Non-dominant Lower Limbs Research Articles

Does Walking with a Load Affect Asymmetry in Bilateral Lower Extremity Mechanics?

PURPOSE This study sought to analyze the velocity and asymmetry between bilateral lower extremity mechanics according to the load during walking.METHODS A total of 14 adults with right leg dominance participated in this study (Male=7, Female=7). We respectively applied 30% of body weight load carriage on the subjects. Gait characteristics were analyzed with 3-dimensional cinematography and ground reaction force (GRF) system consisted of a center of gravity (COG) velocity, center of pressure (COP) area, leg stiffness, and GRF components.RESULTS Change in velocity of the maximum-minimum COG showed statistically significant in the main effect of load. The 1st anterior-posterior GRF (braking force) and vertical GRF were statistically significant in the main effects of load and bilateral lower limbs. The 2nd anterior-posterior GRF (propulsive force) was statistically significant in the main effect of load. COP area and leg stiffness exhibited statistically significant differences in the main effects of load and bilateral lower limbs. Interaction was observed in the vertical GRF, COP area. Furthermore , one-way variance analysis revealed load main effect had a greater influence on the increase in the magnitude of the vertical GRF and COP area than the asymmetry of bilateral lower limbs.CONCLUSIONS This study revealed the differences in asymmetry between the dominant and non-dominant lower limbs according to the load during walking. These findings may explain the differences shock attenuation and stress mechanisms between the bilateral lower limbs.

Acute effects of static stretching and proprioceptive neuromuscular facilitation on non-local range of movement

ABSTRACT Acute effects of static stretching (SS) and proprioceptive neuromuscular facilitation (PNF) on local and non-local range of motion (ROM) were assessed in 29 participants. Three evaluations were performed one week apart: week-1 Control session (CS); weeks 2–3 either SS or PNF interventions (randomized). Dominant and non-dominant limbs, local (hamstring extensibility) and non-local ROMs (Shoulder extension-ShE) were collected at baseline (T0), immediately after (T1), and fifteen minutes post-intervention (T2). No differences were found between time-points during the CS. Local-ROM significantly increased (p=0.0002, ES=0.74 and 0.0079, 0.56, for dominant and non-dominant lower limbs, respectively) after both SS and PNF. No interaction between time and treatment was detected for ShE in both limbs. However, post-hoc analysis revealed a significant increase in dominant upper limb ShE between T0 and T1 only after SS (p=0.002; +6.5%). Acute bouts of SS and PNF can increase local-ROM, however, no clear effects were observed for non-local ROM.

L'influenza della flessione anteriore del tronco sulla biomeccanica del ginocchio e sull'attività mioelettrica durante l'esecuzione del sidestep cut

BACKGROUND: Trunk motion control may be an important factor affecting the risk of anterior cruciate ligament (ACL) injury by changing knee joint load during dynamic motion, there has been few studies investigating the influence of it on knee joint during sidestep cutting currently, and it has not been studied whether asymmetry between the dominant and non-dominant lower limbs in different trunk motion states during sidestep cutting. The objective of this study was to identify the leg laterality during sidestep cutting in trunk forward inclination state and to explore whether trunk forward inclination could reduce ACL injury risk.METHODS: Twenty healthy male college basketball athletes volunteered for this study. Each individual is required to complete sidestep cutting tasks in four states. They performed sidestep cutting using the dominant and non-dominant side with trunk forward inclination or natural position, respectively. Biomechanical testing equipment were used to synchronously collect knee biomechanics and myoelectricity data. A two-way (trunk motion × support side) ANOVA was used to analyze the influence of trunk motion control on knee biomechanics and myoelectricity and leg laterality.RESULTS: There was no leg laterality during sidestep cutting with trunk forward inclination state. During sidestep cutting with trunk forward inclination state, the knee flexion angle at initial contact (P=0.003 for the dominant side; P=0.011 for the non-dominant side), knee peak flexion angle (P=0.001 for the dominant side; P=0.000 for the non-dominant side) and H/Q ratio (P=0.048 for the dominant side) were significantly greater than trunk natural state.CONCLUSIONS: There was no leg laterality during sidestep cutting in trunk forward inclination state, and the trunk forward state may have a protective effect on the ACL during sidestep cutting, especially for the dominant side.

