Grip Endurance Research Articles

The Risk Factors Associated with Handgrip Strength and Endurance in Adolescence

Background Handgrip strength and endurance are some of the ways that can be done to examine the muscle quality of adolescents as well as their physical fitness. It is influenced by various internal and external factors, including body mass index, gender, age, and smoking habits. Handgrip strength can be an important parameter for health. Adolescents with lower muscle strength have an increased mortality rate in adulthood. Thus, this study aimed to determine the factors associated with handgrip strength and endurance in adolescence. Methods The study used analytic observational with a cross-sectional approach using consecutive non-random sampling on 58 adolescents between 15-23 years old. The instruments used a scale and microtoise to measure body mass index, and a hand dynamometer to measure handgrip strength and endurance. The data was analyzed by the Chi-square test using the SPSS program with p<0.05. Results Of the 58 respondents consisting of 48.27% men, and 51.72% women, there were 58.62% normal BMI and 70.68% did not smoke. The percentage of respondents who had weak grip strength was lower (44.82%) compared to weak grip endurance (55.17%). There was no significant relationship between gender and handgrip endurance; body mass index and handgrip strength as well as handgrip endurance; cigarette consumption and handgrip strength. Moreover, there was found a significant relationship between gender and handgrip strength (p=0.000) and between cigarette consumption and handgrip endurance (p=0.011). Conclusions Handgrip strength and endurance were more in the weak-medium category. There was no significant relationship between gender and handgrip endurance; body mass index and handgrip strength as well as handgrip endurance; cigarette consumption and handgrip strength. Moreover, there was found a significant relationship between gender and handgrip strength and between cigarette consumption and handgrip endurance.

Correlation of Body Mass Index and Work Profile on Hand Grip Strength and Endurance in Healthy Adults

Background and need of research: Hand Grip Strength (HGS) is an integral part of performing precise and refined fine motor activities. Many professions necessitate lifting and holding heavy loads with a proportionately static grip or repetitive or forceful gripping movements. Hence it is important to consider measurement of handgrip endurance (HGE) as an important component of assessment of physical performance. Most of studies have shown that HGS and BMI is associated with mortality and cardiovascular disease. So, need of this study is to fulfill the lacunae of literature. Method: A cross-sectional study-conducted on 80 healthy adults(age:18-40) after obtaining Institutional Ethical Committee clearance. Participants who met with the inclusion criteria were invited for study. BMI was calculated using the formula weight(kg)/height(m)2.HGS and HGE were measured in office worker and labourer using hand grip dynamometer. Results: Mean age, BMI, strength and endurance of office worker is (32.78+5.96), (26.15+5.36), (29.04+9.34), (44.63+28.53) and labourer is (32.47+4.46), (25.35+3.33), (37.26+8.57), (32.82+29.44) respectively. Spearman correlation test was used for analysis. Significant negative correlation (r=-0.507, p<0.05) is found between labourer BMI and HSG and very weak correlation found between BMI and HGE (r=-0.010, p>0.05). Weak and very weak correlation found between office worker’s BMI, HGS and HGE (r=-0.274, p>0.05 and r=0.110, p>0.05) respectively. Conclusion and clinical implication: There is significant negative correlation found between BMI and grip strength in labour group. This result supports that HGS can be effective tool for predicting physical fitness. Moreover, through normative value of HGS, clinician can detect low level of physical fitness at early stage in order to prevent future health problems. Keywords: BMI, hand grip strength, hand grip endurance, work profile

Correlation between hand grip endurance and scapular muscle endurance in asymptomatic individuals

