When i'm exercising (playing tennis, walking), i slightly pull my calf muscles, on both legs. do you have any suggestions that i can do to help stretch these muscles?

When : When you say "slightly pull, " i'm making the assumption that there is no injury, it's both legs, and it's limited to when you exercise or walk, and at rest you're fine. Given those parameters, the first thing i would recommend is a stretching program. I've included a link from the mayo clinic on the best way to stretch your calf muscles. If you look on line, you'll find many other ways, but the mayo clinic illustration is by far the most effective. I would do these stretches 5 times a day to start. After a few days, you'll find there is less pulling in your calves as the muscle is stretched. At that point, you can reduce the stretches to once a day, and if you still don't feel pulling, even a few times a week. In time, though, as your calf muscles tighten up again, you'll start feeling the pulling, which is your signal to increase the frequency of the stretching. This will be a lifelong exercise for you, and it should relieve you of the pulling you feel. It's also a good idea to spend a few minutes stretching before and after any tennis or other exercise. If this doesn't help you, i would recommend you see a podiatrist, as an orthotic may be needed. All this is assuming the parameters i noted above. If there was an injury or this involves one leg, or you have pain even at rest, there is probably something else going on. Good luck! happy stretching!