The breathing rate while walking depends on the speed of walking if a person walk slowly - slowly then the breathing rate is normal but if a person walks fast then his breathing rate is increasing according to there speed. when a healthy man in rest he can breath minimum 20 times in a minute but if he is performing some activity or walking fast then it increase to 40 or 50. it also depends on  weight of the body if the size of the body is big and fat then it should be minimum 50 - 70 times breadth but if the size of the body is thin and weight is less it should be normal 30 - 40 times in a minute so the breathing rate is dependent on so many reasons according to a research average breathing rate while walking of a body is 23 - 40 breadths in a minute.
 The breathing rate while walking of a body is 23 - 40 breadths in a minute.