Influence of the Hawthorne effect on spatiotemporal parameters, kinematics, ground reaction force, and the symmetry of the dominant and nondominant lower limbs during gait

The Hawthorne effect is a change in behavior resulting from awareness of being observed or evaluated. This study aimed to determine whether awareness of being evaluated or presence of an observer influence gait. Twenty-one young women were asked to walk in three conditions. In the first condition (unawareness of evaluation; UE), participants were aware that it was a practice trial, and there was no observer. In the second condition (awareness of evaluation; AE), participants were aware that their gait was being evaluated. The third condition (AE + researcher observation; RO) was similar to the second condition except that an additional researcher observed the participant' gait. The spatiotemporal, kinematic, ground reaction forces, and ratio index (symmetry of both lower limbs) were compared among the three conditions. A higher ratio index indicated a relative increase in the value on left versus right. Gait speed (P = 0.012) and stride length (right and left; P = 0.006 and 0.007, respectively) were significantly increased in the AE + RO than in UE. Range of motion of the right hip and left ankle was significantly greater in AE than in UE (P = 0.039 and 0.012, respectively). The ratio index of ground reaction force during push-off was significantly higher in AE and AE + RO conditions than in UE (P < 0.001 and P = 0.004, respectively). The Hawthorne effect (awareness of being evaluated or presence of an observer) potentially influences gait. Thus, factors that influence gait analysis should be considered when evaluating normal gait.

Effects of walking football on adherence, safety, quality of life and physical fitness in patients with prostate cancer: Findings from the PROSTATA_MOVE randomized controlled trial.

To analyze the feasibility and impact of a walking football (WF) program on quality of life (QoL), cardiorespiratory fitness (CRF), muscle strength, and balance program in men with prostate cancer under androgen deprivation therapy (ADT). Fifty patients with prostate cancer (stages IIb-IVb) under ADT were randomized to a 16-week WF program plus usual care (n=25) or usual care control group (n=25). The WF program consisted of three 90-minute sessions per week. Recruitment, withdrawal, adherence, enjoyment rate, and safety of the intervention were recorded throughout the study. Cardiorespiratory fitness was assessed before and after the interventions, while handgrip strength, lower limb muscle strength, static balance, and QoL were assessed before, during (week 8), and after (week 16) the interventions. Adverse events during sessions were also recorded. The WF group showed high levels of adherence (81.6 ± 15.9%) and enjoyment rate (4.5 ± 0.5 out of 5 points). In the intention-to-treat analysis, the WF group showed an improvement in chair sit-to-stand (p=0.035) compared to the control group. Within-group comparisons showed that handgrip strength in the dominant upper limb (p=0.024), maximal isometric muscle strength in the non-dominant lower limb (p=0.006), and balance in the dominant limb (p=0.009) improved over time in the WF group but not in the usual care group. The results obtained from the per-protocol analysis indicate that CRF improved significantly in the WF group as compared to the control group (p=0.035). Within-group analysis revealed that CRF (p=0.036), muscle strength in dominant (p=0.006) and non-dominant (p=0.001) lower limbs, and balance in the non-dominant lower limb (p=0.023) improved after 16 weeks of WF, but not in the control group. One major traumatic injury (muscle tear) was reported with a complete recovery before the end of the intervention. This study suggests that WF is feasible, safe, and enjoyable in patients with prostate cancer under hormonal therapy. Furthermore, patients who adhere to the WF program can expect cardiorespiratory fitness, muscle strength, and balance improvements. clinicaltrials.gov, identifier NCT04062162.

