Runner’s knee—or patellofemoral pain syndrome—is a very common ailment among runners. The condition is characterized by pain underneath, slightly above, or below the kneecap. In many cases, the pain becomes more intense when the affected person runs or walks up or down an incline (e.g., hills or stairs). In some cases, the condition presents with an audible popping sound or local swelling. Often, the pain develops in response to a large increase in mileage. Other factors include improper running form and insufficient core strength. Additionally, mobility and strength imbalance issues in the hips and low back may contribute to the development of runner’s knee. However, many athletes are unaware that such imbalances exist until the pain occurs. Running through the pain is not recommended, as it tends to worsen. Instead, those affected by this problem should cease participating in the activity that caused the pain. They should then consult with a physical therapist who specializes in the treatment of sports injuries. The best approach to treating runner’s knee involves identifying and correcting the underlying issue (for example, pinpointing the exact area of tension and tightness in the hips, legs, low back, and abdomen and restoring mobility). Gait training to improve running mechanics can also aid in pain relief.