The evaluation of rate of force development during rapid contractions has recently become quite popular for characterising explosive strength of athletes, elderly individuals and patients. The main ...aims of this narrative review are to describe the neuromuscular determinants of rate of force development and to discuss various methodological considerations inherent to its evaluation for research and clinical purposes. Rate of force development (1) seems to be mainly determined by the capacity to produce maximal voluntary activation in the early phase of an explosive contraction (first 50–75 ms), particularly as a result of increased motor unit discharge rate; (2) can be improved by both explosive-type and heavy-resistance strength training in different subject populations, mainly through an improvement in rapid muscle activation; (3) is quite difficult to evaluate in a valid and reliable way. Therefore, we provide evidence-based practical recommendations for rational quantification of rate of force development in both laboratory and clinical settings.
Abstract
Background
Aging results in reductions in maximal muscular strength, speed, and power, which often lead to functional limitations highly predictive of disability, institutionalization, and ...mortality in elderly adults. This may be partially due to reduced nitric oxide (NO) bioavailability. We, therefore, hypothesized that dietary nitrate (NO3−), a source of NO via the NO3− → nitrite (NO2−) → NO enterosalivary pathway, could increase muscle contractile function in older subjects.
Methods
Twelve healthy older (age 71 ± 5 years) men and women were studied using a randomized, double-blind, placebo-controlled, crossover design. After fasting overnight, subjects were tested 2 hours after ingesting beetroot juice containing or devoid of 13.4 ± 1.6 mmol NO3−. Plasma NO3− and NO2− and breath NO were measured periodically, and muscle function was determined using isokinetic dynamometry.
Results
N
O
3
−
ingestion increased (p < .001) plasma NO3−, plasma NO2−, and breath NO by 1,051% ± 433%, 138% ± 149%, and 111% ± 115%, respectively. Maximal velocity of knee extension increased (p < .01) by 10.9% ± 12.1%. Maximal knee extensor power increased (p < .05) by 4.4% ± 7.8%.
Conclusions
Acute dietary NO3− intake improves maximal knee extensor angular velocity and power in older individuals. These findings may have important implications for this population, in whom diminished muscle function can lead to functional limitations, dependence, and even premature death.
ObjectiveTo report 3 cases of Guillain⁃Barré syndrome (GBS) caused by heat stroke (HS) and review the relevant literatures, and summarize the clinical characteristics of GBS caused by HS. Methods and ...Results The three patients were all diagnosed and treated by The Second Affiliated Hospital of Nanchang University in August 2022. The clinical manifestations were mainly weakness of limbs and dysarticulation after recovery of consciousness disorder of HS, disappearance of tendon reflex as shown by physical examination, extensive peripheral nerve damage mainly caused by axonal damage and motor nerve involvement as shown by EMG. Cerebrospinal fluid protein cell segregation phenomenon was present in Case 1 and Case 2, and the clinical diagnosis was GBS caused by HS. The muscle strength was better than before after immunotherapy, but obvious neurological dysfunction was still found after one year follow⁃up. ConclusionsGBS caused by HS is a severe condition, often appearing within 3 weeks after HS. Immunotherapy lead
Objective
To assess pelvic floor muscle (PFM) strength and influencing factors among healthy women at different life stages.
Design
Multicentre cross‐sectional study.
Setting
Fourteen hospitals in ...China.
Population
A total of 5040 healthy women allocated to the following groups (with 1680 women per group): premenopausal nulliparous, premenopausal parous and postmenopausal.
Methods
The PFM strength was evaluated by vaginal manometry. Multivariate logistic regression was used to determine the influencing factors for low PFM strength.
Main Outcome Measures
Maximum voluntary contraction pressure (MVCP).
Results
The median MVCP values were 36, 35 and 35 cmH2O in premenopausal nulliparous (aged 19–51 years), premenopausal parous (aged 22–61 years), and postmenopausal (aged 40–86 years) women, respectively. In the premenopausal nulliparous group, physical work (odds ratio, OR 2.05) was the risk factor for low PFM strength, which may be related to the chronic increased abdominal pressure caused by physical work. In the premenopausal parous group, the number of vaginal deliveries (OR 1.28) and diabetes (OR 2.70) were risk factors for low PFM strength, whereas sexual intercourse (<2 times per week vs. none, OR 0.55; ≥2 times per week vs. none, OR 0.56) and PFM exercise (OR 0.50) may have protective effects. In the postmenopausal group, the number of vaginal deliveries (OR 1.32) and family history of pelvic organ prolapse (POP) (OR 1.83) were risk factors for low PFM strength.
Conclusions
Physical work, vaginal delivery, diabetes and a family history of POP are all risk factors for low PFM strength, whereas PFM exercises and sexual life can have a protective effect. The importance of these factors varies at different stages of a woman's life.
