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Electromyography-Informed Estimates of Joint Contact Forces Within the Lower Back and Knee Joints During a Diverse Set of Industry-Relevant Manual Lifting Tasks

Felicia R. Davenport, Jennifer K. Leestma, Adriana Staten, Krishan Bhakta, Joshua Fernandez, Anirban Mazumdar, Aaron J. Young, and Gregory S. Sawicki

Repetitive manual labor tasks involving twisting, bending, and lifting commonly lead to lower back and knee injuries in the workplace. To identify tasks with high injury risk, we recruited N = 9 participants to perform industry-relevant, 2-handed lifts with a 11-kg weight. These included symmetrical/asymmetrical, ascending/descending lifts that varied in start-to-end heights (knee-to-waist and waist-to-shoulder). We used a data-driven musculoskeletal model that combined force and motion data with a muscle activation-informed solver (OpenSim, CEINMS) to estimate 3-dimensional internal joint contact forces (JCFs) in the lower back (L5/S1) and knee. Symmetrical lifting resulted in larger peak JCFs than asymmetrical lifting in both the L5/S1 (+20.2% normal [P < .01], +20.3% shear [P = .001], +20.6% total [P < .01]) and the knee (+39.2% shear [P = .001]), and there were no differences in peak JCFs between ascending versus descending motions. Below-the-waist lifting generated significantly greater JCFs in the L5/S1 and knee than above-the-waist lifts (P < .01). We found a positive correlation between knee and L5/S1 peak total JCFs (R2 = .60, P < .01) across the task space, suggesting motor coordination that favors sharing of load distribution across the trunk and legs during lifting.

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Outdoor Overground Gait Biomechanics and Energetics in Individuals With Transtibial Amputation Walking With a Prescribed Passive Prosthesis and a Bionic Myoelectric Prosthesis

Nicole Stafford, Eddie B. Gonzalez, and Daniel Ferris

The metabolic cost of walking for individuals with transtibial amputation is generally greater compared with able-bodied individuals. One aim of powered prostheses is to reduce metabolic deficits by replicating biological ankle function. Individuals with transtibial amputation can activate their residual limb muscles to volitionally control bionic ankle prostheses for walking; however, it is unknown how myoelectric control performs outside the laboratory. We recruited 6 individuals with transtibial amputation to walk an outdoor course with the Open Source Leg prosthesis under continuous proportional myoelectric control and compared it with their passive device. There were no significant differences (P = .142) in cost of transport between prostheses. Participants significantly increased residual limb vastus lateralis (P = .042) and rectus femoris (P = .029) muscle activity during early and midstance phase of walking with the powered prosthesis compared with their passive device. All but one participant preferred walking with myoelectric control compared with their passive prosthesis. The additional mass of the powered ankle prosthesis coupled with increased residual quadriceps activity could explain why the energy cost of walking was not lower compared with a passive prosthesis. This study demonstrates participants can volitionally control a bionic ankle prosthesis to navigate real-world environments.

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Clinician Knowledge of Anterior Cruciate Ligament Reconstruction Rehabilitation Practices: A Preliminary Survey Study

Xavier D. Thompson, Gabrielle M. DelBiondo, and Joe M. Hart

Context: After completing rehabilitation, patients face a high risk of subsequent injury following anterior cruciate ligament reconstruction. It is important to identify potential barriers to patient success including clinician knowledge. The purpose of this study was to assess clinician knowledge of research related to anterior cruciate ligament reconstruction rehabilitation. Design: This was a survey study using snowball sampling. Methods: Survey development began with the creation of a construct map and contained varying levels of advanced concepts, level I indicating the most basic and level V the most complex. The survey was distributed to advertise to target population. A total of 60 participants (24 athletic trainers, 33 physical therapists, and 3 dual credentialed) completed the study. Results: Overall, participants displayed moderate to high levels of knowledge (79.7%–93.5% correct), apart from the implementation of motor learning principles. Conclusions: Clinician knowledge may not be the primary barrier to patient success, but the implementation of this knowledge should be explored in relation to patient outcomes. Future research should examine a larger cohort to examine differences between clinician types.

