Running may seem like a easy activity to take up to increase fitness. However, it is not quite as straightforward as it may appear with some research finding that up to 70% of runners get an overuse injury each year. Depending upon how bad that overuse injury is and how it is treated, many runners just give up and don't continue to run. The the things that cause running overuse injury are multifactorial but they are associated with issues such as carrying out too much running too quickly before allowing the body to adapt to the increased degrees of running. Inadequate running shoes with design features that do not match up those of the runners requirements will also be a factor. Issues with foot biomechanics and the running technique could also be problems at increasing the probability for an overuse injury.
A good example of a running injury is anterior compartment syndrome. There is fibrous fascia surrounding muscles which support the muscles in position. If that fascia is tight, when we exercise the muscle tries to expand but that tight fascia inhibits it. That pressure inside the fascia compartment may be painful. In anterior compartment syndrome, this affects the muscles in the front of the lower leg. The most frequent cause of this problem is what is known as overstriding. In this the runner is striking the ground with their front leg too far in ahead of the body. To lower the foot to the ground, the anterior leg muscles need to work harder. As they continue to work harder, the muscles expand and if the fascia isn't going to allow it, then this will become painful. It will only hurt when running and won't be painful when not running. The best way to deal with this problem to use techniques for the runner to shorten their stride length so that the front foot does not make contact with the ground too far in front of the body when running.