Test−Retest Reliability of Isokinetic Ankle, Knee and Hip Strength in Physically Active Adults Using Biodex System 4 Pro

The isokinetic dynamometry is considered a gold standard in muscle strength testing. The reliability of lower limb isokinetic strength measurements has not been thoroughly evaluated. To examine the test-retest reliability of isokinetic ankle plantar and dorsiflexion, ankle inversion and eversion, knee extension and flexion and hip abduction and adduction strength in physically active adults using Biodex System 4 Pro. Peak torques (PTs) and average peak torques (APTs) of the dominant and nondominant lower limbs were tested twice in 19 physically active adults 7 to 14 days apart. The intraclass correlation coefficients (ICC) values varied from excellent to moderate and coefficient of variation of typical error (CVTE) values were 6.6-19.5%. Change in the mean expressed as a percent varied from -3.1% to 9.6%. There was no difference in the reliability between PT and APT values. Dominant lower limb was more reliable in every case if there was difference between limbs. Test-retest reliability of isokinetic ankle, knee and hip strength in physically active adults using Biodex System 4 is mostly good or excellent. However, the observed range of the random variation has to be noted when using it in scientific follow-up studies or evaluation of patient progress in clinical settings.

Assessment of Hip Range of Motion Limitations in Cases with Low Back Pain Based on the Classified Movement System Impairment.

The hip joint's limitation causes lumbopelvic compensatory motions, accumulating tissue stress on the lumbar spines. It is essential and valuable to evaluate hip rotation range of motion (ROM) in different low back pain (LBP) classifications to understand them and plan the best exercise program. This study aimed to compare hip rotation ROM between subjects with and without LBP classified in movement system impairment (MSI). In this cross-sectional study, 100 subjects with LBP were classified into different MSI subgroups (mean age of 41.66 ± 7.82 years), and 100 healthy subjects (mean age of 38.96 ± 8.84 years) participated. Passive and active hip medial and lateral rotations ROM in prone and supine positions for dominant and non-dominant lower limbs were measured. Generally, in the LBP group, minimal lateral rotation as compared to controls in movement tests measuring hip rotation ROM actively and passively, in prone and sitting positions, and for dominant and non-dominant limbs (P < 0.05). There were no significant differences among the LBP subgroups (P > 0.05). Due to LBP, regardless of the MSI categories, remarkably restricted hip lateral rotation ROM.

Inter-Limb Asymmetry of Leg Stiffness in National Second-League Basketball Players during Countermovement Jumps

Assessment of the inter-limb asymmetry of leg stiffness is carried out using one-legged jumping tasks. However, the level of asymmetry may vary depending on the performance on one or both lower limbs. Therefore, the purpose of this study was to identify the differences in leg stiffness between the dominant and non-dominant lower limb during a two-legged countermovement jump. The research was conducted on 35 s-league basketball players (body height: 1.90 ± 0.08 m, body mass: 81.9 ± 10 kg, age: 19.5 ± 1.7 years). Each participant performed three countermovement jumps with arm swing to the maximum height. Measurements employed a BTS SMART motion analysis system and two Kistler force plates. Statistically significant differences were found during the comparison of leg stiffness in the dominant and non-dominant lower limbs. Inter-limb asymmetry of leg stiffness reached 22.0% in the countermovement phase and 8.9% in the take-off phase. Significant inter-limb asymmetry of leg stiffness might lead to injury or considerably reduce the performance of athletes. Therefore, an important role is to conduct strength and speed-strength trainings with proper loads to both body sides. Coaches should pay more attention to similar lower limbs movement patterns during two-legged exercises and bilateral strength development.

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.

Effects of Blood Flow Restriction Training on Blood Perfusion and Work Ability of Muscles in Elite Para-alpine Skiers.