INTRODUCTION: Gripping activity is an essential daily activity at home and at the workplace, where lifting and holding loads with a relatively static grip using isometric contraction is often required. Muscle strength and endurance in the proximal aspect of the upper extremities influence hand function, and individuals with reduced strength and endurance are more prone to developing work-related musculoskeletal disorders. Good grip endurance might be influenced by the stabilization provided by shoulder muscles. This study aims to determine the correlation between hand grip endurance and scapula muscle endurance among young asymptomatic individuals. METHOD:The sample size for this study is n = 62, based on previous studies. Healthy individuals of both genders, aged between 18 and 25 years, were included. An objective assessment of grip endurance was performed using a hydraulic hand dynamometer, while scapular endurance was evaluated using the scapular muscle test. RESULTS: Data analysis was performed using SPSS version 20. There were significant positive correlations between scapular endurance measures and the hand grip endurance on both sides (Pearson correlation test, r = 0.612 (p < 0.001) and r = 0.524 (p < 0.001), respectively, for non-dominant and dominant hand grip endurance). FINAL CONSIDERATIONS: The preliminary findings of this study support the notion that scapular muscle endurance is related to hand grip endurance, suggesting that scapular endurance training may be an effective adjunct in the rehabilitation process for upper extremity functions.

Comparative Study of Static and Dynamic Hand Grip Endurance with Correlation of Deep Breathing among Pregnant Women; A Cross-sectional Study

Background: Physiology of the mother, changes constantly during pregnancy including reduced HGS that is require for carrying the child after delivery. Activities of daily living require manual gripping tasks that require dynamic and static contractions. Predictor of upper extremity function is Hand Grip Strength and handgrip endurance. Screening of hand grip strength during antenatal care is still uncommon. Objectives: To compare static and dynamic hand grip endurance in pregnant females and to find its correlation with deep breathing. Material and Methods: The study recruited 40 participants of primi-gravida of 1st and 2nd trimester, between ages 20 and 35 years from SHALAMAR GYNAE OPD. The participants assigned to the groups (Group 1: with DB, Group 2: without DB) based on their trimester and gravidity. Static and dynamic endurance assessed using hand held dynamometer. Results: Mean Age ± Standard deviation for deep and non-deep breathing groups was 22.85 ± 2.30 and 24.05 ± 0.514. Age had negative little or low correlation with all variables of deep and non-deep breathing groups. Peak hand grip strength was moderately correlated with hand grip endurance with deep and non-deep breathing group (r = -0.628, r = -0.566 respectively). Static hand grip endurance was weakly correlated with peak hand grip strength in deep breathing group (r = -0.239) whereas static hand grip endurance had little, if any correlation with peak hand grip strength in deep breathing group (r = -0.165). Clinical implication: Management of hand grip strength and endurance improves general well being of pregnancy. By employing deep breathing exercises hand grip strength can be improved. Conclusion: Peak hand grip strength and endurance improved markedly in 2nd trimester with deep breathing. Deep breathing can improve peak hand grip endurance and peak hand grip strength in pregnancy with increasing trimester. Whereas static and dynamic hand grip endurance has insignificant effect in different trimester. Keywords: Pregnancy, deep breathing, trimester, endurance, peak grip endurance

Assessing the therapeutic impact of resveratrol in ALS SOD1-G93A mice with electrical impedance myography.

To aid in the identification of new treatments for amyotrophic lateral sclerosis (ALS), convenient biomarkers are needed to effectively and uniformly measure drug efficacy. To this end, we assessed the effects of the nutraceutical resveratrol (RSV) on disease onset and overall survival in SOD1-G93A (ALS) mice and compared several standard biomarkers including body mass, motor score (MS), paw grip endurance (PGE), and compound motor action potential (CMAP) amplitude, with the technique of electrical impedance myography (EIM) to follow disease progression. Eighteen ALS mice (nine females, nine males) received RSV in the chow (dose: 120 mg/kg/day) starting at 8 weeks of age; 19 ALS mice (nine females, 10 males) received normal chow; 10 wild type (WT) littermates (five females, five males) fed standard chow served as controls. Biomarker assessments were performed weekly beginning at 8 weeks. No differences in either disease onset or overall survival were found between RSV-treated and untreated ALS mice of either sex; moreover, all biomarkers failed to identify any beneficial effect of RSV when administered at this dose. Therefore, for the comparative evaluation of the ability of the various biomarkers to detect the earliest symptoms of disease, data from all animals (i.e., RSV-treated and untreated ALS mice of both sexes) were combined. Of the biomarkers tested, EIM impedance values, i.e., surface EIM longitudinal phase at 50 kHz (LP 50 kHz), and CMAP amplitude showed the earliest significant changes from baseline. LP 50 kHz values showed a rate of decline equivalent to that of CMAP amplitude and correlated with both PGE and CMAP amplitude [Spearman rho = 0.806 (p = 0.004) and 0.627 (p = 0.044), respectively]. Consistent with previous work, these findings indicate that surface EIM can serve as an effective non-invasive biomarker for preclinical drug testing in rodent models of ALS.

