Table 3.

MyHC isoform expression measured in single muscle fibres and biopsy cross-sections from HRT using and non-using co-twins

	Total number of fibres	Type I (%)	Type I/IIa (%)	Type IIa (%)	Type IIax (%)	Type IIx (%)
HRT non-users	162	60 (47 ± 6)	8	24 (51 ± 6)	6	2 (12 ± 1)
HRT users	164	49 (43 ± 5)	10	30 (52 ± 4)	10	1 (15 ± 3)

Values for cross-sections (in parentheses) are expressed as mean ± SEM. No statistically significant differences were observed in MyHC isoform expression between HRT using and their non-using co-twins.