ABSTRACTPurposeThe effects of short-term blood flow restriction (BFR) exercise on muscle blood flow perfusion and performance during high-intensity exercise were determined in elite para-alpine standing skiers to assess whether this would be an effective training regimen for elite athletes with disabilities.MethodsNine national-level para-alpine standing skiers (mean age, 20.67 ± 1.34 yr; four women) were recruited. Nondominant lower limbs were trained with BFR (eight in final analyses), and dominant lower limbs were trained without BFR (seven in final analyses). The 2-wk protocol included high-load resistance, local muscle endurance (circuit resistance training), and aerobic endurance (stationary cycling) training performed 4 times a week, with BFR during local muscle endurance and aerobic endurance sessions. Muscle strength was measured by maximal voluntary isometric contraction (MVIC) in the knee extensors; microcirculatory blood perfusion (MBP), by laser Doppler blood flow; and muscle strength and endurance, by the total amount of work (TW) performed during high-intensity centrifugal and concentric contractions.ResultsBFR significantly increased absolute and relative MVIC (P < 0.001, P = 0.001), MBP (P = 0.011, P = 0.008), and TW (P = 0.006, P = 0.007) from pretraining values, whereas only absolute MVIC increased without BFR (P = 0.047). However, the MVIC increase with BFR exercise (35.88 ± 14.83 N·m) was significantly greater (P = 0.040) than without BFR exercise (16.71 ± 17.79 N·m).ConclusionsShort-term BFR exercise significantly increased strength endurance, muscle strength, and MBP in national-level para-alpine standing skiers. Our study provides new evidence that BFR exercise can improve local muscle blood perfusion during high-intensity exercise and informs BFR exercise strategies for athletes with disabilities.

Effects of limb dominance on the symmetrical distribution of plantar loading during walking and running

The purpose of this study was to investigate the symmetry or asymmetry in the plantar pressure, foot axis angle and muscle mass of dominant and non-dominant legs. Sixty-eight able-bodied participants (age: 20 ± 1 years, height: 162 ± 8 cm, mass: 53 ± 7 kg, BMI: 20.63 ± 2 kg/m2) were recruited for the walking and running tests. All participants with right dominant feet, defined as the preferred leg when kicking a ball, were asked to perform four successful trials at their self-selected walking and running speeds after warm-up. FootScan force-measuring plate was utilized to collect plantar pressure and foot axis angle. The Tanita Segmental Body Composition Analyzer was used to measure the muscle mass of the lower limbs. The time-series parameters were checked using an open-source statistical parametric mapping 1d package. The result exhibited that the medial foot pressure of the dominant limb was higher than the non-dominant limb ( p &lt; 0.05). Foot balance index range showed asymmetry in both walking and running tasks (absolute symmetry index &lt;10%). There was no significant difference in muscle mass between the dominant and non-dominant lower limbs ( p = 0.79). The quantification of potential differences and asymmetries could provide implications for gait injury prevention and shoe design.

Effect of lower limb dominance on walking adaptations in young adults when stepping into a hole

Background. Depending on the dimensions of a hole, the characteristics of the walking surface, and the position of the hole relative to normal walking, individuals may need to step into the hole with the dominant or non-dominant limb. Aim. We investigated the effect of the lower limb dominance in walking adaptations in the presence of a hole on the ground. Methods: Twenty young adults walked and stepped into a hole positioned in the middle of the pathway using the dominant and non-dominant lower limbs. Results. For the trailing limb, the impulses were not affected by the lower limb dominance, but for the leading limb, the non-dominant leg increased the braking and propulsive impulses compared to the dominant leg. On the other hand, toe-off velocity increased when the non-dominant leg was used as trailing and leading limbs. Stride speed increased when the non-dominant leg was the trailing limb. Interpretation. Our results were consistent with asymmetrical behavior between dominant and non-dominant legs. Although the differences between the dominant and non-dominant legs have not affected the success in the task, they can put the individual at higher risk of stumbling and consequently a fall when stepping with the non-dominant leg into the hole.

