Table 4.

Ergometry results of generalized linear mixed model (GLM model) analysis of 40 subjects without mask (NM) and with three different mask types (SM, CM, FFP2).

	Pre (light work)				E1 (moderate work)				E2 (heavy work)				E3 (very heavy work)				Post (light work)
	NM	SM	CM	FFP2	NM	SM	CM	FFP2	NM	SM	CM	FFP2	NM	SM	CM	FFP2	NM	SM	CM	FFP2
	G.M	Δ p value			G.M	Δ p value			G.M	Δ p value			G.M	Δ p value			G.M	Δ p value
Subjects’ perceived physical exertion
BORG (0–10)	0.81	− 0.05	− 0.04	− 0.18	0.96	0.05 0.651	0.22 0.306	0.33 0.022	2.14	0.33 0.384	0.23 0.522	0.89 0.008	3.68	0.59 0.360	0.54 0.419	1.21 0.016	0.88	0.11 0.498	0.14 0.475	0.22 0.064
Pulmonary parameters
Ttot (s)	2.90	0.31	0.31	0.6	2.45	0.14 0.239	0.20 0.577	0.20 0.007	2.28	0.03 0.012	0.05 0.022	0.04  < 0.001	1.99	0.03 0.018	0.06 0.040	0.04  < 0.001	2.44	0.15 0.250	0.13 0.176	0.07  < 0.001
RR (min1)	19.48	− 1.75	− 1.51	− 3.06	23.69	− 1.20 0.257	− 1.62 0.791	− 1.89 0.018	25.69	− 0.18 0.010	− 0.30 0.040	− 0.5  < 0.001	29.72	− 0.46 0.023	− 0.74 0.107	− 0.74  < 0.001	23.69	− 1.64 0.543	− 1.01 0.312	− 0.67  < 0.001
Metabolic parameters
pH	7.42	0.00	− 0.01	− 0.01	7.41	− 0.01 0.109	− 0.02 0.096	− 0.02 0.158	7.40	− 0.02 0.060	− 0.02 0.030	− 0.02 0.163	7.39	− 0.03 0.001	− 0.03 0.001	− 0.04  < 0.001	7.40	− 0.02 0.063	− 0.03 0.010	− 0.03 0.056
pCO2 (mmHg)	36.01	0.31	− 0.22	0.50	36.69	1.60 0.079	1.31 0.033	2.09 0.033	36.36	1.93 0.023	2.17 0.001	2.92 0.001	34.58	3.04  < 0.001	2.71  < 0.001	4.71  < 0.001	33.28	1.05 0.230	0.97 0.062	2.00 0.017
pO2 (mmHg)	87.86	1.81	1.33	− 0.41	91.53	− 1.40 0.141	− 0.64 0.365	− 2.90 0.259	91.77	− 1.86 0.081	− 2.36 0.079	− 3.62 0.130	90.27	− 3.45 0.008	− 2.70 0.041	− 5.66 0.007	95.00	0.17 0.438	0.69 0.744	0.20 0.774
Lactate (mmol/L)	1.36	0.00	− 0.08	− 0.03	1.69	− 0.07 0.621	− 0.05 0.715	− 0.09 0.672	2.51	− 0.03 0.864	0.01 0.435	− 0.10 0.798	4.50	− 0.13 0.688	− 0.06 0.561	− 0.07 0.971	3.61	0.00 0.980	0.09 0.294	0.02 0.767
sO2 (%)	97.17	0.12	0.17	− 0.17	97.27	− 0.11 0.365	− 0.02 0.468	− 0.32 0.572	96.87	− 0.39 0.049	− 0.31 0.061	− 0.60 0.098	96.72	− 0.78 0.001	− 0.70 0.001	− 1.34  < 0.001	97.17	0.13 0.980	0.04 0.594	− 0.16 0.956
pH	7.42	0.00	− 0.01	− 0.01	7.41	− 0.01 0.109	− 0.02 0.096	− 0.02 0.158	7.40	− 0.02 0.060	− 0.02 0.030	− 0.02 0.163	7.39	− 0.03 0.001	− 0.03 0.001	− 0.04  < 0.001	7.40	− 0.02 0.063	− 0.03 0.010	− 0.03 0.056
pCO2 (mmHg)	36.01	0.31	− 0.22	0.50	36.69	1.60 0.079	1.31 0.033	2.09 0.033	36.36	1.93 0.023	2.17 0.001	2.92 0.001	34.58	3.04  < 0.001	2.71  < 0.001	4.71  < 0.001	33.28	1.05 0.230	0.97 0.062	2.00 0.017
