Strength Asymmetry Research Articles

Association between quadriceps strength asymmetry and incidence of falls among patients with knee osteoarthritis：The SPSS-OK study

Association between quadriceps strength asymmetry and incidence of falls among patients with knee osteoarthritis：The SPSS-OK study

Reliability of the Hip Extension Lower Exercise as a Measure of Eccentric Hamstring Strength

Hamstring strain injury (HSI) is a very common lower-body injury in field sports, and eccentric (ECC) hamstring strength is a potential modifiable risk factor, therefore having reliable eccentric hamstring strength assessments is critical. The aim of this study was to access test–retest reliability of the hip extension lower (HEL) exercise as a measure of ECC hamstring strength and inter-limb asymmetries. Twelve male elite level soccer players (mean; age: 21.8 years; height: 180.4 cm; weight: 75.7 kg) volunteered to participate in this study. Participants were from the same soccer club, covered all playing positions, and had no current injury issues. Participants performed two familiarization sessions to acquaint themselves with the device and exercise protocol. During testing, each participant performed three repetitions with 60s intra-set recovery provided. Average and peak force (N) was recorded for both limbs. Testing sessions took place on the same day and time over a two-week pre-season period and followed a full recovery day. Intraclass Correlation Coefficient (ICC), Coefficient of Variation (CV%), Minimal Detectable Change (MDC) and Typical Error (TE) were used to assess reliability. The HEL showed excellent reliability for average force (N) in the left (ICC (95% CI) = 0.9 (0.7–0.97); TE = 14.1 N, CV% = 1.87; MDC = 39.06 N) and right (ICC (95% CI) = 0.91 (0.73–0.97); TE = 20.89 N, CV% = 3.26; MDC = 57.87 N) limb, and also excellent reliability for peak force in the left (ICC (95% CI) = 0.91 (0.71–0.97); TE = 13.55 N, CV% = 1.61; MDC = 57.87 N) and right (ICC (95% CI) = 0.9 (0.7–0.97); TE = 21.70 N, CV% = 3.31; MDC = 60.11 N) limb. This data suggests the HEL as a reliable measure of both ECC hamstring strength and inter-limb asymmetries. Practitioners should consider the HEL as a reliable choice for measuring and monitoring eccentric hamstring strength in their athletes.

Isometric dynamometry, dependent on knee angle, is a suitable alternative to isokinetic dynamometry when evaluating quadriceps strength symmetry in patients following anterior cruciate ligament reconstruction

BackgroundKnee extensor strength deficits increase re-injury risk following anterior cruciate ligament reconstruction (ACLR). This study investigated whether isometric strength testing methods are a suitable alternative to isokinetic assessment for identifying knee extensor strength asymmetry. MethodsThis study recruited 22 patients at 9–12 months after ACLR and 22 healthy controls. The single hop for distance (SHD) and knee extensor strength via isokinetic (60°/s and 120°/s) and isometric (positions of 90°, 60° and 30° of flexion, from full knee extension) methods were assessed. Absolute scores (normalized to body weight) and limb symmetry indices (LSIs) were calculated, with t-tests employed for statistical comparisons. ResultsThe SHD LSI was significantly higher (p < 0.01) than both isokinetic speeds and the 30° isometric position. No significant LSI differences (p > 0.01) existed within isokinetic or isometric test conditions. In ACLR patients, only the 60°/s isokinetic condition was significantly lower (p = 0.005) than the 60° isometric condition. When normalized to body weight, the operated limb in ACLR patients was significantly weaker than the non-operated limb during peak isokinetic strength testing at 60°/s (p = 0.001) and 120°/s (p = 0.010), as well as isometric testing at 30° (p = 0.009). Compared with controls, ACLR patients demonstrated significantly lower (p < 0.01) mean LSIs across most measures. ConclusionsAssessment of knee extensor strength via isometric methods appears suitable in the absence of isokinetic testing equipment, though consideration of test angle (30° and 90° knee angles better detect asymmetries similar to isokinetic testing) is important.

