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M. Spencer Cain, Kyeongtak Song, J. Troy Blackburn, Kimmery Migel and Erik A. Wikstrom

Ankle joint mobilization has been shown to be effective at improving outcomes in those with chronic ankle instability (CAI), but the neuromuscular mechanisms are still unknown. We aimed to determine the immediate effect of a single Grade III anterior-to-posterior ankle joint mobilization bout on ankle musculotendinous stiffness (MTS) in those with CAI. Seventeen CAI participants had plantar flexor and fibularis MTS assessed before and after a 5-min joint mobilization treatment. MTS outcomes were estimated using the damped oscillation method. Fibularis (0.25 ± 0.41 N/m/kg, p = .028) but not plantar flexor MTS (−2.18 ± 14.35 N/m/kg, p = .539) changed following mobilization and exceeded the calculated minimal detectable change score (0.12 N/m/kg). Increased fibularis MTS may represent a neuromuscular mechanism by which ankle joint mobilizations improve postural control in those with CAI.

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Ainaz Shamshiri, Iman Rezaei, Ehsan Sinaei, Saeed Heidari and Ali Ghanbari

Context: The Balance Error Scoring System (BESS), originally designed to diagnose and assess athletes with concussion syndrome, is now widely used to evaluate postural stability. To interpret balance status, a normative database can be a reliable source. However, different anthropometric characteristics and sociocultural backgrounds across populations hinder the application of previously developed databases in different populations. Objective: The present study was designed to develop a normative data set for the general population of healthy Iranian adults according to their age groups and to study the correlation between BESS scores and the participants’ sex, height, weight, and body mass index. Design: A cross-sectional study. Participants: A total of 1051 community-dwelling adults aged 20–69 years not suffering from balance disorders, dizziness, or other neurological or musculoskeletal diseases were recruited and stratified into 5 different age groups by decade. Main Outcome Measures: The BESS tests were composed of single-leg, double-leg, and tandem stances, each on a rigid surface and a foam pad. The individuals maintained each position for 20 seconds with eyes closed. The assessor recorded the total number of errors as the individuals’ BESS score (range: 0–60). Results: Significant but weak correlations were found between BESS score and height (r = −.13, P < .001) and between BESS score and body mass index (r = .11, P < .001), and the difference between sexes in BESS score was statistically significant in the 50- to 59-year-old (P = .021) and 60- to 69-year-old (P < .001) groups. The BESS scores were significantly different between all age groups (P < .05), except between the 20- to 29-year-old and 30- to 39-year-old groups (P = 1.000) and between the 40- to 49-year-old and 50- to 59-year-old groups (P = .086). Conclusions: This study provided a normative database for different age groups of asymptomatic Iranian adults. The BESS score had weak correlations with height and body mass index and no correlation with weight, and significant differences were found between sexes in 50- to 69-year-old individuals. This study emphasizes the importance of obtaining specific normative data for different populations.

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Jessica G. Hunter, Alexander M.B. Smith, Lena M. Sciarratta, Stephen Suydam, Jae Kun Shim and Ross H. Miller

Studies of running mechanics often use a standardized lab shoe, ostensibly to reduce variance between subjects; however, this may induce unnatural running mechanics. The purpose of this study was to compare the step rate, vertical average loading rate, and ground contact time when running in standardized lab shoes versus participants’ normal running shoes. Ground reaction forces were measured while the participants ran overground in both shoe conditions at a self-selected speed. The Student’s t-test revealed that the vertical average loading rate magnitude was smaller in lab shoes versus normal shoes (42.09 [11.08] vs 47.35 [10.81] body weight/s, P = .013), while the step rate (170.92 [9.43] vs 168.98 [9.63] steps/min, P = .053) and ground contact time were similar (253 [25] vs 251 [20] ms, P = .5227) and the variance of all outcomes was similar in lab shoes versus normal shoes. Our results indicate that using standardized lab shoes during testing may underestimate the loads runners actually experience during their typical mileage.