pO2 (mmHg)	87.86	1.81	1.33	− 0.41	91.53	− 1.40 0.141	− 0.64 0.365	− 2.90 0.259	91.77	− 1.86 0.081	− 2.36 0.079	− 3.62 0.130	90.27	− 3.45 0.008	− 2.70 0.041	− 5.66 0.007	95.00	0.17 0.438	0.69 0.744	0.20 0.774
Hemodynamic parameters
HR (min− 1)	82.64	0.69	− 0.24	2.56	101.92	1.02 0.942	0.98 0.576	2.65 0.827	121.37	1.14 0.963	− 0.10 0.927	2.23 0.573	140.46	1.48 0.942	− 0.90 0.899	1.56 0.498	101.28	2.26 0.548	0.28 0.806	3.81 0.778
SBP (mmHg)	109.31	1.97	− 0.41	0.70	117.55	4.08 0.589	3.51 0.270	2.37 0.652	138.95	2.67 0.969	2.27 0.485	4.04 0.434	155.93	4.80 0.668	4.01 0.315	6.32 0.253	138.34	0.92 0.744	− 1.76 0.792	4.30 0.477
DBP (mmHg)	76.53	0.95	− 0.10	1.05	72.60	2.57 0.501	0.20 0.903	− 2.46 0.153	75.08	1.26 0.899	− 0.77 0.782	1.56 0.837	75.51	2.23 0.624	1.34 0.579	1.74 0.791	73.43	− 0.07 0.676	− 1.06 0.675	1.14 0.956
Capnometric parameters
pCO2in (mmHg)	1.63	0.75	0.86	0.99	1.83	0.57 0.680	0.57 0.947	1.06 0.021	1.89	0.60 0.643	0.65 0.793	1.46  < 0.001	1.84	0.70 0.281	0.68 0.774	1.92  < 0.001	1.83	0.52 0.243	0.66 0.500	1.33 0.061
pCO2ex (mmHg)	26.76	2.14	1.78	2.99	30.00	2.70 0.669	2.28 0.685	3.25 0.901	30.12	2.81 0.586	2.67 0.352	3.31 0.942	28.24	3.81 0.029	3.52 0.019	4.98 0.013	26.58	2.23 0.879	1.85 0.893	2.59 0.597
Mask microclimate
Tmask (°C)	28.93	2.54	3.30	4.57	28.81	3.52 0.049	3.63 0.499	5.12 0.284	28.22	3.35 0.079	3.68 0.359	5.26 0.131	27.98	3.25 0.111	3.69 0.328	5.36 0.076	27.88	3.72 0.014	4.13 0.071	5.86 0.008
RH (%)	43.56	23.74	31.38	29.28	42.81	29.95 0.101	36.60 0.195	33.24 0.297	41.70	31.12 0.043	39.58 0.040	35.23 0.105	45.39	29.28 0.289	36.55 0.415	34.08 0.437	48.95	28.42 0.690	35.30 0.992	33.41 0.913

BORG Borg scale, CM Community mask, DBP Diastolic blood pressure, Δ Difference to NM, FFP2 Filtering face piece class 2, G.M. Geometric mean, HR Heart rate, NM No mask, pCO₂ Partial pressure of carbon dioxide, pO₂ Partial pressure of oxygen, pCO₂ex Expiratory carbon dioxide pressure, pCO₂in Inspiratory carbon dioxide pressure, pH Potential of hydrogen in blood, RH Relative humidity, RR Respiratory rate, SBP Systolic blood pressure, sO₂ Haemoglobin oxygen saturation, SM Surgical mask, Tin Inspiratory time, Tex Expiratory time, Tmask Temperature behind the mask, Ttot Inspiratory and expiratory time.

Masks were worn as in everyday life. The situation without mask in each specific load level (pre, E1, E2, E3, post) was always used as reference. For NM geometric mean (G.M.), for the three mask types (SM, CM, FFP2) differences to NM (Δ) and p values are shown.

Significant values are in bold.