Innovations in the Assessment of Skeletal Muscle Health: A Glimpse into the Future.

Skeletal muscle is the largest organ system in the human body and plays critical roles in athletic performance, mobility, and disease pathogenesis. Despite growing recognition of its importance by major health organizations, significant knowledge gaps remain regarding skeletal muscle health and its crosstalk with nearly every physiological system. Relevant public health challenges like pain, injury, obesity, and sarcopenia underscore the need to accurately assess skeletal muscle health and function. Feasible, non-invasive techniques that reliably evaluate metrics including muscle pain, dynamic structure, contractility, circulatory function, body composition, and emerging biomarkers are imperative to unraveling the complexities of skeletal muscle. Our concise review highlights innovative or overlooked approaches for comprehensively assessing skeletal muscle in vivo. We summarize recent advances in leveraging dynamic ultrasound imaging, muscle echogenicity, tensiomyography, blood flow restriction protocols, molecular techniques, body composition, and pain assessments to gain novel insight into muscle physiology from cellular to whole-body perspectives. Continued development of precise, non-invasive tools to investigate skeletal muscle are critical in informing impactful discoveries in exercise and rehabilitation science.

Exercise induced hypoalgesia during different intensities of a dynamic resistance exercise: A randomized controlled trial.

INTRODUCTION: Exercise produces an immediate lessening of pain sensitivity (Exercise-Induced Hypoalgesia (EIH)) in healthy individuals at local and distant sites, possibly through a shared mechanism with conditioned pain modulation (CPM). Dynamic resistance exercise is a recommended type of exercise to reduce pain, yet limited research has examined the effects of intensity on EIH during this type of exercise. Therefore, the primary purpose of this study is to compare changes in PPT at a local and distant site during a leg extension exercise at a high intensity, a low intensity, or a quiet rest condition. A secondary purpose is to examine if CPM changes after each intervention. The final purpose is to examine if baseline pain sensitivity measures are correlated with response to each intervention. METHODS: In a randomized controlled trial of 60 healthy participants, participants completed baseline pain sensitivity testing (heat pain threshold, temporal summation, a cold pressor test as measure of CPM) and were randomly assigned to complete a knee extension exercise at: 1) high intensity (75% of a 1 Repetition Maximum (RM), 2) low intensity (30% 1RM), or 3) Quiet Rest. PPT was measured between each set at a local (quadriceps) and distant (trapezius) site during the intervention. CPM was then repeated after the intervention. To test the first purpose of the study, a three-way ANOVA examined for time x site x intervention interaction effects. To examine for changes in CPM by group, a mixed-model ANOVA was performed. Finally, a Pearson Correlation examined the association between baseline pain sensitivity and response to each intervention. RESULTS: Time x site x intervention interaction effects were not significant (F(5.3, 150.97) = 0.87, p = 0.51, partial eta2 = 0.03). CPM did not significantly change after the interventions (time x intervention F(1,38) = 0.81, p = 0.37, partial eta2 = 0.02. EIH effects at the quadriceps displayed a significant, positive moderate association with baseline HPT applied over the trapezius (r = 0.61, p<0.01) and TS (r = 0.46, p = 0.04). DISCUSSION: In healthy participants, PPT and CPM did not significantly differ after a leg extension exercise performed at a high intensity, low intensity, or quiet rest condition. It is possible pre-intervention CPM testing with a noxious stimuli may have impaired inhibitory effects frequently observed during exercise but future research would need to examine this hypothesis.

"Figuring out your place at a school like this:" Intersectionality and sense of belonging among STEM and non-STEM college students.

