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NCT Number: NCT07621588

Diaphragmatic Breathing Exercises With KOTS Currents in Patients With Long COVID

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.

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Key information

Conditions

Long COVID Syndrome COVID-19 Chronic Disease Coronaviridae Infections Coronavirus Infections Disease Attributes Infections Lung Diseases Nidovirales Infections Pathologic Processes Pathological Conditions, Signs and Symptoms Pneumonia Pneumonia, Viral Post-Acute COVID-19 Syndrome Post-Infectious Disorders RNA Virus Infections Respiratory Tract Diseases Respiratory Tract Infections Virus Diseases

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Clínica Universitaria Salus Infirmorum, Universidad Pontificia de Salamanca

Madrid, 28015, Spain

Location contact

Sara Perpiña Martínez

CONTACT

[email protected]

(+34) 910053661

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

Diaphragmatic Electrostimulation Using KOTS Currents

Device

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

Diaphragmatic Breathing Exercises

Behavioral

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

Primary outcomes

  1. Forced Vital Capacity

    Time frame: Baseline and 3 weeks

    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.

Secondary outcomes

  1. Forced Expiratory Volume in One Second

    Time frame: Baseline and 3 weeks

    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.

  2. Peak Expiratory Flow

    Time frame: Baseline and 3 weeks

    Peak expiratory flow will be assessed using spirometry. The outcome will evaluate the change in PEF from baseline to after the three-week intervention.

  3. FEV1/FVC Ratio

    Time frame: Baseline and 3 weeks

    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.

  4. Basal Oxygen Saturation

    Time frame: Baseline and 3 weeks

    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

  5. Physical Function

    Time frame: Baseline and 3 weeks

    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

  6. Dyspnea

    Time frame: Baseline and 3 weeks

    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.

  7. Quality of Life with SF-36 questionnaire

    Time frame: Baseline and 3 weeks

    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.

  8. Fatigue

    Time frame: Baseline and 3 weeks

    Fatigue will be assessed using the DePaul Symptom Questionnaire. Higher scores indicate greater fatigue.

Study contacts

Contact information is provided by the study sponsor or research team.

Sara Perpiña-Martinez

CONTACT

[email protected]

(+34) 910053661

Sponsors and collaborators

Lead sponsor

Universidad Pontificia de Salamanca

Other

Registry information

Official study title

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

Acronym: KOTS-LC

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
Jun 2, 2026
Registry last updated
Jun 4, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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