The biochemical compounds between the cytosol and the mitochondria of skeletal muscle for the complete oxidation of carbohydrates. Note that, as noted, the TCA cycle is not complete for all substrates and products. The ATP yield of carbohydrate oxidation is also higher for substrate glycogen than for glucose. For skeletal muscle, there are 37 ATP molecules made from glycogen-derived glucose-6-phosphate, provided the presence of the glycerol-3-phosphate shuttle. Palmitate is the main form of fatty acid, which is catabolized in skeletal muscles at rest and during muscle contraction. Palmitate is a 16-carbon fatty acid, and if it is found in the cytosol of skeletal muscle, it must be activated by adding coenzyme A before it is transported to the mitochondria (4). This reaction is irreversible because the energy transition is so important. All fatty acids containing 15 or more carbons require activation for transport to mitochondria Cellular respiration plays a key role in restoring muscles after exercise, converting excess pyruvate to ATP, and regenerating reserves of ATP, phosphocreatine, and glycogen in muscle, which are needed for faster contractions. In aerobic respiration, pyruvate produced by glycolysis in the mitochondria is converted into additional ATP molecules during the Krebs cycle.
With a lack of oxygen, pyruvate cannot enter the Krebs cycle and accumulates in the muscle fiber. Pyruvate is continuously transformed into lactic acid. The accumulation of pyruvata also increases the production of lactic acid. This buildup of lactic acid in muscle tissue lowers the pH, makes it more acidic, and creates the tingling sensation in the muscles during training. This further inhibits anaerobic breathing and leads to fatigue. It is important to understand the research methodology of SRM 31P, as it has become the primary method of studying the phosphagenic system during and during exercise recovery since its introduction in the 1980s. Many research journals have also expressed specific intentions to invite and publish more research based on the MRS 31P methodology. Research with 31P MRS requires the use of a magnet with a large bore, in which there is a peripheral coil electronically regulated to the frequency of the atomic signal of the atom of interest. For example, most atoms with a negative number of electrons, when placed in a magnetic field, are forced to change orientation when exposed to a brief burst of radiofrequency energy. Once the energy pulse is complete, the atoms release their specific energy frequency for the given magnetic field when they return to their steady state. This data acquisition takes place over several milliseconds, and the resulting data is called free induction decay (FID).
It is this signal that is collected in all forms of magnetic resonance imaging and spectroscopy. For spectroscopy, fid is processed mathematically by a method known as the Fourier transform, which essentially converts data from numbers expressed over time into numbers expressed relative to the frequency of data change. This processing creates a spectrum in which curves or peaks represent the relative frequency of certain frequencies of change (Figure 7). At 31P SRM, the larger the area under these curves, the higher the concentration of the phosphorus-containing metabolite they represent. Muscle contraction and therefore all exercise depends on the breakdown of adenosine triphosphate (ATP) and the associated release of free energy (1). This free release of energy is related to the energy needs of cellular work, of which muscle contraction is only one example If the training lasts more than a few seconds, the energy for atp regeneration is increasingly obtained from blood sugar and muscle glycogen stores . This almost immediate activation of carbohydrate oxidation after the onset of exercise  is caused by the production of AMP, the increase in intramuscular free calcium and inorganic phosphate (both increase the rate of reaction to phosphorylase, since calcium is a phosphorylate activator and inorganic phosphate is a substrate) and the almost spontaneous increase in the absorption of blood sugar into the muscle, caused by muscle contraction. The increased rate of glucose-6-phosphate (G6P) production by glycogenolysis and the increased glucose absorption provide a fast fuel source for a sequence of 8 additional reactions that break down G6P into pyruvate.
This sequence of reactions or the signaling pathway is called glycolysis (Figure 8). Aerobic respiration requires even more chemical reactions to produce ATP than any of the two systems mentioned above. It`s the slowest of the three systems, but it can deliver ATP for several hours or more while fuel supplies last. Many activities have a strong dependence on the phosphagenic system. Success in team sports, weightlifting, field events (p.B shot put and discus, show jumping), swimming, tennis and so on. All require a short-term singular or a limited number of repeated intense muscle contractions. It has long been theorized that creatine phosphate is solely responsible for ATP recovery during the first 10 to 15 seconds of exercise . Additional support for the theory of an almost unique dependence on creatine phosphate during intensive training resulted from the fact that creatine phosphate is stored in the cytosol in the immediate vicinity of places of energy consumption. Hydrolysis of phosphocreatine does not depend on oxygen availability or requires the completion of several metabolic reactions before energy is released to drive ATP regeneration. However, as discussed in the section on glycolysis, a growing body of research has shown that glycolysis is quickly activated during intense exercise and rarely has an almost complete dependence on the phosphagen system .
Nevertheless, the importance of the phosphagenic system lies in the extremely fast rates at which it can regenerate ATP, as shown in Figure 5. Although there is controversy among physiologists about the measurements of the components of energy systems, namely the power, capacity and relative contribution of each system during exercise, it has been generally accepted that with a charging time of up to 5 to 6 seconds, the phosphagenic energy system dominates in terms of the rate and proportion of total ATP regeneration [21-23]. . . .