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Introduction. – We aimed to characterize the physical capacities of a population of professional cyclists using anthropometrical, cardiovascular, respiratory, ventilatory, and energetic measures.Synthesis of facts. – Eight professional cyclists participated in this study. They performed over 1 day, 5 exercises (progressive and constant-load test) on a cyclo-ergometer.Conclusions. – Physical and physiological results confirmed previous observations done on professional cyclists. The values of maximal power tolerated and time to exhaustion at this power are reproducible during the day thus demonstrated the excellent capability to recover of the professional cyclists. [Copyright &y& Elsevier]

Abstract: Purpose: To investigate in vivo comparatively and noninvasively skeletal muscle oxidative capacity from the measurement of PCr resynthesis rates during the post-exercise recovery period in children and adults, using 31-phosphorus magnetic resonance spectroscopy. Method: Seven prepubertal boys and 10 men performed finger flexions at a frequency of 0.7Hz against a weight adjusted to 15% of the maximal voluntary contraction for 3min. Skeletal muscle oxidative capacity was measured during the 15-min post-exercise recovery period from the rate constant of PCr (k PCr) time-dependent changes and from the inferred maximum aerobic rate of ATP production (V max). Results: End-of-exercise pH was not significantly different between children and adults (6.6±0.2 versus 6.5±0.2) indicating that indices of PCr recovery kinetics (k PCr and V max) can be reliably compared. The k PCr and V max values were about twofold higher in young boys as compared to men (k PCr: 1.7±1.2 versus 0.7±0.2min−1; V max: 49.7±24.6 versus 29.4±7.9mMmin−1, P <0.05). Conclusion: The results of the present study clearly illustrate a greater mitochondrial oxidative capacity in young children. [Copyright &y& Elsevier]

31P MRS and 1H MRI of skeletal muscle have become major new tools allowing a complete non invasive investigation of muscle function both in the clinical setting and in basic research. The comparative analysis of normal and diseased muscle remains a major requirement to further define metabolic events surrounding muscle contraction and the metabolic anomalies underlying pathologies. Also, standardized rest-exercise-recovery protocols for the exploration of muscle metabolism by P-31 MRS in healthy volunteers as well as in patients with intolerance to exercise have been developed. The CRMBM protocol is based on a short-term intense exercise, which is very informative and well accepted by volunteers and patients. Invariant metabolic parameters have been defined to characterize the normal metabolic response to the protocol. Deviations from normality can be directly interpreted in terms of specific pathologies in some favorable cases. This protocol has been applied to more than 4,000 patients and healthy volunteers over a period of 15 years. On the other hand, MRI investigations provide anatomical and functional information from resting and exercising muscle. From a diagnostic point of view, dedicated pulse sequences can be used in order to detect and quantify muscle inflammation, fatty replacement, muscle hyper and hypotrophy. In most cases, MR techniques provide valuable information which has to be processed in conjunction with traditional invasive biochemical, electrophysiological and histoenzymological tests. P-31 MRS has proved particularly useful in the therapeutic follow-up of palliative therapies (coenzyme Q treatment of mitochondriopathies) and in family investigations. It is now an accepted diagnostic tool in the array of tests which are used to characterize muscle disorders in clinical routine. As a research tool, it will keep bringing new information on the physiopathology of muscle diseases in animal models and in humans and should play a role in the metabolic characterization of gene and cell therapy.

P-31 MRS has become in a very short time, a major new tool to explore muscle metabolism for clinical diagnostic purposes, while offering a unique non-invasive way to conduct advanced basic research in muscle physiopathology. The comparative analysis of normal and diseased muscle remains a major requirement to further define metabolic events surrounding muscle contraction and the metabolic anomalies underlying pathologies. Also, standardized rest-exercise-recovery protocols for exploration of muscle metabolism by P-31 MRS in healthy volunteers as well as in patients with intolerance to exercise need to be developed. Our protocol is based on a short term intense exercise which is very informative and well accepted by volunteers and patients. Invariant metabolic parameters have been defined to characterize the normal metabolic response to the protocol. Deviations from normality can be directly interpreted in terms of specific pathologies in some favorable cases. In most cases, P-31 MRS provides valuable information which has to be processed in conjunction with traditional invasive biochemical, electrophysiological and histoenzymological tests. For malignant and exercise hyperthermias, P-31 MRS constitutes a diagnostic tool with 100p.cent sensitivity, as compared to contracture tests on muscle biopsies. P-31 MRS has proved particularly useful in the therapeutic follow-up of palliative therapies (coenzyme Q treatment of mitochondriopathies) and in family investigations. It is now an accepted diagnostic tool in the array of tests which are used to characterize muscle disorders in clinical routine. As a research tool, it will keep bringing new information on the physiopathology of muscle diseases in animal models and in humans and should play a role in the metabolic characterization of gene therapy.

The metabolic exploration of skeletal muscle and brain by magnetic resonance spectroscopy (MRS) provides the basis of the main clinical applications of in vivo MRS on humans. Also, high resolution MRS is used in vitro to identify and assay the metabolites contained in physiological fluids (blood, urine, CSF). In these applications, MRS has became and will keep developing as the investigative tool of choice to perform non-invasively "live biochemistry" experiments on organs and tissues.