It's caused by a buildup of lactic acid, but is really a signal your muscle is using to let your brain know it's running out of energy. Eventually, you'll build up enough endurance that your muscles won't freak out so soon.
A deficiency of <span>thiamine causes beriberi. If you need more help use this link </span>http://www.flashcardmachine.com/nursing-nutrition-chapter78.html
