[Dynamic 31phosphorus magnetic resonance spectroscopy of the quadriceps muscle: metabolic changes under 2 different forms of loading].
OBJECTIVE
The aim of the present investigation was to examine the metabolism of the quadriceps muscles of normal young individuals using dynamic 31phosphorus magnetic resonance spectroscopy.


METHODS
22 normal individuals were examined in a 1.5T-MRT using a 6 cm surface coil. The metabolic changes in the quadriceps muscle as shown by the phosphorus spectrum were evaluated during rest, exercise (isometric and isotonic exercise) and during a 36-second period of recovery.


RESULTS
The Pi/PCr quotient rose from its resting value of 0.11 +/- 0.02 following exercise to a maximum of 0.83 +/- 0.47 (isometric) or 1.40 +/- 0.59 (isotonic) (difference p = 0.0001). Half-time recovery of Pi/PCr was 35 +/- 11 s or 31 +/- 10 s, respectively (p = 0.13). During the recovery phase Pi/PCr fell briefly but significantly below its rest value. Following an initial rise in pH, there was a continual fall. Minimum pH (6.68 +/- 0.21 and 6.53 +/- 0.27 respectively; p = 0.01) occurred in the early recovery phase. The recovery process of pH values lasted longer following isotonic than after isometric exercise (half-value recovery time 229 +/- 72 s and 146 +/- 55 s, respectively; p = 0.001).


CONCLUSIONS
Compared with isometric exercise, isotonic stress is more expensive in terms of metabolism. Dynamic 31phosphorus MRT spectroscopy can differentiate changes in muscle metabolism during different forms of exercise.
Schunk
K
K
Klinik und Poliklinik für Radiologie, Johannes Gutenberg-Universität Mainz.
Kersjes
W
W
Schadmand-Fischer
S
S
Thelen
M
M
D000328:Adult; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007537:Isometric Contraction; D007551:Isotonic Contraction; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010759:Phosphorus Isotopes; D012015:Reference Standards; D012146:Rest
D010759:Phosphorus Isotopes