Circulating microRNAs as potential biomarkers of physical activity in geriatric patients with HCV.

BACKGROUND: Circulating microRNAs have been implicated in a diverse array of biological and pathological phenomena. Their potential utility as noninvasive biomarkers for screening and diagnosing various diseases has been proposed. OBJECTIVE: This study aimed to explore the potential role of the miRNAs miR-122 and miR-486 as molecular biomarkers in the pathogenesis of hepatitis C virus (HCV) infection. Thus, miR-122 and miR-486 were detected in the serum of HCV patients and healthy controls. Moreover, the potential correlations of miR-122 and miR-486 with viral complications, such as physical activity, pain, muscle fatigue, and HCV infection, were identified. METHODS: A total of 150 subjects aged 30 to 66 years were included in this study. The patients were classified as patients with chronic hepatitis C virus (CHC) (n = 110) or healthy controls (n = 40). Real-time polymerase chain reaction (PCR) analyses were performed to determine miR-122 and miR-486 expression. Physical activity (PA), pain score, HCV genotyping, viral overload, aspartate transaminase (AST), alanine transaminase (ALT), lactic acid dehydrogenase (LDH), creatine kinase (CK), and antioxidant status were also estimated by using prevalidated questionnaires, PCR, and spectrophotometric analyses. RESULTS: Compared with those in normal controls, significant increases in the serum levels of miR-122 and miR-486 were reported in patients with CHC. In physically active CHC patients, there was a significant correlation between the expression of miRNAs and increased alanine transaminase (ALT), aspartate transaminase (AST), fibrosis scores, and inflammation activity, but no association was reported for hepatitis C virus (HCV) RNA or viral load. Additionally, significant decreases in LDH, CK, GSSG, and pain scores and increases in TAC, GSH, and the GSH/GSSG ratio were reported. Moreover, the expression of miR-122 and miR-486 was positively correlated with changes in body mass index (BMI) and liver fibrosis stage, as well as negatively correlated with sex, PA, TAC, GSH, GSSG, and the GSH/GSSG ratio. CONCLUSION: MiR-122 and miR-486 expression levels were strongly correlated with physical activity, pain perception, and muscle fatigue biomarkers in HCV-infected patients. These miRNA levels were associated with elevated AST, ALT, fibrosis scores, LDH, CK, and antioxidant status, thus suggesting their potential as biomarkers for disease severity and oxidative stress. However, no correlation was observed with viral load or HCV-RNA expression, thus implying that these miRNAs may impact disease progression and symptoms through host factors, rather than directly affecting viral replication. In summary, the results demonstrated that molecular studies of miR-22 and miR-468 and their associations with PA, pain, adiposity, sex differences, and muscle fatigue, as well as routine biomarkers, could be useful as prognostic nanoninvasive biomarkers, thus providing novel therapeutic targets for CHC infection.

Hip rate of torque development, but not strength, is associated with single-leg squat kinematics in individuals with patellofemoral pain.

INTRODUCTION: Isometric hip strength seems to have limited association with frontal plane kinematics in individuals with patellofemoral pain (PFP), but little is known about the association with hip rate of torque development (RTD). OBJECTIVE: To explore the association of hip strength and RTD with trunk, pelvis, hip, and knee kinematics during a single-leg squat (SLS) in individuals with PFP. METHODS: Twenty individuals with PFP participated in this study. Hip abductor and extensor strength and RTD (early phase and late phase) were assessed using a hand-held dynamometer. Lateral trunk motion, pelvic drop, hip frontal plane projection angle (HFPPA), and knee frontal plane projection angle (KFPPA) were evaluated during a SLS using a two-dimensional motion analysis. RESULTS: Lower early and late phase hip abductor RTD were moderately associated with greater HFPPA (early phase: r = -0.501, p = .025; late phase: r = -0.580, p = .007) and KFPPA (early phase: r = -0.536, p = .015; late phase: r = -0.554, p = .011). Lower early phase hip extensor RTD was moderately associated with greater pelvic drop (r = 0.571, p = .009), HFPPA (r = -0.548, p = .012), and KFPPA (r = -0.530, p = .016). Hip abductor and extensor strength were not associated with any kinematic variables (p > .05). CONCLUSION: Lower hip RTD, but not strength, was associated with greater frontal plane kinematics during a SLS in individuals with PFP, indicating that the ability to produce torque rapidly may be important for kinematic control during functional tasks.

