In this case, the Commission again examined the circumstances required to establish a medically distinguishable injury pursuant to Rakestraw. Pain alone is not conclusive evidence of a medically distinguishable condition. Further, an employee sustains a new date of injury when it is shown that the employee has sustained a permanent worsening of the disability due to the subsequent injury or work activity. Where evidence is produced that pain or symptoms are equally attributable to the progression of a pre-existing injury or work-related injury, then the plaintiff has not established a medically distinguishable injury. In other words, an employee sustains a new compensable personal injury when the employee proves a permanent decrease in the ability to perform work within the employee’s qualifications and training. This case further clarifies the Appellate Commission’s holding in Hale.