Indices Of Muscle Function Research Articles

Effects of a ketogenic diet on motor function and motor unit number estimation in aged C57BL/6 mice

ObjectivePathological, age-related loss of muscle function, commonly referred to as sarcopenia, contributes to loss of mobility, impaired independence, as well as increased risk of adverse health events. Sarcopenia has been attributed to changes in both neural and muscular integrity during aging. Current treatment options are primarily limited to exercise and dietary protein fortification, but the therapeutic impact of these approaches are often inadequate. Prior work has suggested that a ketogenic diet (KD) might improve healthspan and lifespan in aging mice. Thus, we sought to investigate the effects of a KD on neuromuscular indices of sarcopenia in aged C57BL/6 mice. DesignA randomized, controlled pre-clinical experiment consisting of longitudinal assessments performed starting at 22-months of age (baseline) as well as 2, 6 and 10 weeks after the start of a KD vs. regular chow intervention. SettingPreclinical laboratory study. Sample sizeThirty-six 22-month-old mice were randomized into 2 dietary groups: KD [n = 22 (13 female and 9 male)], and regular chow [n = 15 (7 female and 8 male)]. MeasurementsMeasures included body mass, hindlimb and all limb grip strength, rotarod for motor performance, plantarflexion muscle contractility, motor unit number estimations (MUNE), and repetitive nerve stimulation (RNS) as an index of neuromuscular junction transmission efficacy recorded from the gastrocnemius muscle. At end point, muscle wet weight and blood samples were collected to assess blood beta-hydroxybutyrate levels. Statistical analysisPrimary analyses were two-way mixed effects ANOVA (diet and time × diet) to determine the effect of a KD on indices of motor function (grip, rotarod) and indices of motor unit (MUNE) and muscle (contractility) function. ResultsBeta-hydroxybutyrate (BHB) was significantly higher at 10 weeks in mice on a KD vs control group (0.83 ± 0.44 mmol/l versus 0.42 ± 0.21 mmol/l, η2 = 0.265, unpaired t-test, p = 0.0060). Mice on the KD intervention demonstrated significantly increased hindlimb grip strength (diet, p = 0.0001; time × diet, p = 0.0030), all limb grip strength (diet, p = 0.0005; time × diet, p = 0.0523), and rotarod latency to fall (diet, p = 0.0126; time × diet, p = 0.0021). Mice treated with the KD intervention also demonstrated increased MUNE (diet, p = 0.0465; time × diet, p = 0.0064), but no difference in muscle contractility (diet, p = 0.5248; time × diet, p = 0.5836) or RNS (diet, p = 0.3562; time × diet, p = 0.9871). ConclusionKD intervention improved neuromuscular and motor function in aged mice. This pre-clinical work suggests that further research is needed to assess the efficacy and physiological effects of a KD on indices of sarcopenia.

Physical activity positively impacts disability outcomes during transition from midlife to early older age irrespective of body mass index

We examined the effects of physical activity (PA) and body mass index (BMI) longitudinal patterns (trajectories) on subjective measures of mobility, function, and disability in adults and assessed whether effects of PA trajectories on function varied due to BMI. Group-based trajectory analyses were used to determine patterns of change in PA and BMI using data from the Health and Retirement Study 1931–1941 birth cohort (n = 10,507). Physical function was assessed by Mobility Limitations (0–5 scale) and Large Muscle Function (0–4 scale) Indexes, as well as with score for activities of daily living (ADLs) and instrumental activities of daily living (IADLs), with higher scores being worse. Our analyses estimated four distinct PA trajectories: decreasing, (2) fluctuating, (3) stable high, and (4) emergent (previously low/sedentary with increased PA over the study period). Worse mobility limitations, large muscle function, ADLs, and IADLs were associated with Decreasing and Fluctuating PA groups. Better outcomes were associated with Emergent and Stable High PA groups. The five BMI trajectories were stable normal/overweight, modest decreasing, fluctuating, steep decreasing, and increasing. No significant interaction existed between PA and BMI trajectories for Mobility Limitations (P= 0.577), Large Muscle Function (P= 0.511), ADLs (P= 0.600), and IADLs (P= 0.152). These findings may empower clinicians to promote messages to midlifers that meaningful changes in PA can improve function in older age.