The Impact of Air Pollution on Physical Functioning Decline and the Benefits of Greenness: Evidence From a Nationwide Cohort Study.

BACKGROUND: Physical functional limitations (PFLs) increase the vulnerability of adults, but their pathogenesis remains unclear. METHODS: We conducted a nationwide longitudinal study on 62 749 records from 18 878 adults (aged ≥45) from 28 provinces in China. Risk of PFLs was assessed using a validated 9-item questionnaire. Exposure levels of air pollutants (PM10, PM2.5, and PM1) and greenness (normalized difference vegetation index, NDVI) were estimated using a satellite-based spatiotemporal model. We used the cumulative link mixed effects model to estimate the associations between short-term and long-term exposure to air pollutants, greenness, and risk of PFLs. We employed the interaction effect model to evaluate interactions between air pollutants and greenness. RESULTS: Participants were 60.9 ±â€…9.6 years, with an average follow-up of 5.87 (1.65) years. Exposure to air pollution was significantly associated with a higher risk of PFLs. For instance, the odds ratio (OR) associated with each 10 µg/m3 higher in 6-month averaged PM10, PM2.5, and PM1 were 1.025 (95% CI: 1.015-1.035), 1.035 (95% CI: 1.018-1.054), and 1.029 (95% CI: 1.007-1.050), respectively. Conversely, exposure to greenness was associated with decreased risk of PFLs; the OR associated with each 1-unit higher in 1-year averaged NDVI was 0.724 (95% CI: 0.544-0.962). Furthermore, higher greenness levels were found to mitigate the adverse effects of 1-year, 6-month, 1-month averaged PM10, and 1-year averaged PM2.5 on the risk of PFLs. CONCLUSIONS: Air pollution raises the risk of PFLs, whereas greenness could mitigate the adverse effects. Reducing air pollution and enhancing greenness could prevent physical functioning.

The linear regression model provides the force-velocity relationship parameters with the highest reliability.

An a-posteriori multicentre reliability study was conducted to compare the between-session reliability of the force-velocity relationship parameters (force-intercept [F0], velocity-intercept [v0], and maximum power [Pmax]) between different regression models during the bench press (BP) and bench press throw (BPT) exercises. Data from four and three studies were considered for the BP (n = 102) and BPT (n = 81) exercises, respectively. The force-velocity relationships were determined using five regression models: linear multiple-point, linear two-point, quadratic polynomial, hyperbolic, and exponential. All regression models provided F0 and Pmax with acceptable reliability (cut-off CV ≤ 9.45%; cut-off ICC ≥ 0.79) with the exceptions of F0 for the quadratic polynomial and hyperbolic models (BPT) and Pmax for the exponential model (BP and BPT). Only the linear multiple- and linear two-point models provided v0 with acceptable absolute reliability (cut-off CV ≤ 7.72%). Regardless of the exercise, the reliability of the three parameters was generally higher for the linear multiple- and two-point models compared to the other models (CVratio ≥ 1.22), and no significant differences were observed between multiple- and linear two-point models (CVratio ≤ 1.11). Linear regression models are recommended to maximise the reliability of the force-velocity relationship parameters during the BP and BPT exercises.

Establishing Reference Values for Isometric Knee Extension and Flexion Strength.

