Hi,
Is it important to do a warm-up before exercising? I was told that it is important to get more oxygen before we start exercising. If this is true, can we use breathing techniques to get more oxygen instead of a warm-up?

Warming up before working out is very important. Stretching before running, weight training or team sports will help prevent strained muscles. Stretching only takes a few minutes but torn muscles can take months to heal so prevention is the best thing.

^ exactly u SHOULD warm up before you exercise. Ill tell u the example my pe teacher told us last year... its like putting a rubber band in the freezar and taking it out and just streaching it reall fast. It'll tear. If you do it slowly and warm it up it won't tear as easly...
other word that's your musclues. They need to be warmed up and scretched both before and after exerssising.