Strength Asymmetry Research Articles

Tension-compression asymmetry in plasticity of nanoporous gold

Tensile and compressive tests are carried out on four nanoporous gold samples with ligament sizes of 56, 149, 402, and 868 nm, all without grain boundaries and with similar number of ligaments regardless of ligament size. We find that tensile yield strengths are greater than compressive yield strengths up to ligament size of 402 nm, while yield strengths are similar in tension and compression for dL of 868 nm. The dependence of tensile yield strength on ligament size is described well using a size-effect exponent -1.18 for four samples, whereas bulk-like behavior, i.e. no ligament-size dependency, is observed for ligament size greater than 402 nm in compression; compressive yield strength depending on ligament size is described by a size-effect exponent -1.49 for ligament sizes ranging from 56 nm to 402 nm. The asymmetries in yield strength and plasticity between tension and compression are discussed in terms of the deformation behavior of individual ligaments based on a suggested open-cell model and dislocation activities in the ligaments.

Preemption contests between groups

AbstractWe consider a preemption game between competing groups; firms lobbying individually for their groups' interests provide an empirical example. Among symmetric groups, the first firm to take action bears an (unobserved) cost and wins the prize on behalf of its group. In equilibrium, the firm with the lowest cost takes action, but with delay. More competition and a smaller ratio of costs to benefits reduce delay. Firms in larger groups wait longer, but group action can occur earlier, as the probability of a low‐cost firm is higher. Asymmetries in group size or strength of externalities also matter.

Bee-Plant Interaction Networks in a Seasonal Dry Tropical Forest of the Colombian Caribbean.

Mutualistic interactions between bees and flowering plants have been widely recognized as one of the most important for the maintenance of these communities throughout ecosystems. Consequently, understanding how these interactions occur is highly important, especially in seasonal dry tropical forest (SDTF), one of the most endangered ecosystems in northern South America. In this study, we analyzed the changes between interaction networks across two well-defined seasons, dry and wet, in a SDTF of the Colombian Caribbean in Taganga, Magdalena. We also determined changes in species composition and their role in interaction networks. To study this system, we compared two approaches: (1) networks constructed with data from direct collections in flowering plants, and (2) networks constructed with pollen data obtained from bees' bodies. A total of 44 species were collected in 18 species of flowering plants; also, we registered 16 additional plants presented in the records only as pollen types. We found that network metrics, connectance, nestedness, specialization (H2'), and interaction strength asymmetry remain stable through seasons. However, when the two types of approximations were compared, there were significant differences. Networks constructed with pollen data are more connected, less specialized, and with lower values of interaction strength asymmetry. The major difference between seasons relied on the interacting species composition, due to a high species turnover. Bee community was more diverse in dry season. Apidae family, mainly eusocial species, persisted in the community, being more abundant and relevant in wet season. For dry season, Megachile and other solitary species from Apidae and Halictidae families were better represented and relevant for the community. We found that Fabaceae is an important resource for bees in both seasons. In addition, herbaceous species from Asteraceae and Convolvulaceae were preferred in wet season, while shrub and tree species from Fabaceae and Polygonaceae were the main resource in dry season.

Persons with Multiple Sclerosis Exhibit Strength Asymmetries in both Upper and Lower Extremities

ObjectiveTo characterize strength asymmetries in the upper and lower extremities in persons with multiple sclerosis (PwMS) with severe disability, and examine associations between asymmetries and functional, symptomatic, and participatory outcomes. DesignCross-sectional. SettingUniversity research laboratory. Participants25 PwMS with Expanded Disability Status Scale scores between 6.0-8.0. Main outcome measuresBilateral strength and asymmetry scores for muscle groups at the ankle, knee, and shoulder joints in addition to grip strength. ResultsSignificant differences were observed between all contralateral strength measures, with asymmetry scores ranging between 20-32%. A high prevalence of asymmetry (i.e., score>10%) was observed for all strength measures, with 92% of participants having four or more affected measures. Significant associations were observed between dorsiflexion asymmetry and physical health-related quality of life (ρ= -0.69; p<0.001), and between shoulder flexion asymmetry and lower extremity function (ρ= -0.62; p=0.001). Plantarflexion (ρ= 0.61; p=0.003) and knee flexion (ρ= 0.63; p=0.002) asymmetry were significantly associated with lower extremity functional asymmetry. ConclusionsA high prevalence of asymmetry in the upper and lower extremities was observed, with asymmetry scores exceeding those previously reported in PwMS with mild-to-moderate disability. Rehabilitation strategies should consider a full body approach to address strength asymmetries.

