In the cells, ATP (3 phosphates) is converted to ADP (2 phosphates) with the release of energy for work. ADP passes into the mitochondria where ATP is remade by oxidative phosphorylation. With excess phosphate ADP cannot be recycled adequately to ATP. There will be a build up of ADP that will create a metabolism disaster: some ADP is inevitably shunted into AMP (1 phosphate) which cannot be recycled and is lost in the urine. If ATP levels drop as a result of leakage of AMP, less high-energy is to be available. Especially the muscle in an effort to make small amount of ATP directly from glucose by converting it into lactic acid, a quickly lactic acid build up will cause muscle pain, heaviness, aching, burning and soreness.