The impact of hearing loss on three-dimensional lower limb joint torques during walking in prepubertal boys

IntroductionIn children, the impact of hearing loss on biomechanical gait parameters is not well understood. Thus, the objectives of this study were to examine three-dimensional lower limb joint torques in deaf compared to age-matched healthy (hearing) children while walking at preferred gait speed. MethodsThirty prepubertal boys aged 8–14 were enrolled in this study and divided into a group with hearing loss (deaf group) and an age-matched healthy control. Three-dimensional joint torques were analyzed during barefoot walking at preferred speed using Kistler force plates and a Vicon motion capture system. ResultsFindings revealed that boys with hearing loss showed lower joint torques in ankle evertors, knee flexors, abductors and internal rotators as well as in hip internal rotators in both, the dominant and non-dominant lower limbs (all p < 0.05; d = 1.23–7.00; 14–79%). Further, in the dominant limb, larger peak ankle dorsiflexor (p < 0.001; d = 1.83; 129%), knee adductor (p < 0.001; d = 3.20; 800%), and hip adductor torques (p < 0.001; d = 2.62; 350%) were found in deaf participants compared with controls. ConclusionThe observed altered lower limb torques during walking are indicative of unstable gait in children with hearing loss. More research is needed to elucidate whether physical training (e.g., balance and/or gait training) has the potential to improve walking performance in this patient group.

Myotendinous asymmetries derived from the prolonged practice of badminton in professional players.

BackgroundThe continued practice of a sport linked to the unilateral predominance of the dominant side can provoke chronic asymmetric adaptations in the myotendinous structure and mechanical properties. Objectives: The main purpose was to determine whether asymmetry between the preferred and non-preferred lower limb is present in the lower limb tendon structure, muscle architecture and stiffness values of professional badminton players.MethodsSixteen male professional badminton players (age = 24.1 ± 6.7 years; body height = 177.90 ± 7.53 cm) participated in this study. The muscle architecture of the vastus lateralis (VL), medial gastrocnemius (MG) and lateral gastrocnemius (LG) and the structure of patellar and Achilles tendons were measured in the dominant and non-dominant lower limb with ultrasonography. Stiffness was also measured at the same points with a hand-held MyotonPro. Significant differences between the dominant and non-dominant lower limb were determined using Student’s t test for related samples.ResultsBilateral differences were observed for thickness, width and cross-sectional area (CSA) in both tendons showing higher values for the dominant side: patellar tendon CSA (2.02 ± 0.64 vs. 1.51 ± 0.42 cm2; p < 0.05) and Achilles tendon CSA (1.12 ± 0.18 vs. 0.92 ± 0.28 cm2; p < 0.05). No significant differences were observed in muscle architecture and myotonic variables between the dominant and non-dominant lower limb.ConclusionsThe prolonged practice of badminton caused asymmetries in the CSA, width and thickness of the patellar and Achilles tendon between the dominant and non-dominant lower limbs. No bilateral differences were found in the muscle architecture of VL, MG and LG or in the stiffness of any muscle or tendon analyzed.

Acute Effects of Unilateral Self-Administered Static Stretching on Contralateral Limb Performance

**Background:** Prolonged static stretching (SS) has been shown to impair subsequent performance of the stretched muscle. There is some evidence that unilateral SS can have crossover or global effects on range of motion (ROM), but there is scant information regarding whether prolonged SS also impairs contralateral muscle groups. **Purpose:** The objective of this study is to investigate the effects of self-administered unilateral SS with a TheraBand® stretch strap on contralateral hip flexion ROM and knee extension isometric maximum voluntary contraction (MVC) force and muscle activation. **Study Design:** This study used an experimental repeated-measures intervention design. **Methods:** In total, 14 male participants performed self-administered SS of the dominant quadriceps and hamstrings (eight repetitions of 30 s each) with a TheraBand stretch strap. The aim was to observe pre- to post-SS-induced changes in hip flexion (hamstrings) ROM, knee extension (quadriceps) isometric force, and muscle activation (as recorded with electromyography [EMG]) in both dominant (experimental limb) and nondominant lower limbs (control lower limb). **Results:** A significant tested leg x time interaction [F(1,13) = 6.58; P = 0.04; eta2 = 0.210) demonstrated that the ROM increases in both the stretched and contralateral nonstretched legs by 6.7% (d = 0.53) and 4.3% (d = 0.38), respectively. There were no significant interactions for MVC force or muscle activation for either leg. **Conclusion:** The lack of crossover MVC changes suggests that the mechanism for contralateral increases in ROM may be stretch tolerance. **Clinical Relevance:** Individuals who are injured or are undergoing rehabilitation should continue to stretch the noninjured limb to maintain or improve flexibility of the injured limb.

