28  MARCH 2014 INTERNATIONAL JOURNAL OF ATHLETIC THERAPY & TRAINING © 2014 Human Kinetics - IJATT 19(2), pp. 28-32 http://dx.doi.org/10.1123/ijatt.2014-0007 Exercise provides systemic benefts that may facilitate recovery of normal function following concussion. Some studies have demonstrated thera- peutic benefts from exercise following concussion. Postconcussion exercise needs to be struc- tured and carefully monitored. Key Points Key Points THERAPEUTIC EXERCISE Exercise and Concussion, Part 2: Exercise as a Therapeutic Intervention Karl Kozlowski, PhD, ATC • Canisius College The use of exercise as a treatment for concussion is not clearly understood. Leddy et al. 1 have suggested that an individualized, progressive exercise program may have wide application for patients with mild to severe traumatic brain injury. A growing body of evidence suggests that exercise may enhance cerebrovascular auto- regulation and central physiologic regulation. 1 Benefits of exercise that may be relevant to con- cussion recovery include an upregulation of brain- derived neurotrophic factor, 2 improved cog- nitive performance, 3,4 increased cardiovascu- lar fitness, 5 improved control of brain perfu- sion, 6 reduced fatigue, 7 reduced stress, 8 reduced anxiety, 9 improved mood, 10 and increased self-esteem. 11 Both local and systemic changes that occur following concussion may be influ- enced by exercise. The purpose of this Part 2 report is to discuss the potential therapeutic benefit that exercise may provide following concussion. Exercise Effects on the Autonomic Nervous System Brain injury has been shown to alter auto- nomic nervous system (ANS) control of heart rate variability (HRV) and blood pressure (BP) regulation. 12,13 There is evidence of greater parasympathetic activity in noninjured ath- letes, 14 and the extent corresponds to the level of conditioning. 15 Aerobic exercise has the potential to alter autonomic equilibrium toward increased vagal tone. 14 This shift to parasympathetic dominance is associated with a decrease in HR and a decrease in sympathetic drive at submaximal intensity. 14 Following myocardial infarction (MI), patients typically exhibit increased sympa- thetic activity, and decreased parasympa- thetic activity, similar to that which is seen following brain injury. 14,16 This autonomic dysfunction was altered by 6 weeks of exer- cise in a post-MI patient population. 16 A study of 30 patients enrolled in an 8-week, 5 days per week training program, which was followed by home exercise that was performed 2–3 days per week for one year, demonstrated significant beneficial changes in autonomic function. 6 Immediately after initiation of exercise, and one year post-MI, there was increased HRV, a decreased ratio