NCT07865975|CompletedDMC
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Sponsor study identifier
interventional
30
1 country
1
Study Start
June 21, 2023
Actual (reported)Primary Completion
February 13, 2026
Actual (reported)Study Completion
May 20, 2026
Actual (reported)The goal of this randomized controlled study is to find out whether an eight-week respiratory muscle training program can improve breathing, respiratory muscle strength and endurance, physical capacity, body composition, fatigue, exercise-related beliefs and barriers, quality of life, and emotional well-being in adults aged 18 years or older with hypothyroidism who have been taking levothyroxine for at least three months. The study asks whether participants who complete progressive inspiratory muscle training show greater improvement in these areas than participants who train at the device's lowest resistance. Women and men will be randomly assigned to one of the two groups. Both groups will perform breathing exercises at home five days a week for eight weeks, with the training group gradually increasing the exercise resistance. Participants will be assessed before and after the program using breathing and lung-function tests, physical-capacity and muscle-strength tests, body-composition measurements, and questionnaires.
Registry-reported information. Elapsed time and enrollment totals alone do not measure study progress or recruitment pace.
May 20, 2026
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Dates and qualifiers reported by the registry. Estimated dates do not confirm that a milestone has occurred.
June 21, 2023
Actual (reported)February 13, 2026
Actual (reported)May 20, 2026
Actual (reported)September 30, 2026
Actual (reported)October 8, 2026
Actual (reported)Respiratory Muscle Strength
Respiratory muscle strength was evaluated using an electronic mouth pressure meter (MicroMPM, Micro Medical Ltd., UK). Measurements were performed in accordance with the American Thoracic Society (ATS) and European Respiratory Society (ERS) criteria. Maximal inspiratory pressure (PImax) was assessed following a maximal expiration to residual volume, whereupon the airway was occluded by a valve, and the participant performed a rapid, maximal inspiratory effort (Müller maneuver) sustained for 1-3 seconds. Conversely, maximal expiratory pressure (PEmax) was measured following a maximal inspiration to total lung capacity, where the participant performed a rapid, maximal expiratory effort (Valsalva maneuver) against an occluded airway for 1-3 seconds. Three measurements were obtained for each maneuver, and the highest value was recorded in cmH₂O.
From enrollment to the end of treatment at 8 weeks
Respiratory Muscle Endurance
Maximum voluntary ventilation (MVV) was measured using the direct method to assess respiratory muscle endurance. Participants were instructed to breathe as deeply and rapidly as possible for 15 seconds, and the recorded volume was subsequently multiplied by four to extrapolate the value to one minute. The normative values for MVV are typically 140-180 L/min for healthy individuals, and 80-120 L/min for females. Additionally, the predicted values calculated based on the variables of age, gender, and height were documented.
From enrollment to the end of treatment at 8 weeks
Pulmonary Function Parameters
Pulmonary functions were evaluated via spirometry. Spirometric measurements were conducted in a seated position using a nose clip, strictly adhering to ERS guidelines. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and inspiratory capacity (IC) were measured using a spirometer (SensorMedics™️ Vmax spectra 229, Bilthoven, The Netherlands). Participants performed three acceptable maneuvers, ensuring a variation of less than 5% between the efforts, and the highest values were recorded as the final result. The ERS reference equations were used to determine the predicted values.
Depression
From enrollment to the end of treatment at 8 weeks
Anxiety
From enrollment to the end of treatment at 8 weeks
Exercise Beliefs
From enrollment to the end of treatment at 8 weeks
Fatigue
From enrollment to the end of treatment at 8 weeks
Sleep Quality
From enrollment to the end of treatment at 8 weeks
The training protocol was administered using the Philips Respironics®️ Threshold IMT device for both groups. The regimen was scheduled for seven days a week, consisting of one session per day (approximately 20 minutes). To enhance treatment adherence, three of the weekly sessions were supervised, while the remaining four were conducted as a home-based program monitored via telephone follow-ups. Each exercise session was structured as three sets of 30 repetitions, with one-minute rest intervals between the sets. In the study group, training intensity was set at 40% of the individual's maximal inspiratory pressure (PImax). To ensure progressive loading, this PImax value was re-evaluated and adjusted every two weeks throughout the entire training process.
To induce a placebo effect, the control group received sham training using the lowest possible resistance setting of the device (9 cmH₂O) for the full eight weeks, with no increments in training intensity.
At this point, the significance of specific rehabilitation approaches added to medical therapy, particularly structured inspiratory muscle training (IMT), becomes evident. Strong evidence in the literature demonstrates that IMT increases the proportion of Type 1 muscle fibers and induces structural hypertrophy in the diaphragm by improving oxidative capacity in other systemic diseases that increase respiratory workload, such as Chronic Obstructive Pulmonary Disease (COPD) and chronic heart failure. Considering that the diaphragmatic myopathy observed in hypothyroidism shares similar pathophysiological and cellular weaknesses, specific Respiratory Muscle Training (RMT) has a high potential to not only provide symptomatic relief but also improve mechanical function by triggering repair at the cellular level in this patient group.