Handgrip Strength Asymmetry and Weakness Are Associated With Future Morbidity Accumulation in Americans.

Klawitter, L, Vincent, BM, Choi, BJ, Smith, J, Hammer, KD, Jurivich, DA, Dahl, LJ, and McGrath, R. Handgrip strength asymmetry and weakness are associated with future morbidity accumulation in americans. J Strength Cond Res 36(1): 106-112, 2022-Identifying strength asymmetries in physically deconditioned populations may help in screening and treating persons at risk for morbidities linked to muscle dysfunction. Our investigation sought to examine the associations between handgrip strength (HGS) asymmetry and weakness on accumulating morbidities in aging Americans. The analytic sample included 18,506 Americans aged ≥50 years from the 2006-2016 Health and Retirement Study. Handgrip strength was measured on each hand with a handgrip dynamometer, and persons with an imbalance in strength >10% between hands had HGS asymmetry. Men with HGS <26 kg and women with HGS <16 kg were considered as weak. Subjects reported the presence of healthcare provider-diagnosed morbidities: hypertension, diabetes, cancer, chronic lung disease, cardiovascular disease, stroke, arthritis, and psychiatric problems. Covariate-adjusted ordinal generalized estimating equations analyzed the associations for each HGS asymmetry and weakness group on future accumulating morbidities. Of those included in our study, subjects at baseline were aged 65.0 ± 10.2 years, 9,570 (51.7%) had asymmetric HGS, and 996 (5.4%) were weak. Asymmetry alone and weakness alone were associated with 1.09 (95% confidence interval [CI]: 1.04-1.14) and 1.27 (CI: 1.11-1.45) greater odds for future accumulating morbidities, respectively. Having both HGS asymmetry and weakness was associated with 1.46 (CI: 1.29-1.65) greater odds for future accumulating morbidities. Handgrip-strength asymmetry, as another potential indicator of impaired muscle function, is associated with future morbidity status during aging. Exercise professionals and related practitioners should consider examining asymmetry and weakness with handgrip dynamometers as a simple and noninvasive screening method for helping to determine muscle dysfunction and future chronic disease risk.

Participation after childhood stroke: Is there a relationship with lesion size, motor function and manual ability?

Childhood arterial ischemic stroke (AIS) is associated with significant morbidity with up to 50% of affected children developing hemiparesis. Hemiparesis is assumed to influence participation within the peer group, but it is unclear to what extent its severity affects participation in different areas of social life. Thirteen children (mean age 9y6m) with AIS (6 without hemiparesis, 7 with hemiparesis) and 21 controls (mean age 9y8m) participated. We scored hemiparesis severity with hand strength asymmetry (pinch and grip strength), measured with a dynamometer. We assessed manual ability (ABILHAND-Kids), socioeconomic status (Family Affluence Scale) and participation (Participation and Environment Measure - Children and Youth). From structural MRI, we measured lesion size. We investigated differences in participation and its relationship with hemiparesis severity using non-parametric partial correlations (controlling for lesion size, manual ability, and socioeconomic status), interpreted as absent (r<0.25), weak (r=0.25-0.50), moderate (r=0.50-0.75) or strong (r>0.75). Analyses were performed in jamovi 1.6.3. Children with AIS (with or without hemiparesis) showed reduced participation frequency at school (p<0.001), whilst participation at home and in the community resembled that of their peers. Severity of hemiparesis was moderately related to frequency and involvement at home and to involvement and desire for change in the community, although unrelated to school participation. Reduced participation in school life requires close attention in the follow-up of children with AIS - regardless of the severity of hemiparesis. Participation at home and in the community is related to hemiparesis severity and may be improved with participation-focused motor intervention strategies.