BACKGROUND: Students' sense of belonging in college-an individual's feelings of contentment, mattering, importance, and "finding one's place" in a social setting-can influence choice of major and career trajectory. We contribute to the belongingness literature through a mixed methods intersectional study of students attending a STEM-focused public university we call Meadow State University (MSU). We assess the potential for students' intersecting social identities to differentially influence their experiences with intersectional oppression-subjection to multiple systems of oppression due to simultaneous membership in more than one marginalized group-that, in turn, may influence their college pathways. In addition, we explore whether intersectional differences affect sense of belonging differently in STEM and non-STEM majors. We employ a mixed-methods approach, informed by critical quantitative methods and in-depth interviews. We utilize quantitative institutional data measuring college satisfaction, expressed as "willingness to return" to the same university, for over 3,000 students during two academic years (2013-14 and 2016-17). Survey data explores college satisfaction as an indicator of intersectional differences in student experiences. Then, we analyze 37 in-depth interviews, collected between 2014-2016 at the same institution, to further contextualize the intersectional variation suggested by survey results. RESULTS: Willingness to return is influenced by major, as well as academic, social, and campus belonging. Moreover, the extent to which these factors affected outcomes additionally varied by race/ethnicity, gender, family income, other background factors, and the ways these factors may intersect. Important components of academic belonging included faculty-student interactions, perceptions of academic support, and a privileging of STEM degree programs and students over non-STEM students and their degree programs at MSU. Faculty responsiveness and high impact practices like internships played an important role, particularly in STEM programs. Taken together, our findings demonstrate that, particularly for students of color and those subject to intersectional oppression due to multiple marginalized identities, satisfaction with academics did not always outweigh deficiencies in other areas of campus life shaping belongingness. CONCLUSIONS: Our mixed-methods approach contributes insights into how and why students' background, individual choices, and institutional practices concurrently-and intersectionally-influence their ability to form a sense of belonging on campus. Structural changes are required to end practices that support intersecting systems of oppression by favoring White, upper-income men as the "default" STEM students in the U.S. Our research supports growing evidence that institutions must actively build models of inclusion for underrepresented and marginalized groups that address inequitable and unjust practices, providing transformative mentoring and educational guidance that attends to intersectional oppression, in order to effectively support the next generation of women and scholars of color.

Biopsychosocial contributors to irritability in individuals with shoulder or low back pain.

OBJECTIVES: Irritability is a foundational clinical reasoning concept in rehabilitation to evaluate reactivity of the examination and treatment. While originally theorized to reflect tissue damage, a large body of evidence supports pain is a biopsychosocial experience impacted by pain sensitivity and psychological factors. Therefore, the purpose of this study was to examine biopsychosocial contributors to irritability. METHODS: 40 patients with shoulder (n = 20) and low back (n = 20) pain underwent Quantitative Sensory Testing (QST) (Pressure Pain Threshold, Heat Pain Threshold, Conditioned Pain Modulation, Temporal Summation), completed pain-related psychological questionnaires, an Exercise-Induced Hypoalgesia protocol, and standardized irritability assessment based on Clinical Practice Guidelines. Participants were then categorized as irritable or not irritable based on Maitland's criteria and by irritability level based on Clinical Practice Guidelines. An independent samples t-test examined for differences in QST and psychological factors by irritability category. A MANOVA examined for differences in QST and psychological factors by irritability level (high, moderate, low). RESULTS: Significantly lower heat and pressure pain thresholds at multiple locations (p < 0.05), as well as less efficient conditioned pain modulation (p = 0.02), were demonstrated in individuals categorized as irritable. Heat and pressure pain thresholds were also significantly lower in patients with high irritability compared to other levels. Significantly higher depression and anger, as well as lower self-efficacy, were reported in individuals with an irritable presentation. DISCUSSION/CONCLUSION: Biopsychosocial factors, including widespread hyperalgesia and elevated psychological factors, may contribute to an irritable presentation.

Improving primary care access for rural women Veterans: the Boost Team.

Objectives: To improve healthcare access for rural cisgender women and gender diverse Veterans, we created the "Boost Team," a clinician-driven telehealth outreach service to connect this population to Veterans Health Administration (VHA) services. Methods: Between 9/2021 and 2/2022, we conducted a needs assessment in the Veterans Integrated Service Network (VISN) 21 and used those data to develop an outreach intervention. We piloted a clinician-led outreach intervention in 3/2022, and formally deployed an outreach team in 9/2022. Results: The needs assessment uncovered opportunities to educate Veterans, staff, and clinicians about available VHA women's health services, and a need for easily-accessible gender-sensitive services. During the pilot, 58% (7/12) rural cisgender women Veterans were successfully contacted, all reported positive experiences with the intervention. The formal outreach team launched in 9/2022 and consists of a nurse practitioner (NP), scheduler, Peer Support Specialist, and medical director. From 9/2022 to 12/2022 the Boost NP called 110 rural cisgender women and gender diverse Veterans and spoke to 65 (59%) of them. Common care needs identified and addressed included care coordination, new referrals, medication management, and diagnostics. Discussion: Data from Boost show that clinician-led outreach can engage rural cisgender women and gender diverse Veterans in VHA services, there is a desire for more gender-sensitive services, and there is a need for systems-level improvements to allow for improved care coordination and decreased leakage outside of VHA. Using robust strategies grounded in implementation sciences, we will continue conducting a program evaluation to study the impact of Boost and scale and expand the program.