Grip endurance in patients with rheumatoid arthritis: Its relationship between clinical characteristics, upper extremity functional disability, and quality of life.

The study's aim was to investigate the relationship of grip strength and endurance with clinical characteristics, upper extremity functional disability, and quality of life in rheumatoid arthritis (RA) patients. We included 45 RA patients and 37 healthy controls in this cross-sectional study. All participants were evaluated using the maximal gripping test, static and dynamic grip endurance test, the Disability of Arm, Shoulder Hand Questionnaire, and Short Form-36, and sociodemographic and clinical characteristics were recorded. Moderate to strong correlations were found between functional disability and all of the grip-related variables. Physical, emotional, and social function sub-scores were correlated with grip strength on both sides and dynamic endurance on the dominant side. The study highlights grip-related variables associated with disability of the upper extremity. The grip strength was related to hand-wrist pain but not other clinical characteristics. Furthermore, grip strength on both sides and dynamic grip endurance on the dominant side were associated with some quality of life sub-scores. While therapists create a rehabilitation plan for RA patients, based on our findings, it may be beneficial to maximize therapeutic benefits on daily life and quality of life.

Grip Strength and Endurance: Influences of Anthropometric Characteristics, Posture, and Gender

Grip Strength and Endurance: Influences of Anthropometric Characteristics, Posture, and Gender

Hand functions and joint position sense in patients with psoriatic arthritis- a comparison with rheumatoid arthritis and healthy controls

BackgroundPsoriatic arthritis is an inflammatory arthropathy accompanied by peripheral and axial joint involvement. Hand involvement has been demonstrated by various imaging methods in patients with psoriatic arthritis. However, few studies evaluated the hand in terms of functionality. The aim of the study is to compare hand functions and wrist joint position sense in psoriatic arthritis with rheumatoid arthritis and healthy controls. MethodsPatients with psoriatic arthritis (n = 21), rheumatoid arthritis (n = 21), and healthy controls (n = 21) were included in this cross-sectional study. The measurements were performed by a hand dynamometer for grip strength and endurance, and by a pinchmeter for pinch strength. Disability of Arm, Shoulder, and Hand Questionnaire was used to evaluate the functional disability. A goniometric test was used to assess wrist joint position sense. FindingPatients with psoriatic arthritis had worse hand functional outcomes and higher position errors than healthy controls (p < 0.05). In addition, in terms of all variables, patients with psoriatic arthritis were found to be similar to the patients with rheumatoid arthritis (p > 0.05). InterpretationOur study revealed that hand functions and wrist joint position sense were affected as much in patients with psoriatic arthritis as in patients with rheumatoid arthritis whose hand involvement is frequently reported in the literature. The grip endurance in psoriatic arthritis was assessed for the first time. Our results highlighted the necessity of treatment programs that include strength, endurance, and proprioception in patients with psoriatic arthritis who have hand involvement at least as much as those with rheumatoid arthritis.

Combined driving: task-specific position impacts grip strength of equestrian athletes

