Energy Metabolism In Human Muscle Research Articles

Regional Differences in Muscle Energy Metabolism in Human Muscle by 31P-Chemical Shift Imaging.

Previous studies have reported significant region-dependent differences in the fiber-type composition of human skeletal muscle. It is therefore hypothesized that there is a difference between the deep and superficial parts of muscle energy metabolism during exercise. We hypothesized that the inorganic phosphate (Pi)/phosphocreatine (PCr) ratio of the superficial parts would be higher, compared with the deep parts, as the work rate increases, because the muscle fiber-type composition of the fast-type may be greater in the superficial parts compared with the deep parts. This study used two-dimensional 31Phosphorus Chemical Shift Imaging (31P-CSI) to detect differences between the deep and superficial parts of the human leg muscles during dynamic knee extension exercise. Six healthy men participated in this study (age 27±1 year, height 169.4±4.1 cm, weight 65.9±8.4 kg). The experiments were carried out with a 1.5-T superconducting magnet with a 5-in. diameter circular surface coil. The subjects performed dynamic one-legged knee extension exercise in the prone position, with the transmit-receive coil placed under the right quadriceps muscles in the magnet. The subjects pulled down an elastic rubber band attached to the ankle at a frequency of 0.25, 0.5 and 1 Hz for 320 s each. The intracellular pH (pHi) was calculated from the median chemical shift of the Pi peak relative to PCr. No significant difference in Pi/PCr was observed between the deep and the superficial parts of the quadriceps muscles at rest. The Pi/PCr of the superficial parts was not significantly increased with increasing work rate. Compared with the superficial areas, the Pi/PCr of the deep parts was significantly higher (p<0.05) at 1 Hz. The pHi showed no significant difference between the two parts. These results suggest that muscle oxidative metabolism is different between deep and superficial parts of quadriceps muscles during dynamic exercise.

On the mechanism by which dietary nitrate improves human skeletal muscle function.

Inorganic nitrate is present at high levels in beetroot and celery, and in green leafy vegetables such as spinach and lettuce. Though long believed inert, nitrate can be reduced to nitrite in the human mouth and, further, under hypoxia and/or low pH, to nitric oxide. Dietary nitrate has thus been associated favorably with nitric-oxide-regulated processes including blood flow and energy metabolism. Indeed, the therapeutic potential of dietary nitrate in cardiovascular disease and metabolic syndrome—both aging-related medical disorders—has attracted considerable recent research interest. We and others have shown that dietary nitrate supplementation lowers the oxygen cost of human exercise, as less respiratory activity appears to be required for a set rate of skeletal muscle work. This striking observation predicts that nitrate benefits the energy metabolism of human muscle, increasing the efficiency of either mitochondrial ATP synthesis and/or of cellular ATP-consuming processes. In this mini-review, we evaluate experimental support for the dietary nitrate effects on muscle bioenergetics and we critically discuss the likelihood of nitric oxide as the molecular mediator of such effects.

The changes in the energy metabolism of human muscle induced by training

The biochemical effects of training programmes have been studied with a kinetic model of central metabolism, using enzyme activities and metabolite concentrations measured at rest and after 30 s maximum-intensity exercise, collected before and after long and short periods of training, which differed only by the duration of the rest intervals. After short periods of training the glycolytic flux at rest was three times higher than it had been before training, whereas during exercise the flux and energy consumption remained the same as before training. Long periods of training had less effect on the glycolytic flux at rest, but increased it in response to exercise, increasing the contribution of oxidative phosphorylation.

Effect of Chronic Alcohol Intake on Energy Metabolism in Human Muscle

We investigated the effect of alcohol on muscle energy metabolism by using 31P magnetic resonance spectroscopy in 12 chronic alcoholics [6 with neurological signs and symptoms (such as cerebellar ataxia or diplopia) and 6 without neurological signs or symptoms], compared with five healthy subjects who also received acute alcohol loading. Intracellular pH and phosphocreatine (PCr) index [PCr/ (PCr + Pi)] were measured during rest, exercise, and recovery in the left flexor digitorum superficialis muscle. In healthy subjects, acute alcohol loading did not influence the changes of muscle pH and PCr index. Alcoholics with neurological signs showed marked decreases in muscle intracellular pH and PCr index during exercise and a marked delay of pH recovery after exercise. There was no delay of PCr index recovery. Alcoholics without neurological signs showed slight decreases in intracellular pH and PCr index, but rapid recovery of both intracellular pH and PCr index was observed. Marked decrease and delayed recovery in pH, but rapid recovery of PCr index, indicate that the muscle of patients with neurological signs produced lactate during and after exercise to maintain the ATP level, which implies that anaerobic metabolism is favored over aerobic metabolism in these patients.