Impact of prior ACL, hamstring or groin injury on lower limb strength and jump kinetics in elite female footballers

Introduction: Prior injury is a risk factor for lower limb injury in female footballers. An improved understanding of the impact of the most common and severe injuries on lower limb strength and biomechanics may help to optimise rehabilitation strategies and decrease subsequent injury rates. The aim of this cross-sectional study was to compare lower limb strength and countermovement jump (CMJ) kinetics between elite female footballers with and without a history of anterior cruciate ligament reconstruction (ACLR), hamstring strain, or hip/groin injury. Methods: 369 elite female Australian football, soccer and rugby league players aged 15–35 years underwent assessments of isometric hip adductor and abductor strength, eccentric knee flexor strength, and CMJ vertical ground reaction forces. Players reported their lifetime history of ACLR, and whether they had sustained a hamstring strain, or hip/groin injury in the previous 12-months. Strength and jump/landing kinetics, including between-leg asymmetry, were compared between players with and without prior injury. Logistic regression was used to determine the variables that best distinguished between players with and without prior injury. Results: Players with a unilateral history of ACLR (n=24) displayed asymmetry (injured<uninjured leg) in eccentric knee flexor strength (mean difference=-6.9%, 95%CI=-9.1 to -4.8%), isometric hip abductor strength (mean difference=-2.4%, 95%CI=-4.4 to -0.4%), and peak landing force (mean difference=-5.9%, 95%CI=-11.0 to -0.9%). Together, between-leg asymmetry in eccentric knee flexor strength, isometric hip abductor strength, and CMJ peak landing force distinguished between players with and without prior ACLR with 93% accuracy. No differences in strength or CMJ kinetics were observed between players with and without a history of hamstring or hip/groin injury. Discussion: Elite female footballers with a history of ACLR, but not hamstring or hip/groin injury, exhibit persistent between-leg asymmetries in lower limb strength and jump kinetics following a return to sport. To address the effects of prior injury, ACLR rehabilitation programs for elite female footballers should consider targeting between-leg asymmetries in eccentric knee flexor strength, isometric hip abductor strength, and CMJ kinetics. Conflict of interest statement: Funding for travel costs associated with data collection was provided by Vald Performance (Brisbane, Australia) and SMA Research Grant. My co-authors and I acknowledge that we have no conflict of interest of relevance to the submission of this abstract.

Bilateral Strength Asymmetry in Elite Youth Soccer Players: Differences between Age Categories

The strength asymmetry of athletes as a negative health and performance factor is increasingly being researched in sports with a high load on the dominant limb when some specific unilateral movements, such as passing, jumping, and tackling, are required. This study aimed to determine the level of isokinetic strength bilateral asymmetry (BA) among knee extensors (KEs) and knee flexors (KFs) of elite youth soccer players. The sample (n = 87) consisted of three age categories of under 13 (U13), under 15 (U15), and under 17 (U17) years old. Isokinetic dynamometry was used to obtain the maximum peak torque of the KEs and KFs in the dominant and non-dominant lower limbs during concentric muscle contraction. The analysis revealed significantly lower values (p &lt; 0.05) of BA in KEs in U17 than in younger categories, U13 and U15, and higher values (p &lt; 0.05) of BA in KFs in the U15 category than in the U17category. The majority of the players in the U15 category (68%) reached KFs BA higher than 10% in comparison with U13 players (50%) and U17 players (28% of players) (p &lt; 0.05). Our results showed a significant effect of age category on BA levels in young soccer players. High incidences of increased BA in the lower limbs occurred in the younger categories (U13, U15) and subsequently decreased in the later adolescent stages.

