Headache and vomiting after functional training?

Did you feel headache, dizziness, and vomiting during a functional training session or in fact you were not able finish it?

Recently a reader told me that she had relatively high body fat percentages a few months ago which qualified her as a woman with obesity but not the morbid one, and for a long time afterwards thanks to aerobic cyclic structure workouts (jogging, swimming, etc., performed with moderate or low intensity).

And also thanks to an adequate nutritional plan, she had been able to lose certain kilograms of body fat, and after that she decided for the first time (after a few weeks of achieving decent goals in terms of reducing body fat) venturing into a class of what is known as "Functional Training".

Well, before continuing to tell you the experience this reader had in this class that is popularly known today as Functional Training or simply "Functional", I want to express my point of view of this concept, term or name, since it is well used, and I do not say this with subjectivity but with total objectivity.

Since the objective of this type of training is in itself the one to improve the Functional Capacity of the organism and body of the person who practices it, and then the Functional Capacity, according to the Control Disease Center Is the capacity or in fact the ability that a cell present to counteract the "aggression" that could alter negatively its internal balance, in order to maintain its homeostasis (Booth, Roberts, & Laye , 2012).

You do not need to vomit during a functional training routine

If we see it from this point, I think you already can infer why this term would be misused because in itself it is as if it meant that this kind of training is the only one focused on improving the Functional Capacities of a person's body, and then the rest of workouts such as those "traditional" which involve the use of external weights (bars, dumbbells, etc.) do not have this objective.

So I ask you: is it possible that the power or strenght to lift more weight after a few weeks performing these kind of "traditional" trainings was not gained thanks to a certain degree of functional capacity improved? Because otherwise, if this type of workout does not improve this ability then a person would always lift the same weight throughout his life performing the same number of repetitions.

Then, all types of training have a goal in terms of improving some type of Functional Capacity at physiological level (including of course also the physical/aesthetic part).

Well, another point I want to mention is that this term of "Functional Training" was born based on a very old concept known as Aerobic Circuit Training where the goal was raised to improve physiological adaptations on the aerobic capacity, mainly (and of course, the tonicity and strength of the skeletal muscles, joints and tendons were also a goal of this type of training).

The Aerobic Circuit Training emphasizes on make the person performs circuits of different exercises which usually are stipulated without external weights (Chtara, 2008).

Later, after several years, certain modifications were adapted where certain types of external weights were included and there was always a time to "beat" and then to move to the next exercise almost with the least resting time possible.

But well, in itself really this last concept mentioned would not be completely correct (or at least would not be complete) since in this type of training the person can reach anaerobic or at least mixed (aerobic / anaerobic) threshold, so naming it simply as Aerobic Circuit Training, considering the workout thresholds, would not be the right thing to do.

For all of the mentioned so far, this type of training should be named as Circuit Resistance Training or something like that, or even better, being more daring could give a more complete title but a little longer, something like this: Circuit Training with Variable Workout Intensity...

... since to reach a positive adaptation for a beginner in this type of training (including a high variety of exercises), probably he first would have to start by performing the exercises at moderate or lower intensities in comparison to someone more advanced, and probably also perform fewer repetitions, perform less time by exercise and perhaps he would have to rest a little more between exercises or circuits of exercises.

Vomiting, dizziness and headache during and after Functional Training

Well, I explained that the term "Functional Training" would not be entirely ok, but I will still use it because to date (January 2017) is still very popular.

Then, returning to the experience of the reader, she told me that a few minutes after performing this kind of Functional Training she started to feel a bit dizzy, and after a few more minutes she started to feel vomiting and also a slight headache, and because of all those symptoms she had to abandone in the middle of the class (which had an approximate duration of 40 minutes).

Why could this have happened to her? The simplest explanation would be that her body was not accustomed to this type of physical "aggression", since the intensity which she started to perform this class was very high, because she was demanded too much to avoid feeling pity for not being able to perform the class at the same level of the most advanced people, so she did not heard her heart...

... and because the myocardium (heart) must have been working at a very high intensity, many beats per minute trying to pump blood to the most distal muscle in the body so she would not die (how could not she be able to listen those beats and act according to this factor to avoid feeling all these annoying symptoms?).

The main factor that made her feel of these annoying symptoms was not having carried out this kind of agreement (functional training class) at her level, first by telling the instructor that she was a beginner so he could have had this in mind at the time to motivate her to demand according to her level (one of the reasons why she felt pity and therefore demanded too much, I mean the instructor did not know that).

If she would have told him all these things, probably she would had focused on performing these exercises proposed in this class in a "slower" intensity, focusing better on the technique of execution of every exercise, and carrying out a longer rest/recovery time between exercises and exercise circuits.

From the physiological point of view, she began to feel dizzy, headache and desire to vomit very fast, first because of the high degree of dehydration she could suffer, given because of very sudden changes in the thresholds of workout and therefore this caused a very abrupt increase in blood pressure and therefore body temperature...

... then her body started to lose much more water than it was accustomed to "lose" (use for thermoregulation, nutrient transport, etc.) during the execution of physical exercises, this also considering that the simple fact of breathing makes our organism loses water too.

On the other hand, the fact that her body entered into a workout threshold so high and almost in a sudden way compared on what it was accustomed, made a high energy expenditure by glycogen (as an energy resource) which generated not only a high production of Lactic acid but also other metabolic waste products which, added to the loss of water, made her blood plasma become more viscous and thereby blood pressure was increased, and of course her body temperature followed a greater loss of water and nutrients (besides the high consumption of oxygen that her organism had to deal with).

Then, all these alterations producing as a result that she felt that annoying desire to vomit, that uncontrollable dizziness and that overwhelming headache that made her leave the class, could have been avoided.

Keep in mind that if the blood plasma becomes very viscous and even more when this happens suddenly, then the pressure on the arteries will increase (and of course, the circulation and therefore the transport of oxygen and nutrients will slow down) and due to the arteries of the head are so sensitive, then the headache during this type of Functional Training and after it, will be quite intense and of course annoying.

The reason all these annoying symptoms occurred is simply because her physiological adaptation was not adequate, so when a beginner person intend to perform this type of training, the adaptation and therefore improvements in physiological qualities must be progressive.

Her mistake was to trust too much with the fact that for many months she had been performing aerobic workouts and achieving certain reductions in body fat levels, an dos she thought she could face a class of this type almost at the level of an expert.

In the article that I leave in this link I explain more in depth why the desire to vomit is generated when doing physical exercise, and also why you can experience headaches and dizziness during the practice of high intensity training routines.


Effect of concurrent endurance and circuit resistance-training sequence on muscular strength and power development. Journal of Strength; Conditioning Research: July 2008 - Volume 22 - Issue 4 - pp 1037-1045.

Lack of exercise is a major cause of chronic diseases. Comprehensive Physiology, 2(2), 1143–1211.