Effects of Hydrotherapy During Post-COVID-19 Rehabilitation (HydroCoVital A)

Effects of Kneipp Hydrotherapy During Inpatient Post-Covid-19 Rehabilitation: A Randomized Controlled Trial

This randomized controlled study evaluates the effects of cold water hydrotherapy as an adjunct to standard rehabilitation in patients with Post-COVID Syndrome. The primary aim is to assess changes in quality of life compared to standard rehabilitation alone.

Study Overview

• Status: Recruiting
• Conditions: Post COVID Syndrome; Post-COVID / Long-COVID; POST-Covid 19; Post-COVID Condition
• Intervention / Treatment: Other: Standard rehabilitation plus cold water hydrotherapy; Other: Standard rehabilitation only

Detailed Description

Patients recovering from Post-COVID Syndrome often experience persistent fatigue, autonomic dysregulation, microcirculatory disturbances, and low-grade inflammation, all of which may hinder their return to full function. Kneipp hydrotherapy-using cold water applications-can address these pathophysiological changes through several mechanisms:

Autonomic regulation: Cold stimuli trigger parasympathetic activation and improve sympathovagal balance, helping to stabilize heart rate variability and reduce symptoms of dysautonomia often seen in Post-COVID.

Enhanced microcirculation: Repeated vasoconstriction and reactive vasodilation promote endothelial function and tissue perfusion, which may alleviate muscle aches, dizziness, and fatigue by improving oxygen and nutrient delivery.

Anti-inflammatory effects: Hydrothermal stimuli have been shown to modulate cytokine profiles, increasing anti-inflammatory mediators and potentially dampening the persistent, low-grade inflammation implicated in Post-COVID pathophysiology.

Musculoskeletal recovery: Thermo-mechanical stimulation relaxes tense muscle fibers, reduces pain perception, and supports gradual increases in physical capacity, all of which are important for overcoming Post-COVID deconditioning.

Taken together, these effects suggest that adjunctive cold water hydrotherapy could accelerate functional recovery, reduce symptom burden, and enhance quality of life in Post-COVID rehabilitation.

Baseline Assessments:

At baseline, demographic data including sex, age, height, and weight will be collected. Participants will report their current main Post-COVID symptoms, which will be categorized into symptom clusters: Fatigue (A), Cognitive (B), and Somatic (C). Smoking history will be assessed, including smoking status (current, former, or never), number of cigarettes per day, years of smoking, and pack-years.

The time (in months) since the COVID-19 infection that led to Post-COVID syndrome will be documented, along with the number of COVID-19 vaccinations received at the time of infection. Employment status will be recorded, distinguishing between full-time or part-time employment, COVID-related work disability, retirement, unemployment, or disability pension.

Comorbidities will be documented across the following categories: cardiovascular, pulmonary, cerebrovascular, metabolic, musculoskeletal, psychiatric, and other conditions. The severity of the acute COVID-19 illness will be assessed using the WHO Clinical Progression Scale, including information on any hospital admission and length of stay (in days).

Pulmonary function testing at baseline (V1) will include FEV₁, FVC, FEV₁/FVC ratio, and total lung capacity (TLC), all expressed as percent predicted. Autonomic function will be evaluated using the Schellong test. Vascular status will be assessed by four-limb blood pressure measurement. Additionally, self-reported work ability and the number of Post-COVID-related sick leave days within the past 12 weeks will be recorded.

• Study Type: Interventional
• Enrollment (Estimated): 50
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Rainer Gloeckl, PhD; Phone Number: +498652931630; Email: rgloeckl@schoen-klinik.de

Study Locations

• Germany
  • Bavaria
    • Schönau am Königssee, Bavaria, Germany, 83471
      • Recruiting
      • Schön Klinik Berchtesgadener Land
      • Contact: Rainer Gloeckl, PhD; Phone Number: +498652931630; Email: rgloeckl@schoen-klinik.de

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Diagnosis of Post-COVID Syndrome (ICD-10 code: U08.9)
• Barthel-Index >80
• Referred to the reference center for Post-COVID rehabilitation
• Owning a smartphone to receive digital questionnaires and to use the measurement app for heart rate variability
• Written informed consent

Exclusion Criteria:

• Existing contraindications for Kneipp hydrotherapy like severe cardiovascular diseases (e.g., decompensated heart failure, unstable angina pectoris, acute myocardial infarction), severe venous diseases (e.g., acute deep vein thrombosis of the leg), severe neurological diseases (e.g., uncontrolled epilepsy)
• Prior regular practice of Kneipp applications

