Our article on swallowing difficulty and choking in Parkinson's disease explains that expiratory muscle strength training (EMST) is the swallowing exercise with the most research support. After reading it, many families ask whether this training really improves swallowing safety, how large the effect is, and whether buying a device and practising at home is an option. This page looks at the therapy in detail. It starts from the key randomised controlled trial and then covers how it works, how much training is used, how long the benefit lasts, its limits, and the reminders from a new study in 2023.
The conclusion first: for protecting swallowing and cough function in Parkinson's disease, EMST is the single exercise therapy with the most research support. It is a supplementary treatment that aims to improve the problem and does not cure it, and a speech therapist (ST) must assess the patient and prescribe it beforehand. The details follow, and every figure is referenced.
Important: EMST is not something to start by buying a device and blowing into it at home.Setting the breathing resistance, judging whether the patient's cognition and lung function allow the training, and finding out whether swallowing or cough is the weaker part all need to be assessed and decided by a speech therapist with instruments first. This page explains how EMST works, what the research shows and where it falls short. It is not a guide for patients to follow on their own.
What is EMST (expiratory muscle strength training), and how does it differ from other swallowing exercises?
EMST (Expiratory Muscle Strength Training) is different from traditional mouth exercises such as moving the tongue. It uses a small device with a built-in spring, and the patient has to breathe out forcefully to open a valve. It is resistance training for the expiratory muscles (including the abdominal and intercostal muscles). It works on the same principle as weight training for other muscles and is a form of progressive resistance training.
How does breathing out relate to swallowing safety? Forceful breathing out and protecting the airway during a swallow use overlapping muscle groups and nerve pathways. These include the suprahyoid muscles, which lift the larynx up and forward to close the entrance to the airway. Training the strength of breathing out therefore also strengthens the muscles that protect the airway during a swallow. It also strengthens the voluntary cough, so that the patient has enough force to cough up anything that goes down the wrong way.
Why people with Parkinson's disease have swallowing difficulty and choking
People with Parkinson's disease have two separate but related gaps in function, and EMST tries to address both:
EMST targets two problems: too little protection during a swallow, and too little force to cough when choking. It helps to improve the swallowing movement and also builds expiratory strength, so that the patient has the force to cough out food that enters the airway.
Results of the Troche 2010 randomised controlled trial
The main evidence for this page comes from a randomised, sham-controlled trial by Troche and colleagues, published in Neurology in 2010. The control group used a sham device that looked identical but had no resistance inside. This removes the placebo effect of patients believing they were receiving treatment, and makes the study design rigorous.
Why does the fall in PAS score from 3 to 2 matter? The PAS is a scale from 1 (no penetration) to 8 (material enters the airway and cannot be coughed out). A fall from 3 to 2 broadly means that the situation improved from food entering the entrance of the larynx to food touching it slightly and being cleared straight away. This is a meaningful clinical improvement. It also confirms a point made later in this article: the result is an improvement, and it does not bring the problem down to zero.
An earlier pilot study (Pitts et al., 2009) reached a similar conclusion. In 10 people with Parkinson's disease who showed signs of penetration or aspiration, voluntary cough improved after 4 weeks of EMST and PAS scores fell significantly. This suggests EMST has a positive effect on both swallowing and cough.
How EMST works: why does breathing out against resistance improve swallowing?
The main reason that training to blow out against resistance can improve swallowing is that muscles and nerve pathways are shared:
- 1Strengthening the suprahyoid musclesBreathing out forcefully and protecting the airway during a swallow both use the suprahyoid muscles under the chin and at the front of the neck. Blowing against resistance trains this muscle group.
- 2Better lifting of the larynxWhen these muscles are strong, the larynx and hyoid bone lift higher and faster during a swallow. In the Troche 2010 study, X-ray imaging did show a greater lift of the larynx and hyoid bone after training.
- 3Better airway closure and coughWhen the larynx lifts high enough, the entrance to the airway closes more tightly, which reduces the chance of food entering the airway. Expiratory force is also stronger, so that the patient has enough force to cough out anything that goes the wrong way.
