 is present, pyruvate (the end product of glycoysis) is converted to lactate.  When enough O2 is present (lower intensity activities), pyruvate is shuttled into the mitochondria, converted to Acetyl CoA and the Krebs Cycle begins.  | And there are no stupid questions.  These systems are complex and really difficult to understand without a course in biology or biochemistry.... 11-28-2012 6:18pm

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