Arterial function in response to a 50 km ultramarathon in recreational athletes.

This study was performed to determine whether prolonged endurance running results in acute endothelial dysfunction and wave-reflection, as endothelial dysfunction and arterial stiffness are cardiovascular risk factors. Vascular function (conduit artery/macrovascular and resistance artery/microvascular) was assessed in 11 experienced runners (8 males, 3 females) before, during and after a 50 km ultramarathon. Blood pressure (BP), heart rate (HR), wave reflection, augmentation index (AIx) and AIx corrected for HR (AIx75) were taken at all time points-Baseline (BL), following 10, 20, 30 and 40 km, 1 h post-completion (1HP) and 24 h post-completion (24HP). Flow-mediated dilatation (FMD) and inflammatory biomarkers were examined at BL, 1HP and 24HP. Reactive hyperaemia area under the curve (AUC) and shear rate AUC to peak dilatation were lower (∼75%) at 1HP compared with BL (P < 0.001 for both) and reactive hyperaemia was higher at 24HP (∼27%) compared with BL (P = 0.018). Compared to BL, both mean central systolic BP and mean central diastolic BP were 7% and 10% higher, respectively, following 10 km and 6% and 9% higher, respectively, following 20 km, and then decreased by 5% and 8%, respectively, at 24HP (P < 0.05 for all). AIx (%) decreased following 20 km and following 40 km compared with BL (P < 0.05 for both) but increased following 40 km when corrected for HR (AIx75) compared with BL (P = 0.02). Forward wave amplitude significantly increased at 10 km (15%) compared with BL (P = 0.049), whereas backward wave reflection and reflected magnitude were similar at all time points. FMD and baseline diameter remained similar. These data indicate preservation of macrovascular (endothelial) function, but not microvascular function resulting from the 50 km ultramarathon.

The effects of myosteatosis on skeletal muscle function in older adults.

Myosteatosis, or the infiltration of fatty deposits into skeletal muscle, occurs with advancing age and contributes to the health and functional decline of older adults. Myosteatosis and its inflammatory milieu play a larger role in adipose tissue dysfunction, muscle tissue dysfunction, and increased passive muscle stiffness. Combined with the age-related decline of sex hormones and development of anabolic resistance, myosteatosis also contributes to insulin resistance, impaired muscle mechanics, loss of force production from the muscle, and increased risk of chronic disease. Due to its highly inflammatory secretome and the downstream negative effects on muscle metabolism and mechanics, myosteatosis has become an area of interest for aging researchers and clinicians. Thus far, myosteatosis treatments have had limited success, as many lack the potency to completely rescue the metabolic and physical consequences of myosteatosis. Future research is encouraged for the development of reliable assessment methods for myosteatosis, as well as the continued exploration of pharmacological, nutritional, and exercise-related interventions that may lead to the success in attenuating myosteatosis and its clinical consequences within the aging population.

An exercise stress test for contrast-enhanced duplex ultrasound assessment of lower limb muscle perfusion in patients with peripheral arterial disease.

OBJECTIVE: The aim of the present study was to develop a standardized contrast-enhanced duplex ultrasound (CE-DUS) protocol to assess lower-extremity muscle perfusion before and after exercise and determine relationships of perfusion with clinical and functional measures. METHODS: CE-DUS (EPIQ 5G, Philips) was used before and immediately after a 10-minute, standardized bout of treadmill walking to compare microvascular perfusion of the gastrocnemius muscle in older (55-82 years) patients with peripheral arterial disease (PAD) (n = 15, mean ankle-brachial index, 0.78 ± 0.04) and controls (n = 13). Microvascular blood volume (MBV) and microvascular flow velocity (MFV) were measured at rest and immediately following treadmill exercise, and the Modified Physical Performance Test (MPPT) was used to assess mobility function. RESULTS: In the resting state (pre-exercise), MBV in patients with PAD was not significantly different than normal controls (5.17 ± 0.71 vs 6.20 ± 0.83 arbitrary units (AU) respectively; P = .36); however, after exercise, MBV was ∼40% lower in patients with PAD compared with normal controls (5.85 ± 1.13 vs 9.53 ± 1.31 AU, respectively; P = .04). Conversely, MFV was ∼60% higher in patients with PAD compared with normal controls after exercise (0.180 ± 0.016 vs 0.113 ± 0.018 AU, respectively; P = .01). There was a significant between-group difference in the exercise-induced changes in both MBV and MFV (P ≤ .05). Both basal and exercise MBV directly correlated with MPPT score in the patients with PAD (r = 0.56-0.62; P < .05). CONCLUSIONS: This standardized protocol for exercise stress testing of the lower extremities quantifies calf muscle perfusion and elicits perfusion deficits in patients with PAD. This technique objectively quantifies microvascular perfusion deficits that are related to reduced mobility function and could be used to assess therapeutic efficacy in patients with PAD.