Effect of 16-week corrective training program on three dimensional joint moments of the dominant and non-dominant lower limbs during gait in children with genu varus deformity

Summary Context Proper treatment of lower limbs alignment in children may prevent the progression of pathologies. However, this is not evaluated from a scientific view-point. Objective The purpose of this study was to evaluate the effects of a 16-week Corrective Exercise Continuum (CEC) programming strategy on three dimensional joint moments of dominant and non-dominant lower limbs during walking. Design Randomized control trials. Setting Sports biomechanics laboratory. Participants Twenty eight male children with genu varus and with permission of their parents were volunteered to participate in this study. They were randomly divided in two equal-sized groups (experimental and control). Intervention Corrective Exercise Continuum (CEC) programming strategy. Main Outcome Measures Data acquisition was carried out using six infrared motion analysis cameras (Vicon motion Systems, Oxford, UK) and two force platforms (Kistler AG, Winterthur, Switzerland). The joint moments of the ankle, knee, and hip of the both lower extremities were calculated using inverse dynamics approach. Results The results indicated that CEC decreased the peak knee internal rotation moment (P Conclusions Performing CEC could reduce excessive knee internal rotation moment as well as hip external rotation moment identified as two key risk factors for medial knee osteoarthritis. Therefore, it would be recommended for children with genu varus, in that it can prevent and slow joint degeneration in adulthood.

COLLEGIATE MALE SOCCER PLAYERS EXHIBIT BETWEEN-LIMB SYMMETRY IN BODY COMPOSITION, MUSCLE STRENGTH, AND RANGE OF MOTION.

Functional and structural asymmetries attributed to limb dominance are equivocal in soccer players. Previous authors hypothesize the existence of between-limb asymmetry secondary to the repetitive unilateral nature of kicking. However, symmetry is often present, particularly in measures of muscle strength. The purpose of the present study was to determine if lateral dominance is accompanied by corresponding between-limb asymmetries in a comprehensive assessment of body composition, muscle strength, and range of motion in healthy soccer players. Cross-sectional, observational. 17 healthy male NCAA Division One collegiate soccer players participated (age 19.6 ± 1.5 years; BMI 23.9 ± 1.4 kg/m2). Footedness was attained via participant self-report. Lower limb muscle strength (hand held dynamometry), range of motion (goniometry), and body composition (dual energy x-ray absorptiometry scan) were measured. Lower-leg symmetry was analyzed comparing the dominant versus non-dominant limb using paired t-tests. Comparisons revealed no statistically different differences in outcomes, indicating remarkable symmetry in all measures of body composition, muscle strength, and range of motion (p>0.05) between the dominant and non-dominant lower limbs. The authors speculate the prevalence of running versus kicking, the longitudinal effects of playing careers, and/or functional compensation attenuates the expected asymmetries in healthy male collegiate soccer players. 2b.

Do different methods for measuring joint moment asymmetry give the same results?

