Contraction Type Research Articles

Challenging the mechanism of distal biceps tendon rupture using a video analysis study.

The conventionally described mechanism of distal biceps tendon rupture (DBTR) is of a 'considerable extension force suddenly applied to a resisting, actively flexed forearm'. This has been commonly paraphrased as an 'eccentric contracture to a flexed elbow'. Both definitions have been frequently used in the literature with little objective analysis or citation. The aim of the present study was to use video footage of real time distal biceps ruptures to revisit and objectively define the mechanism of injury. An online search identified 61 videos reporting a DBTR. Videos were independently reviewed by three surgeons to assess forearm rotation, elbow flexion, shoulder position, and type of muscle contraction being exerted at the time of rupture. Prospective data on mechanism of injury and arm position was also collected concurrently for 22 consecutive patients diagnosed with an acute DBTR in order to corroborate the video analysis. Four videos were excluded, leaving 57 for final analysis. Mechanisms of injury included deadlift, bicep curls, calisthenics, arm wrestling, heavy lifting, and boxing. In all, 98% of ruptures occurred with the arm in supination and 89% occurred at 0° to 10° of elbow flexion. Regarding muscle activity, 88% occurred during isometric contraction, 7% during eccentric contraction, and 5% during concentric contraction. Interobserver correlation scores were calculated as 0.66 to 0.89 using the free-marginal Fleiss Kappa tool. The prospectively collected patient data was consistent with the video analysis, with 82% of injuries occurring in supination and 95% in relative elbow extension. Contrary to the classically described injury mechanism, in this study the usual arm position during DBTR was forearm supination and elbow extension, and the muscle contraction was typically isometric. This was demonstrated for both video analysis and 'real' patients across a range of activities leading to rupture.Cite this article: Bone Jt Open2022;3(10):826-831.

FP.16 The effects of resistance exercise training on mitochondrial myopathy patients

Patients with single, large-scale mitochondrial DNA (mtDNA) deletions often present with mitochondrial myopathy (MM) for which no treatment is available. Exercise intervention induces beneficial effects in mitochondrial myopathy. However, the mechanisms for this are not yet understood. The aim of this study is to investigate genetic, biochemical and molecular changes triggered by 16-week resistance exercise training for the development of exercise mimetic drugs for the cure of MM patients. Quadriceps biopsies were taken from a cohort of single, large-scale mtDNA deletion patients before and after 16-week resistance exercise training. Biopsies were assessed for changes after exercise in oxidative phosphorylation (OXPHOS) staining for Laminin, VDAC1, Ndufb8 and COX1; fibre type distribution, size and contraction force staining for Myh7, Myh2 and Myh1; heteroplasmy using real-time PCR for MT-ND4, MT-CO1, MT-CO3 and MT-CYB genes; differentially expressed (DE) genes and related protein level using RNA-sequencing and imaging mass cytometry, respectively. Myopathy score is a strong predictor of resistance exercise training responsiveness. Compared to healthy controls, all patients present with a significantly lower contraction force of SKM fibres (p=0.003) and differential fibre type distribution with increased type 2a (p<0.04) and decreased fibre I (p<0.0001). After exercise, all cases show an increase in the proportion of fibres with higher level of COX1 (p<0.0012) and increase of Myh7⁺ fibre type size (all patients except P2, p < 0.0001). The majority of patients show a significant increase of mitochondrial mass that positively correlates with the increase of aerobic capability (R=0.81). Furthermore, 13,132 DE genes were identified between pre- and post-exercise cases, of which 40 DE genes were selected with p<0.05 and logarithmic fold change <1.5 or >1.5. Among these, 13 novel exercise-modulated targets were established with an increased protein level localising within the SKM fibres (e.g. Dock11, Edil3, Ikbkg, Gem). Further analysis will assess the protein level of targets with nuclear, perinuclear and extracellular localisation in SKM of MM patients. Resistance exercise training is effective in reducing the OXPHOS defects and induces SKM remodelling in MM patients. The identification of novel exercise-modulated targets may provide insight for the development of exercise mimetic drugs for the cure of mitochondrial myopathy patients.

