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Table 2 Lower maximal oxygen uptake and endurance performance in myositis patients compared to healthy controls.

From: Improved exercise performance and increased aerobic capacity after endurance training of patients with stable polymyositis and dermatomyositis

  Patients n= 23
Mean ± SD
Healthy Controls
n= 12
Mean ± SD
Unpaired t-test
VO2 max test
VO2 max (l min-1) 1.65 ± 0.51 2.28 ± 0.55 P <0.01
VO2, max/body weight (ml min-1 kg-1) 22 ± 5 32 ± 6 P <0.01
Power at VO2 max (W) 120 ± 36 185 ± 38 P <0.001
Respiratory exchange ratio(RQ = CO2/O2) 1.1 ± 0.1 1.2 ± 0.1 n.s.
Maximum heart rate (min-1) 160 ± 15 173 ± 16 n.s.
Borg rating (6 to 20):    
   Peripheral exertion 19 ± 1 19 ± 1 n.s
   Central exertion 17 ± 3 18 ± 2 n.s.
Endurance cycling test
Time to exhaustion (minute) 14.0 ± 5.1 26.1 ± 11.3 P <0.001
Lactate (mM) 10.6 ± 3.6 11.7 ± 3.7 n.s.
Percentage maximum heart rate 91 ± 1 96 ± 1 n.s.
Borg rating (6 to 20):    
   Peripheral exertion 19 ± 1 18 ± 2 n.s
   Central exertion 17 ± 1 18 ± 2 n.s
  1. n.s., Non-significant; VO2 max, maximal oxygen uptake; endurance cycling test, time cycling to exhaustion performed with a constant power, which in each individual was set to requiring 65% of baseline VO2 max; Borg rating, rating of exertion at end of VO2 max test and at the end of the endurance cycling test; Lactate, concentration of lactate measured in muscle vastus lateralis with microdialysis directly after the endurance cycling test.