Neuromuscular dysfunction precedes muscle atrophy in C26 tumor-bearing mice

Background: Cancer patients frequently develop skeletal muscle wasting and weakness, which are hallmarks of cachexia, a wasting disease which worsens quality of life and is directly responsible for up to 30% of all cancer-related deaths. While advancements in detection and treatment have increased the population of cancer survivors, skeletal muscle dysfunction can persist for years following cancer remission. We previously demonstrated that late-stage cachexia is associated with impaired skeletal muscle innervation, linking loss of motor unit (MU) connectivity to cancer-induced wasting and weakness. In the present study, we investigated the onset of neuromuscular dysfunction in a preclinical model of cancer cachexia.
 Methods: CD2F1 male mice (8-week-old) were subcutaneously injected with C26 colorectal cancer cells (1.0x106) or saline and randomized into one the following timepoint groups: day 6, day 8, or day 10 (n=8-10). Animals were assessed for indices of MU connectivity and muscle function at each timepoint. Following functional assessment, skeletal muscles were harvested, weighed, and processed for molecular analyses.
 Results: 6 days post tumor injection, C26 hosts displayed reductions in neuromuscular junction (NMJ) transmission and motor unit connectivity, while muscle torque and mass were preserved. Specific torque was reduced in C26 hosts at day 8, while reductions in muscle mass or cross-sectional area did not occur until day 10. Molecular analysis revealed alterations of NMJ components as early as day 6 in C26 hosts, further suggesting that neuromuscular dysfunction precedes muscle atrophy.
 Conclusions: Altogether our data demonstrate that cancer-induced neuromuscular dysfunction precedes cancer-induced muscle atrophy, identifying impaired innervation as an early prognosticator of cachexia progression. Our work supports strategies to counteract impaired neuromuscular function in the treatment of cancer cachexia, in hopes of sustaining quality of life in cancer patients and the growing population of cancer survivors.

Marked irregular myofiber shape is a hallmark of human skeletal muscle ageing and is reversed by heavy resistance training.

Age-related loss of strength is disproportionally greater than the loss of mass, suggesting maladaptations in the neuro-myo-tendinous system. Myofibers are often misshaped in aged and diseased muscle, but systematic analyses of large sample sets are lacking. Our aim was to investigate myofiber shape in relation to age, exercise, myofiber type, species and sex. Vastus lateralis muscle biopsies (n=265) from 197 males and females, covering an age span of 20-97years, were examined. The gastrocnemius and soleus muscles of 11+22-month-old male C57BL/6 mice were also examined. Immunofluorescence and ATPase stainings of muscle cross-sections were used to measure myofiber cross-sectional area (CSA) and perimeter. From these, a shape factor index (SFI) was calculated in a fibre-type-specific manner (type I/II in humans; type I/IIa/IIx/IIb in mice), with higher values indicating increased deformity. Heavy resistance training (RT) was performed three times per week for 3-4months by a subgroup (n=59). Correlation analyses were performed comparing SFI and CSA with age, muscle mass, maximal voluntary contraction (MVC), rate of force development and specific force (MVC/muscle mass). In human muscle, SFI was positively correlated with age for both type I (R2 =0.20) and II (R2 =0.38) myofibers. When subjects were separated into age cohorts, SFI was lower for type I (4%, P<0.001) and II (6%, P<0.001) myofibers in young (20-36) compared with old (60-80) and higher for type I (5%, P<0.05) and II (14%, P<0.001) myofibers in the oldest old (>80) compared with old. The increased SFI in old muscle was observed in myofibers of all sizes. Within all three age cohorts, type II myofiber SFI was higher than that for type I myofiber (4-13%, P<0.001), which was also the case in mice muscles (8-9%, P<0.001). Across age cohorts, there was no difference between males and females in SFI for either type I (P=0.496/0.734) or II (P=0.176/0.585) myofibers. Multiple linear regression revealed that SFI, after adjusting for age and myofiber CSA, has independent explanatory power for 8/10 indices of muscle mass and function. RT reduced SFI of type II myofibers in both young and old (3-4%, P<0.001). Here, we identify type I and II myofiber shape in humans as a hallmark of muscle ageing that independently predicts volumetric and functional assessments of muscle health. RT reverts the shape of type II myofibers, suggesting that a lack of myofiber recruitment might lead to myofiber deformity.

