Latest Clinical Research Published by ACSM

Aerobic Exercise for Sports-related Concussion: A Systematic Review and Meta-analysis The return-to-play guidelines for sports-related concussion (SRC) continue to evolve. The First International Consensus Statement from Vienna in 2001 recommended “no activity and complete rest” until asymptomatic, while the Third International Consensus Statement from Zurich in 2008 recommended “complete physical and cognitive rest until symptoms resolve.” However, the most recent guidelines from Berlin (2016) state that there is “insufficient evidence” for complete rest and suggests a gradual resumption of physical activity starting 24 to 48 h after an SRC. This systematic review and meta-analysis from Quebec, published in the December 2020 issue of Medicine & Science in Sports & Exercise® (MSSE), critically analyzes the research that compares post-SRC protocols that include early resumption of physical activity to protocols that do not allow any physical activity until complete resolution of all SRC-related symptoms (1). Studies considered for inclusion were randomized controlled trials involving individuals who sustained an SRC and were randomized to an aerobic exercise group or a control group that did not exercise until complete symptom resolution. Adjunct interventions, such as cognitive activation, coordination, or balance exercises, were allowed in either group. Studies were categorized by the timing of the exercise intervention, either “acute stage” (less than 4 wk from the concussion) or “persistent symptom stage” (≥4 wk from the SRC). The intensity of the exercise (light, moderate, or vigorous) also was noted when possible. The primary outcome for the analysis was symptom intensity. Other outcomes were time-to-recovery, balance, cognitive capacity, and adverse events. Each study was assessed for risk of bias (RoB) using the 13 criterion of the Cochrane risk of bias tool, and categorized as low RoB, high RoB, or unclear RoB. Statistical heterogeneity also was calculated. The overall quality of the summarized evidence was assessed by the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach, which evaluates studies in five domains that may decrease the quality of the evidence: RoB, consistency of effect, imprecision, indirectness, and publication bias, and then gives an overall rating of high, moderate, low, and very low quality of evidence. A total of 1368 articles were screened, but only seven studies met the inclusion criteria and were included in the analysis. These studies included 326 participants all in the age range of 13 to 17 years. There were four studies that started aerobic exercise during the “acute stage” (<4 wk from SRC), and three studies started exercise during the “persistent symptom stage” (≥4 wk from SRC). The exercise intervention was 10 to 30 min of symptom-limited aerobic exercise once a day. Four studies indicated that the exercise was of “moderate” intensity, while three studies did not report intensity. Three studies were rated as high RoB and four had low RoB. The most common study weakness was a lack of a description of a cointervention (other than exercise) in six of the seven studies. Quantitative meta-analysis was only possible for symptom severity, which was measured on a postconcussive symptom scale in six studies. Forest plot and analysis of the 227 participants from these six studies showed a statistically significant improvement in symptom severity in the exercise group, but the effect size was small (standard mean difference [SMD] = 0.44). The GRADE assessment concluded that there was a low level of evidence that symptom-limited aerobic exercise programs after SRC are more effective in improving symptom severity than programs that do not start exercise until all symptoms completely resolve. The low level of evidence designation was because of poor generalizability (indirectness) and small effect size. When the analysis was limited to studies which started exercise in the “acute stage” after SRC, the difference was statistically significant with a similar SMD = 0.43, but the GRADE assessment rated the quality of evidence as moderate because the generalizability was improved. When limited to studies which started exercise more than 4 wk after SRC, the difference on symptom severity was not statistically significant, the effect size was low, and the GRADE assessment rated the evidence as very low due to high RoB, poor precision, and small effect size. Descriptive analysis of other outcomes did not find consistent trends. Four trials assessed time to recovery, with only one reporting a faster recovery time in the exercise group. There were no differences reported in cognitive capacity (two studies) and balance measurements (two studies). Bottom Line: Early moderate exercise starting within 4 wk after SRC appears to reduce symptom severity in adolescent athletes, although the effect size is small. It has not been shown to consistently decrease time-to-recovery. There is no evidence that early moderate exercise after SRC prolongs symptoms or time to recovery. Nonsteroidal Anti-inflammatory Drugs and Cardiovascular Risk in American Football Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used by athletes to reduce pain and soreness associated with exercise. However, in the general population, habitual NSAID use has been associated with an increased risk of hypertension, arterial stiffness, atrial fibrillation, and even cardiovascular (CV) mortality. Tso and colleagues (2) from Emory University conducted a cohort study, also published in the December 2020 issue of MSSE, of high school (HS) and freshmen American-style football (ASF) players to assess NSAID use and its association with CV risk. Three cohorts were followed up over one competitive athletic season: a group of HS senior and college freshmen football players, a group of endurance (runners and swimmers) male athletes, and a group of nonathlete healthy male college students. Only the athletes who completed their season without injury that limited practice or game participation were included in the analysis. Anthropometric data, blood pressure, and a cardiac assessment were done at the start of preseason training and then again at the conclusion of the season. The cardiac assessment included a two-dimensional transthoracic echocardiogram and vascular applanation tonometry to assess arterial stiffness. A self-report questionnaire administered at the conclusion of the season was used to assess NSAID use, including the qualitative frequency (never, rarely, weekly, or daily), the specific NSAID taken, and the education level at which NSAID use began (middle school, HS, or college). None of the institutions involved permitted IM ketorolac. Football players were categorized as linemen (LM) or nonlinemen (NLM). A total of 226 ASF, 60 endurance athletes, and 63 controls (average age, 18 years) completed the study. The ASF group was significantly taller, heavier, had a higher BMI, and had a higher baseline diastolic blood pressure compared with the other groups. There was no significant difference in personal or family history of hypertension or CV disease between the groups. Postseason measurements revealed that the ASF group gained weight and increased systolic BP compared with the other groups. On cardiac examination, both the ASF and endurance groups increased LV hypertrophy, but the ASF group increased arterial stiffness and decreased diastolic function, while the endurance group improved diastolic function with no change in arterial stiffness. There were no significant changes in the nonathlete control group. NSAID use was highest among the ASF group with 19% reporting weekly use and 14% daily use. LM reported significantly higher use (41% daily or weekly) compared with NLM (28% daily or weekly. The majority of the ASF athletes who reported NSAID use started to take NSAIDs in middle school (77%). In the endurance group, only two athletes reported daily or weekly NSAID use, while in the college nonathlete control group, 21% reported weekly use and 2% (one student) reported daily use. Daily NSAID intake in the ASF group was associated with increased weight gain and systolic blood pressure (SBP). There also was a trend for daily NSAID users to have higher arterial stiffness and lower diastolic function. There were no significant increases in body weight or blood pressure among students in the control group who reported weekly NSAID use compared with students who reported rare or no NSAID intake. A mixed-effects multivariable analysis controlling for player position, SBP, and measurements of arterial stiffness and diastolic function found that increased weight was an independent factor associated with higher frequency of NSAID use. The major finding of this study was the high frequency of NSAID use in late adolescent football players that starts in middle school. It is difficult to know the cause-and-effect relationship of the NSAID use, weight gain, and cardiac changes that were observed. Increased weight appears to be the unifying feature, so perhaps, it is the combination of excessive weight and NSAID use that contributes to increased BP and diastolic and arterial stiffness. Unfortunately, the heavier players were the most likely to report weekly or daily NSAID use. Bottom Line: NSAID use is very common in senior HS and college freshmen football players, even among players without major injury, and intake usually starts in middle school. Frequent NSAID intake is associated with increased weight and systolic BP, and possibly increased cardiac and arterial stiffness.