Single-joint isometric and isokinetic knee strength assessment plays an important role in strength and conditioning, physical therapy, and rehabilitation. The literature, however, lacks absolute reference values. We systematically reviewed the available studies that assessed isometric knee strength. Two scientific databases (PubMed and PEDro) were searched for the papers that are published from the inception of the field to the end of 2019. We included studies that involved participants of both genders and different age groups, regardless of the study design, that involved isometric knee extension and/or flexion measurement. The extracted data were converted to body-mass-normalized values. Moreover, the data were grouped according to the knee angle condition (extended, mid-range, and flexed). A meta-analysis was performed on 13,893 participants from 411 studies. In adult healthy males, the pooled 95% confidence intervals (CI) for knee extension were 1.34-2.23Nm/kg for extended knee angle, 2.92-3.45Nm/kg for mid-range knee angle, and 2.50-3.06Nm/kg for flexed knee angle, while the CIs for flexion were 0.85-1.20, 1.15-1.62, and 0.96-1.54Nm/kg, respectively. Adult females consistently showed lower strength than adult male subgroups (e.g., the CIs for knee extension were 1.01-1.50, 2.08-2.74, and 2.04-2.71Nm/kg for extended, mid-range, and flexed knee angle condition). Older adults consistently showed lower values than adults (e.g., pooled CIs for mid-range knee angle were 1.74-2.16Nm/kg (male) and 1.40-1.64Nm/kg (female) for extension, and 0.69-0.89Nm/kg (male) and 0.46-0.81Nm/kg (female) for flexion). Reliable normative for athletes could not be calculated due to limited number of studies for individual sports.

Modifiable Physical Factors Associated With Physical Functioning for Patients Receiving Dialysis: A Systematic Review.

BACKGROUND: Patients receiving dialysis have reduced physical function, which is associated with unfavorable clinical outcomes and decreased quality of life. The authors aimed to identify and explore modifiable physical factors associated with physical function for patients receiving dialysis. METHODS: Searches were performed in MEDLINE, Embase, Ovid Emcare, and The Cochrane Library in October 2018. Etiological studies involving dialysis populations that report association or predictive statistics between a modifiable physical factor and physical function were eligible for inclusion. Predictor variables were (1) modifiable via exercise and (2) considered an impairment in the International Classification of Functioning, Disability and Health. RESULTS: Of 5384 titles screened, 23 studies were included. Thirteen studies focused on physical activity levels and muscle strength and the relationship with physical function while 2 studies investigated sedentary behavior. Twenty-one studies focused on hemodialysis populations. Studies related to physical activity levels displayed a moderately strong relationship with physical function, whereas muscle strength displayed a predominantly weak to moderate relationship. CONCLUSIONS: Physical activity levels, sedentary behavior levels, and muscle strength are related to physical function status for patients receiving dialysis. There is a need for robust longitudinal data to confirm the results of this investigation and for more focus on populations receiving peritoneal dialysis.

Interactive effects of osmotic stress and burrowing activity on protein metabolism and muscle capacity in the soft shell clam Mya arenaria.

Bioturbators such as sediment-dwelling marine bivalves are ecosystem engineers that enhance sediment-water exchange and benthic-pelagic coupling. In shallow coastal areas, bivalves are exposed to frequent disturbance and salinity stress that might negatively affect their activity and physiological performance; however, the mechanisms underlying these effects are not fully understood. We investigated the effects of osmotic stress (low and fluctuating salinity) and repeated burrowing on aerobic and contractile capacity of the foot muscle (assessed by the activity of succinate dehydrogenase and myosin ATPase) as well as the levels of organic osmolytes (free amino acids) and biochemical markers of protein synthesis and proteolysis in key osmoregulatory and energy storing tissues (gills and hepatopancreas, respectively) in a common bioturbator, the soft shell clam Mya arenaria. Osmotic stress and exhaustive exercise altered the foot muscle capacity of soft shell clams and had a strong impact on protein and amino acid homeostasis in tissues not directly involved in locomotion. Acclimation to constant low salinity (5 practical salinity units) depleted the whole-body free amino acid pool and affected protein synthesis but not protein breakdown in the gill. In contrast, fluctuating (5-15) salinity increased protein breakdown rate, suppressed protein synthesis, caused oxidative damage to proteins in the gill and selectively depleted whole-body glycine pool. Clams acclimated to normal salinity (15) increased the aerobic capacity of the foot muscle upon repeated burrowing, whereas acclimation to low and fluctuating salinity reduced this adaptive muscle plasticity. Under the normal and low salinity conditions, exhaustive exercise induced protein conservation pathways (indicated by suppression of protein synthesis and catabolism), but this effect was disrupted by fluctuating salinity. These findings indicate that exhaustive exercise and osmotic stress interactively affect whole-body protein homeostasis and functional capacity of the foot muscle in soft shell clams which might contribute to reduced burrowing activity of bivalve bioturbators in osmotically challenging environments such as estuaries and shallow coastal zones.