Fish oil supplementation fails to modulate indices of muscle damage and muscle repair during acute recovery from eccentric exercise in trained young males

ABSTRACT We aimed to investigate the influence of 4-wk of fish oil (FO) supplementation on markers of muscle damage, inflammation, muscle soreness, and muscle function during acute recovery from eccentric exercise in moderately trained males. Sixteen moderately-trained males ingested 5 g/d of FO (n = 8) or soybean oil (placebo) capsules (n = 8) for 4-wk prior to- and 3-d following an acute eccentric exercise bout. Eccentric exercise consisted of 12 sets of isokinetic knee extension and knee flexion. Indices of muscle damage, soreness, function and inflammation were measured at baseline and during exercise recovery. Eccentric exercise elicited an increase in muscle soreness (p < 0.010) and thigh volume (p < 0.001), and reduced peak isometric torque by 31.7 ± 6.9%, (p < 0.05, 95% CI 10.6–52.8) during 3-d of recovery. Blood omega-3 polyunsaturated fatty acid concentration was 14.9 ± 2.4% higher in FO than PLA (p < 0.01, 95% CI 9.8–20.1). However, FO did not ameliorate the cumulative creatine kinase response (expressed as AUC; p = 0.368), inflammation (p = 0.400), muscle soreness (p > 0.140), or muscle function (p > 0.249) following eccentric exercise. FO supplementation confers no clear benefit in terms of ameliorating the degree of muscle damage, or facilitating the muscle repair process, during acute eccentric exercise recovery. These data suggest that FO supplementation does not provide an effective nutritional strategy to promote exercise recovery, at least in moderately-trained young men. Abbreviations: ANOVA: Analysis of variance; AUC: Area under curve; CI: Confidence interval; CK: Creatine kinase; CMJ: Countermovement jump; COX: Cyclooxygenase; CRP: C-reactive protein; DHA: Docosahexaenoic acid; DOMS: Delayed-onset muscle soreness; EIMD: Exercise-induced muscle damage; En%: Energy percent; EPA: Eicosapentaenoic acid; FO: Fish oil; IL-6: Interleukin-6; LDH: Lactate dehydrogenase; LOX: Lipoxygenase; Mb: Myoglobin; mTOR: Mechanistic target of rapamycin; PLA: Placebo; ROM: Range of motion; ROS: Reactive oxygen species; SD: Standard deviation; SEM: Standard error of the mean; TNF-α: Tumour necrosis factor alpha; VAS: Visual analogue scale; Ω3-PUFA: Omega-3 polyunsaturated fatty acids; Ω6-PUFA: Omega-6 polyunsaturated fatty acids Highlights The anti-inflammatory properties of omega-3 polyunsaturated fatty acids, alongside their propensity to incorporate into the muscle phospholipid membrane underpins the idea that fish oil supplementation may attenuate muscle damage and promote muscle repair following eccentric-based exercise. Four weeks of high-dose (5 g/d) fish oil supplementation prior to eccentric exercise failed to attenuate the rise in creatine kinase concentration and muscle soreness during acute exercise recovery in physically-active young men. Future studies are warranted to investigate the efficacy of combining omega-3 polyunsaturated fatty acids with other nutrients (i.e. protein/amino acids) for the promotion of muscle recovery following eccentric-based damaging exercise.

Loaded 5 Sit-to-Stand Test to Determine the Force–Velocity Relationship in Older Adults: A Validation Study

Force–velocity profiling (F-v) evaluates muscle function through the identification of maximum force (F0), velocity (V0), power (Pmax) and optimal velocity (Vopt). The purpose of this study was to investigate the validity and feasibility of loaded 5 Sit-to-Stand (5STS) force-velocity profiling compared to the gold standard instruments (isokinetic Dynamometry, ISO) and asses the relationship between the 5STS-derived muscle function indexes with clinical markers of muscle mass and strength. Forty-six older adults (21 females: 63.8 ± 3.9 yrs) performed 5STS (four different weight conditions) and ISO tests (five different velocities). Paired t-tests, regression analyses, and Bland–Altman analysis were conducted. The results showed significant differences in F0, V0, and Vopt (p &lt; 0.001) but no difference in Pmax (p = 0.259) between tests. Only F0 and Pmax were highly correlated between tests (r = 0.71, r = 0.84, respectively). Bland–Altman analysis showed a not significant bias and good precision (p = 0.260, 34 W) only for Pmax. Large to very large correlations (r = 0.53 to 0.81) were found between F0 and Pmax and clinical markers of muscle mass and strength. In conclusion, loaded 5STS profiling could be a feasible, valid, and cost- and time-efficient alternative to ISO for the characterization of clinically relevant markers of muscle function in healthy older adults.