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A Concussion Management Policy Change Promoted Earlier Initiation of Rehabilitation Services and Improved Clinical Recovery Outcomes in Concussion

Elizabeth F. Teel, Danielle Dobney, Deborah Friedman, Lisa Grilli, Christine Beaulieu, and Isabelle J. Gagnon

Context: In line with emerging research, an interprofessional specialty concussion clinic instituted a policy change permitting earlier physiotherapy-based treatment entry. Our objective was to determine the effect of this policy change on concussion recovery outcomes. Design: Secondary analysis of prospectively collected clinical data. Methods: 600 youth with concussion were included. Active rehabilitation was initiated ≥4 weeks (prepolicy) or ≥2 weeks (postpolicy) postconcussion based on institutional policy. Cox proportional hazard models, linear mixed models, and chi-square analyses were conducted. Results: The postpolicy group (median = 22 d [interquartile range: 17–27]) started treatment earlier than the prepolicy group (median = 26 d [interquartile range: 24–30], P < .001). Length of episode of care (χ 2(1) = 11.55, P < .001, odds ratios = 1.49; 95% confidence interval, 1.19–1.88); rehabilitation (χ 2(1) = 9.47, P = .002, odds ratios = 1.73, 95% confidence interval, 1.22–2.45]); and total recovery (χ 2(1) = 11.53, P < .001, odds ratios = 1.49; 95% confidence interval, 1.18–1.88) were reduced in patients postpolicy change. A significant interaction effect was found for total postinjury symptom (F 2,320 = 3.59, P = .03) and symptom change scores (F 2,315 = 5.17, P = .006), with the postpolicy group having faster symptom resolution over time. No group differences were observed for persisting symptoms. Conclusions: Earlier rehabilitation initiation occurred as intended following an institutional policy change, which had small, but significant, effects on recovery outcomes in youth with concussion. Health care providers should adopt policies to encourage early active rehabilitation services after concussion.

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Fostering the Physical-Literacy Development of Individuals Experiencing Disability Through the Use of PLayTubs: A Pilot Study

Kiana Stacey, Nicholas Gosse, and Kyle Pushkarenko

Physical literacy (PL) is increasingly being implemented as a means for holistic development for children and youth. Despite this, children experiencing disabilities and their families continue to face barriers that impede participation in physical activities and subsequent PL development. To empower families to actively engage in their PL development, this study sought to provide an accessible, home- and play-based, parent-facilitated intervention, namely, PLayTubs. The purpose was to explore parents’ subjective understanding, involvement, and attitudes toward facilitating physical activity opportunities contributing to PL development through this intervention. Four parents with a child (<12 years old) diagnosed with a developmental impairment participated in a 10-week PLayTub experience. Data were collected via semistructured interviews with parents and their children. Making use of an interpretive description methodology and an ecological-dynamics conceptual framework, this study resulted in three themes: (a) a catalyst for autonomy, (b) more than just movement, and (c) an accessible alternative. Parents found that PLayTubs fostered autonomous participation and individual agency, enhanced connections and togetherness, and allowed for the creation of meaningful experiences with physical activity. These positive insights demonstrate the benefit of home-based interventions for this population and highlight the need for larger studies in the future.

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Immediate and Short-Term Effect of Scapula Retraction Exercises on Subacromial Space: Do We Have Enough Evidence in Patients With Subacromial Pain?

