A group of Canadian and American researchers have been examining children with concussions, and their impact that exercise has on their recovery after injury. They publish their findings in the Journal of the American Medical Association, in an article on “Early Physical Activity and Persistent and Postconcussive Symptoms in Children and Adolescents.”

Rest has long been considered the cornerstone of concussion management, and pediatric guidelines universally recommend an initial period of cognitive and physical rest following a concussion. Cognitive rest recommendations include modification of school attendance and mental activities. Physical rest recommendations advocate avoidance of physical activity until postconcussive symptoms have resolved, endorsing gradual resumption of activities only if symptoms are not exacerbated…. [But] recent literature suggests that protracted rest may hamper concussion recovery, leading to secondary symptoms of fatigue, depression, anxiety, and physiological deconditioning. Increasing evidence suggests the introduction of controlled, light aerobic physical activity following pediatric concussion may be safe while promoting recovery by enhancing physical, psychological, and academic outcomes….

The objective of this study was to examine the association between participation in physical activity within 7 days postinjury and the occurrence of persistent postconcussive symptoms (PPCS) following concussion in children and adolescents. It was hypothesized that early participation in physical activity would be associated with lower PPCS rates compared with no physical activity.

The study found 3063 participants between 5 and 18 who had concussions, followed their recovery as their either rested, did “light aerobic exercise (eg, walking, swimming, or stationary cycling), sport-specific exercise (eg, running drills in soccer or skating drills in ice hockey), noncontact training drills (eg, complex passing drills), full-contact practice (eg, normal training activities), and return to competition (eg, normal game play).” About 70% of the participants engaged in “light aerobic exercise” within a week of their concussions.

The researchers found that

resumption of physical activity within 7 days postconcussion was associated with a lower risk of PPCS as compared with no physical activity. This finding was consistent across analytic approaches and intensity of exercise….

Available evidence suggests that gradual resumption of physical activity should begin as soon as tolerated following an acute concussion, with the exception of activities likely to increase the risk of re-injury. Rest exceeding 3 days postinjury was similarly or less effective than treatment regimens allowing for earlier participation in physical activity following a concussion; if prolonged, rest may predispose to secondary symptoms of fatigue, reactive depression, physiological deconditioning, and delayed recovery. Also in symptomatic adolescents, pilot evidence suggests that gradual resumption of aerobic physical activities results in superior symptom recovery from concussion compared with complete rest.

What accounts for these results? Why is exercising (at least aerobic, non-contact exercise) better for recovery than doing nothing at all?

A proposed mechanism by which exercise may improve recovery is through the promotion of neuroplasticity mechanisms and from possible effects on cardioregulatory mechanisms, possibly leading to improved cerebral blood flow. This is of particular importance in pediatric concussion, since autoregulatory dysfunction and abnormal cerebral blood flow regulation have been associated with PPCS in school-aged children. Controlled aerobic exercise may improve recovery by restoring normal cerebral blood flow regulation with the rate of symptom improvement relating directly to the exercise intensity achieved. Conversely, physical inactivity may predispose patients to PPCS through an activity restriction cascade model; it has been theorized that the psychological consequences of removal from life-validating activities, combined with physical deconditioning, may contribute to the development of PPCS after mild traumatic brain injury in youth.

In Rest, I talk about how active rest offers better, more complete recovery from work than passive forms. The Canadian concussion study offers another example, in a rather different context, of the superiority of active over passive rest.