One of the challenges in maintaining focus during intense training and physical exercise is mental fatigue‎.‎ Whereas most athletes worry about and take corrective action to ward against muscle fatigue‎,‎ mental fatigue must be combated as well‎.‎ This mental fatigue is commonly referred to as central fatigue because of the involvement of the central nervous system‎.‎ While central fatigue does not affect muscles‎,‎ it can reduce the capacity to perform optimally‎.‎ There is a correlation between the amino acid tryptophan in the brain and the degree of mental fatigue‎.‎ Upon entry into the brain‎,‎ tryptophan has the ability to ‎"‎calm‎"‎ the central nervous system‎,‎ causing sleep and drowsiness‎.‎ Normally‎,‎ there are sufficient amounts of branched‎-chain amino acids ‎(‎BCAAs‎)‎ circulating in the bloodstream to control the entry of tryptophan into the brain‎.‎ During long‎-term and sustained exercise‎,‎ however‎,‎ muscles use large amounts of amino acids as a source for energy‎.‎ The body prefers to use BCAAs for energy‎,‎ since they readily replace glucose in the energy production pathways‎.‎ As muscles begin to use BCAAs‎,‎ the amounts of these amino acids drop‎,‎ which allows tryptophan to enter the brain‎,‎ inducing fatigue and tiredness‎.‎ Research shows that supplementation with BCAAs can reduce central fatigue by tightly regulating the influx of tryptophan to the brain‎.‎ BCAAs include leucine‎,‎ isoleucine and valine‎.‎ These amino acids are needed for the maintenance of muscle tissue during physical stress and intense exercise‎.‎ BCAAs function as anabolic agents and induce sparing‎,‎ which helps the body not to burn muscle‎.‎ Nutrient needs often increase faster than calorie needs in athletes‎.‎ Ultimate nutrition is committed to providing athletes with the best products to fulfill exactly those needs‎.‎ Ultimate nutrition‎'‎s 100% crystalline BCAA 12‎,‎000 powder is one product designed to increase endurance‎,‎ lengthen the time to fatigue and improve performance‎.‎