Performing more than 20 purposeful gameplay headers in a soccer season may alter autonomic function in female youth soccer players.

This study evaluated the effects of cumulative purposeful soccer heading on autonomic nervous system function in 22 female youth soccer players (13.3 ± 0.9 years). A 10 minute electrocardiogram recording was collected at baseline and following the 20 game season (post-season) to calculate measures of heart rate variability (HRV), including standard deviation of the normal-normal intervals, total power, high frequency (HF), low frequency (LF), LF:HF, normalized HF and normalized LF. Participants were categorized into low- (<20 headers per season; n = 13) and high- (>20 headers per season; n = 9) exposure groups. Mann-Whitney U tests demonstrated no significant differences between groups for any HRV metric. However, the increased normalized LF power (low exposure 8.67 and high exposure -31.17, respectively; r = 0.35) and LF:HF power (-6.39 and 15.80, respectively; r = 0.35), between groups had moderate practical significance. Therefore, female youth players who perform more than 20 purposeful headers during a soccer season may exhibit altered autonomic function.

Concussion in Adolescents Impairs Heart Rate Response to Brief Handgrip Exercise.

OBJECTIVE: Test the hypotheses that (1) concussion in adolescents impairs autonomic neural control of heart rate (HR), and (2) HR reactivity improves with symptom resolution. DESIGN: Observational, case-control. PARTICIPANTS: Nineteen concussed adolescents (8 female adolescents; age 15 ± 2 years) and 16 healthy controls (6 female adolescents, age 15 ± 2 years). INTERVENTION: All participants performed an isometric handgrip (IHG) at 30% maximum voluntary contraction lasting 30 seconds. Heart rate (electrocardiogram) and hemodynamic responses (photoplethysmographic Finometer) were recorded from 30 seconds of baseline and the last 10 seconds of handgrip. MAIN OUTCOME MEASURES: The HR response (ΔHR) at the onset of moderate-intensity IHG using a mixed 1-way analysis of variance. RESULTS: A group × time interaction (P < 0.005) indicated that handgrip evoked a greater ΔHR among control participants (13 ± 10 beats/min) compared with concussed (6.4 ± 6.3 beats/min; group P = 0.63; time P < 0.001; d = 0.77). CONCLUSION: These preliminary results suggest that a concussion impairs the ability to elevate HR at the exercise onset and, given the nature of the task, this could be interpreted to reflect reduced ability to withdraw cardiovagal control. Therefore, the data support the hypothesis of neural cardiac dysregulation in adolescents diagnosed with concussion. CLINICAL RELEVANCE: The IHG test could aid concussion diagnosis and support return-to-play decisions.

Concussion Symptoms Predictive of Adolescent Sport-Related Concussion Injury.

OBJECTIVE: To assess the predictive capability of the postconcussion symptom scale (PCSS) of the sport concussion assessment tool (SCAT) III to differentiate concussed and nonconcussed adolescents. DESIGN: Retrospective. SETTING: Tertiary. PARTICIPANTS: Sixty-nine concussed (15.2 ± 1.6 years old) and 55 control (14.4 ± 1.7 years old) adolescents. INDEPENDENT VARIABLES: Postconcussion symptom scale. MAIN OUTCOME MEASURE: Two-proportion z-test determined differences in symptom endorsement between groups. To assess the predictive power of the PCSS, we trained an ensemble classifier composed of a forest of 1000 decision trees to classify subjects as concussed, or not concussed, based on PCSS responses. The initial classifier was trained on all 22-concussion symptoms addressed in the PCSS, whereas the second classifier removed concussion symptoms that were not statistically significant between groups. RESULTS: Concussion symptoms common between groups were trouble falling asleep, more emotional, irritability, sadness, and anxious. After removal, analysis of the second classifier indicated that the 5 leading feature rankings of symptoms were headache, head pressure, light sensitivity, noise sensitivity, and "don't feel right," which accounted for 52% of the variance between groups. CONCLUSIONS: Collectively, self-reported symptoms through the PCSS can differentiate concussed and nonconcussed adolescents. However, predictability for adolescent patients may be improved by removing emotional and sleep domain symptoms.

An Evaluation of Heart Rate Variability in Female Youth Soccer Players Following Soccer Heading: A Pilot Study.