RATIONAL TYPE CONTRACTION MAPPING THEOREMS ON MULTIPLICATIVE G-METRIC SPACES

In this article, we have extended the results of Y. U. Gaba by taking multiplicative G-metric space instead of G-metric space. In this way, we proved contraction mapping theorems on multiplicative, G-metric spaces using rational type contraction conditions for a single map. Later on, we extended our results in the settings of triplet maps. We have also given examples to support our results.

On some fixed point theorems for ordered vectorial Ćirić-Prešić type contractions

On some fixed point theorems for ordered vectorial Ćirić-Prešić type contractions

Some Fixed Point Results in E-Metric Spaces and an Application

The purpose of this paper is to study several fixed point problems in E-metric spaces. Mainly, we show the existence and uniqueness of fixed points for two contractive mappings, including Ćirić type contraction and α-ψ type contraction in E-metric spaces. Furthermore, we provide examples to support the accuracy of our results and present an application of our solution to a class of differential equations.

Torque and Discomfort During Electrically Evoked Muscle Contractions in Healthy Young Adults: Influence of Stimulation Current and Pulse Frequency

ObjectiveTo investigate (1) how current and pulse frequency of electrical stimulation (ES) as well as contraction mode (isometric, concentric, and eccentric) influence torque output and discomfort and (2) how familiarization by repeated ES sessions influences ratings of perceived discomfort. DesignAn experimental study, 3 sessions. SettingA university laboratory. ParticipantsEight healthy participants (5 men, 3 women; mean age 25.2 years; N=8). InterventionsParticipants completed 3 trial days, each including 17 electrically evoked thigh muscle contractions. On each trial day, the first 6 contractions consisted of 2 isometric, 2 concentric, and 2 eccentric muscle contractions randomly ordered with a fixed stimulation current and pulse frequency (200 mA, 20 Hz), while the remaining 11 muscle contractions were all isometric with randomly ordered combinations of current (100-250 mA) and pulse frequency (20-100 Hz). Main Outcome MeasuresTorque and perceived discomfort were measured for each ES-evoked contraction. ResultsOverall, the findings revealed that a higher stimulation frequency was associated with an increased torque without increased discomfort, while higher currents were associated with increases of both torque and discomfort. Contraction type did not influence level of discomfort, despite eccentric contractions eliciting higher torque compared with concentric and isometric contractions (P<.001). Finally, a significant familiarization to ES (P<.001) was observed after just 1 of 3 identical stimulation sessions. ConclusionsThe outlined data suggest that to elicit high torque levels while minimizing levels of discomfort in young subjects, eccentric muscle contractions evoked with a low stimulation current, and a high pulse frequency are preferable. Furthermore, a single familiarization session significantly lowers rating of perceived discomfort during ES.

On ψ -Caputo Partial Hyperbolic Differential Equations with a Finite Delay

In this work, we are concerned with some qualitative analyses of fractional-order partial hyperbolic functional differential equations under the ψ -Caputo type. To be precise, we investigate the existence and uniqueness results based on the nonlinear alternative of the Leray-Schauder type and Banach contraction mapping. Moreover, we present two similar results to nonlocal problems. Then, the guarantee of the existence of solutions is shown by Ulam-Hyer’s stability. Two examples will be given to illustrate the abstract results. Eventually, some known results in the literature are extended.

Maximal intended velocity enhances strength training-induced neuromuscular stimulation in older adults