Neuromuscular coupling of obligatory respiratory muscles to inspiratory pressure is reduced in dystrophic (mdx) mice

Neuromuscular coupling (NMC) is a recognised clinical index of inspiratory muscle function which reflects the efficiency of conversion of neural activation to inspiratory pressure. Duchenne muscular dystrophy (DMD) is characterised by respiratory insufficiency culminating in respiratory failure. We investigated inspiratory pressure generating capacity and electrical activation of obligatory inspiratory muscles in X-linked muscular dystrophy ( mdx) mice, to evaluate NMC of diaphragm, external intercostal and parasternal intercostal to inspiratory pressure across a range of behaviours in early established to late progressive disease.In urethane anaesthetised mice (1.7 g/kg i.p.), inspiratory pressure was recorded via a pressure transducer positioned in the thoracic oesophagus. Diaphragm EMG activity was recorded using needle electrodes. Studies were performed in male wildtype (WT) and mdx mice at 4, 8, 12 and 16 months old. Recordings were made at baseline and during sustained tracheal occlusion to task failure, defined as an inability to sustain peak pressure. Peak pressure was determined from the average of five successive peak efforts at the maximum response. The corresponding peak inspiratory EMG activities were determined. Two factor (age x genotype) analysis of variance was performed.Obligatory muscle EMG activities were significantly lower in mdx mice from 4 months of age. Peak inspiratory pressure was significantly greater in mdx at 4 months of age. At 8 months, peak inspiratory pressure was equivalent between WT and mdx followed by a significant decrease in peak inspiratory pressure in 12- and 16-month-old mdx. NMC was lower in mdx mice across the ventilatory and non-ventilatory range, emerging early in dystrophic disease.Reduced NMC of obligatory muscles to inspiratory pressure in mdx mice reveals a greater reliance on accessory muscles to support respiratory performance in dystrophic disease. Remarkably, this burden is adequately accommodated in early disease with a preserved capacity to generate peak inspiratory pressure. We reason that the loss of compensation afforded by accessory muscles to peak inspiratory pressure generation underpins the emergence of respiratory compromise in advanced disease. Our results may have implications for the understanding and treatment of DMD. Funded by Science Foundation Ireland SFI/19/6628 INSPIRE DMD. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Endothelial Function Is Preserved in Patients with Wild-Type Transthyretin Amyloid Cardiomyopathy

Heart failure (HF) is associated with endothelial dysfunction. Vascular function per se plays an important role in cardiac function, whether it is a cause or consequence. However, there is no information on vascular function in patients with wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM). The purpose of this study was to evaluate vascular function in patients with ATTRwt-CM. We measured flow-mediated vasodilation (FMD) as an index of endothelial function and nitroglycerine-induced vasodilation (NID) as an index of vascular smooth muscle function and brachial artery intima-media thickness (bIMT) and brachial-ankle pulse wave velocity (baPWV) as indices of arterial stiffness in 22 patients with ATTRwt-CM and in 22 one-by-one matched control patients using vascular function confounding factors. FMD was significantly greater in patients with ATTRwt-CM than in the controls (5.4 ± 3.4% versus 3.5 ± 2.4%, p = 0.038) and the N-terminal pro-brain natriuretic peptide (NT-proBNP) level was significantly greater in patients with ATTRwt-CM than in the controls (2202 ± 1478 versus 470 ± 677 pg/mL, p < 0.001). There were no significant differences in NID, bIMT or baPWV between the two groups. There was a significant relationship between NT-proBNP and FMD in patients with ATTRwt-CM (r = 0.485, p = 0.022). NT-proBNP showed no significant relationships with NID, bIMT or baPWV. Conclusions: Endothelial function was preserved in patients with ATTRwt-CM. Patients with ATTRwt-CM may have compensatory effects with respect to endothelial function through elevation of BNP.

JS-HR-1: UPDATE OF VASCULAR FUNCTION

Atherosclerosis has two aspects: vascular dysfunction and vascular structural alterations. Both vascular dysfunction and vascular structural alterations are associated with future cardiovascular events. Therefore, the assessments of vascular function and vascular structural alterations may be useful not only for the assessment of the severity of atherosclerosis but also for the stratification of cardiovascular risk. Flow-mediated vasodilation and reactive hyperemia index as indices of endothelial function, nitroglycerine-induced vasodilation as an index of vascular smooth muscle function, and pulse wave velocity as an index of arterial stiffness, have been used for the assessment of vascular function in clinical settings. In this session, we summarize the updated information on the usefulness of vascular function tests in the management of patients with cardiovascular risk factors.