Most head impacts in soccer occur from purposeful heading; however, the link between heading and neurological impairment is unknown. Previous work suggests concussion may result in an uncoupling between the autonomic nervous system and cardiovascular system. Accordingly, heart rate variability (HRV) may be a sensitive measure to provide meaningful information regarding repetitive heading in soccer. The purpose of this pilot study assesses the feasibility of measuring HRV to evaluate autonomic function following soccer heading. Sixteen youth female participants underwent heart rate monitoring during a heading and footing condition. Participants completed a five minute resting supine trial at the start and end of each testing session. Standard 450 g soccer balls were projected at 6 m/s towards participants. Participants performed five headers, for the header condition, and five footers for the footer condition. The HRV for resting supine trials, pre- and post-header and footer conditions were assessed for both time and frequency domains. HRV effect sizes were small when comparing conditions, except absolute low frequency (d = 0.61) and standard deviation of the normal-normal (NN) intervals (d = 0.63). Participant retention and adherence were high, without adverse events. Findings suggest HRV is a feasible measure for evaluating the effects of heading on autonomic function.

MRI-based relationships between spine pathology, intervertebral disc degeneration, and muscle fatty infiltration in chondrodystrophic and non-chondrodystrophic dogs.

BACKGROUND CONTEXT: Human studies have revealed a link between muscle degeneration and low back pain, although the cause and effect of this relationship is not clear. Dogs provide a naturally developing model of intervertebral disc (IVD)-related low back pain that may provide insight into relationships between IVD and muscle degeneration. PURPOSE: This study aimed to quantify, via magnetic resonance imaging (MRI), the magnitude and location of fatty infiltration in spine muscles of chondrodystrophic (CD) and non-chondrodystrophic (NCD) dogs suffering from both intervertebral disc herniation (IVDH) and non-disc-related spinal disorders, and relate this to intervertebral disc degeneration (IVDD). STUDY DESIGN: This study used retrospective MRI-based analysis of IVDD and muscle fatty infiltration in CD and NCD dogs. METHODS: A portion of this study was funded ($1,000) by the Pet Trust Fund, Ontario Veterinary College. Magnetic resonance imaging from 180 dogs were separated into four groups: (1) CD with IVDH; (2) CD with non-IVDH spinal pathology; (3) NCD with IVDH; (4) NCD with non-IVDH spinal pathology. For each dog at intervertebral levels T12-T13 to L6-L7, IVDD was subjectively graded and muscle-fat indices (MFIndices) were quantified for multifidus, erector spinae, and psoas muscle groups. RESULTS: Intervertebral disc degeneration grade was higher (p<.0001) for CD compared with NCD dogs, and for dogs diagnosed with IVDH compared with dogs with non-IVDH pathology. Muscle-fat indices of multifidus and psoas were higher (p<.01), indicating greater fatty infiltration, for NCD compared with CD dogs, and for dogs with non-IVDH pathology compared with dogs with IVDH. Erector spinae demonstrated higher (p<.0001) MFIndices compared with multifidus and psoas; however, this level of fatty infiltration was not dependent upon breed or pathology. CONCLUSIONS: Dog groups with higher average IVDD grades demonstrated less fatty infiltration within their multifidus and psoas muscles, compared with groups with lower IVDD grades. This finding was consistent across both CD and NCD breeds as well as across dogs presenting with IVDH and those presenting with a non-IVDH spinal pathology. Thus, the presence or severity of IVDD is not uniquely related to fatty infiltration in these muscles, but rather the presence, or possibly severity or chronicity, of general spine pathology is likely a better predictor of fatty infiltration.

Effects of changes in muscle activation level and spine and hip posture on erector spinae fiber orientation.

INTRODUCTION: During lumbar flexion, the fiber orientation of the lumbar erector spinae (LES) muscle becomes oriented more along the spine compressive axis. It is unknown how changes in LES activation effect fiber orientation. METHODS: Ultrasound images of LES were collected during 2 sets of experimental conditions: (1) varying levels of LES activation while lying prone; and (2) varying spine and hip angles while seated. Electromyographic activity and lumbar spine and hip angles were also recorded. RESULTS: As LES activation increased, increases in fiber orientation (signifying increased orientation along the posterior shear axis) were found (P<0.001). Compared with the relaxed sitting posture, decreases in fiber orientation were found with full spine flexion and combined spine and hip flexion (P<0.001), but there were no changes with full hip flexion alone. CONCLUSIONS: Activation magnitude and spine posture both affect LES fiber orientation, thus modifying its ability to protect the spine against anterior shear forces.