Assessment of the risk and biomechanical consequences of lateral epicondylalgia by estimating wrist and finger muscle capacities in tennis players.

Previous studies suggested that a pronounced weakness of the extensor muscles relative to the flexor muscles could increase the risk of occurrence of lateral epicondylalgia. This study investigates this hypothesis by estimating the ratio of extensor to flexor muscle capacities among healthy non-players (n = 10), healthy tennis players (n = 20), symptomatic players (n = 6), and players who have recovered from lateral epicondylalgia (n = 6). Maximum net joint moments in flexion or extension were measured during seven tasks involving the voluntary contraction of wrist and fingers. Using these data, the muscle capacities of the main muscle groups of the hand (wrist flexors, wrist extensors, finger flexors, finger extensors, and intrinsic muscles) were estimated using a musculoskeletal model. These capacities were then used to compute the extensor/flexor capacity ratios about the wrist and the finger joints. Compared to healthy non-players, healthy players presented higher extensor muscle capacities and greater capacity ratios showing that playing tennis generates specific adaptations of muscle capacities. Interestingly, symptomatic players, similar to those of non-players, showed more imbalanced ratios than healthy players. These results confirm that the ratio of extensor/flexor muscle capacities seems to be associated with lateral epicondylalgia and can be further used to understand its incidence and consequences.

Burst muscle performance predicts the speed, acceleration, and turning performance of Anna's hummingbirds.

Despite recent advances in the study of animal flight, the biomechanical determinants of maneuverability are poorly understood. It is thought that maneuverability may be influenced by intrinsic body mass and wing morphology, and by physiological muscle capacity, but this hypothesis has not yet been evaluated because it requires tracking a large number of free flight maneuvers from known individuals. We used an automated tracking system to record flight sequences from 20 Anna's hummingbirds flying solo and in competition in a large chamber. We found that burst muscle capacity predicted most performance metrics. Hummingbirds with higher burst capacity flew with faster velocities, accelerations, and rotations, and they used more demanding complex turns. In contrast, body mass did not predict variation in maneuvering performance, and wing morphology predicted only the use of arcing turns and high centripetal accelerations. Collectively, our results indicate that burst muscle capacity is a key predictor of maneuverability.

Physical fitness in children with developmental coordination disorder: measurement matters.

Children with Developmental Coordination Disorder (DCD) experience considerable difficulties coordinating and controlling their body movements during functional motor tasks. Thus, it is not surprising that children with DCD do not perform well on tests of physical fitness. The aim of this study was to determine whether deficits in motor coordination influence the ability of children with DCD to perform adequately on physical fitness tests. A case-control study design was used to compare the performance of children with DCD (n=70, 36 boys, mean age=8 y 1 mo) and Typically Developing (TD) children (n=70, 35 boys, mean age=7 y 9 mo) on measures of isometric strength (hand-held dynamometry), functional strength, i.e. explosive power and muscular endurance (Functional Strength Measurement), aerobic capacity (20 m Shuttle Run Test) and anaerobic muscle capacity, i.e. muscle power (Muscle Power Sprint Test). Results show that children with DCD were able to generate similar isometric forces compared to TD children in isometric break tests, but were significantly weaker in three-point grip strength. Performance on functional strength items requiring more isolated explosive movement of the upper extremities, showed no significant difference between groups while items requiring muscle endurance (repetitions in 30s) and items requiring whole body explosive movement were all significantly different. Aerobic capacity was lower for children with DCD whereas anaerobic performance during the sprint test was not. Our findings suggest that poor physical fitness performance in children with DCD may be partly due to poor timing and coordination of repetitive movements.