EFEITOS DA GINÁSTICA DE ALTA INTENSIDADE SOBRE AS PROTEÍNAS MUSCULARES ESQUELÉTICAS

ABSTRACT Introduction: Although the current method of muscle stretching in gymnastics teaching in colleges and universities can reduce sports fatigue, it has been shown to have little effect on the well-being of athletes because it requires a long recovery time from psychological fatigue. Progressive muscle relaxation training is a method that uses the basic principle of sympathetic nerve activity to reduce the impact of negative emotions psychologically and relieve fatigue physiologically, requiring a further study of its impact on muscle protein. Objective: Explore the effect of high-intensity gymnastics on skeletal muscle protein and study the progressive muscle relaxation training method post-workout adjustment. Methods: After three weeks of training, excluding the standard deviations in the experimental data caused by the athletes’ irregular movements, the athletes’ blood lactate content and heart rate were counted and recorded. The collected data were analyzed using Excel software to integrate and compare the data using the T-test method. Results: After exercise training, the skeletal muscle function indices of the subjects increased to different degrees. From the point of view of heart rate recovery efficiency, the rate of heart rate decline of progressive relaxation training was higher than that of the two groups, and the degree of fluctuation was lower than that of the two groups, indicating that the level of recovery in heart rate of progressive relaxation training was better. Conclusion: The action of the high-intensity gymnastics team has a good effect on improving the athletes’ skeletal muscle and skeletal muscle proteins. Post-exercise conditioning training plays an important role in athletes’ physical recovery. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

5-Fluorouracil Alters Skeletal Muscle Mitochondrial Content And Inflammation In Mice

5-fluorouracil (5FU) is one of the most widely used chemotherapy drugs for colon, breast, head & neck, and pancreatic cancers; however, 5FU’s non-selective cytotoxic effects lead to debilitating fatigue coupled with decrements in skeletal muscle health and function. PURPOSE: To investigate the impacts of 5FU on physical activity, indices of skeletal muscle function, and the underlying changes in skeletal muscle mitochondrial content and inflammation. METHODS: Adult male CD2F1 mice were subjected to 1 cycle of 5FU (cycle: 5d, 30 mg/kg Lean Mass, i.p.) or PBS control. Cage activity, grip strength and neuromuscular function were assessed and skeletal muscle protein was isolated 48 hours following the last dose of 5FU or PBS. Mitochondria biogenesis [transcription factor A (TFAM)] and total content [electron transport chain complexes I-V (CI-V), cytochrome c (CytoC), voltage-dependent anion channels (VDAC)] was analyzed via western blot analysis. Real-time polymerase chain reaction was performed to analyze skeletal muscle macrophage [CD68, EGF-like module-containing mucin-like hormone receptor-like 1 (EMR1), integrin subunit alpha X (Itgax), mannose receptor C-type 1 (MRC1)], pro-inflammatory [interleukin (IL) -1ß, -6, -13), tumor necrosis factor (TNF), interferon-gamma (IFNγ)] and anti-inflammatory [IL-10] gene expression. RESULTS: 5FU did not significantly impact grip strength or neuromuscular function (p > 0.05); however, cage activity and body weight (Δ8%) appreciably decreased following 5FU compared to controls (p < 0.05). Moreover, we observed a significant reduction in TFAM, VDAC, CIV, and CV following 5FU administration (p < 0.05) while no differences in CytoC, CI, CII, and CIII were found (p > 0.05). Interestingly, EMR1 (Δ43%) and CD68 (Δ37%) expression significantly decreased along with reductions in IL-1ß (Δ85%), IL-6 (Δ37%), TNF (Δ52%), and IFNγ (Δ42%) expression following 5FU compared to controls (p < 0.05). CONCLUSION: Collectively, these results demonstrate 1 cycle of 5FU notably impacts mitochondrial content and inflammation concomitant with decreases in body weight and cage activity. While changes in skeletal muscle function were not found, the observed changes in mitochondria and the inflammatory micro-environment may precede the functional decrements in skeletal muscle.