Muscle Properties, Gross Motor Performance, and Quality of Life in Children With Sickle Cell Disease.

PURPOSE: To explore muscle properties, gross motor performance, and quality of life (QoL) in children with sickle cell disease (SCD) compared with controls and to assess relationships among these outcomes. METHODS: A cross-sectional study of 24 children assessed muscle properties including: knee extension strength by dynamometry; vastus lateralis (VL) and rectus femoris (RF) muscle thickness by ultrasonography; and VL and RF neuromuscular activation (rate of muscle activation [RoA]) by electromyography (EMG). Gross motor performance and QoL were assessed by standardized tests and questionnaires. RESULTS: Children with SCD had impaired knee extension strength, VL EMG RoA, gross motor performance, and QoL compared with children without SCD. Relationships among muscle properties, gross motor performance, and QoL were identified. CONCLUSIONS: These findings indicate that comprehensive muscle properties, gross motor performance, and QoL assessments should be considered to support and develop individualized physical therapy plans for children with SCD.

Associations between social isolation and diet quality among US adults with disability participating in the National Health and Nutrition Examination Survey, 2013-2018.

Social isolation and disability are established risk factors for poor nutrition. We aimed to assess whether social isolation is associated with diet quality specifically among adults with disabilities. This cross-sectional analysis used data from the National Health and Nutrition Examination Survey, 2013-2018. Adults with a disability, who were not pregnant, breastfeeding, or missing dietary intake data were included (n = 5,167). Disability was defined as a physical functioning limitation based on difficulty with any activities of daily living, instrumental activities of daily living, lower extremity mobility activities, or general physical activities. The Healthy Eating Index (HEI)-2015 measured diet quality; higher scores correspond to higher diet quality. We computed a social isolation index by summing single status, living alone, and two social engagement difficulty measures (one point for each component met; maximum 4 points). Multivariable linear regression, controlling for demographic and health covariates, estimated differences in HEI scores for dietary intake data, by social isolation score. Over half of HEI scores were < 51, corresponding to "poor" diet quality. Higher social isolation score was associated with lower vegetable and seafood/plant proteins intake. Single status and one of two social engagement measures were associated with lower scores on certain adequacy components. Differences were modest. There was little evidence of effect modification by age or gender. Adults with disabilities are not meeting national dietary standards; improving diet quality is a priority. Whether social isolation is associated with specific dietary components in this population requires further investigation. Further research is also needed among younger adults.

Prevalence and socio-economic determinates of food insecurity in Veterans: findings from National Health and Nutrition Examination Survey.

OBJECTIVE: To determine predictors of the association between being a Veteran and adult food security, as well as to examine the relation of potential covariates to this relationship. DESIGN: Data collected during 2011-2012, 2013-2014 and 2015-2016 National Health and Nutrition Examination Survey (NHANES) were pooled for analyses. Veterans (self-reported) were matched to non-Veterans on age, race/ethnicity, sex and education. Adjusted logistic regression was used to determine the odds of Veterans having high food security v. the combination of marginal, low and very low food security compared with non-Veterans. SETTING: 2011-2012, 2013-2014 and 2015-2016 NHANES. PARTICIPANTS: 1227 Veterans; 2432 non-Veterans. RESULTS: Veteran status had no effect on the proportion of food insecurities between Veterans and non-Veterans reporting high (Veterans v. non-Veteran: 79 % v. 80 %), marginal (9 % v. 8 %), low (5 % v. 6 %) and very low (8 % v. 6 %) food security (P = 0·11). However, after controlling for covariates, Veterans tended to be less likely to have high food security (OR: 0·82 (95 % CI 0·66, 1·02), P = 0·07). Further, non-Hispanic White Veterans (OR: 0·72 (95 % CI 0·55, 0·95), P = 0·02) and Veterans completing some college (OR: 0·71 (95 % CI 0·50, 0·99), P < 0·05) were significantly less likely to experience high food security compared with non-Veterans. CONCLUSION: This study supports previous research findings that after controlling for covariates, Veterans tend to be less likely to have high food security. It also highlights ethnicity and level of education as important socio-economic determinates of food security status in Veterans.