Adductor Muscles Strength and Strength Asymmetry as Risk Factors for Groin Injuries among Professional Soccer Players: A Prospective Study.

The aim of this study was to prospectively examine the association between isometric hip adductor strength and between-limb strength asymmetry to groin injuries in male professional soccer players. Isometric hip adductor strength and between-limb strength asymmetry of 45 professional outfield soccer players from three First Division teams were tested during the 2017/2018 preseason. Players were then monitored throughout the 2017/2018 season for groin injuries. Ten groin injuries were recorded. When compared with uninjured players, players who sustained groin injury had significantly lower strength of respective muscle groups and significantly higher between-limb strength asymmetries (all p < 0.05; ES = 1.16 and 0.88; mean % difference = 26% and 51%). Isometric hip adductor strength had a significant inverse relationship with the incidence of occurring groin injuries (p = 0.016). No significant relationship between hip adductor strength asymmetry and the incidence of future groin injury was observed (p = 0.09). Finally, players’ age and previous groin injury were not significantly associated with the incidence of future groin injuries (all p > 0.05). These results generally suggest that isometric adductor strength is a significant predictor of future groin injuries in men’s professional football; however, due to the relatively low sample size, further studies are required.

Can Lateral Weight Shift Be Reliably Observed During The Functional Movement Screen Deep Squat?

Bilateral asymmetries of lower extremity strength have been reported in the literature and their existence may influence performance and increase injury risk. Although functional movement screen (FMS) deep squat (DS) scoring criteria does not include lateral weight shift, previous reports have demonstrated weight distribution asymmetry in both adolescent soccer players and active, adult participants. Lateral weight shifts are often observed in FMS DS, however, no previous report has determined the ability to validly and reliably observe this characteristic. PURPOSE: To determine if lateral weight shift could be reliably rated when compared to bilateral vertical ground reaction forces (vGRF) during FMS DS. METHODS: Thirty-seven active subjects (19 F, 18 M, 20.8 ± 1.4 yrs) granted informed consent and performed three FMS DS trials on two force plates (1200 Hz) while video (30 Hz) captured frontal, sagittal plane views. A Matlab script processed vGRF data with a lowpass filter and computed limb symmetry index (LSI) during the descent phase and full squat position. Two sports medicine professionals independently viewed videos and rated asymmetry using a novel, web-based sliding scale scoring rubric. Raters scored trials from 0-100 in interval increments of 1 with 50 representing a symmetric DS. Scores were averaged across trials and intraclass correlations (ICCs) were performed to determine inter-rater reliability. Receiver operator characteristics (ROC) curves determined cut-off scores that maximized sensitivity and specificity of determining substantial weight shifts (>10%, >15%). RESULTS: Subjects demonstrated average LSI of 9.8 ± 6.9% with eighteen subjects demonstrating LSI > 10%. Raters were able to determine correct shift direction (L, R) in 57.7% of all subjects and 68.1% for those with average LSI > 10%. Inter-rater reliability was poor (ICC=0.41, 95% CI=-0.07, 0.69). All ROC curve areas were < 0.61 indicating the scoring rubric failed to accurately diagnose LSI > 10% or >15%. CONCLUSIONS: Although active, adult subjects demonstrated lateral weight shift during FMS DS, raters weren’t able to reliably observe this shift even in severe cases. Clinicians should demonstrate caution when prescribing interventions based on visual observance of lateral weight shift during the FMS DS.

Asymmetry of Musculature and Hand Grip Strength in Bodybuilders and Martial Artists.