Leyla Eraslan, Ozan Yar, Gazi Huri, and Irem Duzgun

Context: Limited information exists regarding the immediate and short-term effects of scapula retraction exercises (SREs) on acromiohumeral distance (AHD) in subacromial pain syndrome (SPS). This study’s 2 main objectives were to investigate (1) the immediate effect of the SRE on AHD at varying shoulder abduction angles in patients with SPS and healthy controls and (2) the effect of the 8-week SRE program on AHD in patients with SPS. Design: Cross-sectional and pre–post intervention designs were utilized on this study. Methods: Twenty-one patients with SPS and age-matched healthy controls were included. First, AHD at 0°, 30°, 45°, 60°, and 90° of active shoulder abductions were recorded during (1) resting upper quadrant posture and (2) while participants were performing SREs. Patients then underwent an 8-week progressive SRE program. AHD measures, pain intensity (visual analog scale), and disability (Shoulder Pain and Disability Index) were recorded at baseline and 8 weeks. AHD were analyzed using mixed-model analyses of variance. Pain and disability were analyzed using paired samples t test. Results: The immediate effect of the SREs revealed a significant angle-by-exercise-by-group interaction for the AHD values (F 3,155 = 3.956, P = .009, η p 2 = .175 ). Pairwise comparisons yielded that the SRE increased AHD values in patients with SPS (P < .05), yet it did not affect healthy controls (P > .05). Besides, the SRE program revealed a significant angle-by-time interaction for the AHD values (F 3,054 = 9.476, P < .001, η p 2 = .195 ). AHD increased at all elevation angles, and pain and disability improved over time (P < .05). Conclusion: SREs immediately affect AHD in patients with SPS but not in healthy populations. Moreover, SREs applied in progressive abduction angles improve pain, functionality, and AHD values in patients with SPS.

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Loaded Open Kinetic Chain Exercises Caused More Anterior Tibial Translation and Anteromedial Graft Elongation Than Closed Kinetic Chain Following Double-Bundle Anterior Cruciate Ligament Reconstruction

Ling Zhang, Yangyang Yang, Chunjie Xia, Cong Wang, Jiayu Qiu, Jiebo Chen, Tsung-Yuan Tsai, Jinzhong Zhao, and Shaobai Wang

Context: To further improve rehabilitation programs while preventing overstretching the anterior cruciate ligament (ACL), a thorough understanding of the knee kinematics and ACL length change during closed kinetic chain and open kinetic chain (OKC) exercises is essential. The measurement of ACL graft length relates to the changes in strain experienced by the ACL graft during different types of exercises rather than simple physical length. Objective: This study aimed to determine the effects of closed kinetic chain and OKC exercises on tibiofemoral kinematics and ACL graft length changes following double-bundle ACL reconstruction. Design: Cohort study (diagnosis); level of evidence, 3. Setting: Laboratory. Patients: Fifteen patients who underwent double-bundle ACL reconstruction were asked to perform 10-kg loaded seated knee extension (OKC-10) and single-leg lunge. During the seated knee extension, patients were instructed to extend and flex the knee within a range of 0° to 90° of flexion, with a 10-kg load applied to the ankle. For the lunge, patients began in a natural standing position and were instructed to flex the ACL-reconstructed knee to approximately 90°. Interventions: The 3-dimensional tibiofemoral kinematics under different weight-bearing conditions were determined using a dual-fluoroscopic imaging system. Main Outcome Measures: The tibiofemoral kinematics in 6 degrees-of-freedom were measured. And 3-dimensional ligament simulation technique was used to quantify length changes of the anteromedial bundle and posterolateral bundle. Results: The tibia exhibited significantly more external rotation during the OKC-10 motion than during the single-leg lunge from 35° to 70° of knee flexion (P ≤ .028). Beyond 30° of knee flexion, the tibia exhibited significantly more varus during the OKC-10 motion than during the single-leg lunge (P ≤ .028). And a significantly more anterior tibial translation was observed during the OKC-10 motion than during the lunge from 0° to 15° of flexion (P ≤ .018). The anteromedial bundle length was significantly longer during the OKC-10 motion than during the lunge between 0° and 25° of knee flexion (P ≤ .028). Conclusions: The effects of OKC exercises with loads on knee rotational stability should be considered in making rehabilitation programs for patients after ACL reconstruction. Since some degree of anterior tibial translation is physiological, it is important to note that increased translation alone does not necessarily indicate danger or instability.