Impact of prior anterior cruciate ligament, hamstring or groin injury on lower limb strength and jump kinetics in elite female footballers

ObjectiveTo compare lower limb strength and countermovement jump (CMJ) kinetics between elite female footballers with and without a history of anterior cruciate ligament reconstruction (ACLR), hamstring strain, or hip/groin injury. DesignCross-sectional. SettingField-based. Participants369 elite female Australian football, soccer and rugby league players aged 15–35. Main outcome measuresIsometric hip adductor and abductor strength, eccentric knee flexor strength, and CMJ vertical ground reaction forces, including between-leg asymmetry. Players reported their lifetime history of ACLR, and whether they had sustained a hamstring strain, or hip/groin injury in the previous 12-months. ResultsPlayers with a unilateral history of ACLR (n = 24) had significant between-leg asymmetry in eccentric knee flexor strength (mean = −6.3%, 95%CI = −8.7 to −3.9%, P < .001), isometric hip abductor strength (mean = −2.5%, 95%CI = −4.3 to −0.7%, P = .008), and CMJ peak landing force (mean = −5.5%, 95%CI = −10.9 to −0.1%, P = .046). Together, between-leg asymmetry in eccentric knee flexor strength, isometric hip abductor strength, and CMJ peak landing force distinguished between players with and without prior ACLR with 93% accuracy. ConclusionElite female footballers with a history of ACLR, but not hamstring or hip/groin injury, exhibit persistent between-leg asymmetries in lower limb strength and jump kinetics following a return to sport.

The associations between asymmetries in quadriceps strength and gait in individuals with unilateral transtibial amputation.

Individuals with unilateral transtibial amputations (ITTAs) are asymmetrical in quadriceps strength. It is unknown if this is associated with gait performance characteristics such as walking speed and limb symmetry. Are quadriceps strength asymmetries related to walking speed and/ or gait asymmetries in ITTAs? Knee-extensor isometric maximum voluntary torque (MVT) and rate of torque development (RTD) were measured in eight ITTAs. Gait data were captured as the ITTAs walked at self-selected habitual and fast speeds. Step length and single support time, peak knee extension moments and their impulse and peak vertical ground reaction force (vGRF) in the braking and propulsive phases of stance were extracted. Bilateral Asymmetry Index (BAI) and, for gait variables only, difference in BAI between walking speeds (ΔBAI) were calculated. Correlation analyses assessed the relationships between MVT and RTD asymmetry and (1) walking speed; (2) gait asymmetries. Associations between strength and gait BAIs generally became more apparent at faster walking speeds, and when the difference in BAI between fast and habitual walking speed was considered. BAI RTD was strongly negatively correlated with habitual and fast walking speeds (r=∼0.83). Larger BAI RTD was strongly correlated with propulsive vGRF BAI in fast walking, and larger ΔBAIs in vGRF during both the braking and propulsion phases of gait (r = 0.74-0.92). ITTAs who exhibited greater BAI MVT showed greater ΔBAI in single support time (r = 0.83). While MVT and RTD BAI appear to be associated with gait asymmetries in ITTAs, the magnitude of the asymmetry in RTD appears to be a more sensitive marker of walking speed. Based on these results, it's possible that strengthening the knee-extensors of the amputated limb to improve both MVT and RTD symmetry may benefit walking speed, and reduce asymmetrical loading in gait.

Should We Use Unilateral or Bilateral Tasks to Assess Maximal and Explosive Knee Extensor Strength in Patients with Knee Osteoarthritis? A Cross-Sectional Study.

Deficits in maximal and explosive knee extensor strength, which are usually assessed with unilateral tasks, are substantial in patients with knee osteoarthritis (KOA). The aim of this study was to investigate the clinical relevance of unilateral vs. bilateral tasks for assessing knee extensor strength in patients with KOA. This was achieved primarily by comparing unilateral and bilateral inter-limb strength asymmetries and secondarily by examining the relationship between unilaterally and bilaterally measured strength, and performance-based and self-reported function. Twenty-four patients with unilateral KOA (mean age: 65 ± 7 years) performed isometric gradual and explosive maximal voluntary contractions to assess, respectively their maximal and explosive strength. Performance-based and self-reported function were also evaluated with standard functional tests and questionnaires, respectively. Inter-limb asymmetries of maximal and explosive strength did not differ significantly between unilateral (mean asymmetry: 26 ± 15%) and bilateral tasks (22 ± 21%). In the same way, the relationships between knee extensor strength—measured either unilaterally or bilaterally—and performance-based or self-reported function were not influenced by the type of task. In conclusion, it does not seem to make a difference in terms of clinical relevance whether maximal and explosive knee extensor strength are evaluated with unilateral or bilateral tasks in KOA patients.

