Table 2 Pattern matrix: item loadings on exercise for patients and controls, six component solution with Promax rotation
Components (% variance) itemsComponent loadings
(1) Air hunger component (42.6%)
    Cannot breathe deeply enough0.86
    Need to take a deeper breath0.83
    Breathing too shallow0.77
    Not satisfied by my breathing0.67
    Can’t get enough air into my chest0.67
    Cannot breathe enough0.67
(2) Affective component (5.8%)
    Desperate for breath0.89
    Gasping for breath0.74
    Hunger for more air0.520.68
    Fighting for breath0.65
(3) Nociceptive component (4.6%)
    Chest aches0.82
    Chest feels tight0.77
    Raw sensation in chest0.74
    Raw sensation in throat0.50
    Winded in my chest0.41
(4) Regulation component (3.7%)
    Breathing is too deep0.88
    Breathing is too fast0.68
    Breathing is too heavy0.63
    Breathing feels unpleasant0.50
    Can’t control my breathing0.41
(5) Attention component (3.1%)
    Aware of my breathing0.66
    Need breath0.470.53
    Short of breath0.52
    Out of breath0.49
(6) Miscellaneous component (3.0%)
    Want to sigh0.420.61
    Air does not taste right0.480.59
    My breath stops0.470.55
  • The magnitude of the component loadings represents how good each item is as an indicator of the component.

  • All items shown load >0.40 onto PCA components.