Diaphragmatic Breathing Exercises With KOTS Currents in Patients With Long COVID (KOTS-LC)

Effects of Diaphragmatic Breathing Exercises Combined With Diaphragmatic Electrostimulation Using KOTS Currents in Patients With Long COVID: A Pilot Randomized Controlled Trial

This study will evaluate the effects of diaphragmatic breathing exercises combined with diaphragmatic electrostimulation using KOTS currents in patients with Long COVID. Participants will be randomly assigned to one of two groups. The control group will perform diaphragmatic breathing exercises, while the intervention group will perform diaphragmatic breathing exercises combined with diaphragmatic electrostimulation using KOTS currents. The intervention will last three weeks, with two sessions per week. The study will assess respiratory function, quality of life, physical function, dyspnea, fatigue, and basal oxygen saturation.

Study Overview

• Status: Not yet recruiting
• Conditions: Post-Acute COVID-19 Syndrome; Long COVID Syndrome
• Intervention / Treatment: Device: Diaphragmatic Electrostimulation Using KOTS Currents; Behavioral: Diaphragmatic Breathing Exercises

Detailed Description

Long COVID is a multifactorial condition that may be associated with persistent respiratory symptoms, reduced physical capacity, fatigue, dyspnea, and impaired quality of life. Respiratory rehabilitation strategies may contribute to improving breathing patterns and functional recovery in this population. Diaphragmatic breathing exercises are commonly used to promote respiratory control and diaphragmatic activation. In addition, KOTS currents, also known as Russian currents, are medium-frequency alternating currents used in physiotherapy to elicit muscle contraction and may be applied as a complementary strategy to stimulate the diaphragm.

This pilot randomized controlled trial will compare diaphragmatic breathing exercises alone with diaphragmatic breathing exercises combined with diaphragmatic electrostimulation using KOTS currents in patients diagnosed with Long COVID. Participants will be randomly allocated to either the control group or the intervention group. Both groups will receive a three-week intervention consisting of two sessions per week. The control group will perform diaphragmatic breathing exercises, whereas the intervention group will perform the same breathing exercises combined with diaphragmatic electrostimulation.

Assessments will be conducted before and after the intervention period. The study is intended to explore whether adding diaphragmatic electrostimulation to a respiratory exercise program may provide additional benefits compared with diaphragmatic breathing exercises alone in this population.

• Study Type: Interventional
• Enrollment (Estimated): 10
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Sara Perpiña-Martinez; Phone Number: (+34) 910053661; Email: sperpinama@upsa.es

Study Locations

• Spain
  • Madrid
    • Madrid, Madrid, Spain, 28015
      • Clínica Universitaria Salus Infirmorum, Universidad Pontificia de Salamanca
      • Contact: Sara Perpiña Martínez; Phone Number: (+34) 910053661; Email: sperpinama@upsa.es

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Men and women aged 18 to 65 years.
• Medical diagnosis of Long COVID.
• At least 2 months since SARS-CoV-2 infection.
• Ability and willingness to provide informed consent.
• Ability to participate in the assigned intervention and assessment procedures.

Exclusion Criteria:

• Presence of a pacemaker.
• History of epilepsy.
• Pregnancy.
• History of acute cardiac arrest.
• Severe respiratory distress.
• Use of a wheelchair.
• Blurred vision.
• Cyanosis.
• Refusal to perform part or all of the treatment.
• Incomplete or incorrectly completed questionnaires.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Diaphragmatic Breathing Exercises Plus KOTS Currents; Participants assigned to this arm will perform diaphragmatic breathing exercises combined with diaphragmatic electrostimulation using KOTS currents. The intervention will be delivered twice per week for three weeks. KOTS currents will be applied as medium-frequency alternating current stimulation, with stimulation intensity adjusted according to participant tolerance.	Device: Diaphragmatic Electrostimulation Using KOTS Currents; Diaphragmatic electrostimulation will be applied using KOTS currents, a medium-frequency alternating current stimulation. Electrodes will be placed over the seventh and eighth rib region along the mammillary line. Stimulation will be delivered in trains of 4 seconds of stimulation followed by 8 seconds of rest, with a carrier frequency of 2,500 Hz. The standard treatment duration will be 15 minutes: 10 minutes at 30 Hz followed by 5 minutes at 70 Hz. Stimulation intensity will be adjusted according to participant tolerance. The intervention will be delivered twice per week for three weeks, together with diaphragmatic breathing exercises.; Other Names: KOTS Currents; Russian Currents; Behavioral: Diaphragmatic Breathing Exercises; Participants will perform diaphragmatic breathing exercises in a supine position with the knees flexed. One hand will be placed on the chest and the other hand below the sternum. Participants will be instructed to inhale through the nose while expanding the abdomen with minimal thoracic movement, and to exhale slowly through pursed lips. The breathing pattern will include a 4-second inspiration and a 6-second expiration. Exercises will be performed twice per week for three weeks.; Other Names: Diaphragmatic Breathing
Active Comparator: Diaphragmatic Breathing Exercises; Participants assigned to this arm will perform diaphragmatic breathing exercises twice per week for three weeks. Exercises will be performed in a supine position, with slow nasal inspiration and abdominal expansion followed by slow exhalation through pursed lips.	Behavioral: Diaphragmatic Breathing Exercises; Participants will perform diaphragmatic breathing exercises in a supine position with the knees flexed. One hand will be placed on the chest and the other hand below the sternum. Participants will be instructed to inhale through the nose while expanding the abdomen with minimal thoracic movement, and to exhale slowly through pursed lips. The breathing pattern will include a 4-second inspiration and a 6-second expiration. Exercises will be performed twice per week for three weeks.; Other Names: Diaphragmatic Breathing