The functional preference for the upper limb influences the occurrence of bilateral differences in other segments of the human body. The aim of the study is to assess the influence of the applied fighting technique and targeted physical effort on the occurrence of asymmetry in body musculature and isometric strength in bodybuilders and competitors of selected martial arts. Academic athletes practicing judo (J), jiu-jitsu (JJ), and bodybuilding (BB) were examined. The control group (C) consisted of students who do not practice any sports. The assessment of the body structure was conducted through segmental bioelectrical impedance analysis. Moreover, the study took into account the measurements of left- and right-hand grip strength. In judo, the uneven physical exertion of the right and left sides of the body further increases both directional and absolute asymmetry. Bilateral asymmetry of musculature in jiu-jitsu competitors and bodybuilders occurs to a lesser extent. The control group was characterized by cross-asymmetry. So as to avoid the risk of injury of sportsmen, it is important to consistently supervise and correct their body structure, which also includes the symmetrical participation of the active muscle mass in particular segments. The symmetrisation process should be individualized since each particular sportsman has their own side-to-side body morphology.

Injuries and functional performance status in young elite football players: a prospective 2-year monitoring.

Motor function, such as strength asymmetries of the lower extremities and impaired dynamic stability, have a predictive value for the risk of injury. The present study aimed to reveal potential associations between injury and motor performance. Two hundred and five male youth elite (association) football (soccer) players (mean: 13.5±4.5 years, 57.2±30.2 kg, 168±35 cm) were included. A test battery was conducted twice per season, over two consecutive seasons (four times). Mobility (Sit and Reach Test, SnR), dynamic stability (Single Leg Hop for Distance, SLHD), linear sprinting speed (10 m, 30 m [s]), agility (Zig-Zag test with and without dribbling a ball [s]), jump performance (countermovement jump (CMJ) and drop jump (DJ), in cm) and maximal isometric voluntary force (MIVF, in N) of the knee extensors and flexors were assessed. All injuries occurring over the two-year period, as well as training and competition exposure time, were collected and used as grouping variables for statistical difference testing. One hundred and twenty-five injuries in 93 players occurred (an injury incidence of 2.7/1000 hours of exposure). Age was associated with injury incidence (r=0.191; P=0.006). Neither DJ, CMJ, SnR nor agility performance were statistically different between injured and non-injured participants (P>0.05). Group differences did occur for sprint and strength (P=0.011; P=0.016), but these lapsed after the inclusion of age as a covariate. Only for SLHD symmetry was a non-significant trend evident after the correction for age (P=0.08). The occurrence of musculoskeletal injuries in junior football players are, probably, not related to baseline motor function. Group differences between injured and non-injured youth elite football players are mostly explained by age. Only the symmetry in SLHD could be a potential risk factor for injuries and merits further investigation.

Handgrip Strength Asymmetry and Weakness May Accelerate Time to Mortality in Aging Americans

ObjectivesAssessing handgrip strength (HGS) asymmetry may provide insights into HGS as a prognostic assessment of strength capacity and vitality. This study sought to determine the associations of HGS asymmetry and weakness on time to mortality in aging Americans. DesignLongitudinal panel. SettingSecondary analyses of data from participants aged ≥50 years from the 2006‒2014 waves of the Health and Retirement Study. ParticipantsThe analytic sample included 19,325 Americans who identified hand dominance and had measures of HGS for both hands in a single wave. MeasuresA handgrip dynamometer was used to measure HGS. Men and women who were considered weak had HGS <26 kg and <16 kg, respectively. The highest HGS values from the dominant and nondominant hands were used to calculate HGS ratio: (nondominant HGS/dominant HGS). Those with HGS ratio <0.90 or >1.10 had any HGS asymmetry. Moreover, participants with HGS ratio <0.90 had dominant HGS asymmetry, whereas those with HGS ratio >1.10 had nondominant HGS asymmetry. The National Death Index and postmortem interviews verified date of death. Covariate-adjusted Cox models were used for analyses. ResultsThose with any HGS asymmetry had a 1.10 [95% confidence interval (CI) 1.03‒1.17] higher hazard for mortality, while those with weakness had a 1.44 (CI 1.32‒1.58) higher hazard for mortality. Likewise, participants with dominant HGS asymmetry had a 1.11 (CI 1.03‒1.18) higher hazard for mortality, and those with weakness had a 1.45 (CI 1.32‒1.58) higher hazard for mortality; however, the association was not significant for those with nondominant HGS asymmetry (hazard ratio: 1.07; CI 0.96‒1.18). Conclusions and ImplicationsHGS asymmetry and weakness are markers of impaired strength capacity that independently accelerate time to mortality, but the magnitude of these associations was more prominent for weakness. Nevertheless, assessments of asymmetric HGS are a simple adjunct analysis that may show promise for increasing the prognostic value of handgrip dynamometers.