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Peak Weight Acceptance, Mid Stance Trough, and Peak Push-Off Force Symmetry Are Decreased in Older Adults Compared With Young Adults

Theresa L. Libera, Jill Streamer, and Robin M. Queen

Gait abnormalities affect an individual’s ability to navigate the world independently and occur in 10% of older adults. Examining age-related gait symmetry in nonlaboratory environments is necessary for understanding mobility limitations in older adults. This study examined gait symmetry differences between older and younger adults using in-shoe force sensors. Walking trials were performed at a preferred speed. This is a secondary analysis of data from different studies in which young adults completed 7 trials and older adults completed 3 trials to decrease the impact of fatigue on outcomes in the clinical trial. Peak weight acceptance, mid stance trough, peak push-off, stance time, and impulse were collected during each step within a trial. Symmetry was determined using the absolute symmetry index. A linear mixed effects model showed a significant difference in peak weight acceptance force (P = .039), mid stance trough (P < .001), and peak push-off (P = .007) symmetry between groups. These results indicate that older adults have lower symmetry in peak weight acceptance, mid stance trough, and peak push-off during gait compared with young adults. Understanding how natural loading patterns change throughout life could improve our understanding of how load and load symmetry relate to mobility impairments in older adults.

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Relationship of Age and Running Biomechanics in Female Recreational Runners

Heather M. Hamilton, Hunter J. Bennett, Mira Mariano, and Rumit Singh Kakar

Middle-age and older runners demonstrate differences in running biomechanics compared with younger runners. Female runners demonstrate differences in running biomechanics compared with males, and females experience hormonal changes during menopause that may also affect age-related changes in running biomechanics. The purpose of this study was to determine the relationship between age and running biomechanics in healthy female recreational runners. Fifty-two participants (ages 27–65 y) ran on an instrumented treadmill at 2 different self-selected speeds: easy pace and 5 km race pace. Lower-extremity kinematic and kinetic variables were calculated from 14 consecutive strides. Linear regression was used to determine the relationship between age and lower-extremity running biomechanics, controlling for self-selected running speed. There was a negative relationship between age and easy pace (R = −.49, P < .001) and age and 5 km race pace (R = −.43, P = .001). After controlling for self-selected running speed, there were no significant relationships between age and running biomechanics for either running speed. Several biomechanical variables were moderately to strongly correlated with running speed. Running speed should be considered when investigating age-related differences in running biomechanics.

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What Is in a Name? Depression and Anxiety Symptoms in Collegiate Athletes With and Without a History of Concussion

Hilary S. Dunbar, Catherine C. Donahue, Luzita Vela, Jason Freeman, and Jacob E. Resch

Context: Athletes with a history of concussion (CON) have been demonstrated to have heightened levels of anxiety and depression that may continue well beyond the resolution of concussion symptoms. The global events of 2020 resulted in elevated levels of anxiety and depression in the general population, which may have unequally presented in collegiate athletes with (CON) than those without a history of concussion (NoCON). Using a deception design, our survey-based study compared levels of anxiety and depression in CON and NoCON collegiate athletes in response to the pandemic and social injustices. We hypothesized that the CON group would have significantly elevated anxiety and depression as compared to the NoCON group in response to events of 2020. Design and Methods: Collegiate athletes (N = 106) during the academic 2020–2021 academic year were divided into CON and NoCON groups based on their preinjury (baseline) concussion assessment. Participants completed the Social Readjustment Rating Scale (SSRS), Center for Epidemiologic Studies Depression Scale (CES-D), and Generalized Anxiety Disorder Scale-7 (GAD-7) via an electronic survey pertaining to the events of 2020. The term “concussion” was not used in any study materials which was the basis for our deception-based design. An analysis of covariance was used to compare group CES-D and GAD-7 outcome scores while controlling for the SSRS outcome score. Results: Our survey response rate was 14.2% (48/337 [77.1% female]) and 10.1% (58/580 [67.2% female]), for the NoCON and CON groups, respectively. The NoCON group had significantly (F 1 = 5.82, P = .018, η p 2 = .06 ) higher anxiety (8.3 [5.89]) as compared to the CON group (5.5 [2.85]). The NoCON group also had significantly (F 1 = 13.7, P < .001, η p 2 = .12 ) higher levels of depression (21.0 [12.52]) as compared to the CON group (16.07 [9.10]). Discussion: Our deception-based study revealed NoCON participants had elevated and clinically relevant mood states as compared to CON participants in response to the events of 2020.