Physical exercise is considered an effective means to stimulate bone osteogenesis in osteoporotic patients. The authors reviewed the current literature to define the most appropriate features of ...exercise for increasing bone density in osteoporotic patients. Two types emerged: (1) weight-bearing aerobic exercises, i.e., walking, stair climbing, jogging, and Tai Chi. Walking alone did not appear to improve bone mass; however it is able to limit its progressive loss. In fact, in order for the weight-bearing exercises to be effective, they must reach the mechanical intensity useful to determine an important ground reaction force. (2) Strength and resistance exercises: these are carried out with loading (lifting weights) or without (swimming, cycling). For this type of exercise to be effective a joint reaction force superior to common daily activity with sensitive muscle strengthening must be determined. These exercises appear extremely site-specific, able to increase muscle mass and BMD only in the stimulated body regions. Other suggested protocols are multicomponent exercises and whole body vibration. Multicomponent exercises consist of a combination of different methods (aerobics, strengthening, progressive resistance, balancing, and dancing) aimed at increasing or preserving bone mass. These exercises seem particularly indicated in deteriorating elderly patients, often not able to perform exercises of pure reinforcement. However, for these protocols to be effective they must always contain a proportion of strengthening and resistance exercises. Given the variability of the protocols and outcome measures, the results of these methods are difficult to quantify. Training with whole body vibration (WBV): these exercises are performed with dedicated devices, and while it seems they have effect on enhancing muscle strength, controversial findings on improvement of BMD were reported. WBV seems to provide good results, especially in improving balance and reducing the risk of falling; in this, WBV appears more efficient than simply walking. Nevertheless, contraindications typical of senility should be taken into account.
This study investigated the influence of Coronavirus Disease 2019 (COVID-19) on lung function in early convalescence phase.
A retrospective study of COVID-19 patients at the Fifth Affiliated Hospital ...of Sun Yat-sen University were conducted, with serial assessments including lung volumes (TLC), spirometry (FVC, FEV1), lung diffusing capacity for carbon monoxide (DLCO),respiratory muscle strength, 6-min walking distance (6MWD) and high resolution CT being collected at 30 days after discharged.
Fifty-seven patients completed the serial assessments. There were 40 non-severe cases and 17 severe cases. Thirty-one patients (54.3%) had abnormal CT findings. Abnormalities were detected in the pulmonary function tests in 43 (75.4%) of the patients. Six (10.5%), 5(8.7%), 25(43.8%) 7(12.3%), and 30 (52.6%) patients had FVC, FEV1, FEV1/FVC ratio, TLC, and DLCO values less than 80% of predicted values, respectively. 28 (49.1%) and 13 (22.8%) patients had PImax and PEmax values less than 80% of the corresponding predicted values. Compared with non-severe cases, severe patients showed higher incidence of DLCO impairment (75.6%vs42.5%, p = 0.019), higher lung total severity score (TSS) and R20, and significantly lower percentage of predicted TLC and 6MWD. No significant correlation between TSS and pulmonary function parameters was found during follow-up visit.
Impaired diffusing-capacity, lower respiratory muscle strength, and lung imaging abnormalities were detected in more than half of the COVID-19 patients in early convalescence phase. Compared with non-severe cases, severe patients had a higher incidence of DLCO impairment and encountered more TLC decrease and 6MWD decline.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Lower limb stabilizing muscle strength imbalance and changes in functional performance and dynamic balance have been reported as predictors of lower extremity injuries. Lower limb functional tests ...are commonly applied in clinical practice to assess functional performance as well as used as a measure of progression during rehabilitation. Among them, the Star Excursion Balance Test (SEBT) and the Single Leg Hop Test (SLHT) stand out as easy-to-apply and low-cost tools.
To evaluate the relationship between lower limb stabilizing muscle strength and performance in functional tests in individuals without history of injury.
This is a quantitative cross-sectional study. As eligibility criteria, male individuals, aged 18 to 30 years, with no history of previous injury to the lower limbs were included. The data collection was divided into two days. On the first day, anamnesis was performed, anthropometric data were collected, familiarization with the muscle strength test was carried out and the functional tests SLHT and SEBT were applied to the Dominant Limb (DL) and Non-Dominant Limb (NDL). On the second day, the strength of the stabilizing muscles of the hip (lateral rotators and abductors), knee (quadriceps and hamstrings) and ankle (inverters and evertors) were assessed using a portable Lafayette® dynamometer stabilized by an inelastic band. Three maximal voluntary isometric contractions were performed, lasting five seconds, with a thirty-second interval between each contraction, bilaterally. The peak strength of each movement was recorded and later normalized by body mass. Statistical analysis was performed using the SPSS 18.0® software, applying the Shapiro-Wilk normality test and the Pearson correlation test. A significance level of α<0.05 was adopted.