Validation of a non-invasive pressure–time index of the inspiratory muscles in spontaneously breathing newborn infants

To validate the pressure–time index of the inspiratory muscles as a non-invasive index of inspiratory muscle function in spontaneously breathing infants by comparing it against the gold-standard pressure–time index of the diaphragm. Prospective observational cohort study of consecutive infants breathing unsupported in room air in a tertiary neonatal intensive care unit, studied prior to discharge from neonatal care. The invasive pressure–time index of the diaphragm was calculated using a transdiaphragmatic dual-pressure catheter that measured transdiaphragmatic pressure by subtraction of the oesophageal from the gastric pressure. The non-invasive pressure–time index of the inspiratory muscles was calculated using pressure measurements at the level of the mouth via a differential pressure transducer connected to a face mask. Both indices were calculated as the product of the ratio of the mean inspiratory pressure divided by the maximum inspiratory pressure and the ratio of the inspiratory time divided by the total time of a respiratory cycle. One hundred and thirty infants (79 male) were included with a mean (SD) gestational age of 35.2 (3.2) weeks, studied at a median (IQR) postnatal age of 9 (6–20) days. The mean (SD) pressure–time index of the diaphragm was 0.063 (0.019) and the mean (SD) pressure–time index of the inspiratory muscles was 0.065 (0.023). The correlation coefficient for the two indices was 0.509 (p < 0.001). The mean (SD) absolute difference between the pressure–time index of the inspiratory muscles and pressure–time index of the diaphragm was 0.002 (0.021). In convalescent infants, the non-invasive pressure–time index of the inspiratory muscles had a moderate degree of correlation with the invasively derived pressure time index of the diaphragm measured with a transdiaphragmatic catheter.

Volumetric MRI is a promising outcome measure of muscle reinnervation

The development of outcome measures that can track the recovery of reinnervated muscle would benefit the clinical investigation of new therapies which hope to enhance peripheral nerve repair. The primary objective of this study was to assess the validity of volumetric Magnetic Resonance Imaging (MRI) as an outcome measure of muscle reinnervation by testing its reproducibility, responsiveness and relationship with clinical indices of muscular function. Over a 3-year period 25 patients who underwent nerve transfer to reinnervate elbow flexor muscles were assessed using intramuscular electromyography (EMG) and MRI (median post-operative assessment time of 258 days, ranging from 86 days pre-operatively to 1698 days post- operatively). Muscle power (Medical Research Council (MRC) grade) and Stanmore Percentage of Normal Elbow Assessment (SPONEA) assessment was also recorded for all patients. Sub-analysis of peak volitional force (PVF), muscular fatigue and co-contraction was performed in those patients with MRC > 3. The responsiveness of each parameter was compared using Pearson or Spearman correlation. A Hierarchical Gaussian Process (HGP) was implemented to determine the ability of volumetric MRI measurements to predict the recovery of muscular function. Reinnervated muscle volume per unit Body Mass Index (BMI) demonstrated good responsiveness (R2 = 0.73, p < 0.001). Using the temporal and muscle volume per unit BMI data, a HGP model was able to predict MRC grade and SPONEA with a mean absolute error (MAE) of 0.73 and 1.7 respectively. Muscle volume per unit BMI demonstrated moderate to good positive correlations with patient reported impairments of reinnervated muscle; co- contraction (R2 = 0.63, p = 0.02) and muscle fatigue (R2 = 0.64, p = 0.04). In summary, volumetric MRI analysis of reinnervated muscle is highly reproducible, responsive to post-operative time and demonstrates correlation with clinical indices of muscle function. This encourages the view that volumetric MRI is a promising outcome measure for muscle reinnervation which will drive advancements in motor recovery therapy.

The efficacy of intermittent pneumatic compression and negative pressure therapy on muscle function, soreness and serum indices of muscle damage: a randomized controlled trial

BackgroundThe study aimed to assess whether intermittent pneumatic compression (IPC) and intermittent negative pressure (INP) would attenuate the muscle damaging effects of eccentric exercise.MethodsForty-five healthy males were recruited. Immediately post, 24 and 48 h post eccentric exercise consisting of 100 drop jumps, volunteers randomly received 30-min sessions of intermittent pneumatic compression (IPC, n = 15) or intermittent negative pressure (INP, n = 15), or sham microcurrent (PT, n = 15). Creatine kinase (CK), lactate dehydrogenase (LDH), isokinetic muscle strength, soreness and active flexion of the knee joint were measured after every therapy session.ResultsNo significant intergroup differences were observed in biochemical or functional measurements. However, there was an increase in muscle soreness (P < 0.05), CK and LDH activity (P < 0.05), and a reduction in muscle strength (P < 0.05) and range of active knee flexion (P < 0.05).ConclusionsThe prescription of IPC and INP did not attenuate the reduction of markers to muscle function or pain perception up to 48 h after muscle damaging exercise. Future research should focus on the potential impact of treatment frequency and duration on muscle recovery.Trial registration The study was retrospectively registered in the Australian New Zealand Clinical Trials Registry (ANZCTR); The trial registration number: ACTRN12621001294842; date of registration: 24/09/2021.

