A carved six-pack might look nice, but it's not something that most runners value. However, core strength is incredibly important. You don't need rock hard abs showing through your shirt, but you should work on strengthening your core if you want to run more efficiently. Here are just five reasons why all runners should commit to their core. 1. You'll Reduce Your Risk of Injury When your core is nice and strong, your torso is kept stable as you run.