Neural Mechanisms Associated With Postural Control in Collegiate Soccer and Non-Soccer Athletes.

BACKGROUND AND PURPOSE: Sport-specific training may improve postural control, while repetitive head acceleration events (RHAEs) may compromise it. Understanding the neural mechanisms underlying postural control may contextualize changes due to training and RHAE. The goal of this study was to determine whether postural sway during the Balance Error Scoring System (BESS) is related to white matter organization (WMO) in collegiate athletes. METHODS: Collegiate soccer ( N = 33) and non-soccer athletes ( N = 44) completed BESS and diffusion tensor imaging. Postural sway during each BESS stance, fractional anisotropy (FA), and mean diffusivity (MD) were extracted for each participant. Partial least squares analyses determined group differences in postural sway and WMO and the relationship between postural sway and WMO in soccer and non-soccer athletes separately. RESULTS: Soccer athletes displayed better performance during BESS 6, with lower FA and higher MD in the medial lemniscus (ML) and inferior cerebellar peduncle (ICP), compared to non-soccer athletes. In soccer athletes, lower sway during BESS 2, 5, and 6 was associated with higher FA and lower MD in the corticospinal tract, ML, and ICP. In non-soccer athletes, lower sway during BESS 2 and 4 was associated with higher FA and lower MD in the ML and ICP. BESS 1 was associated with higher FA, and BESS 3 was associated with lower MD in the same tracts in non-soccer athletes. DISCUSSION AND CONCLUSIONS: Soccer and non-soccer athletes showed unique relationships between sway and WMO, suggesting that sport-specific exposures are partly responsible for changes in neurological structure and accompanying postural control performance and should be considered when evaluating postural control after injury.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content, available at: http://links.lww.com/JNPT/A472 ).

Cognitive and Behavioral Outcomes in Male and Female NCAA Soccer Athletes across Multiple Years: A CARE Consortium Study.

PURPOSE: The purpose of this study was to determine changes in neurocognitive, psychosocial, and balance functioning in collegiate male and female soccer players across three consecutive years of baseline testing compared with a control group of noncontact athletes. METHODS: Generalized estimating equations were used to compare changes in annual, preseason baseline measures of neurocognitive function, neurobehavioral and psychological symptoms, and postural stability between collegiate soccer players ( n = 75; 51 [68%] female soccer players) and noncontact athletes ( n = 210; 133 [63%] female noncontact athletes) across three consecutive years. RESULTS: Among all participants, the group-time interaction was not significant for any outcome measures. Overall, soccer players reported lower (better) Brief Symptom Inventory 18 Depression ( P = 0.004, Exp(B) = 0.36, 95% confidence interval [CI] = 0.18-0.73), Global Severity Index ( P = 0.006, Exp(B) = 0.53, 95% CI = 0.33-0.84), and Post-Concussion Symptom Scale Symptom Severity ( P < 0.001, Exp(B) = 0.45, 95% CI = 0.22-0.95) scores than noncontact athletes. No other outcome measures were different between soccer players and noncontact athletes. CONCLUSIONS: Among collegiate athletes, soccer players report similar or better psychosocial functioning and symptom scores than noncontact athletes. Importantly, neurocognitive functioning, neurobehavioral and psychological symptoms, and postural stability do not worsen over time in collegiate soccer players relative to their noncontact counterparts. Our findings suggest that despite possible exposure to repetitive head impacts, collegiate soccer players do not exhibit changes in observable function and symptoms across multiple seasons.

A standardized method for quantifying and characterizing repetitive head impacts in soccer matches using video footage.

