As a runner, you should pay attention to how your feet hit the ground. If your heel hits first, you are a heel striker. If your foot rolls over to the balls of your feet or forefoot before it hits, you are a midfoot or forefoot striker. Heel striking places an unnecessary load and excessive pressure on your knees, hips, and lower back. It also increases the risk of developing an IT band injury due to the braking force on your knees with each step.
Heel striking often occurs when you run with a slower running cadence which makes your strides longer and increases the impact on your legs. This increased impact can contribute to overuse injuries.
A forefoot or midfoot strike can help to increase your running economy and improve your efficiency as well as reducing the amount of impact you are putting on your body. However, it can take time to learn how to run with a forefoot or midfoot strike. In addition, switching from a heel strike to a forefoot or midfoot strike may lead to calf and Achilles problems.
Ultimately, you should focus on other aspects of your running form than your footstrike. For most runners, a mild toe or heel strike is acceptable. It is more important to run efficiently and keep up your training than it is to try to alter your footstrike. However, if you do want to change your footstrike, be sure to wear shoes with a wide toe box that allows your toes to splay naturally.