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by Cuyler Hudson, PT, DPT, FAFS

Posted in Blog.

October 29th, 2019

The Physiology of the Taper Tantrum

You just got through the peak of your training. The previous few weeks have worn you down and you can’t wait to kick back with an ice-cold Pedialyte, and relax a bit during your taper for the next two weeks… But the next two weeks are anything but relaxing. You start to notice new aches and pains, you feel more tired, an eight-mile run feels like twenty, and wait, are you getting sick too?? You are in the middle of a full-blown taper tantrum. Not to worry though! It’s important to understand that this is normal for a lot of people. It’s not exclusive to runners either, any athlete who goes through a heavy training period followed by a dramatic decrease in intensity may feel the same way. Although it may feel like you’re in worse shape, you can rest assured that your body is taking the necessary steps to be maximally prepared to perform come race day. 


So what is going on with your body that causes you to feel so bad when all logic tells you should start to feel better? The answer lies in the physiologic and anatomical changes that happen when you go from peak training to tapering. Significant changes are occurring in your cardiorespiratory, neuromuscular, hormonal, and immune systems.


Most of these changes are extremely beneficial to your race-day performance.

  • Your oxygen-carrying red blood cell volume increases. More red blood cells mean more oxygen to your muscles, which means they can perform better for a longer period of time.
  • Neuromuscularly, your muscle fiber size is increasing at a faster rate, and an increase in oxidative enzymes starts to allow for faster contractions of your muscles.
  •  The taper also allows your heart to recover properly so it can perform properly on race day, as the heart is, itself, a muscle too.


The negative aspects that can occur during the taper (low energy, sluggishness, poor mood, random pains) are most likely a combination of a number of factors.  The most obvious is anxiety associated with the upcoming race-day, but a number of factors related to our hormonal system may contribute as well.

  • Two important hormones that have been skyrocketing during your training, Human Growth Hormone, and testosterone, can start to plummet during a taper. While the primary job of these hormones is to facilitate muscle growth, there is plenty of research that shows a relationship between these hormones and how you feel on a daily basis.
    • A decrease in growth hormone has been associated with low energy levels, a decrease in cognitive function, and even depression. In fact, it’s actually been suggested to use growth hormone as an anti-depressant drug (or, you know, you could just exercise).
    • A lowering of testosterone has been associated with decreased attention and memory function. The significant drop in these hormones that occur during a taper can absolutely be enough to make you feel a little low in energy and fatigued. 


It’s also important to understand that any aches and pains you may be feeling are perfectly normal, and no reason to worry. No, you did not sprain your ankle while sitting on the couch watching HBO’s Sunday programming. Think about it like this, your muscles, tendons, ligaments, and fascia has gotten used to sliding and gliding over each other for 8+ hours a week. When this goes drops by more than half, your body starts to adapt. This means muscles can recover and start to grow faster, ligaments get stiffer, and your tendons start to regain some of their precious elasticity. As with all changes in your body, this can come with some aches and pains as your brain tries to catch up to what your body is doing. 


If you are currently undergoing a taper tantrum, do your best not to worry. You have worked hard, and the way you’re feeling should do nothing but affirm all the hard work you put in, and the amazing changes your body has gone through to get you ready. Ride it out, and get ready for a great performance come race-day!

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