Energy Expenditure of Dynamic Submaximal Human Plantarflexion Movements: Model Prediction and Validation by Magnetic Resonance Spectroscopy.

To understand the organization and efficiency of biological movement, it is important to evaluate the energy requirements on the level of individual muscles. To this end, predicting energy expenditure with musculoskeletal models in forward-dynamic computer simulations is currently the most promising approach. However, it is challenging to validate muscle models in humans, because access to the energy expenditure of single muscles is difficult.

The reproducibility of different metabolic markers for muscle fiber type distributions investigated by functional P-MRS during dynamic exercise.

Purpose: The objective of the study was to investigate the reproducibility of exercise induced pH-heterogeneity by splitting of the inorganic phosphate (Pi) signal in the corresponding P-MRS spectra and to compare results of this approach with other fiber-type related markers, like phosphocreatine/adenosine triphosphate (PCr/ATP) ratio, and PCr-recovery parameters.

Material And Methods: Subjects (N=3) with different sportive background were tested in 10 test sessions separated by at least 3 days. A MR-compatible pedal ergometer was used to perform the exercise and to induce a pH-based splitting of the Pi-signal in P-MR spectra of the medial gastrocnemius muscle.

The pH heterogeneity in human calf muscle during neuromuscular electrical stimulation.

Purpose: The aim of the study was to examine pH heterogeneity during fatigue induced by neuromuscular electrical stimulation (NMES) using phosphorus magnetic resonance spectroscopy ( P-MRS). It is hypothesized that three pH components would occur in the P-MRS during fatigue, representing three fiber types.

Methods: The medial gastrocnemius of eight subjects was stimulated within a 3-Tesla whole body MRI scanner.

Glutamatergic dysfunction linked to energy and membrane lipid metabolism in frontal and anterior cingulate cortices of never treated first-episode schizophrenia patients.

Background: Glutamatergic dysfunction and altered membrane lipid and energy metabolism have been repeatedly demonstrated in the frontal/prefrontal and anterior cingulate cortex (ACC) in schizophrenia. Though having been already studied in animals, the presumed link between glutamatergic function and structural plasticity has not been investigated directly in the human brain yet. We measured glutamate (Glu), focal energy metabolism, and membrane phospholipid turnover to investigate main pathologies in those key brain regions of schizophrenia.