Study on tensile/compressive asymmetry in creep ageing behavior of Al–Cu alloy under different stress levels

Creep-ageing behavior of an Al–Cu alloy has been investigated under both tensile and compressive stress ageing conditions, with different stress levels at 165 °C for 9 h. The corresponding creep strain and age strengthening of the samples were studied by creep tests and uniaxial tensile tests. Microstructures observations of specimens have been examined by Scanning TEM (STEM) and X-Ray Diffraction (XRD). It has been found that the creep strains after tension creep tests are significantly greater than those after compression creep tests, and the asymmetry of creep strain decreases with increasing stress level. However, the yield strength of the creep aged-samples in compressive stresses are higher than those in tensile stresses, but the asymmetry of yield strength does not change significantly with the stress level. The stress exponents were found to be n = 2.95 and n = 4.21 for tension and compression creep test, respectively. The corresponding variance in dislocation density and the size of precipitates are the main reasons for the asymmetry of creep strain and yield strength, and the decreasing asymmetry in creep ageing behavior with increasing stress level is also related to the above two factors. In addition, the asymmetric creep ageing behavior of the Al–Cu alloy is discussed from both the macro and the micro aspect and a deeper understanding is achieved.

Bargaining and conflict with up-front investments: How power asymmetries matter

We examine settings—such as litigation, labor relations, or arming and war—in which players first make non-contractible up-front investments to improve their bargaining position and gain advantage for possible future conflict. Bargaining is efficient ex post, but we show that a player may prefer Conflict ex ante if there are sufficient asymmetries in strength. There are two sources of this finding. First, up-front investments are more dissimilar between players under Conflict, and they are lower than under Bargaining when one player is much stronger than the other. Second, the probability of the stronger player winning in Conflict is higher than the share received under Nash bargaining. We thus provide a rationale for conflict to occur under complete information that does not depend on long-term commitment problems. Greater balance in institutional support for different sides is more likely to maintain peace and settlements.

Relationship between lower limb asymmetries, impulsion and balance in senior football players

Abstract Introduction Football is the most popular sport in the world and there are over 38 million players practicing it worldwide. In this sport, players usually have a prefered lower limb over other. This preference can lead to bilateral asymmetries and improve the risk of injury in the players. It is important to understand if asymmetries have an influence on athletes’ performance, on balance or impulsion. Objectives The main objective of this study is to evaluate the bilateral and unilateral asymmetries related to the lower limb muscle strength of individuals who practice senior football, and relate them to eventual impulse and balance deficits. Methodology 11 soccer players (age 21.91 ± 3.14 years; weight: 73.45 ± 7.59 Kg; height: 178.91 ± 8.02; BMI: 22.97 ± 2,12) were evaluated. The protocol defined in this study consisted of collecting data on maximum concentric torque at 60o/s, 180o/s and 300o/s in Biodex System 3. Both lower limbs were tested. Then the Y-balance test was performed on a force platform and the athletes’ flight time were recorded. We also calculated the bilateral deficit between the dominant lower limb and the non-dominant lower limb for the quadriceps and hamstrings and the hamstring/quadriceps (H/Q) ratio for each lower limb Results There were no statistically significant differences between the maximum torque produced by the dominant lower limb and the maximum force torque produced by the dominant lower limb (p &amp;lt; 0.05). The conventional I / Q ratio has values similar to those described in the literature. The relationship between bilateral asymmetry of lower limb strength, balance and impulsion was not statistically significant (p &amp;gt; 0.05) at any angular velocity. Conclusion There are no statistically significant differences between bilateral and unilateral asymmetries of lower limb strength, balance and impulsion.

Identification of Ankle Injury Risk Factors in Professional Soccer Players Through a Preseason Functional Assessment.