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Brian Catania, Travis Ross, Bradley Sandella, Bradley Bley and Andrea DiTrani Lobacz

Context: Training and assessment of the abdominal and trunk muscles are widely used in the clinical setting. However, it is unknown what types of exercises are most effective in activation of both the global and local stabilizers in these regions. Objective: The purpose of this study was to establish the reliability of a novel clinical screening tool (sling screen) to assess the muscles of the abdomen and trunk. The second aim was to use the clinical screening tool and musculoskeletal ultrasound to compare the effects of a rotary-based exercise program that targets both the global and local muscles to the effects of a traditional exercise program on the activation of the abdominal and trunk muscles. Design: Double-blind, randomized controlled trial. Setting: Sports medicine facility. Participants and Interventions: Thirty-one healthy participants were randomly allocated to receive a single-session rotary-based or traditional “core” exercise program. Main Outcome Measures: The participants were assessed at the baseline and immediately postintervention. The primary outcome measures were muscle thickness examined by musculoskeletal ultrasound and clinical examination of muscle activation using a screening tool. The data were collected by blind assessors. Reliability and validity of a clinical screening tool (sling screen) were also assessed. Results: The analysis of the covariance tests showed a significant increase in oblique thickness for the rotary exercise group. All participants displayed a significant increase in multifidus thickness. The Wilcoxon signed-rank tests revealed a significant increase in clinical assessment scores in the rotary exercise group but not the traditional exercise group. Reliability of the sling screen ranged from moderate to good. Conclusion: This clinical trial provides evidence that a rotary-based exercise program may be more effective in producing increases in oblique muscle thickness than traditional “core” exercises in young, healthy adults. The sling screen tool was able to identify these muscle thickness changes. Future studies should investigate how these results correlate to injury risk, other populations, and also how to implement the sling screen into clinical practice.

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Hayley M. Ericksen and Rachele E. Vogelpohl

Anterior cruciate ligament (ACL) injury in female athletes is common. Team sport athletes experience more ACL injuries than ballet and modern dancers. Examining biomechanical differences between these two groups may help to explain the discrepancy in ACL injury rates. The purpose of this study was to examine lower extremity kinematic differences between collegiate dancers and National Collegiate Athletic Association Division I soccer athletes during a rebound jump-landing task. Peak hip, knee, and ankle kinematics were collected during a jump-landing task. Results showed more knee flexion and less ankle eversion in the dancers compared to the soccer athletes. Differences in training and strategies used during landing may explain the kinematic differences between groups.

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Graig M. Chow, Matthew D. Bird, Nicole T. Gabana, Brandon T. Cooper and Martin A. Swanbrow Becker

Student-athletes are susceptible to mental health problems that disrupt optimal functioning and well-being. Despite having many protective factors, student-athletes represent an at-risk subgroup of college students who experience mental health concerns due to the distress of balancing multiple obligations. However, many student-athletes underutilize psychological services. Stigma is the main barrier preventing student-athletes from seeking help, and mental health literacy (MHL) interventions addressing knowledge and beliefs about mental disorders have traditionally been used to destigmatize mental illness. This study investigated the impact of a 4-week program on stigma, MHL, and attitudes and intentions toward seeking help with 33 National Collegiate Athletic Association Division I student-athletes. The program was composed of four science-based interventions—MHL, empathy, counter stereotyping, and contact—delivered face-to-face within a group setting. MHL, attitudes toward seeking help, and intentions to seek counseling improved from preintervention to postintervention and to 1-month follow-up. Self-stigma was reduced from preintervention to postintervention.

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Iván Chulvi-Medrano, Moisés Picón-Martínez, Juan Manuel Cortell-Tormo, Juan Tortosa-Martínez, Diego Alexandre Alonso-Aubin and Yasser Alakhdar

Context: Blood flow restriction research has focused on muscular strength and hypertrophy. Limited data have been reported about the blood flow restriction effect on the tendon. Objective: To analyze and compare the time course of recovery in Achilles tendon thickness after a single bout of low-intensity resistance training (LI-RT) and low-intensity blood flow restriction training (LI-BFRT). Methods: A total of 56 healthy participants (24.60 [4.0] y; 23.65 [3.4] body mass index) were included. The dominant leg was assigned for LI-BFRT using low load (30% 1-repetition maximum) and 30% of the total occlusion pressure (52.21 [17.89] mm Hg) in plantar-flexion exercise (1 × 30 + 3 × 15 repetitions). The nondominant leg was assumed as a control condition. Main Outcome Measure: Sonography images were taken before the intervention, immediately posttraining, and 24 hours after exercise (post-24) for the Achilles tendon thickness. Results: Changes in Achilles tendon thickness for LI-BFRT group were significant post- (−14.5%; P < .05) and post-24 (−9.2%; P < .05). In contrast, LI-RT group showed a transient decrease after exercise (−9.67%; P < .05) followed by a recovery of thickness post-24 (−1.06%; P < .05). Thickness post-24 was different between LI-BFRT versus LI-RT (P < .01). Hedge effect size analysis showed a large effect (g = 0.90) in LI-BFRT pre–post condition and a medium effect (g = 0.57) in post- to post-24. The LI-RT obtained a medium effect (g = 0.53) in pre–post condition and a small effect (g = 0.49) in post- to post-24. Conclusions: This study showed a different time course of the acute response in Achilles tendon thickness between LI-BFRT and LI-RT. This may be associated with intratendinous fluid movement in response to LI-BFRT.

