What are ACBT Exercises?

ACBT stands for Active Cycle of Breathing Techniques and are for people who have lung or respiratory conditions which make clearing excess sputum or phlegm from their lungs difficult. It is important to clear this sputum/phlegm as not doing so can make a person susceptible to chest infections or get frequent coughing fits. ACBT exercises help to clear these fluids off the lungs through a series of techniques which are used in a cycle. These exercises consist of deep breathing, breathing control, and huffing. 

How to perform these exercises correctly

Breathing control

  • Breathing control consists of gentle, low-effort breathing
  • It is ideally done through the nose
  • If unable to breathe through your nose, then use your mouth with ‘pursed lips breathing’ 
  • Try to keep your body very relaxed and let go of any tension
  • Try to slow your breathing
  • Breathing control should be done in between each step of the ACBT cycle as it relaxes the airway

Deep breathing

  • Consists of taking long, slow breaths in through the nose with chest and shoulders relaxed
  • Breathing out is done gently and should be similar to a sigh
  • Usually, 3-5 deep breaths are done
  • Some people find it useful to hold their breath for 2-3 seconds before exhaling


  • A huff is forced exhaling through the mouth instead of coughing
  • It is preferred to a cough as it generally does not cause pain or tightness in the chest
  • To huff air is quickly squeezed out of the lungs and mouth as if you were trying to fog up glasses or a mirror
  • The huff helps to move sputum up your airway so it can be cleared more easily
  • Huffing should always be followed by breathing control
  • The first huff should consist of a small-medium breath in and the huff the air out of the lungs until they feel quite empty, this should move the sputum to higher up in the chest
  • The next huff should be done when the sputum feels ready to be cleared, and consists of a deep breath in and short huff out, which should allow you to clear the sputum without coughing


  • Ideally, huffing clears your sputum, and you will not need to cough, however, that is not always the case
  • You should only cough if your sputum can be cleared easily
  • It is important to avoid long bouts of coughing as this can bring on feelings of breathlessness and pain in chest or throat

The ACBT cycle

All our physiotherapists at Watsonia Physiotherapy are trained and able to teach and answer any questions regarding these exercises!