Summary of changes occurring in respiratory muscle fibres in relation to changes in physiological conditions, diseases, and pharmacological treatments
| Fibre type | Fibre size | Fatigue resistance | Contractile strength | |
|---|---|---|---|---|
| ↑, increase; ↓, decrease; = , no change; NA, not available. | ||||
| *Data available on limb skeletal muscle fibres, no information about respiratory muscles. | ||||
| †Change restricted to diaphragm as opposite changes have been found in limb skeletal muscles165–167 and in expiratory muscles.171 | ||||
| Perinatal development19,33,34 | ↑ slow fibres | ↑ | ↑ | ↑ |
| Ageing102–109 | ↑slow fibres | ↓ | = ↓ | ↓ |
| Endurance training64–75 | = | ↓ | ↑ | NA |
| Disuse42–47* | ↑ fast fibres | ↓ | NA | ↓ |
| Malnutrition128–140,142–145 | ↑ fast fibres | ↓ (fast fibres) | ↑ | ↓ (in proportion to fibre size) |
| Chronic corticosteroid treatment147–151 | ↑ slow fibres | ↓ (fast fibres) | ↑ | ↓ |
| Chronic β agonist treatment152–156 | ↑ fast fibres | ↓ (slow fibres) | = | = |
| COPD | ↑ slow fibres18† | NA | NA | NA |
| Hypoxia173–177 | ↑ fast fibres | NA | ↑ | NA |