Background:Etiologically, the risk of an ankle injury depends on extrinsic and intrinsic factors, such as muscle strength asymmetry, decreased flexibility, and decreased proprioception, as well as patient age and history of injuries.Purpose/Hypothesis:The purpose of this study was to identify risk factors present in the preseason assessment that may predispose professional soccer players to ankle injuries. We hypothesized that analysis of these parameters could relate the incidence of injuries to the deficits found during the preseason period, enabling the identification of risk factors to predict the occurrence of injuries.Study Design:Cohort study; Level of evidence, 2.Methods:A total of 89 professional soccer athletes were evaluated in the preseason period; the evaluation included athlete history and anthropometric data collection, an isokinetic ankle evaluation, and functional tests: the Dorsiflexion Lunge Test and Y-Balance Test (YBT). The athletes were monitored during the competitive period, and the incidence of injuries was surveyed. The association of quantitative variables and injury outcomes was analyzed using the Student t test for independent samples, with P < .05. For the association of categorical variables and injury outcomes, the chi-square test was performed, with P < .05.Results:A higher incidence of ankle injuries was associated with lower YBT scores in the dominant (P = .04) and nondominant (P = .01) limbs. A higher body mass index was also associated with a higher injury occurrence (P = .01).Conclusion:Functional tests, such as the YBT, are indicated tools for assessing the physical capacities and possible risks of ankle sprains, as they can evaluate the ankle functional capacity in a complex way, identifying athletes more prone to ankle injuries. Athletes’ body mass index should also be taken into account to prevent such injuries.

Handgrip Strength Asymmetry and Weakness Are Associated with Lower Cognitive Function: A Panel Study.

Examining handgrip strength (HGS) asymmetry and weakness together may extend the predictive capacity of HGS for capturing possible health problems such as cognitive impairment. The purpose of this study was to determine the associations of HGS asymmetry and weakness on lower cognitive functioning in a national sample of aging Americans. Longitudinal panel. Participant residences. The analytic sample included 17,163 Americans aged 65.0 years (standard deviation = 10.1 years) who participated in the 2006 to 2016 waves of the Health and Retirement Study (HRS). A handgrip dynamometer was used to measure HGS; weakness was defined as HGS below 26 kg (men) or below 16 kg (women). Persons with HGS above 10% stronger on either hand were considered as having any HGS asymmetry. Those with HGS that was more than 10% stronger on their dominant or nondominant hand were considered as having dominant or nondominant HGS asymmetry, respectively. The Telephone Interview of Cognitive Status determined lower cognitive functioning (≤11 for ages 50-64 years; ≤10 for ages ≥65 years). Covariate-adjusted linear mixed-effects models analyzed the associations of each HGS asymmetry and weakness group on lower cognitive functioning. Relative to those with symmetric HGS and no weakness, each HGS asymmetry and weakness group had greater odds for lower cognitive functioning: 1.15 (95% confidence interval [CI] = 1.03-1.27) for any HGS asymmetry alone, 1.64 (95% CI = 1.21-2.23) for weakness alone, and 1.95 (95% CI = 1.51-2.53) for any HGS asymmetry and weakness. Each HGS asymmetry dominance and weakness group also had greater odds for lower cognitive functioning: 1.12 (95% CI = 1.01-1.25) for asymmetric dominant HGS alone, 1.27 (95% CI = 1.05-1.53) for asymmetric nondominant HGS alone, 1.64 (95% CI = 1.21-2.23) for weakness alone, 1.89 (95% CI = 1.39-2.57) for weakness and asymmetric dominant HGS, and 2.10 (95% CI = 1.37-3.20) for weakness and asymmetric nondominant HGS. The presence of both HGS asymmetry and weakness may predict accelerated declines in cognitive functioning.

Factors influencing bilateral deficit and inter-limb asymmetry of maximal and explosive strength: motor task, outcome measure and muscle group.

