Table 7 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 the intention-to-treat analysis.

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

Parameter name (range)

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

26

28

26

28

     

VO2peak relative (ml/min/ kg body weight)

27.69 ± 5.62

26.39 ± 9.11

28.48 ± 6.16

27.43 ± 8.90

0.79

1.04

− 0.25 [− 6.15,5.65]

− 0.03 [− 0.81,0.74]

−

VE/VCO2-Slope

29.96 ± 7.18

31.49 ± 6.15

29.75 ± 4.62

30.279 ± 4.62

− 0.21

− 1.21

1.00 [− 3.41,5.41]

0.13 [− 0.45,0.71]

−

Peak power (Watt)

187.81 ± 48.18

169.57 ± 56.63

192.68 ± 52.61

172.29 ± 55.97

4.87

2.71

2.16 [− 38.98,43.29]

0.04 [− 0.73,0.82]

+

Peak heart rate (beats/min)

164.15 ± 20.06

157.93 ± 15.96

163.84 ± 18.35

160.96 ± 16.75

− 0.31

3.04

− 3.35 [− 17.01,10.31]

− 0.18 [− 0.94,0.57]

+

Peak breathing rate (breaths/min)

41.54 ± 5.29

40.54 ± 7.07

43.88 ± 12.59

41.96 ± 7.13

2.34

1.43

0.91 [− 5.52,7.34]

0.15 [− 0.89,1.18]

+

Peak respiratory exchange ratio (RER)

1.14 ± 0.05

1.14 ± 0.07

1.15 ± 0.08

1.13 ± 0.07

0.01

− 0.01

0.02 [− 0.04,0.07]

0.27 [− 0.55,1.10]

+

Power ventilatory threshold 1 (Watt)

97.35 ± 22.17

85.30 ± 38.09

99.52 ± 35.21

86.52 ± 34.97

2.17

1.22

0.95 [− 24.79,26.70]

0.03 [− 0.78,0.84]

+

Heart rate ventilatory threshold 1 (beats/min)

117.27 ± 18.97

112.93 ± 15.51

114.96 ± 14.17

115.26 ± 13.57

− 2.31

2.33

− 4.64 [− 16.80,7.51]

− 0.27 [− 0.97,0.44]

+

Power ventilatory threshold 2 (Watt)

152.72 ± 39.34

138.20 ± 48.68

156.08 ± 40.54

139.29 ± 38.95

3.36

1.09

2.27 [− 31.33,35.87]

0.05 [− 0.71,0.81]

+

Heart rate ventilatory threshold 2 (beats/min)

145.60 ± 21.02

140.36 ± 15.70

144.40 ± 17.74

143.00 ± 16.45

− 1.20

2.64

− 3.84 [− 18.09,10.41]

− 0.21 [− 0.98,0.56]

+

Power 2 mmol lactate threshold (Watt)

112.50 ± 42.56

101.89 ± 44.95

111.32 ± 40.54

105.48 ± 44.04

− 1.18

3.60

− 4.78 [− 38.63,29.08]

− 0.11 [− 0.88,0.67]

−

Heart rate 2 mmol lactate threshold (beats/min)

124.81 ± 16.75

122.73 ± 15.06

118.68 ± 14.96

122.96 ± 14.64

− 6.13

0.23

− 6.36 [− 18.45,5.74]

− 0.40 [− 1.17,0.36]

+

Power 4 mmol lactate threshold (Watt)

154.96 ± 41.49

141.44 ± 43.77

155.36 ± 38.78

143.54 ± 42.01

0.40

2.09

− 1.69 [− 34.24,30.86]

− 0.04 [− 0.80,0.72]

−

Heart rate 4 mmol lactate threshold (beats/min)

146.76 ± 18.05

142.33 ± 14.02

142.08 ± 16.96

144.58 ± 14.08

− 4.68

2.24

− 6.92 [− 19.31,5.46]

− 0.43 [− 1.20,0.34]

+

Heart Rate Recovery (HRR2) (beats/min)

− 10.92 ± 8.06

− 12.27 ± 5.36

− 13.20 ± 4.36

− 11.866 ± 6.67

− 2.28

0.41

− 2.69 [− 7.59,2.22]

− 0.40 [− 1.12,0.33]

+

Weight (kg)

87.10 ± 16.50

84.02 ± 22.95

84.91 ± 16.50

84.17 ± 23.51

− 2.19

0.15

− 2.34 [− 17.98,13.30]

− 0.12 [− 0.90,0.67]

+

BMI (kg/m2)

27.82 ± 3.96

27.80 ± 6.42

27.00 ± 3.55

28.35 ± 6.66

− 0.82

0.54

− 1.36 [− 5.52,2.80]

− 0.26 [− 1.04,0.53]

+

Skeletal muscle mass (kg)

34.64 ± 7.82

31.64 ± 7.66

33.80 ± 7.82

31.39 ± 7.72

− 0.84

− 0.25

− 0.59 [− 6.66,5.47]

− 0.11 [− 0.85,0.70]

−

Body fat mass (kg)

25.39 ± 8.75

26.69 ± 14.75

23.93 ± 8.40

27.23 ± 15.31

− 1.46

0.54

− 1.99 [− 11.65,7.66]

− 0.16 [− 0.96,0.63]

+

  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 x 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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