Vertical jump impulse deficits persist from six to nine months after ACL reconstruction

ABSTRACT Later-stage rehabilitation following anterior cruciate ligament (ACL) reconstruction (ACLR) provides a valuable opportunity to target performance deficits before return to sport. This study aimed to: (1) evaluate bilateral counter-movement jump (CMJ) phase-specific impulse and isokinetic strength inter-limb asymmetry progression from 6 to 9 months post-ACLR; and (2) examine the extent to which individual changes in strength asymmetry could explain changes in impulse asymmetry. Male athletes (n = 44) with a hamstring tendon or bone-patellar tendon-bone autograft were tested 6 and 9 months post-ACLR. Two-way mixed-model ANOVAs were used to identify inter-session and inter-graft differences in CMJ phase-specific impulse asymmetries and knee isokinetic flexor and extensor strength asymmetries, as well as in absolute impulse and strength values of independent (ACLR/uninvolved) limbs. Linear regression models were used to assess the relationship between changes in impulse asymmetry and strength asymmetry. Reductions in strength asymmetry arose from improved ACLR-limb performance, whereas concentric impulse asymmetry reduced consequent to decreased uninvolved-limb performance and eccentric deceleration impulses decreased bilaterally. Graft type did not modulate findings. Changes in strength asymmetry had little or no ability to explain changes in impulse asymmetry. Consideration of approaches that may influence persisting deficits observed bi-laterally throughout vertical jumping performance post-ACLR may enhance rehabilitation practice.

Does piriformis muscle syndrome impair postural balance? A case control study

Background and purpose While patients with musculoskeletal disorders reported postural balance impairments, it is unknown whether patients with piriformis muscle syndrome (PMS) may exhibit postural balance disorders compared to controls. The aim was to compare postural balance in patients with PMS to controls in static and dynamic conditions. Material and methods Twelve patients with PMS and twelve controls were enrolled. Static postural balance was assessed by calculating the symmetry index (SI) in the unipedal posture. To measure vision contribution, the Romberg index (RI) was computed. Dynamic postural balance was evaluated with the Timed up and go test (TUGT). Besides, inter-limb strength asymmetry (SA), pain and the short form-36 (SF-36) were assessed. Results The PMS group (PMSG) exhibited significant (p < 0.001) higher SI in eyes opened (EO) and eyes closed (EC) conditions compared to the control group (CG). Besides, PMSG had significant higher RI (p < 0.05), TUGT scores (p < 0.001), SA values (p < 0.05), pain intensity (p < 0.001), and worse SF-36 scores on all physical health (p < 0.05) and psychological health (only in vitality and mental health [p < 0.05]), compared to CG. Conclusion Our data revealed impaired static and dynamic postural balance, and reduced quality of life in PMSG compared to CG. Postural balance impairments could explain the poor quality of life, which are likely due to the higher SA and higher pain intensity. Clinicians and physiotherapists should consider postural balance disorders while designing rehabilitation programs in these patients.

Intra- and Inter-Limb Strength Asymmetry in Soccer: A Comparison of Professional and Under-18 Players.

(1) Background: the present study examined the isokinetic peak torque exerted by both knee extensors and flexors, anterior–posterior imbalance and the magnitude and direction of inter-limb asymmetry in professional and academy soccer players. (2) Methods: one hundred soccer players (professional = 50, elite academy = 50) volunteered to take part in this investigation. An isokinetic dynamometer was used to measure the knee extensor (quadriceps) and flexors muscle (hamstrings) torques of the limbs as well as inter-limb asymmetries—using a standard percentage difference equation. (3) Results: professional players exhibited significantly greater (effect size [ES] = large) strength levels in the quadriceps and hamstrings under both testing conditions, significantly higher (small to moderate) intra-limb ratio values for 60°·s−1 but not for the 300°·s−1 test condition, significantly (small to moderate) lower inter-limb asymmetry values for all test conditions, with the exception of the hamstrings at 60°·s−1 and the direction of asymmetry was poor to slight, indicating that limb dominance was rarely the same between groups. (4) Conclusions: this study shows that isokinetic assessments, i.e., peak torque exerted by both knee extensors and flexors and intra-limb ratio, and the subsequent inter-limb asymmetry, i.e., magnitude and direction, can differentiate between professional and academy soccer players.