Soccer athletes experience repetitive head impacts (RHI) through purposeful heading and unintentional head impacts, which may be associated with acute and chronic brain injury. Previous soccer studies have sought to quantify and characterize RHI, but to-date no consistent, standardized methods exist. The Heads-Up Checklist (HUC), originally used for characterizing head impacts in hockey, was modified to be used in soccer (soccer HUC [SHUC]). Our aim was to determine the reliability of quantifying ball-to-head impacts using video verification and to develop and test the reliability of the SHUC to characterize RHI in soccer. Two trained reviewers used the SHUC to quantify ball-to-head impacts and characterize non-ball-to-head impacts in 38 male and female collegiate soccer matches. Intraclass correlation coefficient (ICC) and Cohen's Kappa were used to assess interrater reliability. Independent t-tests and chi-square analyses were used to examine sex differences. The interrater reliability for quantifying ball-to-head impacts was excellent (ICC = 0.97); however, only half of the non-ball-to-head impact characteristics had acceptable interrater reliability with two reviewers. The number of ball-to-head-impacts and RHI characteristics were consistent between males and females (gggp > 0.05). Our results suggest that the SHUC is an applicable standardized method to quantify and characterize RHI from video footage of soccer matches; however, accurately characterizing some aspects of RHI is a challenging task that may be supplemented by head impact sensor data.

The relation between neck strength and psychological distress: preliminary evidence from collegiate soccer athletes.

AIM: To examine whether neck strength and symmetry are associated with psychological function in athletes with exposure to repetitive head impacts. METHODS: Collegiate soccer (n = 29) and limited/noncontact (n = 63) athletes without a history of concussion completed the Brief Symptom Inventory 18 and assessments of isometric neck strength. Neck strength symmetry was calculated as the difference in strength between opposing muscle groups. RESULTS: The results demonstrated that lower neck strength was associated with more symptoms of anxiety, whereas asymmetry in neck strength was associated with more symptoms of somatization and depression in soccer athletes only. CONCLUSION: These preliminary results suggest that greater neck strength/symmetry is related to better psychological function in athletes who have higher exposure to repetitive head impacts.

The ENIGMA sports injury working group:- an international collaboration to further our understanding of sport-related brain injury.

Sport-related brain injury is very common, and the potential long-term effects include a wide range of neurological and psychiatric symptoms, and potentially neurodegeneration. Around the globe, researchers are conducting neuroimaging studies on primarily homogenous samples of athletes. However, neuroimaging studies are expensive and time consuming, and thus current findings from studies of sport-related brain injury are often limited by small sample sizes. Further, current studies apply a variety of neuroimaging techniques and analysis tools which limit comparability among studies. The ENIGMA Sports Injury working group aims to provide a platform for data sharing and collaborative data analysis thereby leveraging existing data and expertise. By harmonizing data from a large number of studies from around the globe, we will work towards reproducibility of previously published findings and towards addressing important research questions with regard to diagnosis, prognosis, and efficacy of treatment for sport-related brain injury. Moreover, the ENIGMA Sports Injury working group is committed to providing recommendations for future prospective data acquisition to enhance data quality and scientific rigor.

The Potential Role of the Cervical Spine in Sports-Related Concussion: Clinical Perspectives and Considerations for Risk Reduction.

SYNOPSIS: Sports-related concussion (SRC) occurs due to biomechanical forces to the head or neck that can result in pathophysiological changes in the brain. The musculature of the cervical spine has been identified as one potential factor in reducing SRC risk as well as for underlying sex differences in SRC rates. Recent research has demonstrated that linear and rotational head acceleration, as well as the magnitude of force upon impact, is influenced by cervical spine biomechanics. Increased neck strength and girth are associated with reduced linear and rotational head acceleration during impact. Past work has also shown that overall neck strength and girth are reduced in athletes with SRC. Additionally, differences in cervical spine biomechanics are hypothesized as a critical factor underlying sex differences in SRC rates. Specifically, compared to males, females tend to have less neck strength and girth, which are associated with increased linear and rotational head acceleration. Although our ability to detect SRC has greatly improved, our ability to prevent SRC from occurring and decrease the severity of clinical outcomes postinjury is limited. However, we suggest, along with others, that cervical spine biomechanics may be a modifiable factor in reducing SRC risk. In this commentary, we review the role of the cervical spine in reducing SRC risk, and how this risk differs by sex. We discuss clinical considerations for the examination of the cervical spine and the potential clinical relevance for SRC prevention. Additionally, we provide suggestions for future research examining cervical spine properties as modifiable factors in reducing SRC risk. J Orthop Sports Phys Ther 2019;49(3):202-208. Epub 15 Jan 2019. doi:10.2519/jospt.2019.8582.