Orbicularis Oculi Muscle Size and Function: Exploring the Influence of Aging and Exercise Training

The orbicularis oculi muscle is the sphincter muscle of the eyelids that blinks and closes the eyes. In this review, our aim was threefold: (1) to introduce the performance characteristics of blinking activity in young and older adults, (2) to discuss the influence of aging on the orbicularis oculi muscle in healthy adults, and (3) to provide information about the effect of facial exercise training on the orbicularis oculi muscle. To achieve the purpose of this review, a search using two electronic databases (PubMed and Scopus) and a search engine (Google Scholar) was conducted. The amplitude and peak velocity of spontaneously blinking behavior, which is an index of muscle function of the orbicularis oculi, appear to be affected by aging. The muscle thickness of the orbicularis oculi tends to be low in older adults, but there are issues that need to be examined further, such as differences in sex and measurement positions. There was no study on the effect of exercise training; however, the results of a highly trained man indicate that the orbicularis oculi muscles might elicit muscle hypertrophy through non-traditional resistance exercise.

Full characterisation of knee extensors' function in ageing: effect of sex and obesity.

Muscle function is a marker of current and prospective health/independence throughout life. The effects of sex and obesity (OB) on the loss of muscle function in ageing remain unresolved, with important implications for the diagnosis/monitoring of sarcopenia. To characterise in vivo knee extensors' function, we compared muscles torque and power with isometric and isokinetic tests in older men (M) and women (W), with normal range (NW) of body mass index (BMI) and OB. In 70 sedentary older M and W (69 ± 5 years), NW and OB (i.e. BMI < 30 kg m-2 and ≥30 kg m-2, respectively) we tested the right knee's extensor: (i) isometric torque at 30°, 60°, 75° and 90° knee angles, and (ii) isokinetic concentric torque at 60, 90, 150, 180 and 210° s-1 angular speeds. Maximal isometric T-angle, maximal isokinetic knee-extensor torque-velocity, theoretical maximal shortening velocity, maximal power, optimal torque and velocity were determined in absolute units, normalised by body mass (BM) and right leg lean mass (LLMR) and compared over sex, BMI categories and angle or angular speeds by three-way ANOVA. In absolute units, relative to BM and LLMR, sex differences were found in favour of M for all parameters of muscle function (main effect for sex, p < 0.05). OB did not affect either absolute or relative to LLMR isometric and isokinetic muscle function (main effect for BMI, p > 0.05); however, muscle function indices, when adjusted for BM, were lower in both M and W with OB compared to NW counterparts (p < 0.05). We confirmed sex differences in absolute, relative to BM and LLMR muscle function in favour of men. While overall muscle function and muscle contractile quality is conserved in individuals with class I OB, muscle function normalised for BM, which defines the ability to perform independently and safely the activities of daily living, is impaired in comparison with physiological ageing.

Examining the association between muscle mass, muscle function, and fat indexes in an elderly population.

Skeletal muscle mass with function decline indicated as sarcopenia, which may cause disability in elderly adults. Studies regarding fat composition in sarcopenia have gained attraction recently; however, different fat indexes have yielded different findings. It is necessary to explore the association between muscle mass, muscle function, and fat indexes among elderly adults. Community-dwelling elderly adults ages 65 and older who received annual health examination or outpatient services were enrolled. Hand grip strength and gait speed were measured. Muscle and fat mass were estimated by bioelectrical impedance analyzer. Presarcopenia was defined as loss of muscle mass only; sarcopenia was loss of muscle mass accompanied by low grip strength or/and slow gait speed. The relationships between sarcopenia parameters and different fat indexes among elderly adults were analyzed. There were 295 participants recruited. The presarcopenia group showed lower fat indexes compared to the sarcopenia group. Negative correlations existed between sarcopenia parameters (skeletal muscle mass index, grip strength, gait speed) and fat indexes (body-fat percentage, fat-to-muscle ratio). In the multiple hierarchical regression model, gait speed was negatively associated with body-fat percentage (β=-0.255, P=0.009) and fat-to-muscle ratio (β=-0.272, P=0.005) in the male group. In the female group, grip strength was inversely associated with body-fat percentage (β=-0.232, P=0.009) and fat-to-muscle ratio (β=-0.195, P=0.031). Individuals in the presarcopenia group had lower fat indexes than those in the sarcopenia group. Gait speed in men and hand grip strength in women-but not muscle mass for either- were negatively associated with body-fat percentage and fat-to-muscle ratio.