Profesyonel futbolcularda alt ekstremite kas kuvveti asimetrisi, denge ve ayak bileği yaralanma riski arasındaki ilişkinin incelenmesi

Amaç: Bu çalışmada profesyonel futbolcularda alt ekstremite kas kuvvet asimetrisi, dinamik denge ve ayak bileği yaralanma riski arasındaki ilişkinin incelenmesi amaçlandı. Yöntem: Çalışmaya 20 profesyonel erkek futbolcu dahil edildi. Bilateral dinamik dengeyi değerlendirmek için Y denge testi kullanıldı. Alt ekstremiteye ait bilateral kalça fleksör, kalça ekstansör, kalça abduktör, kalça adduktör, diz fleksör, diz ekstansör, ayak bileği dorsifleksör, ayak bileği plantar fleksör, ayak bileği evertör ve ayak bileği invertör kas gruplarının maksimal izometrik kontraksiyonu değerlendirmek için Groinbar sistemi kullanıldı. Bulgular: Çalışmaya dahil edilen oyuncuların yaş ortalaması 27,80±5,80 yıl ve vücut kütle indeksi ortalaması 24,04 ± 1,55 kg/m² olarak bulundu. Her iki ayak bileği dorsifleksör ve plantarfleksör kas grupları arasındaki oran ile denge testinde anteriorposterior bilateral fark arasında istatistiksel açıdan anlamlı sonuç elde edildi (Sol: p=0,012, rho=-0,552, Sağ: p=0, rho=- 0,727). Anterior-posterior denge farkının yaralanma riski açısından değerlendirildiğinde; kalça abduktör ve adduktör kas grupları arasındaki oran ile ayak bileği yaralanma riski açısından anlamlı korelasyon bulundu (Sol: p=0,026, rho=-0,498, Sağ: p=0,006, rho=-0,595). Sonuç: Profesyonel futbolcularda alt ekstremiteye ait plantarfleksör/dorsifleksör ve adduktör/abduktör kas gruplarının izometrik kuvvet oranının ve bilateral plantar fleksör kuvvet asimetrisinin dinamik denge ve ayak bileği yaralanma riskiyle ilişkili olduğu bulundu.

Network robustness and structure depend on the phenological characteristics of plants and pollinators.

Many structural patterns have been found to be important for the stability and robustness of mutualistic plant–pollinator networks. These structural patterns are impacted by a suite of variables, including species traits, species abundances, their spatial configuration, and their phylogenetic history. Here, we consider a specific trait: phenology, or the timing of life history events. We expect that timing and duration of activity of pollinators, or of flowering in plants, could greatly affect the species' roles within networks in which they are embedded. Using plant–pollinator networks from 33 sites in southern British Columbia, Canada, we asked (a) how phenological species traits, specifically timing of first appearance in the network and duration of activity in a network, were related to species' roles within a network, and (b) how those traits affected network robustness to phenologically biased species loss. We found that long duration of activity increased connection within modules for both pollinators and plants and among modules for plants. We also found that date of first appearance was positively related to interaction strength asymmetry in plants but negatively related to pollinators. Networks were generally more robust to the loss of pollinators than plants, and robustness increased if the models allow new interactions to form when old ones are lost, constrained by overlapping phenology of plants and pollinators. Robustness declined with the loss of late‐flowering plants, which tended to have higher interaction strength asymmetry. In addition, robustness declined with loss of early‐flying or long‐duration pollinators. These pollinators tended to be among‐module connectors. Our results point to networks being limited by early‐flying pollinators. If plants flower earlier due to climate change, plant fitness may decline as they will depend on early emerging pollinators, unless pollinators also emerge earlier.