The age-related attenuation in neuromuscular function can be mitigated with strength training. Current recommendations for untrained and elderly recommend performing the strength training with a controlled movement velocity (CON). However, applying maximal intended velocity (MIV) in the concentric phase of movement may augment neuromuscular stimulation and potentially enhance training adaptations. Thus, applying rate of electromyography (EMG) rise (RER) recordings, we examined the acute early phase neuromuscular response to these two contraction types in quadriceps femoris during leg extension, along with actual movement velocity, in 12 older (76 ± 6 years) and 12 young men (23 ± 2 years). Results revealed that older adults had a lower one repetition maximum (1RM) than young (33 ± 9 kg vs. 50 ± 9 kg; p = 0.001) and lower actual velocity across relative intensities of ~ 10%, 30%, 50%, 70% and 90% of 1RM for CON and MIV (all p < 0.05). Older adults also had consistently reduced RER compared to young during both conditions (old: 1043–1810 μV; young: 1844–3015 μV; all p < 0.05). However, RER was higher in contractions with MIV compared to CON for both age groups, and across all intensities (98–674%, all p < 0.05). In conclusion, despite decreased maximal strength and attenuated neuromuscular response with advancing age, our results document an augmented neuromuscular activation when repetitions are performed with MIV in the concentric phase of movement.

Equivalence between the Existence of Best Proximity Points and Fixed Points for Some Classes of Proximal Contractions

In the year 2014, Almeida et al. introduced a new class of mappings, namely, contractions of Geraghty type. Additionally, in the year 2021, Beg et al. introduced the concept of generalized F-proximal contraction of the first kind and generalized F-proximal contraction of the second kind, respectively. After developing these concepts, authors mainly studied the best proximity points for these classes of mappings. In this short note, we prove that the problem of the existence of the best proximity points for the said classes of proximal contractions is equivalent to the corresponding fixed points problems.

Cutaneous silent period modulation by tooth clenching, tonic and phasic limb movements in healthy subjects.

We aimed to examine the modulation of the cutaneous silent period (CSP) by tooth clenching and contralateral tonic dorsiflexion of lower limb and phasic voluntary movements of upper limb. In 18 healthy subjects, we recorded CSP on right thenar muscle after painful stimulation of index finger during mild contraction at six conditions: baseline, maximum tooth clenching, contralateral tonic dorsiflexion of foot, as well as at the beginning (RT1), in the middle (RT2) and at last part (RT3) of the contralateral phasic wrist extension. We measured latency and duration and calculated suppression indices. During tooth clenching, the suppression index of second inhibitory phase (I2) was significantly higher than that at baseline condition. The suppression index of first inhibitory phase (I1) was reduced in tonic dorsiflexion. The I2 durations in RT2 and RT3 were longer than that at baseline. The I2 suppression indices during RT1, RT2, and RT3 were significantly higher than that at baseline condition (p < 0.05). The tooth clenching has an inhibitory effect on CSP. The contralateral phasic hand movements caused higher suppression index. The CSP is modulated by remote influences differently depending on the type of muscle contraction (tonic vs. phasic) and/or where it is realized (tooth, upper or lower limb).

Meir–Keeler Type Contraction in Orthogonal M-Metric Spaces

In this article, we prove fixed point results for a Meir–Keeler type contraction due to orthogonal M-metric spaces. The results of the paper improve and extend some recent developments in fixed point theory. The extension is assured by the concluding remarks and followed by the main theorem. Finally, an application of the main theorem is established in proving theorems for some integral equations and integral-type contractive conditions.

A Study on the Fractal-Fractional Epidemic Probability-Based Model of SARS-CoV-2 Virus along with the Taylor Operational Matrix Method for Its Caputo Version

SARS-CoV-2 is a strain of the large coronavirus family that has led to COVID-19 disease. The virus has been one of the deadliest known viruses in the world to date. Rapid mutations and the creation of new strains cause researchers to focus on the dynamic behaviors of the virus and to analyze it accurately through clinical research and mathematical models. In this paper, from the point of view of mathematical modeling, we intend to focus on the dynamic behavior of the system and examine its analytical and numerical aspects in two different structures. In other words, by recalling newly formulated hybrid fractional-fractal operators, we present a fractal-fractional probability-based model of SARS-CoV-2 virus for the first time and extract its equivalent compact fractal-fractional IVP to investigate its existence and stability criteria. A type of special admissible contractions will help us in this regard. Moreover, based on the source data, we simulate our system according to algorithms derived by Adams-Bashforth method and explain the effects of variation of the dimension of fractal and fractional order on dynamics of solutions. Finally, we transform our fractal-fractional model into a Caputo probability-based model of SARS-CoV-2 to derive solutions via the operational matrix method under Taylor’s basis. The numerical simulations show close behaviors for both of models.

