Table 9 Baseline (T0) and follow-up (T1) means and standard deviation (SD) in intervention and control group, difference between T1 and T0 within groups, difference in differences of intervention and control group with corresponding 95% confidence intervals (95%-CI) of spiroergometric and body composition parameters in as-treated analysis.

From: Feasibility of an unsupervised aerobic exercise training program for participants with persistent symptoms after SARS-CoV-2 infection

Parameter name (unit)

Intervention baseline (T0)

Mean ± SD

Control baseline (T0)

Mean ± SD

Intervention follow-up (T1)

Mean ± SD

Control follow-up (T1)

Mean ± SD

Difference intervention

T1-T0

Difference control

T1-T0

Difference in differences (DID) T1-T0 [95%-CI]

Difference in differences (DID) T1-T0 [95%-CI] standardized §

Direction of DID $

N

17

26

17

26

     

VO2peak relative (ml/min/ kg body weight)

29.53 ± 7.75

25.73 ± 8.23

31.29 ± 8.25

26.08 ± 7.92

1.77

0.35

1.42 [− 5.64,8.48]

0.17 [− 0.69,1.04]

+

VE/VCO2-Slope

28.19 ± 7.51

32.01 ± 6.41

28.98 ± 3.54

29.97 ± 4.68

0.79

− 2.04

2.83 [− 2.18,7.85]

0.40 [− 0.31,1.12]

−

Peak power (Watt)

192.18 ± 46.65

166.35 ± 53.54

200.47 ± 49.62

165.08 ± 51.81

8.29

− 1.27

9.56 [− 35.16,54.28]

0.18 [− 0.68,1.04]

+

Peak heart rate (beats/min)

164.53 ± 22.73

159.12 ± 15.36

164.18 ± 19.39

161.39 ± 15.52

− 0.35

2.27

− 2.62 [− 18.31,13.06]

− 0.14 [− 0.99,0.70]

+

Peak breathing rate (breaths/min)

41.12 ± 5.00

40.23 ± 6.92

41.65 ± 5.61

40.89 ± 6.99

0.53

0.65

− 0.12 [− 5.71,5.46]

− 0.02 [− 0.92,0.88]

−

Peak respiratory exchange ratio (RER)

1.15 ± 0.06

1.15 ± 0.07

1.13 ± 0.08

1.14 ± 0.07

− 0.02

− 0.01

− 0.01 [− 0.07,0.05]

− 0.11 [− 1.06,0.84]

−

Power ventilatory threshold 1 (Watt)

101.29 ± 25.73

83.64 ± 35.68

99.82 ± 29.55

84.08 ± 34.39

− 1.47

0.44

− 1.91 [− 30.49,26.67]

− 0.06 [− 0.93,0.81]

−

Heart rate ventilatory threshold 1 (beats/min)

120.29 ± 20.51

112.52 ± 16.13

115.71 ± 16.62

114.48 ± 13.80

− 4.59

1.96

− 6.55 [− 21.21,8.11]

− 0.36 [− 1.17,0.45]

+

Power ventilatory threshold 2 (Watt)

154.53 ± 36.92

132.74 ± 45.15

159.63 ± 35.45

136.61 ± 39.03

5.10

3.87

1.22 [− 34.99,37.44]

0.03 [− 0.82,0.88]

+

Heart rate ventilatory threshold 2 (beats/min)

145.35 ± 23.31

140.35 ± 15.27

149.00 ± 18.17

141.52 ± 16.30

3.65

1.17

2.47 [− 14.00,18.94]

0.13 [− 0.74,1.00]

−

Power 2 mmol lactate threshold (Watt)

112.41 ± 40.02

99.75 ± 47.65

121.29 ± 36.66

98.61 ± 45.59

8.88

− 1.14

10.02 [− 28.90,48.94]

0.22 [− 0.65,1.10]

+

Heart rate 2 mmol lactate threshold (beats/min)

127.47 ± 15.57

121.29 ± 16.51

123.82 ± 13.48

120.96 ± 16.73

− 3.65

− 0.34

− 3.31 [− 17.48,10.85]

− 0.20 [− 1.08,0.67]

+

Power 4 mmol lactate threshold (Watt)

156.94 ± 36.11

136.44 ± 44.19

161.24 ± 33.62

138.67 ± 42.21

4.29

2.23

2.07 [− 33.53,37.67]

0.05 [− 0.80,0.90]

+

Heart rate 4 mmol lactate threshold (beats/min)

147.18 ± 17.90

142.28 ± 15.13

145.29 ± 15.91

144.08 ± 15.23

− 1.88

1.80

− 3.69 [− 17.83,10.46]

− 0.23 [− 1.10,0.64]

+

Heart Rate Recovery (HRR2) (beats/min)

− 12.41 ± 7.70

− 11.63 ± 6.00

− 14.15 ± 3.58

− 11.94 ± 6.90

− 1.74

− 0.30

− 1.43 [− 7.03,4.16]

− 0.22 [− 1.06,0.63]

+

Weight (kg)

84.14 ± 16.50

85.33 ± 22.53

82.99 ± 16.35

85.19 ± 23.47

− 1.15

− 0.14

− 1.01 [− 19.21,17.19]

− 0.05 [− 0.95,0.85]

+

BMI (kg/m2)

27.42 ± 4.11

28.09 ± 6.36

27.02 ± 3.98

28.55 ± 6.70

− 0.40

0.45

− 0.85 [− 5.87,4.17]

− 0.15 [− 1.06,0.76]

+

Skeletal muscle mass (kg)

33.59 ± 6.98

31.90 ± 7.49

32.90 ± 6.78

31.50 ± 7.62

− 0.69

− 0.40

− 0.29 [− 6.83,6.25]

− 0.04 [− 0.94,0.86]

−

Body fat mass (kg)

24.14 ± 9.81

27.58 ± 14.78

23.06 ± 9.63

28.05 ± 15.41

− 1.08

0.46

− 1.54 [− 13.40,10.32]

− 0.12 [− 1.03,0.80]

+

  1. \(\dot {V}\)O2peak and RERpeak were defined as the highest 30-second rolling averages during the test, Peak power was calculated as follows: Wf + [(t/D × P)], where Wf represents the value of the last completed workload (W), t is the time (s) the last uncompleted workload was sustained, D is the duration (s) of each stage, and P is the power output difference between workloads, Watt and heart rate at ventilator threshold 1 and ventilator threshold 2 were determined visually by combining four methods: the ventilatory equivalent method, the excess carbon dioxide method, the V-slope method, and the end-tidal method. §Difference in difference (DID) per standard deviation (SD) of the analysis population at study baseline (T0),$ “+” means direction of effect consistent to a positive DID ((T1-T0 intervention group) - (T1-T0 control group)) with a stronger positive difference (T1-T0) in the intervention group for parameters where higher values represent better fitness or consistent to a negative DID with a stronger negative difference in the intervention group for parameters where lower values represent better fitness and “−” direction of effect consistent to a positive DID ((T1-T0 intervention group) - (T1-T0 control group)) with a stronger positive difference (T1-T0) in the intervention group for parameters where higher values represent better fitness or consistent to a negative DID with a stronger negative difference in the intervention group for parameters where lower values represent better fitness.
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