BETA-ALANINE -been shown to increase muscle carnosine concentrations by up to 58 percent in just four weeks, and 80 percent in 10 weeks. Potent antioxidant, this peptide is one of your muscles' first lines of defense against the buildup of hydrogen ions (H+) during high-intensity exercise. This rise in H+ dramatically lowers the pH within muscle cells, negatively effecting enzyme function and muscle excitation-contraction coupling events that support continued, high-intensity output. Put simply, a drop in muscle pH is a major contributor to muscle fatigue. 

beta-alanine seems most effective for supporting exercise lasting longer than 60 seconds, not in shorter duration bouts of exercise, where ATP-phosphocreatine energy system is in higher demand.