Confidence to Return to Play After ACL Reconstruction: An Evaluation of Quadriceps Strength Symmetry and Injury Mechanism in Male Athletes.

After anterior cruciate ligament reconstruction (ACLR), diminished quadriceps strength symmetry and reduced psychological readiness to return to play (RTP) increase the risk for subsequent injury. Although the relationship between quadriceps strength symmetry and psychological readiness to RTP has been reported to be influenced by injury mechanism in female athletes, it is unclear whether such a relationship exists in male athletes. Quadriceps strength symmetry would be positively associated with greater psychological readiness to RTP after ACLR, regardless of injury mechanism. Retrospective cohort. Level 3 (cohort study). Sixty male patients completed strength testing and the Injury-Psychological Readiness to Return to Sport Scale (I-PRRS) at an outpatient clinical facility as part of return to sport testing after ACLR. Linear regression analysis was used to assess the relationship between the I-PRRS and the independent variables of interest (quadriceps strength symmetry and injury mechanism). For all patients combined, no symmetry × mechanism interaction was found (P = 0.11). A significant positive relationship was found between quadriceps strength symmetry and the I-PRRS score (P < 0.001, R2 = 0.31), after adjusting for time post-ACLR and injury mechanism. Greater quadriceps strength symmetry was associated with greater psychological readiness to RTP after ACLR in male athletes. In contrast to what has been reported in female athletes, this relationship was independent of injury mechanism. Given the potential negative consequences of quadriceps strength deficits on one's confidence to RTP, the need to restore quadriceps symmetry during the postoperative period is readily apparent. Low confidence or low psychological readiness to RTP may be indicative of quadriceps strength asymmetry or poor physical function in general.

Increased Asymmetry of Trunk, Pelvis, and Hip Motion during Gait in Ambulatory Children with Spina Bifida

Spina bifida (SB) is caused by incomplete neural tube closure and results in multiple impairments, including muscle weakness. The severity of muscle weakness depends on the neurologic lesion level. Though typically symmetric, there can be asymmetries in neurologic lesion level, motor strength, skeletal structures, and body composition that affect patients’ gait and function. Using body segment and joint motion obtained through 3D computerized motion analysis, we evaluated asymmetry and range of motion at the hip, pelvis, and trunk in the frontal and transverse planes during gait in 57 ambulatory children with SB and 48 typically developing controls. Asymmetry and range of hip, pelvis, and trunk motion in the frontal and transverse planes were significantly greater for patients with mid-lumbar and higher level lesions compared with those having sacral/low-lumbar level lesions and controls without disability (p ≤ 0.01). Crutch use decreased asymmetry of trunk rotation in mid-lumbar level patients from 10.5° to 2.6° (p ≤ 0.01). Patients with asymmetric involvement (sacral level on one side and L3-4 on the other) functioned similarly to sacral level patients, suggesting that they may be better categorized using their stronger side rather than their weaker side as is traditional. The information gained from this study may be useful to clinicians when assessing bracing and assistive device needs for patients with asymmetric SB involvement.

Solar Wind Entry Into Midtail Current Sheet via Low‐Latitude Mantle Under Dominant IMF By: ARTEMIS Observation