Skeletal Muscle Measurements in Pediatric Hematology and Oncology: Essential Components to a Comprehensive Assessment.

Children with hematologic and oncologic health conditions are at risk of impaired skeletal muscle strength, size, and neuromuscular activation that may limit gross motor performance. A comprehensive assessment of neuromuscular function of these children is essential to identify the trajectory of changes in skeletal muscle and to prescribe therapeutic exercise and monitor its impact. Therefore, this review aims to (a) define fundamental properties of skeletal muscle; (b) highlight methods to quantify muscle strength, size, and neuromuscular activation; (c) describe mechanisms that contribute to muscle strength and gross motor performance in children; (d) recommend clinical assessment measures; and (e) illustrate comprehensive muscle assessment in children using examples of sickle cell disease and musculoskeletal sarcoma.

Quantifying muscle strength, size, and neuromuscular activation in adolescent and young adult survivors of musculoskeletal sarcoma: Identifying correlates and responses to functional strengthening.

BACKGROUND: Medical and surgical treatment for musculoskeletal sarcoma (MSS) place survivors at risk for impairments in muscle properties including muscle strength, muscle size, and neuromuscular activation. The purpose of this study was to explore muscle properties, gross motor performance, and quality of life (QoL) and the changes in response to a 6-week functional strengthening intervention (PT-STRONG) in MSS survivors of childhood cancer (CCS). METHODS: Eight lower extremity MSS CCS (13-23 years old) performed baseline testing and three completed PT-STRONG. Participants completed measurements of knee extension strength using handheld dynamometry, vastus lateralis (VL) and rectus femoris (RF) muscle thickness using ultrasonography at rest, and neuromuscular activation using electromyography during strength testing and a step-up task. Participants also completed gross motor and QoL assessments. RESULTS: Compared with the non-surgical limb, MSS CCS had lower surgical limb knee extension strength, VL muscle thickness, and RF step-up muscle rate of activation (RoA). Compared with normative values, MSS CCS had decreased bilateral knee extension strength, gross motor performance, and physical QoL. Positive correlations among muscle strength, muscle thickness, and gross motor performance were identified. After PT-STRONG, MSS CCS had improvements in VL muscle thickness, VL and RF RoA duing step-up, gross motor performance, and physical QoL. CONCLUSIONS: Positive association between larger muscle thickness with greater knee extension strength, and higher knee extension strength with better gross motor performance indicate that comprehensive physical therapy assessment and interventions that identify and target impairments in muscle properties to guide clinical decision making should be considered for MSS CCS into survivorship.

Muscle thickness and inflammation during a 50km ultramarathon in recreational runners.

PURPOSE: This study examined changes in circulating levels of inflammatory cytokines [IL-6, sIL-6R, TNF-α, and calprotectin], skeletal muscle morphology, and muscle strength following a 50km race in non-elite athletes. METHODS: Eleven individuals (8 men; 3 women) underwent pre-race assessments of rectus femoris muscle thickness (resting and contracted) using ultrasound, isometric knee extensor torque, and plasma cytokines. Measures were repeated after 10km of running, the 50km finish (post-race), and again 24-hrs post-race. RESULTS: Compared with baseline values, Δ muscle thickness (resting to contracted) increased significantly 24 hrs post-race (11 ± 11% vs. 22 ± 8%; P = 0.01). Knee extensor torque was significantly reduced immediately post-race (151 ± 46 vs. 134 ± 43 Nm; P = 0.047) but remained similar to post-race values at 24 hrs post-race (P = 0.613). Compared with pre-race levels, IL-6 and calprotectin concentrations increased 302% and 50% after 10km, respectively (P<0.017 for both), peaked post-race (2598% vs. pre-race for IL-6 and 68% vs. pre-race for calprotectin; P = 0.018 for both), and returned to pre-race levels at 24-hrs post-race (P>0.05 for both). Creatine kinase levels rose steadily during and after the race, peaking 24-hrs post-race (184 ± 113 U/L pre-race vs. 1508 ± 1815 U/L 24-hrs post-race; P = 0.005). CONCLUSION: This is the first report of delayed increases in Δ muscle thickness at 24 hrs post-50km, which are preceded by reductions in knee extensor torque and elevations in plasma IL-6, and calprotectin. Recreational athletes should consider the acute muscle inflammatory response when determining training and recovery strategies for 50km participation.