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: Post-COVID Rehabilitation with hydrotherapy; Cold water hydrotherapy (5-10 minutes each), twice daily during the 3-week multimodal inpatient rehabilitation program and once daily during the 6-month follow-up period	Other: Standard rehabilitation plus cold water hydrotherapy; Cold water hydrotherapy (5-10 minutes each), twice daily during the 3-week multimodal inpatient rehabilitation program and once daily during the 6-month follow-up period
Active Comparator: Post-COVID Rehabilitation without hydrotherapy; 3-week inpatient multimodal inpatient rehabilitation program without hydrotherapy	Other: Standard rehabilitation only; same rehabilitation program than the experimental group but without hydrotherapy

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Health-related quality of life by Short Form-12 Health Survey (SF-12)	Change in the Short Form-12 physical and mental component summary scores	From baseline (Visit 1) to end of inpatient rehabilitation (3 weeks, Visit 2)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fatigue severity by Fatigue Severity Scale	Change in Fatigue Severity Scale score	From baseline (Visit 1) to end of inpatient rehabilitation (3 weeks, Visit 2)
Sleep quality by Pittsburgh Sleep Quality Index	Change in Pittsburgh Sleep Quality Index score	From baseline (Visit 1) to end of inpatient rehabilitation (3 weeks, Visit 2)
Health status by EuroQol-5 Dimensions-5 Levels	Change in EuroQol-5 Dimensions-5 Levels questionnaire score	From baseline (Visit 1) to end of inpatient rehabilitation (3 weeks, Visit 2)
Autonomic function (heart rate variability by photoplethysmography)	Change in heart rate variability (root mean square of successive differences) measured by Kyto 2935 via photoplethysmography	Daily during first 3 weeks of rehabilitation (Visit 1 to Visit 2)
Resting blood pressure (systolic and diastolic)	Change in morning resting systolic and diastolic blood pressure	Daily during first 3 weeks of rehabilitation (Visit 1 to Visit 2)
Post-COVID work-absence days	Number of days of work absence due to Post-COVID-19 symptoms during the past 12-weeks	From baseline (Visit 1) to 3 months (Visit 3) and to 6 months (Visit 4)
Long-term quality of life by Short Form-12	Change in Short Form-12 scores at follow-up	From baseline (Visit 1) to 3 months (Visit 3) and to 6 months (Visit 4)
Long-term fatigue by Fatigue Severity Scale	Change in Fatigue Severity Scale score at follow-up	From baseline (Visit 1) to 3 months (Visit 3) and to 6 months (Visit 4)
Adherence to hydrotherapy	Proportion of prescribed hydrotherapy applications in the intervention group performed, as recorded in diary or app. Short-term Adherence: During the 3-week intervention phase, patients are considered "adherent" if they perform at least one hydrotherapy session per day on at least 75% of study days. We will compare health improvements between high-adherence and low-adherence participants. Long-term Adherence and Effects: Over the 3- and 6-month follow-up, "adherent" patients are those who continue self-administered hydrotherapy at least four times per week on at least 75% of follow-up weeks. We will assess whether these patients sustain greater gains in quality of life.	During the 3-week intervention phase (up to Visit 2) and over the 6-month follow-up period (to Visit 4)
Adverse events recording	Number and severity of adverse events related to Kneipp hydrotherapy	From start of intervention (Visit 1) through end of study (Visit 4, 6-month follow-up)
Long-term heart rate variability changes (HRV)	Change in heart rate variability parameters (root mean square of successive differences) measured by photoplethysmography. At follow-up visits patients will measure HRV for 7 consecutive days	From baseline (Visit 1) to 3 months (Visit 3) and to 6 months (Visit 4)
Post-exertional malaise severity	Change in Post-Exertional Malaise score measured by the DePaul Symptom Questionnaire-Post-Exertional Malaise	From baseline (Visit 1) to 6-month (Visit 4) follow-up
Daily well-being documentation	Self-reported daily well-being recorded via digital diary on a scale from 0 to 100	Daily throughout the intervention and 6 months follow-up phase (Visit 1 to Visit 4)

Collaborators and Investigators

• Sponsor: Schön Klinik Berchtesgadener Land
• Collaborators: Bavarian Health and Food Safety Authority (LGL)
• Investigators: Principal Investigator: Rembert Koczulla, MD, Schön Klinik Berchtesgadener Land

Study record dates

Study Major Dates

• Study Start (Actual): August 21, 2025
• Primary Completion (Estimated): January 31, 2027
• Study Completion (Estimated): October 31, 2027

Study Registration Dates

• First Submitted: June 5, 2025
• First Submitted That Met QC Criteria: June 5, 2025
• First Posted (Actual): June 10, 2025

Study Record Updates

• Last Update Posted (Estimated): August 28, 2025
• Last Update Submitted That Met QC Criteria: August 21, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Keywords: rehabilitation; quality of life; intervention; Long COVID; therapy; hydrotherapy; Post-COVID; balneotherapy; Post-COVID condition; Kneipp
• 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: HydroCoVital A

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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