Some Boyd–Wong contraction type mappings in b-metric spaces

Some Boyd–Wong contraction type mappings in b-metric spaces

Acute effect of auxotonic and isometric contraction evaluated by infrared thermography in handball players

The Infrared Thermography (IRT) is being used in the field of sport as a means of quantifying the effects of workload. The aims of this study were (i) to determine the variations in skin temperature (Tsk) of the lower limbs after an effort of auxotonic and isometric squat contractions using infrared thermography and (ii) to study jumping performance variations in handball players after those two different contraction types. A total of 15 national level handball players voluntarily participated in the study (age: 23.20 ± 5.23 years). Two types of protocols – isometric and auxotonic – were performed on different days, having previously calculated the maximal isometric squat strength and auxotonic 1RM. During the data collection, participants performed a specific standardized warm-up and then randomly performed 4x10 repetitions of auxotonic squat to 90° of knee flexion at 70% of 1RM and 4x10 s of isometric squat effort at 90° of knee flexion, at 70% of maximal isometric squat strength (both with a passive recovery of 90 s seated). Rate of perceived exertion (RPE) and countermovement jumping performance (CMJ) were measured before and immediately after efforts. Additionally, infrared thermography data from twelve regions of interest of the lower limbs were registered before, immediately after and 15 min after finishing the effort. The main results indicated no significant differences for RPE (p = 0.486), CMJ vertical height (VH; p = 0.344) and Tsk (p > 0.05) in any of the regions of interest after protocols. Significant differences (p < 0.05) were found for the time of data collection on Tsk with similar pre- and post-15 min values. In conclusion, Tsk decreased after both isometric and auxotonic effort at 70% of the maximal performance and recovered baseline values within 15 min of completion. Both efforts produced similar effects on skin temperature and did not affect jumping performance after exercise.

Fixed-Point Results for Meir–Keeler Type Contractions in Partial Metric Spaces: A Survey

In this paper, we aim to review Meir–Keeler contraction mappings results on various abstract spaces, in particular, on partial metric spaces, dislocated (metric-like) spaces, and M-metric spaces. We collect all significant results in this direction by involving interesting examples. One of the main reasons for this work is to help young researchers by giving a framework for Meir Keeler’s contraction.

Access to Land for Agricultural Entrepreneurial Activities in the Context of Sustainable Food Production in Borgou, according to Land Law in Benin

Access to land is crucial for food systems to address the challenges caused by habitat and biodiversity loss, land and water degradation, and greenhouse gas emissions. Sustainable food production requires land security upstream for agricultural production. Land security emanates from the land law implemented in-country by government policy. In the span of a decade (2007–2017), three different land reforms have been adopted in Benin. This paper aims to investigate the land rights and land tenure security for sustainable food production according to land law and the factors that influence agricultural entrepreneurial activities in North Benin. The study was carried out in the Borgou department, mainly in five communes that are beneficiaries of the Responsible Land Policy Project of GIZ (Promotion d’une Politique Foncière Responsible: ProPFR/GIZ). A multistage sampling procedure was used to select the agricultural entrepreneur respondents. A total of 102 agriculture entrepreneurs were interviewed in 25 villages. According to land law in Benin, the results highlight the different levels of land tenure security and land rights represented by types of land documents: type contract (use right), certificates of customary ownership (ADC), and land title. The research reveals that 44.3% of the land of agriculture entrepreneurs’ respondents possessed the certificates of customary ownership and 18% possessed the land title. The facilitation of access to legal land documents such as certificates of customary ownership and land titles can protect agricultural entrepreneurship for sustainable food production.

Interpolative Meir–Keeler Mappings in Modular Metric Spaces

Modular metric space is one of the most interesting spaces in the framework of the metric fixed point theory. The main goal of the paper is to provide some certain fixed point results in the context of modular metric spaces and non-Archimedean modular metric spaces. In particular, we examine the existence of interpolative Meir–Keeler contraction types via admissible mappings for fixed point theory. Our results bring together several results available in the current corresponding literature.

