RT Journal Article SR Electronic T1 McArdle disease does not affect skeletal muscle fibre type profiles in humans JF Biology Open JO Biology Open FD Company of Biologists SP 1224 OP 1227 DO 10.1242/bio.20149548 VO 3 IS 12 A1 Kohn, Tertius Abraham A1 Noakes, Timothy David A1 Rae, Dale Elizabeth A1 Rubio, Juan Carlos A1 Santalla, Alfredo A1 Nogales-Gadea, Gisela A1 Pinós, Tomas A1 Martín, Miguel A. A1 Arenas, Joaquin A1 Lucia, Alejandro YR 2014 UL http://bio.biologists.org/content/3/12/1224.abstract AB Patients suffering from glycogen storage disease V (McArdle disease) were shown to have higher surface electrical activity in their skeletal muscles when exercising at the same intensity as their healthy counterparts, indicating more muscle fibre recruitment. To explain this phenomenon, this study investigated whether muscle fibre type is shifted towards a predominance in type I fibres as a consequence of the disease. Muscle biopsies from the Biceps brachii (BB) (n = 9) or Vastus lateralis (VL) (n = 8) were collected over a 13-year period from male and female patients diagnosed with McArdle disease, analysed for myosin heavy chain (MHC) isoform content using SDS-PAGE, and compared to healthy controls (BB: n = 3; VL: n = 10). All three isoforms were expressed and no difference in isoform expression in VL was found between the McArdle patients and healthy controls (MHC I: 33±19% vs. 43±7%; MHC IIa: 52±9% vs. 40±7%; MHC IIx: 15±18% vs. 17±9%). Similarly, the BB isoform content was also not different between the two groups (MHC I: 33±14% vs. 30±11%; MHC IIa: 46±17% vs. 39±5%; MHC IIx: 21±13% vs. 31±14%). In conclusion, fibre type distribution does not seem to explain the higher surface EMG in McArdle patients. Future studies need to investigate muscle fibre size and contractility of McArdle patients.