BackgroundLoss of hand strength is a predictor of mortality in aging populations. Despite reliance on the hands to participate in equestrian driving activity, no existing studies focus on associations of hand strength to athletic performance. Therefore, this study 1) established baseline handgrip of equestrian combined drivers in standing and task-specific positions, 2) determined endurance of task-specific handgrip, 3) compared handgrip strength to normative data, and 4) evaluated associations of handgrip and equestrian-specific variables.MethodsThere were 51 combined drivers (9 males, 42 females) ages 21–78 who completed a survey, standing handgrip, and grip strength and endurance in a task-specific position. Sixty-three percent of participants were 50 years or older. The dynamometer grip bar was normalized by hand size for standing tests; to duplicate sport-specific tasks, the bar was set to the closest setting. Significances were determined at p < 0.05.ResultsDrivers with more than 30 years of experience demonstrated highest summed standing (73.1 ± 5.2 kg) and summed sitting (59.9 ± 6.3 kg) grip strength. Females 60-years and older had greater handgrip endurance (Χ2 = 8.323, df = 2, p = .0156) in non-dominant (left) hands. Males (60%) reported more cold weather fatigue than females. Glove wearing was associated with bilateral endurance balance; a higher proportion of endurance balance between dominant and non-dominant (49% high-high and 29% low-low; Χ2 = 11.047, df = 1, p = .0009) was realized. There were no associations of handgrip and prior injury.ConclusionsOur results have implications in understanding task-specific and normative grip strengths in aging equestrian populations. Bilateral balance in handgrip strength and endurance is important particularly in maintaining strength in non-dominant hands over time. Equestrian driving sport promotes greater endurance in older females. Strength can be improved by participating in combined driving, and engagement in this sport over several years’ benefits hand strength over time. This cohort of equestrian participants provides evidence that participating in hand-specific activities promotes greater strength, which has been previously shown to improve aging outcomes.

INVESTIGATION OF THE RELATIONSHIP BETWEEN ANTHROPOMETRIC MEASUREMENTS AND FOREARM POSTURES WITH GRIP STRENGTH IN YOUNG ADULTS

BACKGROUND: Grip strength is widely accepted as an indicator of maximum hand strength and contraction of active muscles of the hand and forearm. OBJECTIVE: The aim of this study was to assess the effects of forearm posture (pronation, supination and neutral) and anthropometric variation on MVC grip strength and grip endurance time in young university adults. METHODS: Fifty healthy, right-handed men volunteered to participate in this study. The experiment was characterized by measuring MVC grip strength and endurance time of 50% MVC randomly in three different postures (supine, pronation and neutral). Performance was assessed in terms of dependent variables: MVC grip strength and grip endurance time. RESULTS: MANCOVA results showed no significant effect of posture on MVC grip strength (p = 0:333) and grip endurance time (p = 0:772). There was a significant effect of age (p = 0.044), height (p = 0.012) and forearm length (p = 0.039) on the grip endurance time in supine position. However, palm circumference had a significant effect on MVC grip strength (p = 0.036) in pronation posture only. The pronation forearm posture produces 7.4% more grip strength than a supine posture. In addition, the grip endurance time was improved in the supine position, compared to the neutral and pronation forearm posture. CONCLUSIONS: This study showed that the MVC grip strength is affected by the weight and palm circumference. In addition, palm circumference was the most influential factor affecting grip strength. Thus, anthropometric and posture-specific grip strength data are essential for clinical and industrial applications. The results can be used to prepare guidelines for rehabilitation, health care, sport and medicine.

Repositioning doxycycline for treating Parkinson’s disease: Evidence from a pre‐clinical mouse model

Parkinson's disease (PD) is a neurodegenerative disorder orphan of valuable therapies. PD is neuropathological characterized by intracellular Lewy bodies formed by aggregated α-synuclein (α-syn ) in mesencephalic region and neuroinflammation significantly contribute to the pathogenesis of the disease. In the complex scenario of PD single target therapy cannot be beneficial, a therapeutic strategy simultaneously affecting α-syn aggregation and neuroinflammation may be useful to affect PD progression. Recently, the antimicrobial drug Doxycycline (Doxy) has been demonstrated to inhibit α-syn aggregation. In addition, we have reported that Doxy at sub-antibiotic doses efficiently counteracts memory impairment and neuroinflammation in a transgenic (Tg) mouse model of Alzheimer's Disease. Based on the multiple action mechanism of Doxy, we herein investigate the potential therapeutic properties of Doxy in a Tg PD mouse model.A53T mice and their non-Tg (NTG) litter mates were intraperitoneally treated with 10mg/Kg Doxy for 30 days. At the end of treatment, cognitive and motor performances were evaluated in the Novel object recognition test (NORT), Nesting test, Beam-walk and Paw grip endurance. In addition, hippocampal long term potentiation (LTP) was assessed. Neuropathological markers were explored through immunohistological and biochemical approaches.Doxy abolished the cognitive deficit in the NORT. Moreover, Doxy restored daily life activity of A53T mice in the Nesting test, which is dependent by hippocampal and cortical networks. Aside from an effect at cognitive level, we found that Doxy treatment ameliorated motor performances in both the Beam-walk test and in the Paw grip endurance. The effect on cognitive functions was strictly linked to a reduced neuronal loss in the cortex and hippocampus of A53T+Doxy compared to A53T+Veh group. Moreover, glial activation were blocked by our pharmacological approach both in the cortex and hippocampus. In addition, Doxy treatment restored hippocampal LTP in association with the dampening of pro-inflammatory cytokines expression.Doxy emerges as a valuable therapeutic approach to counteract both symptoms and neuropathological hallmarks in the complex scenario of a Tg PD mouse model. Moreover, our results depict PD as a novel field for repurposing Doxy and corroborate previous data indicating Doxy as a multi-target drug.

