Table 3.

Multiple linear regression examining the associations of symptoms severity with physical fitness, and cardiopulmonary function in people with post-COVID-19 condition (n = 72)

	Dyspnea		Fatigue
	mMRC		CFQ-11		FSS		DSQ-14
	β	p	β	p	β	p	β	p
Physical fitness
Higher Work rate (W)	− 0.04	0.869	0.07	0.770	− 0.21	0.364	− 0.17	0.377
Final HR (b·m−1)	− 0.67	0.019*	− 0.11	0.700	− 0.41	0.138	− 0.34	0.151
Final RPE (score)	− 0.24	0.211	− 0.37	0.053	− 0.21	0.240	− 0.31	0.048*
VO2max (ml·kg·min−1)	− 1.12	0.027*	− 0.14	0.762	− 0.36	0.445	− 0.01	0.980
Sit-to-stand (s)	0.01	0.943	0.25	0.221	− 0.08	0.674	0.21	0.202
Handgrip (kg)	− 0.37	0.286	0.29	0.382	− 0.32	0.338	0.14	0.616
BP-50% 1RM (kg)	− 0.14	0.783	− 0.72	0.150	0.22	0.648	− 0.09	0.820
HSQ-50% 1RM (kg)	− 0.18	0.578	0.39	0.220	− 0.64	0.046*	− 0.14	0.587
Leg extension (N)	− 0.05	0.847	0.08	0.749	0.37	0.118	0.24	0.237
Adjusted R2 of the model	0.28		0.30		0.33		0.51
Cardiopulmonary function
FVC (L)	− 0.10	0.644	− 0.57	0.021*	0.30	0.133	0.22	0.260
FEV-1 (L)	− 0.24	0.634	− 0.47	0.376	0.44	0.345	0.40	0.373
FEV/FVC	0.04	0.768	0.16	0.278	0.21	0.112	0.06	0.620
FEV 25–75% (L·s−1)	0.31	0.112	− 0.14	0.496	0.05	0.777	− 0.06	0.710
MVV (L)	− 0.57	0.013*	− 0.29	0.241	− 0.76	< 0.001*	− 0.46	0.024*
LVEF (%)	− 0.24	0.038*	− 0.01	0.986	− 0.08	0.459	− 0.21	0.049*
RV-TAPSE (mm)	− 0.05	0.717	− 0.10	0.480	0.08	0.537	0.05	0.692
LVEDV (cm−3·m−2)	0.07	0.519	0.07	0.542	− 0.01	0.945	0.15	0.125
E/A (cm·s−1)	0.16	0.294	− 0.14	0.400	− 0.19	0.184	− 0.14	0.289
Adjusted R2 of the model	0.47		0.36		0.55		0.58

β indicates standardized regression coefficients with significance levels of t. All the analyses were adjusted for age, body mass index, sex, number of comorbidities, and number of symptoms. All adjusted R² values were significant; all P < 0.010

Variables excluded for collinearity (VIF > 10): Initial Work rate, Initial RPE, Initial HR, %FVC, FEV-1%, FEV-1, FEV/FVC, and %MVV

HR Heart rate, VO_2max Maximum oxygen uptake estimated by sex-specific equations [34], HG Handgrip, BP Bench Press, HSQ Half Squat, FVC Forced ventilatory capacity, FEV Forced expiratory volume, MVV Maximum voluntary ventilation, LVEF Left Ventricular Ejection Fraction, RV-TAPSE Right ventricular-Tricuspid Annular Plane Systolic Excursion, LVEDV Left Ventricular End Diastolic Volume, E/A ratio early diastolic velocity (E), late diastolic velocity (A), CFQ-11 Chalder Fatigue Scale (bimodal), FSS Fatigue Severity Scale, DSQ-14 The DePaul Symptom Questionnaire (composite), mMRC Modified Medical Research Council) dyspnea scale