Rehabilitation Outcomes among Frail Older Adults in the United States.

BACKGROUND: Current rehabilitation care paradigms are not well aligned with the needs of frail older adults, but the resultant impact on rehabilitation outcomes is unclear. Understanding how frailty may impact rehabilitation outcomes, and understanding some of the underlying mechanisms, may help inform payment policy changes. DESIGN: This study was a cross-sectional analysis of data from Round 5 of the National Health and Aging and Trends Study (NHATS). We identified older adults who had completed one or more episodes of rehabilitation care and used a validated 5-item NHATS Fried Frailty scale to categorize patients as frail (3/5 or more) or non-frail (≤2/5). We then evaluated the association between frailty status and three key patient outcomes: (1) achievement of rehabilitation goals, (2) functional improvement during rehabilitation episodes, and (3) discontinuation of therapy after exhausting insurance benefits. Lastly, we used multivariable, survey-weighted logistic regression models to estimate adjusted relationships between frailty and rehabilitation outcomes. RESULTS: An estimated 5.6 million survey-weighted older adults in the United States (95% CI 5.1 to 6.0 million) completed an episode of rehabilitation in the past year, an estimated 1,271,290 (95% CI 921,758 to 1,620,822; weighted: 22.8%) of whom were frail. Frail rehabilitation recipients were generally older, had a greater comorbidity burden, and had a higher prevalence of dementia. In adjusted models, frailty was associated with poorer functional outcomes, a lower probability of meeting rehabilitation goals and a greater likelihood of exhausting rehabilitation insurance benefits. CONCLUSIONS: Exercise is a well-supported intervention for the management of frailty, but our results suggest that frail older adults are not getting the volume or intensity of rehabilitation treatment needed to maximally improve outcomes-in part due to limited payer coverage of rehabilitation services in the United States.

Geriatric Vulnerabilities Among Obese Older Adults With and Without Sarcopenia: Findings From a Nationally Representative Cohort Study.

BACKGROUND AND PURPOSE: Sarcopenic obesity is associated with loss of independence among older adults, but the epidemiology of sarcopenic obesity and associated geriatric vulnerabilities are poorly understood. Thus, our objectives were to: (1) estimate the prevalence of older adults with sarcopenic obesity and (2) examine rates of geriatric vulnerabilities among obese older adults, with and without sarcopenia. METHODS: A nationally representative sample of 1600 community-dwelling older adults 65 years and older with obesity and documented measures of muscle function from the National Health and Aging Trends Study (NHATS) was identified as sarcopenic using sex-adjusted grip strength and Short Physical Performance Battery scores. Differences in the prevalence of geriatric vulnerabilities (including pain, depression, disability, and social isolation) were compared between obese older adults with and without sarcopenia. RESULTS AND DISCUSSION: Among obese older adults, 18% (n = 318/1600) were sarcopenic. After adjusting for age and sex, sarcopenic obese older adults had 3.7 times the odds of having 2 or more comorbid conditions (odds ratio [OR] = 3.7; 95% CI 2.2-5.0) and 6.4 times the odds of being frail (OR = 6.4; 95% CI 4.4-9.5) as compared with nonsarcopenic obese older adults. Sarcopenic obese older adults were also more likely to have 1 or more activities of daily living disabilities (OR = 3.7; 95% CI 2.5-5.4), be socially isolated (OR = 2.1; 95% CI 1.3-3.2), and report activity-limiting pain (OR = 2.0; 95% CI 1.5-2.7) as compared with nonsarcopenic obese older adults. These findings, in a nationally representative cohort, suggest obese older adults who are sarcopenic have higher rates of geriatric vulnerabilities that could impact delivery and outcomes of exercise and nutrition interventions. CONCLUSIONS: Concomitant obesity and sarcopenia are associated with higher rates of geriatric vulnerabilities among a nationally representative sample of older adults. More comprehensive interventions, beyond exercise and diet modifications, may be necessary to additionally address these newly identified social and physiological risks.

