Table 1.

Histology injury scoring system (HISS) for hypoxia‐induced muscle injury [12, 14].

Morphological changes	Categories
Interstitial oedema	0. No significant increase 1. Minimal 2. Intermediate 3. Severe/diffuse
Inflammation	0. Not significant 1. Minimal 2. Intermediate 3. Diffuse
Variation in shape and size of myocytes	0. Homogeneous 1. Mild heterogeneous 2. Intermediate heterogenous 3. Severe heterogenous
Damaged muscle fibres*	0–5 myocytes/10 HPF (20 × magnification) 6–20 myocytes/10 HPF (20 × magnification) 21–50 myocytes/10 HPF (20 × magnification) >51 myocytes/10 HPF (20 × magnification)
Total score	0–4 No/minimal degeneration 5–7 Intermediate degeneration 8–12 Severe degeneration

^*Damaged muscle fibres: a sum of necrotic, hypoxic and phagocytic myocytes.