Plain English Summary
Background and study aims
Parkinson's disease is a condition in which parts of the brain become progressively damaged over many years. In patients with Parkinson’s disease, the main cause of death is a lung inflammation produced by the entrance of bronchial secretions or other foreign materials into the lungs. The high incidence of this complication has been attributed to deglutition (swallowing) and pulmonary (breathing) problems such as reduced respiratory muscle strength and respiratory muscle slowness. Cough is an important defence mechanism that removes foreign material from the bronchus (the main passageway into the lungs). To produce an effective cough, it is necessary to breathe in an adequate volume of air before coughing, to then expel an adequate volume of air while coughing to push the foreign material out of the bronchus. Strengthening inspiratory (breathing in) and expiratory (breathing out) muscles may lead the muscles to produce a greater expiratory airflow and velocity and therefore a cough able to clean the bronchus efficiently. The aims of this study are to compare the effects of an inspiratory versus an expiratory muscle-training program on the amount of airflow produced during cough, and to determine which training (inspiratory or expiratory), produces greater improvements in the amount of cough airflow in patients with Parkinson’s disease.
Who can participate?
Patients with Parkinson's disease
What does the study involve?
Participants are randomly allocated into three groups. The first group receives home-based inspiratory muscle training, the second group receives home-based expiratory muscle training, and the third group receives home-based expiratory muscle training at a minimum and fixed load. Respiratory muscle training involves performing 25 inspiratory or expiratory efforts, from Monday to Saturday, using a specific, personal and transportable device provided by the researchers of the study. The training period lasts 2 months, and each training session takes about 15-20 minutes. Participants undergo lung assessments before and after the training. They also were also contacted every two weeks to check the progress of the training. Participants also receive phone calls and/or text messages as reminders to perform the breathing exercises and arrange appointments.
What are the possible benefits and risks of participating?
Possible benefits include improved cough effectiveness by increasing the volume of air during coughing, improved safety during deglutition and decreased risk of bronchial secretions or food getting into the airway, improved voice volume, and receiving comprehensive assessments of breathing, voice and deglutition functions. Possible risks include respiratory muscle soreness and fatigue. The risks associated with the respiratory muscle training are low, but to minimize them the training is tailored to each participant and the necessary resting time is provided to avoid fatigue.
Where is the study run from?
Chilean League Against Parkinson's Disease (Chile)
When is the study starting and how long is it expected to run for?
December 2016 to November 2017
Who is funding the study?
Fondo Nacional de Desarrollo Científico y Tecnológico (Chile)
Who is the main contact?
Mr Alvaro Reyes
Fernandez Concha #700
The effects of respiratory muscle training on peak cough flow in patients with Parkinson's disease
An expiratory muscle-training program is more effective than an inspiratory muscle-training program to improve voluntary and reflex peak cough flow in patients with Parkinson's disease.
Pontificia Universidad Católica de Chile (Pontifical Catholic University of Chile) ethics committee, 18/05/2017, ID number: 16-292
Single-centre randomised controlled trial
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not available in web format, please use the contact details to request a patient information sheet
The study employed a 3 (groups) x 2 (measure times: baseline and 2 months) repeated measures design. Forty participants completed all baseline measurements and then were randomly divided into three groups using the randomisation block method. Thirteen participants were assigned to receive home-based inspiratory muscle training, 13 participants were assigned to receive home-based expiratory muscle training, and 14 participants were assigned to receive home-based expiratory muscle training at minimum and fixed load (control group). Thirty-one participants completed the study protocol. The intervention lasted 2 months for all study groups. Allocation concealment was implemented using sequential sealed envelopes prepared by an independent research assistant. The assessors were not blinded to patients allocation group.
Participants in the inspiratory training group performed a home-based inspiratory (5 sets of 5 repetitions) muscle-training program using a Threshold® Inspiratory Muscle Trainer (HS730-010. Phillips Respironics, USA).
Participants in the expiratory training group performed a home-based expiratory (5 sets of 5 repetitions) muscle-training program using an Expiratory Muscle Trainer (EMST150. Aspire Products, LLC). Both groups trained 6 times a week for 2 months. These training parameters were chosen because previous studies have shown significant improvements in pulmonary function in patients with Parkinson’s disease using a similar protocol.
Participants in both groups started training at a resistance equal to 50% of their maximum inspiratory pressure and maximum expiratory pressure, which was calculated based during baseline measurements described below. The resistance was adjusted every two weeks to reach a training intensity of 75% during the last 2 weeks of training.
Participants in the control group used a Threshold® PEP (HS-735-010. Phillips Respironics, USA) for expiratory muscle training because this device provides lower resistance for expiratory flows than those devices used by the training groups. They trained using the same protocol of the participants in the training groups for the same number of repetitions, frequency and duration, but the intensity was fixed at the minimum load of the device (9 cmH20) throughout the training period.
All participants were asked to mark on the provided training diary when a training session was completed. All participants were contacted every two weeks, to ensure that they were training and to adjust the resistance of the training devices. Phone calls or messages throughout the study period were sent to remind participants to perform the training as instructed.
Primary outcome measures
Voluntary and reflex peak cough flow, measured using a pneumotachograph (MLT 1000; ADInstruments, Inc) coupled to a data acquisitions system (PowerLab 8/35, ADInstruments, Inc.), before and after 2 months of inspiratory or expiratory muscle training
Secondary outcome measures
1. Maximum inspiratory and expiratory pressure, measured using a pressure manometer (Micro RPM, Micro Medical-Care Fusion, Kent, UK) before and after 2 months of inspiratory or expiratory muscle training
2. Slow vital capacity, forced vital capacity and forced expiratory volume in 1s, measured using a digital spirometer (FE141, ADInstruments, Inc.) coupled to a data acquisitions system (PowerLab 8/35, ADInstruments, Inc.) before and after 2 months of inspiratory or expiratory muscle training
Overall trial start date
Overall trial end date
Participant inclusion criteria
Participants of both genders with diagnosis of idiopathic Parkinson's disease (stage I-III Hoehn and Yahr scale) in the “on dopaminergic” state were initially recruited in the study. Inclusion criteria were:
1. Diagnosis of idiopathic Parkinson's disease confirmed by a neurologist
2. Participants with the ability to understand and respond to the instructions given in the study
3. Unaltered dose and type of antiparkinsonian medication
4. Stable disease at the moment of inclusion in this study
Target number of participants
Participant exclusion criteria
1. Other concomitant neurological disease
2. Current smokers
3. Participants with a history of cardiovascular pathology, lung disease or the presence of respiratory symptoms such as cough, phlegm, wheezing or dyspnoea at the time of assessment
4. Participants with difficulties in maintaining a proper mouth seal or unable to avoid air leakage during pulmonary function testing
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Chilean League Against Parkinson's Disease
Fondo Nacional de Desarrollo Científico y Tecnológico
National Fund for Scientific and Technological Development, FONDECYT
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Planned publication in a high impact peer reviewed journal in early 2018.
IPD sharing statement
The dataset will not be made available because the informed consent document that all participants signed for this study states that “the information obtained from this investigation will be kept strictly confidential. The results of this investigation will be presented in scientific journals and/or conferences; however, your name will not be revealed”. All printed documents used to collect data are kept and secured in a locked drawer placed in the principal investigator office. Digital information is kept in a desktop computer located in the principal investigator office of the sponsoring institution (Andres Bello University). The desktop computer is password locked.
Intention to publish date
Participant level data
Not expected to be available
Results - basic reporting