Active Cycle of Breathing Technique
Date: August 2026
Revision Date: August 2028
Ref: B-342/AS/Physiotherapy/Active cycle of breathing technique
PDF: Active cycle of breathing technique [pdf] 164KB
The Active Cycle of Breathing Technique (ACBT)
Active Cycle of Breathing is a technique which uses breathing exercises to remove phlegm from the lungs. It is sometimes used alongside other clearance techniques such as postural drainage, chest percussion or devices such as an Aerobika® or Acapella®.
If you perform ACBT regularly it may help to:
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Reduce your need to cough throughout the day
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Improve your feelings of breathlessness
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Help reduce the number of infections
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Reduce any further damage to your lungs
The three stages of ACBT
Breathing control (relaxed breathing)
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Breathe in through your nose, at a comfortable speed
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Breathe out through your mouth, at a comfortable speed
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Avoid letting your shoulder rise up
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You should feel your tummy softly moving in and out with your breathing
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Maintain this relaxed breathing for one to two minutes, or as guided by your physiotherapist
Thoracic expansion exercises (deep breathing)
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Take a long slow breath in through your nose to fill your lungs as much as possible.
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Hold your breath in for 3 seconds.
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Breathe out through your mouth gently.
Forced expiratory technique (Huff)
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Take a slow breath in through your nose, a little deeper than a normal breath.
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Open your mouth to an ‘O’ shape and huff the air out, as if you are trying to steam up a mirror.
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The secretions should move upwards so that you can cough them up or perform a short, sharp huff to move them into your mouth.
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Limit the number of huffs to one or two to reduce the chance of becoming wheezy or starting a ‘coughing fit’.
Completing the full cycles
How should I prepare?
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Find a comfortable position or use the position you find helps to clear the most secretions. This may be sitting in a chair, lying on your side or propped up with pillows in bed. Your physiotherapist will discuss the most appropriate position with you.
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Relax your head, upper chest and shoulders.
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If prescribed you can take any inhalers or nebulised bronchodilators (e.g.salbutamol) followed by a Saline nebuliser before you start. Your physiotherapist will advise you on this where appropriate.
Completing ACBT
The separate parts of ACBT are combined into a cycle that can be repeated as many times as needed. It is usually best to start with breathing control.
Circle showing breathing control cycle:
- Breathing control, 20 to 30 seconds
- 3 to 4 deep breaths
- Breathing control
- 3 to 4 deep breaths
- Breathing control
- Huffing followed by cough if needed
After ACBT
If you have a nebulised antibiotic, then use this after your airway clearance. This will ensure that the nebulised antibiotic can get into the smallest airways and be more effective.
How often?
Your physiotherapist will advise you on how many cycles to repeat and how many sessions you should do every day. This will depend upon the amount of sputum that you usually produce. During an exacerbation (a worsening of your symptoms) you may need to increase the number of times you perform ACBT through the day.
Other formats
If you need this leaflet in another format such as Braille, large print, high contrast, British Sign Language or translated into another language, contact the Patient Advice and Liaison Service (PALS):
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01752 439694