AbstractIt is expected from global simulations that the low‐latitude mantle may be an important pathway for the solar wind entry into the tail current sheet when interplanetary magnetic field (IMF) By is dominant, which is different from the pathways for northward or southward IMF dominant conditions. To evaluate this pathway and the predicted plasma asymmetries between the southern and northern lobes resulting from the low‐latitude mantle, we analyze 222 current sheet crossing events observed in the midtail. Each of the events is selected to have the spacecraft observe both lobes within 20 min. For the majority of the events, the different north‐south asymmetries of the lobe density observed on the dawnside and duskside corresponding to different IMF By directions are consistent with the appearance of the low‐latitude mantle plasma. No significant north‐south asymmetry in the lobe magnetic field strength is found so that the density asymmetry also results in north‐south asymmetric lobe Alfvén speed. Within the tail current sheet, the cross‐tail profiles show that density can be higher, but temperatures and peak flow speed lower, near the flanks than near midnight. Magnitudes of these current sheet plasma parameters are found to positively correlate with the values of the asymmetric lobe parameters concurrently observed, indicating that the low‐latitude mantle can be a particle source for the current sheet. Also, the asymmetric lobe parameters are positively correlated with some solar wind parameters. These good correlations support the expectation that the pathway through the low‐latitude mantle becomes more important as the IMF By becomes more dominant.

The Calculation, Thresholds and Reporting of Inter-Limb Strength Asymmetry: A Systematic Review.

The prevalence of inter-limb strength differences is well documented in the literature however, there are inconsistencies related to measurement and reporting, and the normative values and effects associated with inter-limb asymmetry. Therefore, the aims of this systematic review were to: 1) assess the appropriateness of existing indices for the calculation of asymmetry, 2) interrogate the evidence basis for literature reported thresholds used to define asymmetry and 3) summarise normative levels of inter-limb strength asymmetry and their effects on injury and performance. To conduct this systematic review, scientific databases (PubMed, Scopus, SPORTDiscus and Web of Science) were searched and a total of 3,594 articles were retrieved and assessed for eligibility and article quality. The robustness of each identified asymmetry index was assessed, and the evidence-basis of the identified asymmetry thresholds was appraised retrospectively using the references provided. Fifty-three articles were included in this review. Only four of the twelve identified indices were unaffected by the limitations associated with selecting a reference limb. Eighteen articles applied a threshold to original research to identify "abnormal" asymmetry, fifteen of which utilised a threshold between 10-15%, yet this threshold was not always supported by appropriate evidence. Asymmetry scores ranged between and within populations from approximate symmetry to asymmetries larger than 15%. When reporting the effects of strength asymmetries, increased injury risk and detriments to performance were often associated with larger asymmetry, however the evidence was inconsistent. Limitations of asymmetry indices should be recognised, particularly those that require selection of a reference limb. Failure to reference the origin of the evidence for an asymmetry threshold reinforces doubt over the use of arbitrary thresholds, such as 10-15%. Therefore, an individual approach to defining asymmetry may be necessary to refine robust calculation methods and to establish appropriate thresholds across various samples and methodologies that enable appropriate conclusions to be drawn.

Upper limb muscle strength and knee frontal plane projection angle asymmetries in female water-polo players

ABSTRACT Water-polo players frequently perform overhead throws that could result in shoulder imbalances. For overhead throws, execution of the ‘eggbeater kick’ (cyclical movement of the legs) is required to lift the body out of the water. Although a symmetrical action, inter-limb differences in task execution could lead to knee frontal plane projection (FPPA) differences. The present study examined imbalances shoulder and knee FPPA in female players. Eighteen competitive female field players (24.1 ± 5.5 years, 1.68 ± 0.06 m, 72.9 ± 13.3 kg) had their shoulder strength assessed in a shot-mimicking position with a portable dynamometer, standing and seated (isolating the shoulder contribution). Anterior: posterior and shooting: non-shooting shoulder comparison were made. Additionally, players performed a drop jump. Knee FPPA was recorded from digitising and comparing the frames just before landing and at stance phase. During standing, players exhibited higher shooting: non-shooting asymmetry (p = 0.032) in the anterior contraction direction, while during seated the shooting shoulder anterior: posterior asymmetry was higher (p = 0.032). Interlimb knee FPPA asymmetry was higher in the stance phase (p = 0.02). Despite the overhead throwing and egg-beater demands impacting differently on each limb, considerable asymmetries do not develop, suggesting the overall training requirements (e.g. swimming, resistance training) were sufficient to maintain the asymmetry within desirable limits.