Marco
Jauslin1, Anke Henning1, Ulrike Dydak2,
Haiko Sprott3, Dieter Meier1, Hans H. Jung4,
Peter S. Sndor4, Peter Boesiger1
1Institute for Biomedical Engineering,
ETH and University Zrich, Zrich, Switzerland; 2School of Health
Sciences, Purdue University, West Lafayette, IN, United States; 3Department
of Rheumatology and Institute of Physical Medicine, University Hospital
Zrich, Zrich, Switzerland; 4Department of Neurology, University
Hospital Zrich, Zrich, Switzerland
Differences
in phosphocreatine recovery (represented by its time constant, normalized for
pHmin) between controls and patients with mitochondrial
encephalomyopathies (and migraine with aura) have been detected with 31P-MRS
exercise protocols of both low and increasing intensity at low contraction
frequency. By employing a protocol of high intensity and high contraction
frequency these differences vanish, which may be explained by higher
fractions of activated fast twitch fibers and interindividual variations in
muscle fiber type composition in controls. Our observations therefore
challenge the notion of absolute workload independence of PCr recovery due to
different recovery characteristics of fast and slow twitch fibers.