Cyprus International University
Mersin, Lefkosa, 99040, Turkey (Türkiye)
Green ME, Bernet V, Cheung J. Thyroid Dysfunction and Sleep Disorders. Front Endocrinol (Lausanne). 2021 Aug 24;12:725829. doi: 10.3389/fendo.2021.725829. eCollection 2021.
Mohammed RN, Kadhum HJ, Hashim AR. Spirometry in adult hypothyroid patients: a comparative study. J Basic Clin Physiol Pharmacol. 2020 Nov 13;32(3):189-195. doi: 10.1515/jbcpp-2019-0359.
Weiner M, Chausow A, Szidon P. Reversible respiratory muscle weakness in hypothyroidism. Br J Dis Chest. 1986 Oct;80(4):391-5. doi: 10.1016/0007-0971(86)90093-8.
Mehtap Malkoc, Prof. Dr.
Eastern Mediterranean University
Ayse Volkan, MSc.
Cyprus International University
30 participants (actual enrollment reported by the registry).
First Submitted
September 30, 2026
First Posted
October 8, 2026
The Effect of Two Different Cognitive-Behavioral Combined Programs in Blood Collection
From enrollment to the end of treatment at 8 weeks
Functional Capacity
Functional capacity will be assessed using the 6-Minute Walk Test (6MWT). Participants will be instructed to walk as far as possible for six minutes along a flat corridor at least 30 meters long. The total distance walked will be recorded in meters.
From enrollment to the end of treatment at 8 weeks
Dyspnea and Fatigue Assessment
Dyspnea and fatigue will be assessed immediately before and after the 6MWT using the modified Borg scale. Changes in dyspnea and fatigue scores from pre-test to post-test will be recorded separately.
From enrollment to the end of treatment at 8 weeks
To induce a placebo effect, the control group received sham training using the lowest possible resistance setting of the device (9 cmH₂O) for the full eight weeks, with no increments in training intensity.
Registry-reported names are shown in full. Names without a link have not yet been matched to a Syfrah profile.
Contact the study team to confirm eligibility.
Terzano C, Romani S, Paone G, Conti V, Oriolo F. COPD and thyroid dysfunctions. Lung. 2014 Feb;192(1):103-9. doi: 10.1007/s00408-013-9537-6. Epub 2013 Nov 27.
Sorensen JR, Winther KH, Bonnema SJ, Godballe C, Hegedus L. Respiratory Manifestations of Hypothyroidism: A Systematic Review. Thyroid. 2016 Nov;26(11):1519-1527. doi: 10.1089/thy.2015.0642.
Saad NS, Mashali MA, Elnakish MT, Hare A, Campbell CM, Kiduko SA, Peczkowski KK, Huang AW, Fazlollahi F, Torres Matias GS, Ahmed AAE, Whitson BA, Mokadam NA, Janssen PML. Effect of hypothyroidism on contractile performance of isolated end-stage failing human myocardium. PLoS One. 2022 Apr 11;17(4):e0265731. doi: 10.1371/journal.pone.0265731. eCollection 2022.
Ringel MD, Sosa JA, Baloch Z, Bischoff L, Bloom G, Brent GA, Brock PL, Chou R, Flavell RR, Goldner W, Grubbs EG, Haymart M, Larson SM, Leung AM, Osborne JR, Ridge JA, Robinson B, Steward DL, Tufano RP, Wirth LJ. 2025 American Thyroid Association Management Guidelines for Adult Patients with Differentiated Thyroid Cancer. Thyroid. 2025 Aug;35(8):841-985. doi: 10.1177/10507256251363120.
Pancholi C, Chaudhary SC, Gupta KK, Sawlani KK, Verma SK, Singh A, Verma AK, Usman K, Atam V. Obstructive sleep apnea in hypothyroidism. Ann Afr Med. 2022 Oct-Dec;21(4):403-409. doi: 10.4103/aam.aam_134_21.
Study Start
June 21, 2023
Actual (reported)Primary Completion
February 13, 2026
Actual (reported)Study Completion
May 20, 2026
Actual (reported)Last Updated
October 8, 2026
Record last verified: 2026-10
Individual participant data that underlie the results reported in this study-including de-identified sociodemographic and clinical characteristics, body composition metrics, and pre- and post-intervention scores for respiratory parameters (spirometry and lung volumes), respiratory and peripheral muscle strength, respiratory muscle endurance, functional exercise capacity (6MWT), fatigue (FIS), psychological status (BDI, BAI), and exercise beliefs-will be shared.
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Source: ClinicalTrials.gov.
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