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Context: Neuromuscular function is altered acutely following concussion and theoretically linked to the subsequent postconcussion musculoskeletal injury risk. Existing research has only examined voluntary muscle activation, limiting mechanistic understanding. Therefore, our study aimed to examine voluntary and involuntary muscle activation between college-aged, concussed individuals when symptom-free and healthy matched controls. Design: Prospective, cross-sectional cohort laboratory study. Methods: Concussed and healthy participants (n = 24; 58% male, age: 19.3 [1.1] y, mass: 70.3 [16.4] kg, height: 177.3 [12.7] cm) completed the superimposed burst (SB) neuromuscular assessment on their dominant limb within 72 hours after self-reporting asymptomatic (22.4 [20.2] d postinjury). Unnormalized and bodyweight-normalized quadriceps maximal voluntary isometric contraction torque (in newton meters), unnormalized and bodyweight-normalized electrically stimulated SB torque, pain (numeric 1–10) during SB, and the central activation ratio (in percentage) were assessed via the SB. Parametric and nonparametric analyses, 95% confidence intervals (95% CIs), and Hedges g (parametric) and Spearman ρ (nonparametric) effect sizes were used to examine group differences (α =.05). Results: The maximal voluntary isometric contraction torque (concussed: 635.60 N·m [300.93] vs control: 556.27 N·m [182.46]; 95% CI, −131.36 to 290.02; P =.443; d = 0.33), SB torque (concussed: 203.22 N·m [97.17], control: 262.85 N·m [159.07]; 95% CI, −171.22 to 51.97; P =.280; d = −0.47), and central activation ratio (concussed: 72.16% [17.16], control: 70.09% [12.63]; 95% CI, −10.68 to 14.83; P =.740; d = 0.14) did not differ between the concussed and control groups regardless of bodyweight normalization (P ≥.344). Pain during the SB was significantly higher with a medium effect for participants with a concussion versus healthy controls (concussed: median = 7, control: median = 5; P =.046; ρ = −0.42). Discussion: These findings suggest concussed participants do not have statistically altered voluntary or involuntary quadricep neuromuscular function once asymptomatic compared with controls. Therefore, the elevated postconcussion musculoskeletal injury risk may not be attributed to lower-extremity muscle activation. Concussed participants displayed greater pain perception during the SB, which suggests somatosensory or perception changes requiring further examination. [ABSTRACT FROM AUTHOR]

Context: To determine (1) whether physical function and fear of movement are prospectively associated with the risk of females developing patellofemoral pain (PFP) and (2) whether they change following development of PFP. Design: Prospective observational study. Methods: A total of 114 asymptomatic females (18–22 y old) completed assessment of physical function (forward step-down test and single-leg hop for distance) and fear of movement using the Tampa Scale for Kinesiophobia at baseline and 2-year follow-up. Presence of symptoms of PFP was monitored bimonthly. Results: Ninety participants (retention rate = 79%) completed the 2-year follow-up assessment, with 27 (24% of the cohort) developing PFP. Physical function, including forward step-down test (P =.659) and single-leg hop for distance (P =.825), and fear of movement (P =.479) were not associated with the risk of developing PFP. Females who developed PFP presented with reduced forward step-down repetitions (mean difference = 2.8; 95% confidence interval, 0.2 to 5.3) and single-leg hop for distance (10.2; 95% confidence interval, 2.7 to 17.7 cm) at 2-year follow-up. There was no statistically significant difference between those who did and did not develop PFP for fear of movement (−3.4; 95% confidence interval, −7.0 to 0.2). Conclusions: Physical function and fear of movement were not associated with the risk of developing PFP in young females. However, the change over time in the step-down and single-leg hop for distance tests may suggest that, even in the early stages of PFP, young females present impaired physical function compared with females who did not develop symptoms. Fear of movement may develop due to persistent PFP, and does not appear to be a risk factor or key feature in females with PFP of short symptoms duration. [ABSTRACT FROM AUTHOR]

Objective: To find the short-term psychological and hormonal effects of virtual reality training on chronic low back pain in American soccer players. Design, Setting, Participants: The 3-block random sampling method was used on 54 university American soccer players with chronic low back pain, and they were allocated into 3 groups: virtual reality training (VRT; n = 18), combined physical rehabilitation (n = 18), and control (n = 18) groups at University Hospital. They underwent different balance training exercises for 4 weeks. The participants and the therapist who is assessing the outcomes were blinded. Psychological (pain intensity and kinesiophobia) and hormonal (glucose, insulin, Homeostatic Model Assessment of Insulin Resistance, growth hormone, prolactin, adrenocorticotropic hormone, and cortisol) values were measured at baseline, after 4 weeks, and after 6 months. Results: The baseline demographic, psychological, and hormonal data between the VRT, combined physical rehabilitation, and control groups show no statistical difference (P ≥.05). Four weeks following training, the VRT group shows more significant changes in pain intensity and kinesiophobia than the combined physical rehabilitation and control groups (P <.001), and the improvement was noted in the 6-month follow-up. All the hormonal variables (glucose, insulin, growth hormone, prolactin, adrenocorticotropic hormone, and cortisol) show significant changes at 4-week training (P <.001), except for the Homeostatic Model Assessment of Insulin Resistance (P =.075) between the 3 groups. At 6-month follow-up glucose, prolactin, adrenocorticotropic hormone, and cortisol show more significant difference in the VRT group than the other 2 groups (P <.001). At the same time, insulin (P =.694), Homeostatic Model Assessment of Insulin Resistance (P =.272), and growth hormone (P =.145) failed to show significant changes between the groups. Conclusion: Training through virtual reality is an effective treatment program when compared with conventional exercise training programs from a psychological and hormonal analysis perspective in American soccer players with chronic low back pain. [ABSTRACT FROM AUTHOR]

