Reader Question – Lactic Acid Energy System

Posted by on Jul 22, 2013 in Exam Preparation, Reader Question, Review Topics | 0 comments

This question comes from a reader who was studying the third practice exam.  Because he quotes the practice exam directly, I have made up a new question in its place so as to not violate the NSCA’s copyright on the exam material.

Hey Julian,

I’ve been following your blog. I’m having some trouble with a question from volume 3 practice exam Here’s the question and my possible explanation of why I think their answer is correct. Just wondering what your explanation might be?

Which training variable should be decreased in order to increase the capacity of the lactic acid energy system?

A. exercise intensity


B. rest period

He originally chose (A)  However upon trying to understand why the correct answer is B, he asked me for some help.  Below is my response, italicized text I have added in after I wrote him the email.


The question asks which variable we need to decrease in order to, with training, increase the capacity of the lactic acid energy system. I had to hunt around a bit to make sure I understood everything here, but part of the confusion lies from their use of the word lactic acid instead of lactate.  Turns out this is normal, and it is never referred to as that “lactate energy system” – so much for that idea! (edited 4/19)

Lactate is produced during anaerobic glycolysis, and reaches peak levels 5 minutes after exercise.  By decreasing the rest period, you do not allow sufficient time for the lactate to peak, and clear.  Essentially you are causing lactate to further increase, and bringing it closer to the lactate threshold.  This provides a greater training stimulus to your lactic acid (or lactate) energy system, causing your body to respond so you become more efficient with it next time.

Your original answer was wrong because decreasing exercise intensity would decrease the amount of lactate produced, since at sufficiently low levels of intensity you do not produce lactate because you aren’t in anaerobic glycolysis.

Hope this helps!


PS – I want to add how key it is to know that lactate is produced in anaerobic glycolysis (hence the bolding above).  Remember that fast glycolysis isn’t triggered heavily at low intensities, so lowering the intensity would produce less lactic acid, therefor not producing a strong training stimulus.


Cori Cycle - Creative Commons

Cori Cycle – Creative Commons


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