Ingesting a Post-Workout Vegan-Protein Multi-Ingredient Expedites Recovery after Resistance Training in Trained Young Males

Post workout multi-ingredient admixtures are commonly used to maximize recovery after exercise. The present double-blind, cross-over study compared the acute effects of ingesting a protein-vegan multi-ingredient (VGMT) vs. maltodextrin (MALT) on indices of muscle function. Ten trained males, (26.8 ± 1.9 years) performed two identical, 3-day resistance training periods (one workout-session per day) while receiving either VGMT or MALT (10 min after the completion of each workout). Following a baseline evaluation, we conducted assessments at, 1-h, 24-h and 48-h after the 3-day training period. Primary outcome included the evoked tensiomyography contraction velocity (Vc) of vastus medialis (VM), biceps femoris long head (BFLH) and anterior deltoids (AD). Secondary outcomes involved strength and power performance while the other tensiomyography variables [muscle displacement (Dm), contraction time (Tc)] were considered as exploratory. After 1-h, all the tensiomyography variables measured at VM and BFLH were similarly depressed in both treatments. Only MALT showed a significantly lower Vc (−0.02 m. s −1, 95% CI, −0.04, −0.01) in the AD. After 24-h, the VGMT treatment normalized all tensiomyography values. Conversely, impaired scores were observed in Vc for the VM (−0.03 m. s −1, 95% CI, −0.06, −0.01) and BFLH (−0.02 m. s −1, 95% CI, −0.05, 0.01) in the MALT treatment. Particularly, the Vc in VM was lower (p = 0.043) in MALT compared to VGMT. Overall, both treatments required 48-h to regain their performance capacity; however, VGMT produced better vertical jump and squat performance at 24-h vs. MALT. Compared to MALT, a vegan-protein multi-ingredient appears to hasten the recovery of muscular function over a 24-h period.

Characterization of muscle function, lifestyle and motivational indices in obese women

Characterization of muscle function, lifestyle and motivational indices in obese women

Characterization Of Muscle Inflammation Susceptibility: A Potential Prognostic Factor For Optimal Post-surgical Rehabilitation

BACKGROUND: Many individuals with end-stage osteoarthritis undergo elective total hip/knee arthroplasty (THA/TKA) to relieve pain and improve mobility and quality of life. However, ~35% suffer long-term mobility impairment following surgery. Previously, we have shown this may be in part due to muscle inflammation susceptibility (MuIS(+)), an overt pro-inflammatory state localized to skeletal muscle surrounding the diseased joint, found in some but not all TKA/THA patients. PURPOSE: We are interrogating the hypotheses that a) MuIS(+/-) status will result in a differential perioperative expression profile that may partially explain low functional outcomes, and b) resistance training rehabilitation will more effectively overcome MuIS(+) status than usual care for effective recovery post-surgery. METHODS: Muscle samples were leveraged from our ongoing two-site, randomized, controlled trial (N=84). Participants were dichotomized to MuIS status (+/-) based on surgical (SX) muscle gene expression of Fn14 which drives pro-inflammatory signaling via NFκB. MuIS(+/-) samples were probed for pro-inflammatory gene and protein expression targets, and indices of skeletal muscle function. Preliminary perioperative comparisons were made using two-tailed T-tests; alpha P≤0.05. RESULTS: 84 participants (29M/55F; 62±8yrs; BMI 30.7±5.4kg/m2) undergoing THA/TKA were assessed. Thus far, 37 have been clustered as MuIS(+) (n=14, ~4-fold greater Fn14 mRNA) or MuIS(-) (n=23). SX thigh muscle mass (TMM), quadriceps power and torque were lower (P<0.05) than the contralateral limb (CTR). Additionally, skeletal muscle fibrosis and type II cross-sectional area were greater in the SX leg and MuIS(+) respectively (P<0.05). Tumor necrosis factor-α receptor and IL-6 trended higher in MuIS(+) (P>0.05). Phosphorylated (P)-RPS6 was lower in the SX leg and P-4E-BP1 was significantly lower in MuIS(+) (P>0.05). CONCLUSIONS: Preliminary results suggest patients undergoing TKA/THA exhibit more inflammation on the SX limb, accompanied by lower TMM, torque and power. MuIS(+) leads to greater inflammation and blunted anabolic signaling, highlighting the profound impact of muscle inflammation and emphasizing the potential value in perioperative MuIS assessment to inform optimal post-surgical care. Grant: R01HD084124