Notes+on+Energy+Systems

The cell's ability to generate phosphocreatine from excess [|ATP] during rest, as well as its use of phosphocreatine for quick regeneration of [|ATP] during intense activity, provides a spatial and temporal buffer of [|ATP] concentration. In other words, phosphocreatine acts as high-energy reserve in a coupled reaction; the energy given off from donating the phosphate group is used to regenerate the other compound - in this case, [|ATP]. Phosphocreatine plays a particularly important role in tissues that have high, fluctuating energy demands such as muscle and brain. Contrary to popular belief, this increased concentration of lactate does not directly cause [|acidosis], nor is it responsible for [|delayed onset muscle soreness] .[|[1]] This is because lactate itself is not capable of releasing a [|proton] , and secondly, the acidic form of lactate, lactic acid, cannot be formed under normal circumstances in human tissues.[//[|citation needed]//] Analysis of the glycolytic pathway in humans indicates that there are not enough hydrogen ions present in the glycolytic intermediates to produce lactic or any other acid. The [|acidosis] that is associated with increases in lactate concentration during heavy exercise arises from a separate reaction. When [|ATP] is [|hydrolysed], a hydrogen ion is released. ATP-derived hydrogen ions are primarily responsible for the decrease in pH. During intense exercise, [|aerobic metabolism] cannot produce ATP quickly enough to supply the demands of the muscle. As a result, [|anaerobic metabolism] becomes the dominant energy producing pathway as it can form ATP at high rates. Due to the large amounts of ATP being produced and hydrolysed in a short period of time, the [|buffering] systems of the tissues are overcome, causing pH to fall and creating a state of acidosis, a natural process which facilitates the easier dissociation of [|Oxyhaemoglobin] and allows easier transfer of oxygen from the blood[|[2]]. This may be one factor, among many, that contributes to the acute muscular discomfort experienced shortly after intense exercise.[//[|citation needed]//]