With some sports, it is difficult to drink during the exercises. Cycling and running are the perfect examples of such sports. A number of bag brands acknowledged this problem and have designed several backpacks. The most know brand is Camelbak. This brand designs lightweight backpacks that are comfortable to carry, and most bags have a compartment with a water reservoir. A drinking tube runs from the shoulder straps to the front, so you can easily take a sip when being outdoor.