Variations in single fibre areas and fibre composition in needle biopsies from the human quadriceps muscle

Cross-sectional area of a single fibres and the fibre distribution were measured for the two main types of fibres in needle biopsies from the quadriceps muscle of ten healthy young males. Methodological errors expressed as coefficient of variation (CV) of a single value for the area measurements were analysed and found to be 2.4% including the intraindividual error in handling the planimeter. An inhomogeneity in distribution and size of the fibres within the quadriceps muscle was indicated by a CV within the same section of 6-8% and between repeated biopsies of 15-20%.