A 2025 systematic review and meta-analysis of 10 RCTs supports this mechanism with data. Respiratory muscle training clearly raised maximum expiratory pressure (MEP) (pooled mean difference MD = 17.08, 95% CI 2.32–31.84, p = 0.02) and also improved voluntary peak expiratory flow, but it showed no significant effect on maximum inspiratory pressure (MIP) (Navas-Garrido et al., 2025). The benefit of EMST is therefore concentrated on breathing out and cough, which fits the theory of how it works.
EMST equipment, resistance settings and training schedule
For EMST to work, the resistance must be high enough, because training at too low a resistance has no effect. A standard training prescription is outlined below (for reference only; the actual resistance level must be set by an ST according to the patient's own MEP):
| Resistance level | Resistance is usually set at about 75% of the patient's maximum expiratory pressure (MEP), and is raised step by step as expiratory strength improves. |
| Daily training | Each session lasts about 20 minutes, with repeated sets of forceful blowing to open the valve inside the device. |
| Frequency | 5 days a week. |
| Course | In the Troche 2010 study the course lasted 4 weeks. After that, the speech therapist (ST) assesses the patient and decides how to arrange maintenance training. |
The blowing resistance setting is very important in EMST.There is a reason for setting it at 75% of MEP. If the resistance is too low, the exercise has no training effect. If it is too high, a patient who already has heart or lung problems may feel dizzy or unwell. Each patient's MEP can only be known by measuring it with an instrument, so patients should not buy a device online and adjust the resistance on their own.
How long does the benefit last after training stops?
Whether the benefit fades quickly after training stops is a key question in clinical use. On this point the research on EMST is reassuring.
One further point should be stated plainly. The studies on how long the benefit lasts are small, and Parkinson's disease is a progressive condition, so the swallowing ability of the patient will change over time. In clinical practice an ST will usually advise that the patient has regular reassessment and, when needed, maintenance training. One course of training does not settle the problem for good.
Limits of EMST and other training methods
Three limits of the training are easy to overlook and should be stated clearly:
- The effect of EMST is moderate. It improves swallowing difficulty and does not cure it. In the research the PAS score improved by only about 1 point on average, so the patient still has to follow the speech therapist's (ST) advice on food textures, and should not assume that any food is safe after training.
- The certainty of the current evidence is low. A 2022 systematic review of 26 papers found that the better-designed studies mostly showed EMST helping swallowing efficiency more than swallowing safety (Gandhi & Steele, 2022).
- EMST is not the only way to improve cough function. The speech therapist (ST) first needs to assess which part is weaker, and then choose a suitable combination of training (see the explanation below).
A finding from 2023: Troche and colleagues published a randomised controlled trial of 65 people in 2023. It found that sensorimotor cough training (smTAP), which targets the cough directly, worked better than EMST for improving the reflex cough (including peak expiratory flow, expired volume and urge to cough)(Troche et al., 2023). This means that if the patient's main problem is that the reflex cough is not triggered when choking, EMST may not be the most suitable choice. Before training, a speech therapist (ST) must therefore assess whether swallowing or cough is weaker, and whether the problem lies in voluntary cough or reflex cough, before deciding which training to use.
Another reminder comes from a study across diseases. In people with amyotrophic lateral sclerosis (ALS), EMST improved MEP and hyoid displacement but did not significantly change PAS scores or cough measures (Plowman et al., 2016). In other words, the benefit of EMST for swallowing safety is not the same in every neurological condition, and conclusions should be applied to other conditions with great care.
Why a speech therapist (ST) should assess first
Taking the points above together, the reasons why EMST should not be tried by trial and error at home are clear:
For families of people with Parkinson's disease who have difficulty moving, or who are at an advanced stage and cannot go out often, home visits by a speech therapist are a practical option. An ST can do a bedside swallowing assessment at home, teach safe eating strategies and, where the situation allows, guide the patient through rehabilitation exercises such as EMST. Families should be aware of one limit: a home-visit ST generally cannot do VFSS in the home. If silent aspiration is suspected, the ST may first refer the patient to a hospital for an instrument-based assessment, so that the training is safe and addresses the right problem. More information is available on our speech therapy at home page.