For a runner, especially one who runs any distance longer than a half-marathon, the long run is arguably the most important workout of the week. It's this run that creates stamina and the ability to endure. While it's true that running is as much mental as it's physical, few things will halt progress as quickly as a physical injury. It only takes a few weeks to lose stamina, and many of these injuries will require you to abstain from running completely during the recovery period. Here are 3 of the most prevalent stamina-sucking injuries, as well as their common causes and length of recovery. #1 Achilles Tendinitis The Achilles is the large tendon connecting your heel to the two major muscles of the lower leg. Achilles tendinitis occurs when the tendon becomes inflamed and painful and is usually caused by a sudden increase in your training load or weak or tight calf muscle. The length of recovery is around 2-6 months. #2 Pulled Muscle This one sounds like “No big deal” and that's what makes it so dangerous. A pulled muscle is different than a strained muscle. A strain is mildly uncomfortable, even a little painful but with caution you can continue running and the feeling will eventually subside. A pull is much more severe and there's no mistaking it. It's not the type of pain that can be trained through. A true pull is really a torn muscle and is accompanied by swelling and bruising and a whole lot of hurt. Trust me, you won't want to try and run on it. Common pulls for runners involve the hamstrings, a group of three muscles making up the back of the thigh. The length of recovery for a pulled muscle can be 6 months or greater. #3 Stress fractures The tibia, or shinbone, is the most common area for a runner to develop a stress fracture. Stress fractures are caused by a mild trauma repeated many times, rather than a single large impact, like other types of fractures. The danger with stress fractures is that they're often misdiagnosed as something less severe, such as shin splints (which can be trained through). The runner then attempts to continue training, and the injury worsens. The length of recovery for a stress fracture depends on its severity, but usually requires an orthopedic boot to be worn for a minimum of several weeks, then continued rest until being released to run again. These are three of the more commonly seen running injuries that require significant recovery time and have a negative impact on training. Remember that running related injuries almost always take a long time to heal simply because the legs are used every day and so it's difficult to give them complete rest. If you suspect you've a running related injury, go see a podiatrist or sports medicine therapist who's also a runner, or is at least sympathetic toward runners. Then be sure to follow their advice.