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Jung-Hoon Choi, Heon-Seock Cynn, Chung-Hwi Yi, Tae-Lim Yoon and Seung-Min Baik

Context: The improvement of hip joint stability can significantly impact knee and rearfoot mechanics. Individuals with pes planus have a weak abductor hallucis (AbdH), and the tibialis anterior (TA) may activate to compensate for this. As yet, no studies have applied isometric hip abduction (IHA) for hip stability during short-foot exercise (SFE). Objective: To compare the effects of IHA on the muscle activity of the AbdH, TA, peroneus longus (PL), and gluteus medius (Gmed), as well as the medial longitudinal arch (MLA) angle during sitting and standing SFE. Design: Two-way repeated analyses of variance were used to determine the statistical significance of AbdH, TA, PL, and Gmed electromyography activity, as well as the change in MLA angle. Setting: University research laboratory. Participants: Thirty-two participants with pes planus. Intervention(s): The participants performed SFE with and without isometric hip abduction in sitting and standing positions. Main Outcome Measures: Surface electromyography was used to measure the activity of the AbdH, TA, PL, and Gmed muscles, and Image J was used to measure the MLA angle. Results: Significant interactions between exercise type and position were observed in terms of the PL muscle activity and in the change in MLA angle only, while other muscles showed significant main effects. The IHA during SFE significantly increased the AbdH muscle activity, while the TA muscle activity was significantly lower. The muscle activity of Gmed and PL was significantly increased in the standing position compared with sitting, but there was no significant difference with or without IHA. The change in the MLA angle was significantly greater in SFE with IHA in a standing position than in the other SFE conditions. Conclusions: IHA may be an effective method for reducing compensatory TA activity and increasing AbdH muscle activity during SFE for individuals with pes planus.

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Stijn Schouppe, Jessica Van Oosterwijck, Jan R. Wiersema, Stefaan Van Damme, Tine Willems and Lieven Danneels

The contribution of central factors to movement preparation (e.g., the contingent negative variation [CNV]) and the influence of fatigue on such factors are still unclear, even though executive cognitive functions are regarded as key elements in motor control. Therefore, this study examined CNV amplitude with electroencephalography in 22 healthy humans during a rapid arm movement task prior to and following three experimental conditions: (a) a no exertion/control condition, (b) a physical exertion, and (c) a cognitive exertion. CNV amplitude was affected neither by a single bout of physical/cognitive exertion nor by the control condition. Furthermore, no time-on-task effects of the rapid arm movement task on the CNV were found. Exertion did not affect cortical movement preparation, which is in contrast to previous findings regarding time-on-task effects of exertion on CNV. Based on the current findings, the rapid arm movement task is deemed suitable to measure cortical movement preparation, without being affected by learning effects and physical/cognitive exertion.

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Lydia M. Kocher, Jonisha P. Pollard, Ashley E. Whitson and Mahiyar F. Nasarwanji

Footwear plays an important role in worker safety. Work boots with safety toes are often utilized at mine sites to protect workers from hazards. Increasingly, mining operations require metatarsal guards in addition to safety toe protection in boots. While these guards provide additional protection, the impact of metatarsal guards on gait are unknown. This study aimed to measure the effects of 4 safety work boots, steel toe, and steel toe with metatarsal protection in wader- and hiker-style boots, on level and inclined walking gait characteristics, during ascent and descent. A total of 10 participants completed this study. A motion capture system measured kinematics that allowed for the calculation of key gait parameters. Results indicated that gait parameters changed due to incline, similar to previous literature. Wader-style work boots reduced ankle range of motion when ascending an incline. Hip, knee, and ankle ranges of motion were also reduced during descent for this style of boot. Wader-style boots with metatarsal guards led to the smallest ankle range of motion when descending an inclined walkway. From these results, it is likely that boot style affects gait parameters and may impact a miner’s risk for slips, trips, or falls.