Dietary Quality and Perceived Barriers to Weight Loss among Older Overweight Veterans with Dysmobility.

Healthier diets are associated with higher muscle mass and physical performance which may reduce the risk of developing frailty and disability later in life. This study examined the dietary quality and self-reported weight loss barriers among older (>60 years), overweight (BMI ≥ 25 kg/m2) Veterans with dysmobility (low gait speed, impaired mobility diagnosis, or a comorbidity that results in impaired mobility). Habitual dietary intake and healthy eating index (HEI-2015) were assessed using 24-h recalls and compared to US nationally representative dietary intake data and national recommendations. The "MOVE!11" Patient Questionnaire assessed weight loss barriers. The sample (n = 28) was primarily male (93%), black (54%) and obese (BMI = 35.5 ± 5.4 kg/m2) adults aged 69.5 ± 7.0 years with two or more comorbidities (82%); 82% were prescribed four or more medications. Daily intakes (mean ± SD) were calculated for total energy (2184 ± 645 kcals), protein (0.89 ± 0.3 g/kg), fruits (0.84 ± 0.94 cup·eq.), vegetables (1.30 ± 0.87 cup·eq.), and HEI-2015 (52.8 ± 13.4). Veterans consumed an average of 11% less protein than the recommendation for older adults (1.0 g/kg/d) and consumed fewer fruits and vegetables than comparisons to national averages (18% and 21%, respectively). Mean HEI-2015 was 17% below the national average for adults >65 years, suggesting poor dietary quality among our sample. Top weight loss barriers were not getting enough physical activity, eating too much and poor food choices. This data suggests that dietary quality is suboptimal in older, overweight Veterans with disability and highlights the need to identify strategies that improve the dietary intake quality of older Veterans who may benefit from obesity and disability management.

Ultrasound measures of muscle thickness and subcutaneous tissue from the hip abductors: Inter- and intra-rater reliability.

BACKGROUND: Ultrasound imaging is important in many fields such as medicine, sports, and health sciences to assess parts of muscle structure (e.g., muscle thickness [MT]) or composition (subcutaneous tissue [SubT]). OBJECTIVE: The aim of the present study was to investigate the intra- and inter-rater reliability of MT and SubT measurements of the hip abductor muscles gluteus medius (GM) and tensor fascia latae (TFL). DESIGN: Cross-sectional study. METHOD: Twenty young adults participated in the study. Intra-rater reliability was established by measuring the same two images twice by the same rater, while inter-rater reliability was assessed between two raters by measuring the same two images for each muscle. For both intra- and inter-rater reliability, the reliability of the TFL and GM outcomes (MT- SubT) were determined by the intraclass correlation coefficient (ICC), coefficient of variation (CV), standard error of the measurement (SEM), and Bland-Altman plots. RESULTS: For intra-rater reliability, variables of both muscles showed an excellent ICC (≥0.90), lower CV and SEM, and bias near zero. Inter-rater reliability also showed an excellent ICC for both variables and muscles (≥0.81) with lower CV, SEM, and bias. CONCLUSION: Therefore, these results provide strong evidence of a reliable measure of MT and SubT from GM and TFL. The present study provides health care professionals and researchers increased confidence in using 2D ultrasound to assess the hip abductors muscles reliably.

High-intensity functional exercise does not cause persistent elevations in augmentation index in young men and women.

Elevations in central augmentation index (AIx) are predictive of cardiovascular disease. The objective of this study was to examine AIx immediately and 24 h following an acute bout of high-intensity functional training (HIFT) in apparently healthy young adults. A second aim compared the exercise-induced AIx recovery response between men and women. Thirty-two recreationally active younger adults (n = 16 men) were tested. Baseline central hemodynamic measures were assessed, followed by a single bout of bodyweight HIFT. The HIFT included 4 rounds of burpees, jump squats, split squats, and walking lunges. Assessments were repeated 5, 10, 15, and 24 h post-exercise. AIx was normalized to a heart rate of 75 bpm (AIx75). There was a significant main effect of time on AIx75 across all groups (P < 0.001) with AIx75 increasing at all acute time points compared with baseline and returning to resting values 24 h post-exercise. When examining sex differences after covarying for height and body fat percentage, the authors found no time × sex interaction (P = 0.62), or main effect for sex (P = 0.41), but the significant main effect of time remained (P < 0.001). The AIx75 response to HIFT follows a similar recovery pattern as previously studied modes of exercise with no residual effects 24 h later and no differences between men and women indicating no persistent cardiovascular strain in younger adults participating in this mode of exercise.