The Effects of Forearm Kinesio-Taping on Hand Grip Strength and Endurance in Female Squash Elites

Background: Hand grip plays a fundamental role in most daily and athletic activities of the upper extremities. Objectives: The study compared the effect of various methods of forearm Kinesio-taping (KT) on the hand grip strength and endurance of Iranian elite squash players during their sporting activities at different times. Methods: Thirty-three female squash players were assigned to a quasi-experimental study, and KT was applied on their dominant forearm (on the flexor area, on the extensor area, and placebo taping). Grip strength was evaluated before, immediately, 30, and 60 minutes after KT, and grip endurance was also assessed before and 60 minutes after KT using MIE digital grip analyzer. Friedman and Kruskal-Wallis tests were used to analyze the results of grip strength, and ANOVA and the sample t-test were applied to analyze the grip endurance data. Results: The findings revealed no significant differences within the grip strength at different phases (P &gt; 0.05). However, p values for the outcomes of KT on the flexor area‎, KT on the extensor area‎, and placebo mode were respectively 0.145, 0.178, 0.065 in each phase of the evaluation. A significant difference ‎among KT groups and the LSD test revealed a significant increase in grip endurance in the mode of KT on the extensor area, whereas there have been no significant differences in grip endurance in KT on flexor (P = 0.785) and extensor (P = 0.457) areas. Conclusions: There was no obvious superiority of the various methods of forearm ‎ KT ‎ on grip strength at different times; nevertheless, KT was an efficient method for retaining grip endurance in squash players with no significant differences between the flexor and extensor locations.

Evidence for a Behaviourally Measurable Perseverance Trait in Humans.

The aim was to create and study a possible behavioural measure for trait(s) in humans that reflect the ability and motivation to continue an unpleasant behaviour, i.e., behavioural perseverance or persistence (BP). We utilised six different tasks with 54 subjects to measure the possible BP trait(s): cold pressor task, hand grip endurance task, impossible anagram task, impossible verbal reasoning task, thread and needle task, and boring video task. The task performances formed two BP factors. Together, the two-factor solution is responsible for the common variance constituting 37.3% of the total variance in the performances i.e., performance times. Excluding the impossible anagram task, the performance in any given task was better explained by performances in the other tasks (i.e., “trait”, η2 range = 0.131–0.253) than by the rank order variable (“depletion”, i.e., getting tired from the previous tasks, η2 range = 0–0.096).

Electromyography-based Fatigue Assessment During Endurance Testing by Different Vibration Training Protocols

