You are here: Home Training Design Anatomy and Physiology Physiological Responses and Adaptations

Physiological Responses and Adaptations

Here's an overview of the immediate responses and longer term adaptations of the body in response to different types of exercise. To achieve the desired adaptation you must choose the ideal training type - simple really, and explained right here.

As you read through the pages in this folder that cover the physiological responses to exercise and the longer term adaptations to exercise you may encounter some 'foreign' terms.  We've defined a few of these terms here to help you on your journey...

Acute physiological responses and chronic physiological adaptations – key new terms




Acute physiological response

An immediate change (increase or decrease) in one or more of the bodies systems in response to a stimuli


Chronic physiological adaptations

Changes to one or more of the bodies systems as result of long term consistent stimulus, such as exercise 



Means to increase in size or volume, such as increasing muscle size as a result of weight training


Is a disease that affects bone and causes it to lose mass, become brittle and susceptible to fracturing


RPE stands for ‘rate of perceived exertion’ and is a scale used to help rate the intensity of exercise

Blood shunt

Refers to the movement of blood from one area to another as a response to demands.  For example blood shunt to the working muscles and away from the organs when exercising


Occurring in a similar line as something else.  For example increases in exercise intensity and heart rate occur linearly


EPOC stands for ‘excessive post-exercise oxygen consumption’.  It is when heart rate and breathing rate stay elevated for longer after exercise in order to take in more oxygen and aid recovery


Refers to the development of capillaries to a specific part of the body as result of a chronic adaptation.  For example capillarisation of the working muscles from running regularly


Is a gel-like substance found within all muscle fiber cells, which also stores things such as glycogen for energy

What are acute physiological responses?personal%20training%20acute%20physiological%20response%20-%20bike

An acute physiological response refers to an immediate response of one or more of the bodies systems to exercise, such as the heart rate increasing as a gym member sits on the bike and starts their warm up. 


What are chronic physiological adaptations?

personal%20training%20chronic%20physiological%20adaptation%20-%20before%20%26%20afterA chronic adaptation refers to the long term affects on one or more of the bodies systems as a person sustains their exercise habit. 

Chronic adaptations are essentially the benefits a client receives over the long term if they ‘stick to it’.  An example of this is an increase in muscle mass and a reduction in fat mass as long term adaptations to resistance exercise.


Why are acute physiological responses important?

Acute physiological responses are a vital part of our ability to respond to the changes and demands being placed on our bodies various systems.

Just the act of getting up in the morning and walking to the bathroom requires acute physiological responses such as an increased heart rate, increased respiration rate, release of hormones, increased neuromuscular activation.

The type of and degree to which physiological responses occur is down to the demands being placed on the body.  For example only very small changes are required in the cardiovascular and respiratory systems in order to walk to the bathroom in the morning, whereas significant changes are required if you go for a 30 minute run.

Without acute physiological responses we simply would not even be able to get up in the morning, let alone exercise.


Why are chronic physiological adaptations important?

Chronic physiological adaptations are a vital part of our ability to develop and improve over time.  Allowing us to cope with changes and demands being placed on our bodies various systems more efficiently.personal%20training%20runner

For example, if you are not very fit and you decide to go for a 5km run you will likely find it hard on the bodies various systems, as your heart rate rises sharply and your respiration increases drastically.  You will also likely find that over the next couple of days your muscles will be a little sore as well.

If you then don’t do any exercise for a few weeks and you try and repeat the same run you will get the same outcome – as your heart rate raises sharply, respiration increases drastically and your muscles will be sore.

However one of the great things about our bodies various systems is their ability to adapt.

Instead of doing one 5km run in three weeks, if you were to run 5km every third day over a three week period your body would adapt. 

This is because you are repeatedly asking it to do more than it is used to but you are allowing enough recovery time.  As a result your bodies systems have the stimulation and the time needed to adapt and become more efficient at coping with a 5km run.

Without chronic physiological adaptations we simply would never improve our fitness or strength as a result of training.  In fact if our bodies didn’t adapt to the chronic stresses that it experiences we would not even change from the day we were born!


Acute responses, chronic adaptations and fitness

Our body’s ability to respond to the changes and demands being placed on its various systems is what enables us to exercise and improve our fitness.

So when working in the fitness industry and especially as a personal trainer, it is crucial that you are knowledgeable about the typical acute responses and chronic adaptation that a client should experience as a result of exercising.  As this will help you ensure you are prescribing the correct durations and intensities of exercise to produce the desired adaptations as well as keeping them safe.personal%20training%20heart%20rate%20monitor

For example when it comes to acute responses, if a client is doing a gentle 5minute warm up jog before doing some interval training, you would expect their heart rate and respiration rate to gradually increase over the 5minute period.