Relationships between diaphragm ultrasound, spirometry, and respiratory mouth pressures in children.

Diaphragm ultrasound (DUS) is a noninvasive method of evaluating the diaphragm's structure and function. This study explored the relationships between DUS, spirometry, and respiratory mouth pressures in 10 healthy children (median age: 11 [range: 7-14 years]; 5 females, 5 males). Thickening fraction correlated with maximal inspiratory pressure (MIP) (Spearman's rho [rs] = 0.64, p = 0.05). During quiet breaths, excursion time correlated with MIP (rs = 0.78, p = 0.01) while velocity correlated with maximal expiratory pressure (rs = -0.82, p = 0.01). During deep breaths, MIP correlated with excursion (rs = 0.64, p = 0.05) and time (rs = 0.87, p = 0.01). Excursion time during deep breaths also correlated with forced vital capacity (rs = 0.65, p = 0.04). Our findings suggest that DUS parameters are closely related to spirometry and respiratory mouth pressures in healthy children and further support the use of DUS as a noninvasive method of respiratory assessment.

Intervention in Older Urban-Dwelling Veterans With Dysmobility: Protocol for a Pilot Feasibility Clinical Trial.

BACKGROUND: The majority of older veterans do not meet the minimum healthy diet or physical activity recommendations despite known benefits. Identifying ways to increase adherence to programs that improve dietary quality and physical activity may reduce the risk of disability in older veterans. Peer-based interventions may be one method for facilitating lasting behavior change because peers often share a common culture and knowledge regarding problems their community experiences. OBJECTIVE: This study aims to develop, pilot, and evaluate a theory-driven, 12-week, peer-led nutrition and exercise intervention that targets older veterans with dysmobility and assess its feasibility in 2 diverse urban areas with underrepresented populations. METHODS: Community-dwelling veterans aged >65 years with self-reported dysmobility (defined as difficulty in at least 1 of the following: walking quickly across a street, walking a mile, ascending a flight of stairs, rising from a chair without the use of arms, or a fear of falling) from 2 Department of Veterans Affairs Geriatric Research, Education, and Clinic Centers (Baltimore, Maryland, and San Antonio, Texas) will be eligible to participate. First, this study will use validated mixed methods via web-based surveys (n=50 per site) to assess potential physical, social or environmental, and behavioral or lifestyle barriers that affect physical activity and dietary quality (phase 1). Next, we will use knowledge gained from these assessments and feedback from a focus group (n=10 per site) to adapt established Department of Veterans Affairs diet and exercise program materials to develop peer-led intervention materials and train peer leaders (n=3 per site). Finally, we will determine the feasibility and acceptability of the intervention to assess reach (recruitment and retention), adoption (satisfaction, perceived utility, attendance, and engagement), and implementation (fidelity of intervention), as well as the estimated magnitude and potential impact on selected outcomes (ie, diet quality and mobility) in 20 older veterans with dysmobility (n=10 per site). RESULTS: The study was funded on January 1, 2022, with a projected data collection period of June 1, 2022, to December 31, 2023. CONCLUSIONS: This study offers an innovative approach to identifying strategies that increase long-term adherence to lifestyle modification programs that improve dietary quality and physical activity in older veterans with dysmobility. TRIAL REGISTRATION: ClinicalTrials.gov NCT04994938; https://clinicaltrials.gov/ct2/show/NCT04994938. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/39192.

Systematic Review of the Importance of Hip Muscle Strength, Activation, and Structure in Balance and Mobility Tasks.