Objectives: This study presents a method of assessing muscle fatigue during endurance testing at 50% maximal voluntary contraction (MVC) using electromyography (EMG) information as indirect indices of fatigability in the forearm muscles, namely, flexor digitorum superficialis (FDS); flexor carpi ulnaris (FCU); extensor carpi ulnaris (ECU) and extensor carpi radialis brevis (ECRB)." This study presents a method of assessing muscle fatigue during endurance testing at 50% maximal voluntary contraction (MVC) using electromyography (EMG) information as indirect indices of fatigability in the forearm muscles, namely, flexor digitorum superficialis (FDS); flexor carpi ulnaris (FCU); extensor carpi ulnaris (ECU) and extensor carpi radialis brevis (ECRB). Methods: A randomized comparative experimental design was used during endurance test with 8 VT protocols; based on different combinations of vibration frequency (35 &amp; 45 Hz), amplitude (3±0.5g &amp; 9±0.5g), and exposure duration (30 &amp; 60 seconds), i.e., were given to the study participants for 4 days. A random sampling of participants was conducted from two groups (n=56/group), as follows: individuals with a Sedentary Lifestyle (SL) and a group of Construction Workers (CW). Results: Multivariate Analysis of Variance (MANOVA) results indicated a significant increase in EMG rms, median frequency, waveform length, mean absolute value (P&lt;0.001), and the variance of EMG signal (P&lt;0.05) (except in ECU for the SL group and ECRB for the CW group on the variance of EMG signal) after VT in all muscles of both research groups. Therefore, an increase in the EMG parameter value after a grip endurance task revealing an elevation in EMG signal amplitude is indicative of muscle fiber fatigue. Furthermore, the strongest correlation was found between grip endurance and WL (r=0.471, P&lt;0.001), and EMG rms (r=0.401, P&lt;0.001) of the ECU muscle in the SL group only. Discussion: The patterns of EMG signal represented the amplitude and spectral parameters of the signal, enabling real-time fatigue analysis. Additionally, surface EMG information is useful for indirectly evaluating performance fatigue during the endurance test.

Effects of short-term icing of forearm muscles between exercises on the grip endurance of judo athletes

Effects of short-term icing of forearm muscles between exercises on the grip endurance of judo athletes

Effects of vibratory massage therapy on grip strength, endurance time and forearm muscle performance.

Vibration therapy (VT) causes an increase in motor unit activation tendency, an involuntary recruitment of earlier sedentary motor units, which increases the muscle fiber force generating capacity and muscle performance. To evaluate the effect of vibratory massage therapy at 23 Hz and 35 Hz on grip strength, endurance, and forearm muscle performance (in terms of EMG activity). Ten healthy and right-handed men participated voluntarily in this study. The experiment was characterized by the measurement of MVC (maximal voluntary contraction) grip strength and grip endurance time at 50%MVC, accompanied by the corresponding measurement of the EMG signals of the muscles viz., flexor digitorum superficialis (FDS); flexor carpi ulnaris (FCU); extensor carpi radialis brevis (ECRB); and extensor carpi ulnaris (ECU) in supine posture. MANCOVA results showed significant effects of VT frequency on endurance time (p < 0.001); but no significant effect on the grip strength (p = 0.161) and muscle performance (in terms of EMG activities of the forearm muscles). However, VT improves the MVC grip strength and grip endurance time (better at 35 Hz). The Pearson correlation was significant between: weight, palm length, palm circumference, and forearm length with MVC grip strength; and the palm length with the endurance time. In addition, the palm length, palm circumference, and forearm circumference generally serve to better predict MVC grip strength and grip endurance time. Vibration therapy at 35 Hz for 10 minutes on the forearms had a significant positive effect on the neuromuscular performance to enhance muscle performance of upper extermitites and can be used as the optimal range to study the effect of VT. Findings may be used to prepare guidelines for VT in rehabilitation, healthcare, sports, and medical for therapists.

유산소를 병행한 근력운동이 유방암 절제술 환자의 팔 둘레, 악력, 통증, 장애지수, 지구력에 미치는 영향

유산소를 병행한 근력운동이 유방암 절제술 환자의 팔 둘레, 악력, 통증, 장애지수, 지구력에 미치는 영향

Vitamin D Insufficiency Reduces Grip Strength, Grip Endurance and Increases Frailty in Aged C57Bl/6J Mice.