Through the Lens of Movement-Evoked Pain: A Theoretical Framework of the "Pain-Movement Interface" to Guide Research and Clinical Care for Musculoskeletal Pain Conditions.

Over 120 million Americans report experiencing pain in the past 3 months. Among these individuals, 50 million report chronic pain and 17 million report pain that limits daily life or work activities on most days (ie, high-impact chronic pain). Musculoskeletal pain conditions in particular are a major contributor to global disability, health care costs, and poor quality of life. Movement-evoked pain (MEP) is an important and distinct component of the musculoskeletal pain experience and represents an emerging area of study in pain and rehabilitation fields. This focus article proposes the "Pain-Movement Interface" as a theoretical framework of MEP that highlights the interface between MEP, pain interference, and activity engagement. The goal of the framework is to expand knowledge about MEP by guiding scientific inquiry into MEP-specific pathways to disability, high-risk clinical phenotypes, and underlying individual influences that may serve as treatment targets. This framework reinforces the dynamic nature of MEP within the context of activity engagement, participation in life and social roles, and the broader pain experience. Recommendations for MEP evaluation, encompassing the spectrum from high standardization to high patient specificity, and MEP-targeted treatments are provided. Overall, the proposed framework and recommendations reflect the current state of science in this emerging area of study and are intended to support future efforts to optimize musculoskeletal pain management and enhance patient outcomes. PERSPECTIVE: Movement-evoked pain (MEP) is a distinct component of the musculoskeletal pain experience and emerging research area. This article introduces the "Pain-Movement Interface" as a theoretical framework of MEP, highlighting the interface between MEP, pain interference, and activity engagement. Evaluating and treating MEP could improve rehabilitation approaches and enhance patient outcomes.

Modulation of a critical period for motor development in Drosophila by BK potassium channels.

Critical periods are windows of heightened plasticity occurring during neurodevelopment. Alterations in neural activity during these periods can cause long-lasting changes in the structure, connectivity, and intrinsic excitability of neurons, which may contribute to the pathology of neurodevelopmental disorders. However, endogenous regulators of critical periods remain poorly defined. Here, we study this issue using a fruit fly (Drosophila) model of an early-onset movement disorder caused by BK potassium channel gain of function (BK GOF). Deploying a genetic method to place robust expression of GOF BK channels under spatiotemporal control, we show that adult-stage neuronal expression of GOF BK channels minimally disrupts fly movement. In contrast, limiting neuronal expression of GOF BK channels to a short window during late neurodevelopment profoundly impairs locomotion and limb kinematics in resulting adult flies. During this critical period, BK GOF perturbs synaptic localization of the active zone protein Bruchpilot and reduces excitatory neurotransmission. Conversely, enhancing neural activity specifically during development rescues motor defects in BK GOF flies. Collectively, our results reveal a critical developmental period for limb control in Drosophila that is influenced by BK channels and suggest that BK GOF causes movement disorders by disrupting activity-dependent aspects of synaptic development.

Task-specific resistance training adaptations in older adults: comparing traditional and functional exercise interventions.

Muscle strength declines ∼3% per year after the age of 70. Resistance training guidelines for older adults are often based on free-weight and machine exercises, which may be inaccessible and lack carryover to activities of daily living. We tested the hypothesis that resistance training adaptations in older adults are task-specific. Thirty adults (8 males, 22 females; mean age = 71 years) were randomly assigned to participate in 6 weeks of supervised, high-intensity resistance training (twice per week) utilizing free-weight and machine exercises (traditional) versus functional activities that were overloaded with a weighted vest (functional). Participants were thoroughly familiarized with the exercises and testing prior to beginning the study. Major outcome measures included assessments of functional performance, five-repetition maximum strength, isometric knee extensor force, and quadriceps muscle size. Physical activity and nutrition were monitored. The study results demonstrate that the magnitude of improvement within a given outcome was largely dependent on group assignment, with greater improvements in gait speed and the timed-up-and-go in the functional group, but 2-3× greater five repetition maximum strength improvements for the trap bar deadlift, leg press, and leg extension following traditional resistance training. Both groups showed improvements in isometric knee extensor force and muscle size, suggesting that some aspects of the observed adaptations were generic, rather than specific. Overall, these novel findings suggest that, among older adults, 1) resistance training adaptations exhibit a high degree of task specificity and 2) significant improvements in functional outcomes can be achieved with the use of a weighted vest.