The purpose of the present study was to investigate the influence of strength outcome [maximal voluntary contraction (MVC) torque vs. rate of torque development (RTD)], motor task (unilateral vs. bilateral) and muscle group (knee extensors vs. flexors) on the magnitude of bilateral deficits and inter-limb asymmetries in a large heterogeneous group of athletes. 259 professional/semi-professional athletes from different sports (86 women aged 21 ± 6years and 173 men aged 20 ± 5years) performed unilateral and bilateral "fast and hard" isometric maximal voluntary contractions of the knee extensors and flexors on a double-sensor dynamometer. Inter-limb asymmetries and bilateral deficits were compared across strength outcomes (MVC torque and multiple RTD measures), motor tasks and muscle groups. Most RTD outcomes showed greater bilateral deficits than MVC torque for knee extensors, but not for knee flexors. Most RTD outcomes, not MVC torque, showed higher bilateral deficits for knee extensors compared to knee flexors. For both muscle groups, all RTD measures resulted in higher inter-limb asymmetries than MVC torque, and most RTD measures resulted in greater inter-limb asymmetries during unilateral compared to bilateral motor tasks. The results of the present study highlight the importance of outcome measure, motor task and muscle group when assessing bilateral deficits and inter-limb asymmetries of maximal and explosive strength. Compared to MVC torque and bilateral tasks, RTD measures and unilateral tasks could be considered more sensitive for the assessment of bilateral deficits and inter-limb asymmetries in healthy professional/semi-professional athletes.

The Effects of 6 Weeks Eccentric Training on Speed, Dynamic Balance, Muscle Strength, Power, and Lower Limb Asymmetry in Prepubescent Weightlifters.

Hammami, R, Duncan, MJ, Nebigh, A, Werfelli, H, and Rebai, H. The effects of 6 weeks eccentric training on speed, dynamic balance, muscle strength, power and lower limb asymmetry in prepubescent weightlifters. J Strength Cond Res 36(4): 955-962, 2022-This study examined whether 6 weeks of twice-weekly in-season hamstring eccentric training would enhance selected performance-related abilities in prepubescent male weightlifters. Twenty elite weightlifters (11.1 ± 0.8 years) were randomly split into an eccentric training intervention group (INT n = 10) or a control group (CON) that maintained their standard in-season regimen (n = 10). Pre-intervention and postintervention speed, dynamic balance, muscle strength, power, and lower limb (LL) asymmetry were assessed. Analysis of covariance controlling for maturation was used to determine any differences in the performance variables. There were no significant changes in muscle strength, dynamic balance, or LL asymmetry (all p < 0.05) because of the intervention. Both 10-m (p = 0.001) and 30-m (p = 0.007) sprint speed and agility (p = 0.049) improved to a greater extent in INT compared with the CON group. Similar results were evident for the standing long jump (p = 0.015) and 3 hop test (p = 0.004) where performance improved to a greater magnitude in INT compared with CON groups. This study suggests that eccentric training, undertaken twice weekly for 6-weeks results in positive changes in sprint speed, change of direction speed, and power performance, but not muscle strength, dynamic balance, or LL asymmetry in prepubertal weightlifters.

Association between Lysholm score and muscular torque deficit after anterior cruciate ligament reconstruction.

The asymmetry of muscular strength after anterior cruciate ligament reconstruction (ACLR) is associated with increase in the development of new lesions. This asymmetry is precisely assessed by isokinetic dynamometry which is a high-cost technique, limited to major centers and hospitals. Thus, the aim of this study was to test the accuracy of one of the most frequently used functional questionnaires, the Lysholm score, to diagnose the knee torque deficit. In total, 115 patients were evaluated after ACLR. Knee symptoms were evaluated using the Lysholm questionnaire and knee extensor and flexor peak torque during maximal isokinetic concentric contractions at 60° s-1 (5 repetitions) and 180° s-1 (15 repetitions). Patients with <20% peak torque deficit were considered symmetric (normal). An increase in the Lysholm score was associated with a deficit reduction in the peak torque of knee extensors at 60° s-1 (r = -0.294) and 180° s-1 (r = -0.297) (p < 0.05 for both). Cutoff Lysholm scores of >90 points for 60° s-1 allowed the correct diagnosis of symmetry in 71% and of >89 points for 180º·s-1 allowed the correct diagnosis of symmetry in 73%, for knee extensors. Patients with a Lysholm score of >89 points presented an isokinetic deficit 36% lower than patients with a Lysholm score of ≤89 points (p < 0.05). A Lysholm score of >89 points has predictive value for deficits in the peak torque of knee extension (<20%). However, replacement of the isokinetic evaluation by this instrument must be performed with caution because of its accuracy.