Low 25-OH serum vitamin D (VitD) is pervasive in older adults and linked to functional decline and progression of frailty. We have previously shown that chronic VitD insufficiency in “middle-aged” mice results in impaired anaerobic exercise capacity, decreased lean mass, and increased adiposity. Here, we examine if VitD insufficiency results in similar deficits and greater frailty progression in old-aged (24 to 28 months of age) mice. Similar to what we report in younger mice, older mice exhibit a rapid and sustained response in serum 25-OH VitD levels to differential supplementation, including insufficient (125 IU/kg chow), sufficient (1000 IU/kg chow), and hypersufficient (8000 IU/kg chow) groups. During the 4-month time course, mice were assessed for body composition (DEXA), physical performance, and frailty using a Fried physical phenotype-based assessment tool. The 125 IU mice exhibited worse grip strength (p = 0.002) and inverted grip hang time (p = 0.003) at endpoint and the 8000 IU mice transiently displayed greater rotarod performance after 3 months (p = 0.012), yet other aspects including treadmill performance and gait speed were unaffected. However, 125 and 1000 IU mice exhibited greater frailty compared to baseline (p = 0.001 and p = 0.038, respectively), whereas 8000 IU mice did not (p = 0.341). These data indicate targeting higher serum 25-OH vitamin D levels may attenuate frailty progression during aging.

Absence of complement factor H reduces physical performance in C57BL6 mice

Complement (C) system is a double edge sword acting as the first line of defense on the one hand and causing aggravation of disease on the other. C activation when unregulated affects different organs including muscle regeneration. However, the effect of factor H (FH), a critical regulator of the alternative C pathway in muscle remains to be studied. FH deficiency results in excessive C activation and generates proinflammatory fragments C5a and C3a as byproducts. C3a and C5a signal through their respective receptors, C5aR and C3aR. In this study, we investigated the role of FH and downstream C5a/C5aR signaling in muscle architecture and function. Using the FH knockout (fh-/-) and fh-/-/C5aR-/double knockout mice we explored the role of C, specifically the alternative C pathway in muscle dysfunction. Substantial C3 and C9 deposits occur along the walls of the fh-/- muscle fibers indicative of unrestricted C activation. Physical performance assessments of the fh-/- mice show reduced grip endurance (76 %), grip strength (14 %) and rotarod balance (36 %) compared to controls. Histological analysis revealed a shift in muscle fiber populations indicated by an increase in glycolytic MHC IIB fibers and reduction in oxidative MHC IIA fibers. Consistent with this finding, mitochondrial DNA (mtDNA) and citrate synthase (CS) expression were both reduced indicating possible reduction in mitochondrial biomass. In addition, our results showed a significant increase in TGFβ expression and altered TGFβ localization in this setting. The architecture of cytoskeletal proteins actin and vimentin in the fh-/- muscle was changed that could lead to contractile weakness and loss of skeletal muscle elasticity. The muscle pathology in fh-/- mice was reduced in fh-/-/C5aR-/- double knockout (DKO) mice, highlighting partial C5aR dependence. Our results for the first time demonstrate an important role of FH in physical performance and skeletal muscle health.

Effects of vibration therapy on neuromuscular efficiency & features of the EMG signal based on endurance test

BackgroundVibration Therapy (VT) stimulate the muscle spindles, which in turn enhances its afferent activities. ObjectiveThe present study was designed to investigate the effect of VT at 23 and 35 Hz on muscle performance. The EMG features (six time-domain (TD) and four frequency-domain (FD)) and a new formula for computing neuromuscular performance were used as dependent variables to evaluate the effect of VT. MethodThe EMG recording was performed at 50% MVC during grip endurance test before and after VT. The EMG features were extracted out of raw EMG signals acquired from four forearm muscles, viz., flexor digitorum superficialis (FDS); flexor carpi ulnaris (FCU); extensor carpi radialis brevis (ECRB); and extensor carpi ulnaris (ECU) in supine position. Fatigue assessments were evaluated based on the pattern of TD and FD features. ResultsStatistical analysis showed a significant difference in the effect of vibration exposure frequency on IEMG (p < 0.001), MAV (p = 0.041), SSI (p = 0.032), and WL (p < 0.001) of FCU muscle. In addition, the greatest increase in neuromuscular efficiency (NME) was observed in the performance of ECRB after 35 Hz of VT and ECU muscles after 23 Hz of VT. ConclusionsThe features of EMG signals could be used for fatigue analysis. However, the slope based on the median frequency regression line may be the best feature for fatigue assessment.