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Forced Vital Capacity	Forced vital capacity will be assessed using spirometry. The outcome will evaluate the change in forced vital capacity from baseline to after the three-week intervention.	Baseline and 3 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Forced Expiratory Volume in One Second	Forced expiratory volume in one second will be assessed using spirometry. The outcome will evaluate the change in FEV1 from baseline to after the three-week intervention.	Baseline and 3 weeks
Peak Expiratory Flow	Peak expiratory flow will be assessed using spirometry. The outcome will evaluate the change in PEF from baseline to after the three-week intervention.	Baseline and 3 weeks
FEV1/FVC Ratio	The FEV1/FVC ratio will be calculated from spirometry measurements. The outcome will evaluate the change in the FEV1/FVC ratio from baseline to after the three-week intervention.	Baseline and 3 weeks
Basal Oxygen Saturation	Basal oxygen saturation will be measured using a finger pulse oximeter. The outcome will evaluate the change in basal oxygen saturation from baseline to after the three-week intervention	Baseline and 3 weeks
Physical Function	Physical function will be assessed using the 30-second Sit-to-Stand test. The outcome will evaluate the change in the number of completed sit-to-stand repetitions from baseline to after the three-week intervention	Baseline and 3 weeks
Dyspnea	Dyspnea will be assessed using the modified Medical Research Council scale. The outcome will evaluate the change in perceived dyspnea from baseline to after the three-week intervention. Lower scores indicate lower dyspnea.	Baseline and 3 weeks
Quality of Life with SF-36 questionnaire	Quality of life will be assessed using the SF-36 questionnaire. The outcome will evaluate the change in quality-of-life dimensions from baseline to after the three-week intervention. Higher scores indicate better quality of life.	Baseline and 3 weeks
Fatigue	Fatigue will be assessed using the DePaul Symptom Questionnaire. Higher scores indicate greater fatigue.	Baseline and 3 weeks

Collaborators and Investigators

• Sponsor: Universidad Pontificia de Salamanca
• Investigators: Principal Investigator: Sara Perpiña-Martínez, Pontifical University of Salamanca

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): July 1, 2026

Study Registration Dates

• First Submitted: May 27, 2026
• First Submitted That Met QC Criteria: May 27, 2026
• First Posted (Actual): June 2, 2026

Study Record Updates

• Last Update Posted (Actual): June 4, 2026
• Last Update Submitted That Met QC Criteria: June 2, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Quality of Life; Spirometry; Diaphragmatic Breathing; KOTS Currents; Russian Currents; Diaphragmatic Electrostimulation; Respiratory Rehabilitation
• Additional Relevant MeSH Terms: Post-Infectious Disorders; COVID-19; Pathologic Processes; Chronic Disease; Disease Attributes; Respiratory Tract Infections; Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases; Lung Diseases; Pneumonia, Viral; Pneumonia; Coronavirus Infections; Coronaviridae Infections; Nidovirales Infections; Pathological Conditions, Signs and Symptoms; Post-Acute COVID-19 Syndrome
• Other Study ID Numbers: UPSA-KOTS-LC-2025

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared because the study involves health-related data from a small sample of participants. Data will be pseudonymized and handled in accordance with applicable data protection regulations and the informed consent approved for the study.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No