Handgrip Strength Asymmetry and Weakness are Differentially Associated with Functional Limitations in Older Americans.

Background: Handgrip strength (HGS) is a convent measure of strength capacity and associated with several age-related health conditions such as functional disability. Asymmetric strength between limbs has been linked to diminished function. Therefore, both HGS asymmetry and weakness could be associated with functional disability. We examined the associations of HGS asymmetry and weakness on functional limitations in a nationally representative sample of older Americans. Methods: Data were analyzed from 2689 adults ≥ 60 years who participated in the 2011–2012 and 2013–2014 waves of the National Health and Nutrition Examination Survey. Weakness was defined as HGS < 26 kg for men and < 16 kg for women. Asymmetry was determined from the ratio of the dominant and non-dominant HGS. Those with HGS ratio 0.9–1.1 were considered as having HGS symmetry, and those outside this range had asymmetry. Results: Compared to those with symmetric HGS and were not weak, those with weakness alone, and both weakness and HGS asymmetry had 2.47 (95% confidence interval [CI]: 1.14–5.35) and 3.93 (CI: 1.18–13.07) greater odds for functional limitations, respectively. However, HGS asymmetry alone was not associated with functional limitations (odds ratio: 0.80; CI: 0.62–1.03). Conclusion: The use of HGS asymmetry in protocols could improve the prognostic value of handgrip dynamometers.

Strength properties of extant hominoid hallucal and pollical metapodials

Functional comparisons of cortical bone strength properties between hominoid hallucal and pollical metapodials (Mt1 and Mc1, respectively) are lacking. Determining which of these two elements is stronger, and by how much, could be informative because the hallux and pollex are used differently both within and among extant hominoids during locomotion and manipulation (i.e., functional differentiation between autopod pairs). Here, we compare Mt1 and Mc1 midshaft cortical area, polar section modulus, and polar second moment of area, calculated from high-resolution computed tomography images in humans (n = 21), chimpanzees (n = 47), gorillas (n = 24), orangutans (n = 20), siamangs (n = 8), and gibbons (n = 21). Intraindividual comparisons between bones within species were made using paired t-tests. Log10-transformed Mt1:Mc1 ratios were created to assess relative strength asymmetry between bones, and interspecific comparisons of these proportions were made using analyses of variance. Absolute strength differences between the Mt1 and Mc1 for all variables were significantly larger in the Mt1 for all species (p < 0.05). Significant differences across species in Mt1:Mc1 proportions were also found, thereby demonstrating that strength asymmetry between bones differs among taxa (p < 0.05); asymmetry was lowest in orangutans, intermediate in gorillas, and greatest in humans, chimpanzees, siamangs, and gibbons. These findings support the hypothesis that the Mt1 is better adapted structurally than the Mc1 for bearing mechanical loads during weight support of locomotion in all extant hominoids and that pedal hallucal grasping likely engenders higher loads than manual pollical grasping in nonhuman hominoids. Thus, functional differentiation in autopod use within and among hominoids is reflected in hallucal and pollical metapodial strength properties.

Predicting textural variability effects in the anisotropic plasticity and stability of hexagonal metals: Application to magnesium and its alloys

This work systematically investigates the texture-property linkages in hexagonal close-packed (hexagonal) materials using a three-dimensional computational crystal plasticity approach. Magnesium and its alloys are considered as a model system. We perform full-field, large-strain, micromechanical simulations using a wide range of surrogate textures that sample several experimental datasets for a range of Mg alloys. The role of textural variability and the associated sensitivity of deformation mechanisms on the evolution of macroscopic plastic anisotropy and strength asymmetry is mapped under uniaxial tensile and compressive loading along the material principal and off-axes orientations. To assess the role of crystallographic plastic anisotropy, two distinct material datasets are simulated, which represent pure and alloyed magnesium. The results provide insights into experimental observations reported for magnesium alloys over a range of material textures. We further discuss potential implications on the damage tolerance from the aggregate plastic anisotropy arising from intrinsic crystallographic and textural effects.