Gait asymmetry is defined as a loss of perfect agreement between the dominant and non-dominant lower limbs. Conflicting results from gait asymmetry studies may be due to different definitions of asymmetry, different research methods, and/or different variables and formulas used for asymmetry calculation. As a result, this makes it difficult to compare joint asymmetry values between studies. An accurate and precise understanding of asymmetry during human walking is an important step towards developing enhanced rehabilitation protocols for pathological gait. This study examined bilateral lower extremity joint moment asymmetry during the stance phase of walking using three different methods. Fourteen male children (with flat feet) aged 8–14 years participated in this study. The three-dimensional lower limb kinetics was evaluated during a comfortable gait. Then, right and left lower limb joint moments were used to calculate the joint moment asymmetry via three different methods (Lathrop-Lambach method: equation used by Lathrop-Lambach et al. (2014); Su method: equation used by Su et al. (2015); Nigg method: equation used by Nigg et al. (2013)). Repeated-measures ANOVAs (α = 0.05) were used to compare the values of net joint moment asymmetry calculated by the three methods. The results of the statistical analyses found that the amounts of moment symmetry between limbs calculated by the first two methods were significantly greater than that of using the Nigg method (except for the values of the frontal ankle moment computed by the Lathrop-Lambach method). Furthermore, in comparison of the first two methods, using the Su method showed a reduction in moment asymmetry for all joints and for all moments (p < 0.05). We conclude that, although all of three common methods for determining asymmetry between limbs have documented merit, they sometimes differ dramatically in results.

Sex differences in anticipatory postural adjustments during rapid single leg lift

The aim of this study was to assess the influence of sex on the kinetic, kinematic and neuromuscular correlates of anticipatory postural adjustments (APAs) during a single leg lift task performed by healthy participants. Fifty healthy age and body mass index matched participants (25 women and 25 men) performed 20 single leg lift task (hip flexion to 90 ° as quickly as possible) with their dominant and their non-dominant lower limbs. A force plate was used to determine the medial-lateral displacement of the center of pressure (COPML), and the initiation of weight shift (T0); kinematics was used to determine leg lift (T1); and electromyography was used to determine onset times from eight muscles: bilateral external oblique, internal oblique and lumbar multifidus, and unilateral (stance limb) gluteus maximus and biceps femoris. Movement control limb dominance was included in the analysis. Statistically significant interactions between sex and limb dominance (p < .001) were observed for T1, COPML, and muscle onsets. Also, statistically significant main effect of sex on T0 was observed. Women showed increased APA time (T1) and magnitude (COPML) in their dominant limbs compared to men. Such differences between sexes did not occur in the non-dominant limb. Women recruited proximal muscles later than their man counterparts. Overall, women appear to have a stronger effect of limb dominance on their anticipatory postural control strategy which requires further investigation. The findings of the current study indicate that women and men differ in their anticipatory postural control strategy for rapid single leg lift.

Knee extension and flexion strength asymmetry in Human Immunodeficiency Virus positive subjects: a cross-sectional study

BackgroundHuman Immunodeficiency Virus positive subjects present impairment in muscle function, neural activation, balance, and gait. In other populations, all of these factors have been associated with muscle strength asymmetry. ObjectiveTo investigate the existence of muscle strength asymmetry between dominant and non-dominant lower limbs and to determine the hamstrings-to-quadriceps strength ratio in Human Immunodeficiency Virus positive subjects. MethodsIn this cross-sectional study, 48 subjects were included (22 men and 26 women; mean age 44.6 years), all of them under highly active antiretroviral therapy. They performed isokinetic strength efforts at speeds of 60°/s and 180°/s for knee extension and flexion in concentric-concentric mode. ResultsPeak torque was higher (p<0.01) at 60°/s for quadriceps (193, SD=57 vs. 173, SD=55% body mass) and hamstrings (97, SD=36 vs. 90, SD=37% body mass) in dominant compared to non-dominant. Similarly, peak torque was higher at 180°/s (quadriceps 128, SD=44 vs. 112, SD=42; hamstrings 64, SD=24 vs. 57, SD=26% body mass) in dominant. Average power was also higher for all muscle groups and speeds, comparing dominant with non-dominant. The hamstrings-to-quadriceps ratio at 60°/s was 0.50 for dominant and 0.52 for non-dominant, and at 180°/s, it was 0.51 for both limbs, with no significant difference between them. The percentage of subjects with strength asymmetry ranged from 46 to 58%, depending upon muscle group and speed analyzed. ConclusionHuman Immunodeficiency Virus positive subjects present muscle strength asymmetry between lower limbs, assessed through isokinetic dynamometry.