Acute Resistance Exercise Performance Is Negatively Impacted by Prior Aerobic Endurance Exercise.

Ratamess, NA, Kang, J, Porfido, TM, Ismaili, CP, Selamie, SN, Williams, BD, Kuper, JD, Bush, JA, and Faigenbaum, AD. Acute resistance exercise performance is negatively impacted by prior aerobic endurance exercise. J Strength Cond Res 30(10): 2667-2681, 2016-The purpose of the present study was to examine acute resistance exercise (RE) performance after 4 different aerobic endurance (AE) protocols. Eleven healthy, resistance-trained men (21.0 ± 1.2 years) performed a control RE protocol and 4 RE protocols 10 minutes after different AE protocols in random sequence. The RE protocol consisted of 5 exercises (high pull, squat, bench press, deadlift, and push press) performed for 3 sets of 6-10 repetitions with 70-80% of one repetition-maximum (1RM) with 3-minute rest intervals in between sets. The AE protocols consisted of treadmill running at velocities corresponding to: (a) 60% of their V[Combining Dot Above]O2 reserve (V[Combining Dot Above]O2R) for 45 minutes (P1); (b) 75% of their V[Combining Dot Above]O2R for 20 minutes (P2); (c) 90-100% of V[Combining Dot Above]O2R in 3-minute intervals (1:1 ratio) for 5 sets (P3); and (d) 75% of V[Combining Dot Above]O2R (4.5 mph) uphill (6-9% grade) for 20 minutes (P4). Completed repetitions, average power and velocity, heart rate (HR), and ratings of perceived exertion (RPE) were assessed each set. Protocols P1-P4 resulted in 9.1-18.6% fewer total repetitions performed compared with the control RE protocol with the squat experiencing the greatest reduction. Average power and velocity were significantly reduced for the high pull, squat, and bench press after most AE protocols. Ratings of perceived exertion values for the high pull and squat were significantly higher in P1-P4 compared with control. Heart rate was significantly higher during RE after P1-P4 compared with control by 4.3-5.5%. These results indicate acute RE performance is significantly compromised in healthy men after AE exercise of different type, intensity, and duration with largest reductions observed after high-intensity interval exercise.

Metabolic responses to whole-body vibration: effect of frequency and amplitude.

PURPOSE: This study assessed the effect of whole-body vibration (WBV) of varying frequency and amplitude on metabolic responses during WBV treatment and subsequent aerobic exercise. METHODS: Eight men and eight women (21.0 ± 1.9 years) underwent one no-WBV (NV) and six WBV at 30 Hz/low amplitude (30L), 30 Hz/high amplitude (30H), 40 Hz/low amplitude (40L), 40 Hz/high amplitude (40H), 50 Hz/low amplitude (50L), and 50 Hz/high amplitude (50H). During each protocol, subjects performed ten sets of ten body weight squats with 1-min rest period between sets on a vibration platform with a load that represented one of the six frequency-amplitude combinations. Each WBV treatment was immediately followed by 20 min of cycle exercise at 65 % VO2peak. Oxygen uptake (VO2) and rates of carbohydrate (COX) and fat oxidation (FOX) were measured during both the WBV session and subsequent exercise. RESULTS: During WBV, VO2 was higher (p < 0.05) in 40H, 50L and 50H than NV and in 50H than 30L, 30H and 40L. COX was higher (p < 0.05) in 40H, 50L, and 50H than NV, whereas FOX remained indifferent across all protocols. During subsequent exercise, VO2 was higher (p < 0.05) in 50L and 50H than NV and in 50H than 30L. No between-protocol differences were seen for COX or FOX. CONCLUSION: WBV combined with body weight squats can augment VO2 at 40 Hz of high amplitude and 50 Hz of both low and high amplitudes. This metabolic potentiation remains in effect during subsequent aerobic exercise. WBV did not affect fat oxidation across all vibratory loads.