The Effects of Training Interventions on Modifiable Hamstring Strain Injury Risk Factors in Healthy Soccer Players: A Systematic Review

ABSTRACT Despite promising research on various soccer-specific injury prevention programs, hamstring strain injuries (HSIs) persist in being a major problem in the sport. Therefore, in an attempt to expand the current knowledge on the prevention of HSIs, this systematic review aimed to identify how modifiable risk factors for HSIs (hamstring strength, hamstring:quadriceps [H:Q] strength ratios, biceps femoris long head fascicle length, and hamstring angle of peak torque) were altered following various training interventions. The protocol was preregistered on PROSPERO (CRD42020177363). The literature search was conducted on PubMed, SportDISCUS, and Web of Science. Following the search process, 20 studies were included in the systematic review, and the methodological quality of these studies was reported. Interventions were categorized based on exercise characteristics (movement velocity and contraction type), and the effects of each intervention subgroup were analyzed separately for all proposed risk factors for HSIs. Our findings show that a broad variety of exercise types (i.e., high- and low-velocity movements, eccentric only and traditional exercises) improves all risk factors for HSIs compared with fewer exercise types. Therefore, these findings suggest that hamstring injury risk factors can best be modified using a wide variety of exercises compared with, for example, only 1 or 2 specific exercises.

Risk factors of pelvic floor muscle strength in south Chinese women: a retrospective study

ObjectivesTo evaluate pelvic floor muscle strength using surface electromyography and risk factors for pelvic floor muscle strength in the early postpartum period.MethodsThis retrospective study included 21,302 participants who visited FujianMaternity and Child Health Hospital from September 2019 to February 2022. All participantswere assessed bymedical professionals for general information and surface electromyography.ResultsUnivariate analysis indicated that age was inversely related to tonic and endurance contractions. In contrast, all the other variables, including education level, body mass index, neonatal weight, and number of fetuses, had a positive impact on rapid, tonic, and endurance contractions. Likewise, parity was also positively associated with rapid contractions. In addition, compared with vaginal delivery, cesarean section delivery had a protective effect on the amplitude of the three types of contractions. Stepwise regression analysis showed that both age and neonatal weight had a negative linear relationship with the amplitude of rapid, tonic and endurance contractions. In contrast, the amplitude of rapid, tonic and endurance contractions significantly increased as body mass index, parity (≤ 3), education level and gestational weight gain (endurance contractions only) increased. Participants with cesarean section delivery showed positive effects on rapid, tonic, and endurance contractions compared to participants with vaginal delivery.ConclusionsWe found that age, neonatal weight, vaginal delivery, episiotomy, and forceps delivery were risk factors for pelvic floor muscle strength; in contrast, body mass index, parity (≤ 3) and gestational weight gain had a positive relationship with pelvic floor muscle strength.

Aging and skeletal muscle force control: Current perspectives and future directions.

During voluntary muscle contractions, force output is characterized by constant inherent fluctuations, which can be quantified either according to their magnitude or temporal structure, that is, complexity. The presence of such fluctuations when targeting a set force indicates that control of force is not perfectly accurate, which can have significant implications for task performance. Compared to young adults, older adults demonstrate a greater magnitude and lower complexity in force fluctuations, indicative of decreased steadiness, and adaptability of force output, respectively. The nature of this loss‐of‐force control depends not only on the age of the individual but also on the muscle group performing the task, the intensity and type of contraction and whether the task is performed with additional cognitive load. Importantly, this age‐associated loss‐of‐force control is correlated with decreased performance in a range of activities of daily living and is speculated to be of greater importance for functional capacity than age‐associated decreases in maximal strength. Fortunately, there is evidence that acute physical activity interventions can reverse the loss‐of‐force control in older individuals, though whether this translates to improved functional performance and whether lifelong physical activity can protect against the changes have yet to be established. A number of mechanisms, related to both motor unit properties and the behavior of motor unit populations, have been proposed for the age‐associated changes in force fluctuations. It is likely, though, that age‐associated changes in force control are related to increased common fluctuations in the discharge times of motor units.