Table 2– Respiratory muscle myosin heavy chain (MHC) areal density and fibre cross-sectional area (CSA)
Type 1Type 2AType 2XType 2B
Sternohyoid
 MHC isoform areal density %
  Normoxia0.52±0.1014.1±1.47.3±1.077.2±2.2
  CH0.49±0.2013.6±1.211.0±1.277.1±1.5
 Fibre CSA μm2
  Normoxia993±641192±311999±433792±64
  CH891±441489±52*2235±70*3834±53
Diaphragm
 MHC isoform areal density %
  Normoxia21.8±1.724.3±2.127.8±4.019.1±4.4
  CH25.3±2.722.0±1.325.5±3.126.9±6.1
 Fibre CSA μm2
  Normoxia1410±381422±262565±805024±177
  CH1232±25*1384±232040±75*3424±85*
  • Data are presented as mean±sem (n = 8–11 per group). CH: chronic hypoxia (6 weeks). *: p<0.05 versus normoxia (unpaired t-test).