Gender Differences in the Recovery Rate Following a Hybrid Pulmonary Rehabilitation Programme in Patients With Long COVID-19 Syndrome
Conditions: Post Acute COVID-19 Syndrome
Sponsor: National and Kapodistrian University of Athens

Study protocol 
Study design 
This study is a retrospective, single centre study, comparing the rate of improvement in men 
and women with long COVID-19 syndrome, following the completion of a hybrid PR 
programme from August 2022 to December 2022. The study flowchart is presented in Figure 
1. All patients will have been diagnosed with long COVID-19 based on the persistence of 
fatigue at least three months following hospital discharge due to COVID-19. Exclusion 
criteria include participation in another clinical trial, occurrence of myocardial infarction, 
hospitalisation for unstable angina, stroke, coronary artery bypass graft (CABG), 
percutaneous coronary intervention (PCI), implantation of a cardiac resynchronization 
therapy device (CRTD), active treatment for cancer or other malignant disease, uncontrolled 
congestive heart disease (NYHA class >3), acute psychosis or major psychiatric disorders or 
continued substance abuse within 3 months prior to informed consent. No change in the 
medical treatment will be made during the duration of the PR program. During the first phase 
of the PR programme, patients will undergo a structured, outpatient, supervised hospital-
based PR program for 4 weeks with a frequency of 2 training sessions per week. Following 
the completion of the first phase patients will undergo 24 home-based tele-rehabilitation 
sessions for 8 weeks with a frequency of 3 training sessions per week. Assessment will be 
performed at baseline and following completion of the PR programme and include pulmonary 
function tests, exercise capacity, daily physical activity levels, functional capacity, peripheral 
and respiratory muscle strength and quality of life. Informed written consent will be obtained 
from all patients. The investigations will be carried out following the rules of the Declaration 
of Helsinki of 1975 and the study was approved by the University Hospital Ethics Committee 
(Protocol ID-24633). 
 
 
 
 
 
 
 

 
 
 
 
 
 
 
Figure 1. Study flow chart 
 
Respiratory function assessment 
Standard spirometry will be performed with a metabolic cart using the “fast inspiratory 
manoeuvre”. Maximum static inspiratory (PImax) and expiratory (PEmax) mouth pressures 
will be measured with a plastic semi-rigid flanged mouthpiece fitted to a metallic stem 
incorporating a 3-way tap, manufactured according to the design of Ringqvist. Static lung 
volumes will be determined by the multiple nitrogen washout technique. The diffusing 
capacity for carbon monoxide (DLCO) via the single-breath technique will also be determined. 
Predicted values for spirometry, static lung volumes, and DLCO are from the European 
Community for Coal and Steel.  
Peripheral muscle strength, body mass composition and quality of life 
Prior to the onset and following completion of the 3 month hybrid PR program all 
participants will be assessed for quadriceps isometric muscle strength with a strain gauge 
Myometer and handgrip strength. Furthermore, body mass composition will be assessed with 
the method of bio-impedance. Quality of life will be assessed via FACIT, CAT, HADS, SF-
36 and the Revised Impact of Events Scale questionnaires. 
Incremental cycle-ergometer exercise test 
Participants will perform a ramp incremental exercise protocol on the cycle ergometer. The 
exercise protocol will be as follows: after 3-min of baseline measurements and 3-min of 
unloaded pedalling, the work rate will be increased by 10-25 Watt every 1-min to the limit of 
tolerance. During each test, arterial oxygen saturation (SpO2%) will be obtained by a pulse 
oximeter connected to the metabolic cart. Blood pressure will be monitored automatically via 
Screened (n=80) 
Eligible (n=58) 
Started PR with no missing 
assessment at baseline (n=30) 
Women (n=15) 
Men (n=15) 
No long COVID-19 
Missing assessment at 
baseline (n=31) 

a cuff that is connected to the metabolic cart at predetermined time points. The modified Borg 
1-10 scale will be used to rate the magnitude of perceived dyspnoea and leg discomfort every 
3-min throughout the test and at the end of exercise. 
Functional capacity 
The 6-min walk test (6MWT) will be performed according to the instructions of the 
American Thoracic Society, i.e.: the maximum distance walked by each patient on a 20-meter 
hospital corridor in 6 minutes will be assessed. Intensity of dyspnoea and leg discomfort will 
be assessed by the modified Borg 1-10 scale, whereas heart rate (HR) and SpO2% will be 
recorded at rest and at the end of 6MWT. Moreover, Short Physical Performance Buttery Test 
(SPPB) will be performed prior and following the completion of the 3-month period. 
Daily physical activity  
Daily physical activity was assessed for a period of seven consecutive days, one week prior 
and one week following the completion of the PR program, using a free application installed 
in the patients’ smartphones (Leap Fitness Group). Patients instructed to have their phone in 
their pocket for as much as possible during the seven day period in order to minimise the data 
loss. 
Exercise training protocol 
During the outpatient PR programme, patients will perform supervised exercise training 
consisting of 30 minutes interval aerobic exercise on electromagnetically braked cycle 
ergometers at 100% of peak work rate and resistance exercises for the upper body. During 
each training session dyspnoea and leg discomfort will be recorded on the modified 1-10 
Borg scale, whereas HR and SpO2% will be continuously monitored by a portable pulse 
oximeter. Based on symptoms of breathlessness and fatigue reported at the end of each 
exercise session (i.e. both dyspnoea and leg discomfort <4 at the Borg scale), the exercise 
intensity will be increased by 5-10% of the baseline WRpeak in the next session. The remote 
24 home-based PR sessions will be consisted of 30 minutes walking with an individualised 
target of steps (recorded via the mobile app installed in the patients’ mobile phone). The 
steps, leg discomfort and dyspnoea symptoms will be reported by the patient using a physical 
activity diary on a weekly basis. The assessors will set new step targets based on the steps 
and the symptoms reported by the patient. If dyspnoea and leg discomfort are both <4 at the 
Borg scale the weekly target of steps will be increased by 5-10%, otherwise the target will 
remain the same. 

Statistical analysis 
Normal distribution of the data will be checked with the Shapiro-Wilk test. Comparisons of 
baseline characteristics will be made using independent t-test. Two-way ANOVA with 
repeated measures will be applied to detect differences between the two sexes across different 
time points. The LSD post hoc correction method will be used where appropriate. A p value 
<0.05 is considered significant.