Running can help strengthen muscles, particularly your legs or if you’re new to running. Over time, your muscles will adapt to stimulus, which means it will have less of an effect as time goes by.
How you run will exert your muscles differently. Doing sprints will exert your body different in a different way than if you were to run a long distance like a marathon. A sprinter would typically have higher Type 2 muscle fibre ratio than long distance runner who would typically have a higher type 1 muscle fibre ratio. This ratio plays a part in their function but also in their appearance.
If your main aim is to build muscle, focus on lifting weights or including resistance workouts. Pairing strength training with sprints would be more optimal than running long distances.
For more advice on this topic, check out our running and strength training workout guide.