20 male individuals were collected. A moderate positive correlation was observed between peak strength of the NDL lateral rotators and hip abductors with performance in the DL SLHT and posteromedial SEBT. In addition, the strength of the knee extensors of both limbs was positively correlated with performance in the SLHT of the NDL. Furthermore, a correlation was observed between peak strength of NDL lateral rotators, DL ankle inverters and hip abductors with NDL posteromedial SEBT.
The maximum isometric strength of the lower limbs stabilizing muscles is related to the performance in functional tests.
The weakness of the stabilizing muscles of the hip and knee is directly related to a lower performance in functional tests, which may cause instability during movements, resulting in biomechanical changes that increase the risk of injury to the lower limbs. Still, the findings of this study elucidate that the performance analysis should take into account the bilateral force for the parameters of rehabilitation and injury prevention.
Summary
This systematic review summarizes the effect of combined exercise and nutrition intervention on muscle mass and muscle function. A total of 37 RCTs were identified. Results indicate that ...physical exercise has a positive impact on muscle mass and muscle function in subjects aged 65 years and older. However, any interactive effect of dietary supplementation appears to be limited.
Introduction
In 2013, Denison et al. conducted a systematic review including 17 randomized controlled trials (RCTs) to explore the effect of combined exercise and nutrition intervention to improve muscle mass, muscle strength, or physical performance in older people. They concluded that further studies were needed to provide evidence upon which public health and clinical recommendations could be based. The purpose of the present work was to update the prior systematic review and include studies published up to October 2015.
Methods
Using the electronic databases MEDLINE and EMBASE, we identified RCTs which assessed the combined effect of exercise training and nutritional supplementation on muscle strength, muscle mass, or physical performance in subjects aged 60 years and over. Study selection and data extraction were performed by two independent reviewers.
Results
The search strategy identified 21 additional RCTs giving a total of 37 RCTs. Studies were heterogeneous in terms of protocols for physical exercise and dietary supplementation (proteins, essential amino acids, creatine, β-hydroxy-β-methylbuthyrate, vitamin D, multi-nutrients, or other). In 79% of the studies (27/34 RCTs), muscle mass increased with exercise but an additional effect of nutrition was only found in 8 RCTs (23.5%). Muscle strength increased in 82.8% of the studies (29/35 RCTs) following exercise intervention, and dietary supplementation showed additional benefits in only a small number of studies (8/35 RCTS, 22.8%). Finally, the majority of studies showed an increase of physical performance following exercise intervention (26/28 RCTs, 92.8%) but interaction with nutrition supplementation was only found in 14.3% of these studies (4/28 RCTs).
Conclusion
Physical exercise has a positive impact on muscle mass and muscle function in healthy subjects aged 60 years and older. The biggest effect of exercise intervention, of any type, has been seen on physical performance (gait speed, chair rising test, balance, SPPB test, etc.). We observed huge variations in regard to the dietary supplementation protocols. Based on the included studies, mainly performed on well-nourished subjects, the interactive effect of dietary supplementation on muscle function appears limited.
Abstract
Objectives
Muscle weakness in idiopathic inflammatory myopathies (IIMs) is conventionally assessed using manual muscle testing (MMT). However, more objective tools must be developed to ...accurately and reliably quantify muscle strength in myositis patients. Hand-held dynamometry (HHD) is a quantitative, portable device with reported reliability in neuromuscular disorders. Our aim was to assess the reliability, validity and responsiveness of HHD in myositis.
Methods
Myositis patients DM, necrotizing myopathy (NM), PM and anti-synthetase syndrome evaluated at the University of Pittsburgh myositis centre were prospectively enrolled. Each patient was assessed at 0, 3 and 6 months for validated outcome measures of myositis disease activity and physical function. At each visit, muscle strength was assessed using both MMT and HHD (Micro FET2, Hoggan Health Industries, Draper, UT, USA). The reliability, validity and responsiveness of the HHD was assessed using standard statistical methods.
Results
Fifty IIM patients (60% female; mean age 51.6 years; 6 PM, 9 NM, 24 DM and 11 anti-synthetase syndrome) were enrolled. HHD showed strong test–retest intrarater reliability (r = 0.96) and interrater reliability (r = 0.98). HHD correlated significantly with the MMT score (r = 0.48, P = 0.0006) and myositis disease activity and functional measures. Longitudinal analysis showed a significant and strong association between the HHD and MMT as well as 2016 ACR/EULAR myositis response criteria (r = 0.8, P < 0.0001) demonstrating responsiveness. The mean effect size and standardized response mean of HHD was large: 0.95 and 1.03, respectively. MMT had a high ceiling effect compared with HHD.
Conclusion
HHD demonstrated strong reliability, construct validity and responsiveness in myositis patients. External validation studies are required to confirm these findings.
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