Effect of Chronic Alcohol Intake on Energy Metabolism in Human Muscle

Effect of Chronic Alcohol Intake on Energy Metabolism in Human Muscle

Effect of low glycogen on carbohydrate and energy metabolism in human muscle during exercise.

The effect of preexercise muscle glycogen content on the metabolic responses to exercise has been investigated. Seven men cycled at a work load calculated to elicit 75% of maximal oxygen uptake [211 +/- 17 (SE) W] on two occasions: 1) to fatigue (37.2 +/- 5.3 min) and 2) at the same work load and for the same duration as the first. Biopsies were obtained from the quadriceps femoris muscle before and after exercise. Before the first experiment, muscle glycogen was lowered by exercise and diet, and before the second experiment, muscle glycogen was elevated. In the low-glycogen condition (LG), muscle glycogen decreased from 182 +/- 15 at rest to 7 +/- 4 mmol glucosyl units/kg dry wt at fatigue, while in the high-glycogen condition (HG), glycogen decreased from 725 +/- 31 at rest to 353 +/- 53 mmol glucosyl units/kg dry wt at the end of exercise. Hexose monophosphates were not increased after LG exercise but increased approximately fivefold after HG exercise. Lactate increased more during HG exercise (LG = 16 +/- 5, HG = 61 +/- 7 mmol/kg dry wt; P less than or equal to 0.001), whereas IMP increased more during LG (LG = 2.8 +/- 0.6, HG = 0.9 +/- 0.2 mmol/kg dry wt; P less than or equal to 0.05). The increases in the sum of tricarboxylic acid cycle intermediates (TCAI; citrate+malate+fumarate) and acetylcarnitine (which is in equilibrium with acetyl CoA) were significantly greater during HG exercise (P less than or equal to 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Energy metabolism in human muscle.

Conference Abstract| April 01 1973 Energy Metabolism in Human Muscle Eric Hultman Eric Hultman 1Department of Clinical Chemistry, Beckomberga Sjukhus, 161 04 Bromma, Sweden Search for other works by this author on: This Site PubMed Google Scholar Clin Sci Mol Med (1973) 44 (4): 12P–13P. https://doi.org/10.1042/cs044012Pa Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation Eric Hultman; Energy Metabolism in Human Muscle. Clin Sci Mol Med 1 April 1973; 44 (4): 12P–13P. doi: https://doi.org/10.1042/cs044012Pa Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsClinical Science Search Advanced Search This content is only available as a PDF. © 1973 The Biochemical Society and the Medical Research Society1973 Article PDF first page preview Close Modal You do not currently have access to this content.

Exercise Physiology: Energy Metabolism of Human Muscle . J. Keul, E. Doll, and D. Keppler. Translated from the German edition (Munich, 1969) by J. S. Skinner. University Park Press, Baltimore, 1972. xii, 314 pp., illus. $22.50. Medicine and Sport, vol. 7.

Exercise Physiology: <i>Energy Metabolism of Human Muscle</i> . J. Keul, E. Doll, and D. Keppler. Translated from the German edition (Munich, 1969) by J. S. Skinner. University Park Press, Baltimore, 1972. xii, 314 pp., illus. $22.50. Medicine and Sport, vol. 7.

Developmental Process: Oogenesis . Proceedings of a symposium, Baltimore, Oct. 1970. John D. Biggers and Allen W. Schuetz, Eds. University Park Press, Baltimore, and Butterworths, London. 1972. xii, 544 pp., illus. $19.50.

Developmental Process: <i>Oogenesis</i> . Proceedings of a symposium, Baltimore, Oct. 1970. John D. Biggers and Allen W. Schuetz, Eds. University Park Press, Baltimore, and Butterworths, London. 1972. xii, 544 pp., illus. $19.50.

Exercise Physiology: Energy Metabolism of Human Muscle . J. Keul, E. Doll, and D. Keppler. Translated from the German edition (Munich, 1969) by J. S. Skinner. University Park Press, Baltimore, 1972. xii, 314 pp., illus. $22.50. Medicine and Sport, vol. 7.

Exercise Physiology: <i>Energy Metabolism of Human Muscle</i> . J. Keul, E. Doll, and D. Keppler. Translated from the German edition (Munich, 1969) by J. S. Skinner. University Park Press, Baltimore, 1972. xii, 314 pp., illus. $22.50. Medicine and Sport, vol. 7.

Energy Metabolism of Human Muscle.

Energy Metabolism of Human Muscle.