So if their heart rate and respiration rate was not increasing much then it would indicate that they were not warming up sufficiently and the intensity should be increased.

On the other hand if their heart rate and respiration rate shot up very quickly it could be that the intensity is too high or that there is a potential cardiac problem and that exercise should be stopped immediately.

Knowing what adaptations to expect from clients will also help to ensure that you are prescribing the correct types of training, intensities, durations, recovery times and frequency of sessions.

personal training treadmillFor example if you are training a client and their goal is to run 10km in eight weeks time, then you should see steady improvements week by week that indicate they are adapting and will achieve their goal.

If however they do not show signs of improving or they appear to even be losing fitness then this is an indication that they are either not training regularly enough or hard enough.  It could also be a sign that they are overtraining and their body is not being given enough time to recover and adapt.

A general rule for the success of your clients and the success of your personal training business is that you should always expect your clients to adapt positively to their training (i.e. they should always be progressing favourably towards their goals).  If they aren’t then something is wrong with their training that you must address immediately.


The different training types and general rules on adaptations they produce

personal%2520training%2520runner%25202personal%2520training%2520bicep%2520curlEvery acute response and chronic adaptation the body makes is specific to the training stimulus the person is exposed to.  For example heavy weight training will produce significantly different responses and adaptations within the bodies systems compared to jogging or cycling. 

The following table summarises the most common types of training in order to help you understand how different training stimuli produce different responses and adaptations.


Type of training

Explanation of training and examples.

Aerobic fitness

Longer duration (≥15mins), at low-moderate intensity, continuous activity (without rest breaks), i.e. walking, jogging, and cycling.

Anaerobic fitness

Short (10-60 seconds) repetitive bursts of high intensity activity (sprinting, cycling) with short recovery intervals between bursts to allow minimal recovery.

Muscular strength

Low repetition (≤ 6) resistance training with very heavy loads and long rests (≥ 3mins) between sets to allow maximal replenishment of energy systems between sets.

Muscular hypertrophy

Moderate repetition (6-12) resistance training with heavy loads and moderate rests (1-2 minutes) between sets to allow partial replenishment of energy systems.

Muscular endurance

High repetition resistance training (≥ 13) with moderate loads and short rests (≤ 1min) to allow minimal replenishment of energy systems.

Muscular power

Low repetition resistance training with moderate-heavy loads focusing on high intensity ‘explosive’ lifts with long rests between sets to allow maximal replenishment of energy systems.


Maximal / near maximal intensity efforts (5 -20 seconds) to get from point A to point B in shortest time possible, with long rests between repeats (e.g. sprint training).


Similar to speed, short sharp bursts of activity with changes in direction incorporated throughout.  E.g. weaving through a course of cones requiring quick changes in direction, as quickly as possible.


Low intensity stretching (or similar activity, e.g. yoga) focusing on extending muscles and joints to their full range.  Stretches for major muscle groups must be held for at least 15 seconds if flexibility is to be improved, as this is the approximate time required for the stretch reflex to ‘turn off’ and allow a muscle to be stretched beyond its immediate limits.


General rules on adaptations

personal%25252520training%25252520female%25252520weightsNow in order for the body to adapt to any of these different types of training then the training will need to be repeated time and time again.

If we are successful and our personal training clients stick at their training over the long term (at least six weeks plus), how does the body adapt and what benefits will they receive? 

In general there seem to be some basic rules regarding chronic adaptations, these being:

1.    Higher intensity anaerobic fitness / muscular endurance training tends to increase the capacity of various systems.  (Capacity refers to how much you can do and how hard you can go)

2.    Low – moderate aerobic fitness training tends to increase the endurance of various systems. (Endurance refers to how long you can go for)personal%2520training%2520before%2520%2526%2520after

3.    Short, quick, heavy, explosive type training causes the greatest adaptations in the neuromuscular system.  The more intense the greater the adaptations, but also the greater the risks.

4.    There is no single best way to alter body composition – other than finding a type of exercise a person will be most likely to repeat time and again.

Registration content image - exercise program templates.

PT Program Template

FREE Download

Make writing personal training programs easy with these custom designed exercise templates, and keep your clients focused and progressing.

Link to PT Program Exercise Templates

Registration content image - client back care guide.

Client Back Care Guide

FREE Download

Pain-free clients are happy clients. Claim your free copy of the client back care guide today. Your clients will thank you for it!

Link to Client Back Care Guide