Table 8 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 per-protocol 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

14

23

14

23

     

VO2peak relative (ml/min/ kg body weight)

28.86 ± 6.32

26.09 ± 8.64

30.29 ± 6.92

26.44 ± 8.26

1.43

0.35

1.08 [− 6.40,8.56]

0.14 [− 0.81,1.09]

+

VE/VCO2-Slope

28.16 ± 8.33

31.64 ± 6.38

29.01 ± 3.47

29.95 ± 4.53

0.85

− 1.69

2.54 [− 3.066,8.15]

0.35 [− 0.42,1.12]

−

Peak power (Watt)

187.00 ± 47.37

168.44 ± 56.32

194.00 ± 47.12

168.70 ± 53.32

7.00

0.26

6.74 [− 43.12,56.60]

0.13 [− 0.81,1.06]

+

Peak heart rate (beats/min)

167.79 ± 21.33

160.09 ± 14.66

166.71 ± 16.50

162.04 ± 15.44

− 1.07

1.96

− 3.03 [− 18.96,12.90]

− 0.17 [− 1.08,0.73]

+

Peak breathing rate (breaths/min)

41.21 ± 5.48

40.22 ± 7.24

41.29 ± 5.77

41.35 ± 7.23

0.07

1.13

− 1.06 [− 7.45,5.33]

− 0.16 [− 1.13,0.81]

−

Peak respiratory exchange ratio (RER)

1.16 ± 0.05

1.15 ± 0.07

1.14 ± 0.08

1.13 ± 0.07

− 0.02

− 0.01

− 0.00 [− 0.07,0.06]

− 0.06 [− 1.08,0.96]

−

Power ventilatory threshold 1 (Watt)

96.36 ± 22.85

82.32 ± 37.63

97.36 ± 31.89

86.77 ± 35.22

1.00

4.46

− 3.45 [− 35.67,28.76]

− 0.10 [− 1.08,0.87]

−

Heart rate ventilatory threshold 1 (beats/min)

121.00 ± 21.04

113.00 ± 14.68

117.00 ± 16.33

115.73 ± 13.51

− 4.00

2.73

− 6.73 [− 22.24,8.78]

− 0.38 [− 1.26,0.50]

+

Power ventilatory threshold 2 (Watt)

148.79 ± 33.79

134.67 ± 46.71

157.71 ± 36.99

139.85 ± 38.98

8.93

5.18

3.75 [− 35.64,43.14]

0.09 [− 0.85,1.03]

+

Heart rate ventilatory threshold 2 (beats/min)

147.36 ± 22.53

140.95 ± 14.27

150.00 ± 17.44

142.45 ± 16.39

2.64

1.50

1.15 [− 15.92,18.21]

0.06 [− 0.88,1.01]

−

Power 2 mmol lactate threshold (Watt)

111.43 ± 44.20

101.67 ± 49.10

117.71 ± 39.68

104.75 ± 45.64

6.29

3.08

3.20 [− 41.21,47.61]

0.07 [− 0.88,1.02]

+

Heart rate 2 mmol lactate threshold (beats/min)

130.43 ± 14.97

123.48 ± 15.83

125.07 ± 13.02

123.80 ± 15.33

− 5.36

0.32

− 5.68 [− 20.35,9.00]

− 0.36 [− 1.30,0.57]

+

Power 4 mmol lactate threshold (Watt)

153.43 ± 38.95

139.39 ± 44.79

157.86 ± 36.29

142.71 ± 43.13

4.43

3.32

1.11 [− 39.13,41.34]

0.03 [− 0.92,0.97]

+

Heart rate 4 mmol lactate threshold (beats/min)

150.50 ± 16.72

143.65 ± 13.67

147.21 ± 14.83

145.62 ± 13.39

− 3.29

1.97

− 5.25 [− 19.20,8.69]

− 0.35 [− 1.28,0.58]

+

Heart rate recovery (HRR2) (beats/min)

− 12.00 ± 7.97

− 12.32 ± 5.09

− 14.40 ± 3.78

− 12.14 ± 7.15

− 2.40

0.19

− 2.59 [− 8.54,3.36]

− 0.42 [− 1.37,0.54]

+

Weight (kg)

83.99 ± 17.07

85.93 ± 23.82

82.54 ± 17.09

86.03 ± 24.76

− 1.44

0.10

− 1.54 [− 22.52,19.45]

− 0.07 [− 1.06,0.91]

+

BMI (kg/m2)

27.50 ± 3.98

28.34 ± 6.74

27.00 ± 3.86

28.93 ± 7.03

− 0.50

0.59

− 1.09 [− 6.82,4.63]

− 0.19 [− 1.18,0.80]

+

Skeletal muscle mass (kg)

33.34 ± 7.58

32.06 ± 7.86

32.32 ± 7.37

31.62 ± 8.02

− 1.01

− 0.44

− 0.58 [− 8.20,7.04]

− 0.08 [− 1.07,0.92]

−

Body fat mass (kg)

24.45 ± 9.95

27.93 ± 15.76

23.32 ± 9.75

28.66 ± 16.41

− 1.13

0.73

− 1.85 [− 15.64,11.93]

− 0.13 [− 1.14,0.87]

+

  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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