Context: Patient-reported outcome measures (PROs) and functional performance tests are recommended in the National Athletic Trainers' Association's position statement on the prevention and management of ankle sprains during the return-to-play process. Evaluating perceived confidence may be another valuable method to evaluate an athlete's readiness to return-to-play following an ankle sprain. Objective: To evaluate the relationship between PROs and perceived confidence when performing functional performance tasks in high school athletes with a history of ankle sprain. Design: Descriptive study. Setting: Public high school. Patients or Other Participants: A total of 25 high school student-athletes (6 males and 19 females, age 16.2 [1.1] y, height 169.3 [7.7] cm, mass 63.2 [9.8] kg). Intervention(s): None. Main Outcome Measures: The Cumberland Ankle Instability Tool, visual analog scale (VAS) for pain, Identification of Functional Ankle Instability, and Tampa Scale of Kinesiophobia-11 were completed by all participants. Participants then completed the weight-bearing lunge test; star excursion balance test; lateral, up–down, and triple hop tests; the single-leg vertical jump; and Southeast Missouri agility test and were asked to report their confidence in completing each task using a VAS with anchors of "no confidence" and "complete confidence." Pearson r correlations were calculated between the PROs and the confidence VAS scores of the functional tests. Results: Moderate to strong negative correlations were identified between pain VAS measures and confidence VAS measures for all functional tests except the star excursion balance test and vertical jump. Moderate negative correlations were found between Tampa Scale of Kinesiophobia-11 scores and perceived confidence during the star excursion balance test and vertical jump. Finally, a moderate positive correlation was identified between Cumberland Ankle Instability Tool scores and perceived confidence measures during the Southeast Missouri agility test. Conclusions: High school athletes with a history of ankle sprain demonstrated significant correlations between several PROs and perceived confidence during various functional performance tests. The value of perceived confidence measures when making return-to-play decisions after ankle sprains warrants further investigation. [ABSTRACT FROM AUTHOR]

Context: The relationship between physical activity (PA) and fear of pain with movement (ie, kinesiophobia) during concussion recovery is unknown. Kinesiophobia may limit PA, while PA after concussion may reduce kinesiophobia. Our purpose was to examine the correlation between PA and self-reported kinesiophobia during concussion recovery for adolescents with and without persistent symptoms., Design: Prospective cohort study of children ages 10-18 years within 14 days of concussion., Methods: Participants rated kinesiophobia using the Tampa Scale of Kinesiophobia (TSK) at initial (≤14 d postconcussion) and return to play (RTP) assessments, and wore activity monitors between assessments. Our primary outcome was TSK score change from initial to RTP assessments. We grouped participants based on whether they experienced persistent symptoms (symptoms ≥28 days) or not (symptoms <28 days) and calculated correlation coefficients (Pearson r for normally distributed and Spearman rho for nonnormally distributed variables) between PA variables and TSK change scores., Results: Among the 41 participants enrolled, 44% developed persistent symptoms (n = 18; age = 14.5 [2.0] y; 50% female; symptom duration = 57.3 [6.2] d; RTP = 66.8 [6.4] d) and 56% did not (n = 23; age = 14.9 [1.8] y; 48% female; symptom duration = 15.2 [1.5] d; RTP = 21.7 [1.9] d). For the persistent symptoms group, greater TSK change scores (mean = -2.5 [5.7] point change) were significantly and moderately correlated with higher daily step count (r = -.60, P = .008) and exercise frequency (r = -.63, P = .005), but were not correlated with exercise duration (ρ = -.12, P = .65). Among the no persistent symptoms group, TSK change scores (mean = -6.0 [5.0] point change) were not correlated with step count (r = -.18, P = .41) or exercise duration (ρ = .10, P = .67), and the correlation with frequency was low and not significant (r = -.34, P = .12)., Conclusions: Regular PA during concussion recovery, regardless of duration or intensity, may help reduce kinesiophobia for those experiencing persistent symptoms.

Context: Athletes with a history of sport concussion (SC) have an increased risk of musculoskeletal injury (MSK); however, the underlying mechanisms have yet to be determined. The purpose of our study was to evaluate kinesiophobia in college athletes with or without a time-loss MSK within 180 days of unrestricted return to play following a SC., Design: This was a retrospective cohort study within a sports medicine facility., Methods: Participants were eligible if they were diagnosed with a SC, completed the Tampa Scale of Kinesiophobia (TSK), and completed an unrestricted return to play. Fifty-six college athletes (40 men and 16 women) with an average age of 19.5 (1.25) years, height of 183.5 (10.45) cm, and mass of 94.72 (24.65) kg, were included in the study. MSK participants were matched to non-MSK participants 1:1. Demographic and TSK outcome scores were compared using independent t tests. The proportion of participants in each group who scored above the clinical threshold (TSK ≥ 37) was compared using a chi-square analysis. Alpha was set at α = .05., Results: The MSK group (31.2 [6.30]) reported similar TSK scores to the matched group (28.9 [3.34]; t54 = 1.70, P = .10, d = 0.45 [-0.08 to 0.97]). A greater proportion of athletes who were diagnosed with an MSK-reported scores above the cutoff (χ2[1] = 6.49, P = .01)., Conclusions: Athletes diagnosed with SC had similar kinesiophobia values regardless of MSK status. However, a higher proportion of athletes with a time-loss MSK injury reported a TSK score greater than the clinical cutoff. Our results suggest that factors such as kinesiophobia should be considered following a SC.