OBJECTIVE: The aim of this systematic review was to identify the associations of the hip abductor muscle strength, structure, and neuromuscular activation on balance and mobility in younger, middle-aged, and older adults. DATA SOURCES: We followed PRISMA guidelines and performed searches in PubMed, Embase, CINAHL, and Physiotherapy Evidence Database. STUDY SELECTION: Study selection included: (1) studies with patients aged 18 years or older and (2) studies that measured hip abduction torque, surface electromyography, and/or muscle structure and compared these measures with balance or mobility outcomes. DATA EXTRACTION: The extracted data included the study population, setting, sample size, sex, and measurement evaluated. DATA SYNTHESIS: The present systematic review is composed of 59 research articles including a total of 2144 young, middle-aged, and older adults (1337 women). We found that hip abductor strength is critical for balance and mobility function, independent of age. Hip abductor neuromuscular activation is also important for balance and mobility, although it may differ across ages depending on the task. Finally, the amount of fat inside the muscle appears to be one of the important factors of muscle structure influencing balance. CONCLUSIONS: In conclusion, a change in all investigated variables (hip abduction torque, neuromuscular activation, and intramuscular fat) appears to have an effect during balance or mobility tasks across age ranges and may elicit better performance. Future studies are necessary to confirm the effect of these variables across age ranges and the effects of interventions.

Hip Abductor and Adductor Rate of Torque Development and Muscle Activation, but Not Muscle Size, Are Associated With Functional Performance.

Understanding the physiological variables that contribute to a functional task provides important information for trainers and clinicians to improve functional performance. The hip abductors and adductors muscles appear to be important in determining the performance of some functional tasks; however, little is known about the relationship of the hip abductor/adductors muscle strength, activation, and size with functional performance. This study aimed to investigate the relationship of maximum torque, rate of torque development (RTD), rate of activation (RoA), and muscle thickness of the hip abductors [tensor fascia latae (TFL) and gluteus medius (GM)] and adductor magnus muscle with the Four Square Step Test (FSST) and the two-leg hop test in healthy young adults. Twenty participants (five males) attended one testing session that involved ultrasound image acquisition, maximal isometric voluntary contractions (hip abduction and hip adduction) while surface electromyography (EMG) was recorded, and two functional tests (FSST and two-leg side hop test). Bivariate correlations were performed between maximum voluntary torque (MVT), RTD at 50, 100, 200, and 300ms, RoA at 0-50, 0-100, 0-200, and 0-300, and muscle thickness with the dynamic stability tests. For the hip abduction, MVT (r=-0.455, p=0.044) and RTD300 (r=-0.494, p=0.027) was correlated with the FSST. GM RoA50 (r=-0.481, p=0.032) and RoA100 (r=-0.459, p=0.042) were significantly correlated with the two-leg side hop test. For the hip adduction, there was a significant correlation between the FSST and RTD300 (r=-0.500, p=0.025), while the two-leg side hop test was correlated with RTD200 (r=0.446, p=0.049) and RTD300 (r=0.594, p=0.006). Overall, the ability of the hip abductor and adductor muscles to produce torque quickly, GM rapid activation, and hip abductor MVT is important for better performance on the FSST and two-leg hop tests. However, muscle size appears not to influence the same tests.

Assessing the Reliability of Handheld Dynamometry and Ultrasonography to Measure Quadriceps Strength and Muscle Thickness in Children, Adolescents, and Young Adults.

Aims: Muscle strength testing is a core aspect in the pediatric physical and occupational therapy clinical examination and evaluation, and quadriceps muscle strength is associated with the ability to perform gross motor skills. The aim of this study was to assess the reliability of handheld dyamometry (HHD) and ultrasonography to measure quadriceps muscle strength and thickness in children, adolescents, and young adults. Methods: In 30 participants (6-26 years), without motor impairment, quadriceps strength was measured with HHD in seated and supine with the knee flexed to 90° and 35°. Rectus femoris (RF) and vastus lateralis (VL) muscle thickness was measured using ultrasonography. Typical error of measurement (TEM), coefficient of variation (CV%), and intra-class correlation coefficient (ICC) were used to assess the error and reliability of measures. Results: The average CV% among three trials of strength testing was 7.07%-9.94% and improved when using the top two trials (4.49%-5.61%). The average TEM was 2.21 Nm for strength and 0.03 cm for muscle thickness. Intra-rater and inter-rater reliability of muscle thickness was good to excellent (0.91-1.00).Conclusions: The results of this study suggest quadriceps muscle strength and thickness measurements using HHD and ultrasonography are reliable in children, adolescents, and young adults.