Concussion, a peculiar type of mild traumatic brain injury (mTBI), is an injury frequently encountered in various contact and noncontact sports, such as boxing, martial arts, American football, rugby, soccer, ice hockey, horse riding, and alpine skiing. Concussion occurs anytime external forces of specific intensities provoke acceleration–deceleration of the brain, and it is characterized by the rapid onset of short-lived impairment of neurologic functions, spontaneously resolving within weeks, persisting for longer times only in a small percentage of cases. A wide range of molecular alterations, including mitochondrial dysfunction, energy deficit, and gene and protein expression changes, is triggered by concussion and lasts longer than clinical symptoms. In recent years, concussion has become a primary issue of discussion among sports medicine professionals, athletes, media, and sports sponsors in relation to athletes’ return to play, after a concussion. Continued improvement in prevention and management of concussed athletes requires extensive research from different disciplines. Research work needs to focus on both prevention and management. Researchers and clinicians’ efforts should be dedicated to a better understanding of the molecular changes occurring in the post-concussed brain and to clearly define healing after concussion for a safe return of athletes to play. It is essential for sports medicine professionals to stay informed about the advances in understanding concussions and how to rehabilitate each single player who sustained a concussion.