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Scanning Sports Medicine

Latest Clinical Research Published by ACSM

Jaworski, Carrie A. MD, FACSM, FAAFP

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doi: 10.1249/JSR.0000000000000213
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Exertion Testing in Youth with Mild Traumatic Brain Injury/Concussion

It is well recognized that the decision regarding return to activity (RTA) after concussion is one of the most difficult and controversial areas in concussion management. Young patients, in particular, are treated on the more conservative side, with clinicians typically waiting for all symptoms to clear for a designated period of time before allowing RTA. In the more complicated cases of young patients with comorbid conditions or postconcussive syndrome (PCS), this can lead to months of inactivity and result in more confusion on what is appropriate in terms of activity. One dilemma often encountered by clinicians is determining whether PCS symptoms are the result of concussion pathophysiology or are caused by factors secondary to the concussion such as depression. It has been proposed that if acute PCS symptoms are exacerbated by exertion and relieved by rest, then the individual has not had sufficient time to heal from the pathophysiology associated with concussion. On the other hand, if the exacerbation of symptoms after minimal activity is not improved by rest, it may represent psychological symptoms due to frustration, prolonged inactivity, and/or the delayed return to one’s usual routine.

In the November 2015 issue of Medicine & Science in Sports & Exercise®, authors hypothesized that controlled exertion testing in youth with persisting symptoms after a concussion would improve self-reported symptoms, both the severity and the number of reported symptoms, in most youth and would help to distinguish which subjects are ready to increase his or her activity level (1).

This study employed a cross-sectional design with youth participating in testing on one occasion. Each participant performed exertion testing on a cycle ergometer and completed a Post-Concussion Symptom Scale (PCSS) at baseline, 5 min, 30 min, and 24 h postexertion. Additionally, a modified PCSS was administered at 2-min intervals during exertion. Participants of the study had a mean symptom duration of 6.3 + 6.9 months.

The study evaluated 54 subjects between the ages of 7 and 18 yr who had previously sustained a confirmed concussion and who were experiencing PCS. Thirty-seven of the 54 participants completed the full evaluation, which included the 24-h postexertion online survey. Testing was done at a follow-up clinic visit where the participants were tested using the McMaster All-Out Progressive Continuous Cycling test. The goal was to examine how youth with PCS were affected by exertion and to determine whether standardized testing could help to contribute to decision making as part of an RTA protocol.

The results of the study demonstrated that 63% of participants had symptoms during exertion testing. A participant’s number and severity of symptoms at baseline significantly affected the perception of exertion at 50% peak mechanical power. During acute assessment of symptoms at 30 min postexertion, headache, nausea, and dizziness did not change. However, both the number and the severity of symptoms significantly improved over 24 h with 56.8% of youth reporting improvements.

Bottom Line: Controlled exertion testing may play an important role in the evaluation of symptoms and readiness to RTA in young patients with persistent concussion symptoms.

The Role of Exercise-Induced Cardiovascular Adaptation in Brain Health

The unprecedented aging of our population in recent decades has resulted in equally unprecedented increases in age-related conditions such as Alzheimer’s disease (AD). It is estimated that by 2050, the rate of AD in the population will triple if no effective prevention or treatments are developed. While there is currently no cure for AD, studies reveal that a percentage of AD cases may be related to modifiable risk factors such as physical inactivity and cardiovascular risk factors. In the October 2015 edition of Exercise and Sport Sciences Reviews, authors took a critical look at the effects of cardiovascular exercise on brain health (2).

Compelling evidence suggests that habitual aerobic exercise attenuates age-related cognitive decline which is linked with the preservations of the brain structure. The mechanisms related to such exercise-related improvements in the brain structure and function are not well understood and seem to be multifactorial. One possible mechanism is that cardiovascular adaptations to endurance exercise ameliorate brain health through attenuation of age-related arterial stiffness and/or endothelial dysfunction. This results in a favorable, systemic, and cerebral hemodynamic environment where the brain may benefit from the improvements in arterial pressure regulation, blood flow homeostasis, and metabolic waste clearance. In addition, exercise-related reductions in other cardiovascular risk factors may contribute to the reduced risk of cognitive impairment and dementia.

Another important consideration is whether a “dose-response” relation exists between the intensity of exercise and brain health. It is currently unknown whether more exercise leads to better brain health, if such benefits plateau or even have deleterious effects, beyond a certain “dose” of exercise. The existing evidence suggests the presence of a hormetic relation between the intensity of exercise and the brain structure and function, such that strenuous exercise performed without an adequate recovery may be deleterious to brain health. This is evidenced by gray matter atrophy and white matter lesions seen in such populations.

To gain further insights into these questions, the authors investigated a group of masters athletes (MA) who have participated in long-term or life-long endurance exercise training. Investigating two independent samples of MA, they found higher cognitive performance in memory and executive function compared with their sedentary peers. Another study of older MA also exhibited better cognitive performance in global intelligence and executive function when compared with age-, sex-, and educational level-matched sedentary older adults. In addition, a systematic review of prospective studies demonstrated that efficacy of exercise training on cognitive function increased when performed longer than 6 months with the exercise sessions lasting 30 to 45 min. The favorable effect of exercise training was greater when performed earlier than later in life and when combined with strength exercise compared with aerobic exercise alone.

Bottom Line: Improvement of cardiovascular health, particularly via regular aerobic exercise, may prevent or slow age-related cognitive decline and delay the onset of dementia when performed at moderate intensities with allowance for adequate recovery between training sessions.

References

1. DeMatteo C, Volterman KA, Breithaupt PG, et al. Exertion testing in youth with mild traumatic brain injury/concussion. Med. Sci. Sports Exerc. 2015; 47: 2283–90.
2. Tarumi T, Zhang R. The role of exercise-induced cardiovascular adaptation in brain health. Exerc. Sport Sci Rev. 2015; 43: 181–9.
Copyright © 2015 by the American College of Sports Medicine.