Strength training has been shown to not only improve performance, but also help runners avoid the risk of developing overuse injuries. One of the primary ways strength training helps prevent these injuries is by correcting muscle imbalances. Muscle imbalances are common among runners as we learn to rely on specific muscles to generate the same movement over and over again. Over time, these muscles get stronger and can start to compensate for less active muscles that may be working synergistically with them, resulting in overuse and strain injuries.
A great example are your glutes, more specifically your gluteus medius, which helps in hip abduction (lateral movement away from the midline). As runners, our primary plane of movement is in the sagittal plane (forward and back movement) versus the coronal (toward or away from midline) and transverse planes (twisting and rotating). In this plane, it is easy for the quadriceps and calf muscles to take on the majority of the workload, leaving the glutes, especially the gluteus medius, effectively "off the hook" from working as hard. As training continues, a muscle imbalance forms between the muscles that are more active (quadriceps and calf muscles) and the muscles that are less active (glutes). This imbalance gets more significant as training intensity increases in the form of volume and/or intensity. Unless exercises are performed to help correct this imbalance, the risk of injury due to overuse and strain of the more active muscles continues to increase.
Strength training is a fantastic way to target specific imbalances such as weak glutes so that some of the workload of running can be taken off the more active muscles, the quads and calfs in the previous example. Some of my favorite exercises to help strengthen your glutes include single and double legged squats, lateral leg raises, hip bridges, and donkey kicks.