Table 2 Pattern matrix: item loadings on exercise for patients and controls, six component solution with Promax rotation

Components (% variance) items	Component loadings
Components (% variance) items	1	2	3	4	5	6
(1) Air hunger component (42.6%)
Cannot breathe deeply enough	0.86
Need to take a deeper breath	0.83
Breathing too shallow	0.77
Not satisfied by my breathing	0.67
Can’t get enough air into my chest	0.67
Cannot breathe enough	0.67
(2) Affective component (5.8%)
Desperate for breath		0.89
Suffocating		0.86
Gasping for breath		0.74
Hunger for more air	0.52	0.68
Fighting for breath		0.65
(3) Nociceptive component (4.6%)
Chest aches			0.82
Chest feels tight			0.77
Raw sensation in chest			0.74
Wheezy			0.65
Raw sensation in throat			0.50
Winded in my chest			0.41
(4) Regulation component (3.7%)
Breathing is too deep				0.88
Breathing is too fast				0.68
Breathing is too heavy				0.63
Breathing feels unpleasant				0.50
Can’t control my breathing				0.41
(5) Attention component (3.1%)
Puffed					0.71
Aware of my breathing					0.66
Need breath	0.47				0.53
Short of breath					0.52
Out of breath					0.49
(6) Miscellaneous component (3.0%)
Want to sigh					0.42	0.61
Air does not taste right		0.48				0.59
My breath stops		0.47				0.55

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.