Hip Extensor Research Articles

Short-term effects of a trunk modification program on patellofemoral joint stress in asymptomatic runners

ObjectivesTo evaluate short-term effects of a four-week gait retraining program using visual feedback on trunk flexion angle, patellofemoral joint (PFJ) stress, lower extremity biomechanics and motor skill automaticity. DesignLongitudinal interventional study. SettingsUniversity research laboratory. ParticipantsTwelve asymptomatic recreational runners (seven male and five female). Main outcome measuresTrunk kinematics as well as lower extremity kinematics and kinetics were assessed prior to training at week 1 (baseline) and week 2, 3, 4 and 8 (retention). PFJ stress was computed using a sagittal plane model. A dual-task procedure was performed to examine automaticity. ResultsAt week 8, runners demonstrated 10.1° increase in trunk flexion angle (p < .001) and 17.8% reduction in peak PFJ stress (p < .001) compared to baseline. This is associated with a 16.8% decrease in knee extensor moment and less than 2.5° change in knee flexion angle. Participants also showed 33.3% increase in peak hip extensor moment and small reduction in peak ankle plantar flexor moment. Lastly, runners demonstrated automaticity of the modified skill with a dual-task cost of less than 3%. ConclusionThe gait retraining program is effective to elicit short term changes in trunk position, PFJ stress, and automaticity of the new motor skill.

Effect of Whole-Body Vibration Exercise on Power Profile and Bone Mineral Density in Postmenopausal Women With Osteoporosis: A Randomized Controlled Trial

ObjectiveThe purpose of this study was to investigate the effect of whole-body vibration (WBV) on muscle work and bone mineral density (BMD) of the lumbar vertebrae and femur in postmenopausal women. MethodsForty-three postmenopausal women with low BMD were randomly assigned to WBV and control groups. Both groups received calcium and vitamin D supplementations once daily, while the WBV group additionally received WBV exercise (twice/wk) for 24 successive weeks. Qualisys gait analysis system was used to measure hip power generation by hip extensors (H1S) and flexors (H3S), hip power absorption by hip flexors (H2S), knee power absorption by quadriceps during loading response (K1S) and preswing (K3S), knee power absorption by hamstring (K4S), knee power generation by quadriceps (K2S), ankle power absorption by dorsiflexors (A1S) and plantar flexors (A2S), and ankle power generation by plantar flexors (A3S). Also, dual-energy X-ray absorptiometry was used to measure BMD of the lumbar vertebrae and femur before and after the intervention. ResultsThere were significant increases (P < .05) in the hip muscle work (H1S, H2S, and H3S), knee muscle work (K1S, K2S, K3S, and K4S), ankle muscle work (A1S, A2S, and A3S) during gait, and BMD of the lumbar vertebrae and femur of the WBV group. However, there were no significant changes (P > .05) in the control group. The posttreatment values of the hip, knee, and ankle muscle work and BMD of the WBV group were significantly (P < .05) higher than the posttreatment values of the control group. ConclusionWhole-body vibration training improved the leg muscle work and lumbar and femoral BMD in postmenopausal women with low BMD.

THE RELATIONSHIP BETWEEN CHRONIC LOW BACK PAIN AND PHYSICAL FACTORS IN COLLEGIATE POLE VAULTERS: A CROSS-SECTIONAL STUDY

The low back is the most common injury location in pole vaulters, and low back pain (LBP) can easily become chronic. Therefore, knowing the physical characteristics of athletes experiencing repeated LBP may be beneficial for recovery and injury prevention. The purpose of this study was to describe and analyze the physical characteristics of pole vaulters with chronic LBP. A cross-sectional study. Twenty male pole vaulters participated in this study. A questionnaire was used to garner descriptive and personal data, including personal best performance in the pole vault. Additionally, the following physical characteristics were measured: 1) isokinetic muscle strength of hip and knee flexors and extensors, 2) active/passive range of motion and muscle flexibility in multiple joints and regions, 3) performance on the Functional Movement Screen™ (FMS™) and 4) spinal column alignment. Subjects were categorized using the questionnaire and divided into two groups, one with and one without chronic LBP. The personal best performance and angle on the active straight leg raise test (SLR) were significantly lower and smaller, respectively, in the chronic LBP group than in the non-chronic LBP group. Additionally, the difference between the passive SLR angle and active SLR angle (ΔSLR) was significantly larger in the chronic LBP group than in the non-chronic LBP group. Those with chronic LBP had were more likely to have a FMS™ composite score ≤14. The active SLR angle and ΔSLR were significantly smaller and larger, respectively, in the chronic LBP group than in the non-chronic LBP group. This may be because of the poor stability of trunk or incompetence of the kinetic chain required for raising the lower limbs. The chronic LBP group had a significantly higher probability of having an FMS™ composite score of ≤14. it may be important to examine the active straight leg raise (vs. passive only), and fundamental movements as screened by the FMS ™ in pole vaulters. 2b.

Physiotherapy Management for Patients with Dextra Knee Osteoarthritis at RSJ Prof. Hospital. Dr. Soerojo Magelang

Background: Osteoarthritis Knee Dextra is a degenerative joint disease in the form of damage to joint cartilage that develops slowly, the cause is unknown and the joint disease is more common than other joint diseases. Objective: To determine the implementation of Physiotherapy in reducing pain, increasing joint range of motion and increasing muscle strength in cases of Dextra Knee Osteoarthritis using Infra-Red (IR) Transcutaneous Electrical Nerve Stimulation (TENS) and exercise therapy (TL) modalities. Results: After undergoing therapy 6 times, pain assessment results were obtained for T1 silent pain: 1 becomes T6 : 1, tenderness T1 : 4 becomes T6 : 2, movement pain T1 : 4 becomes T6 : 3, increased joint range of motion S: T1 : S 0 – 0 – 125 becomes T6 : S 0 – 0 – 135 , increase in right knee muscle strength, hip flexor T1: 4- to T6: 4+, hip extensor T1: 4- becomes T6 : 4+. Conclusion: Infra-Red (IR) can reduce pain in the right knee in cases of Osteoarthritis Knee Dextra, exercise therapy Transcutaneous Electrical Nerve Stimulation (TENS) can reduce pain in the right knee in cases of Osteoarthritis Knee Dextra (TL), can increase the range of motion of the right knee joint in cases of Osteoarthritis Knee Dextra and can increase muscle strength in cases of Osteoarthritis Knee Dextra.

Isokinetic Force and Work Capacity After Long-Duration Space Station Mir and Short-Term International Space Station Missions.

INTRODUCTION: The effects of long-duration (213.0 ± 30.5 d) stays aboard the orbital station Mir and short-term (∼10 d) spaceflights aboard the International Space Station (ISS) on the joint torques of various muscles and work capacity of knee extensors were studied in male cosmonauts.METHODS: Joint torque and muscle endurance testing was performed 30 d before and 3-5 d after a spaceflight, using a LIDO® Multi-Joint Isokinetic Rehabilitation System (USA).RESULTS: Greater postflight changes in maximal joint torque were observed for back, knee, and ankle extensors compared with flexors, and the difference was especially clearly seen after long-term spaceflights. The decrease in maximal joint torque of hip extensors substantially varied, being the greatest in voluntary concentric movements in a low-velocity high-force mode at angular velocities of 30 and 60° · s-1 (by 16 and 13%, respectively) and the lowest in high-velocity modes at velocities of 120 and 180° · s-1 (by 9 and 11%, respectively). Muscle work capacity was inferred from the gradient of declining muscle force produced in a series of rhythmic voluntary concentric movements and was found to decrease after both short- and long-term spaceflights. The area under the muscle contraction curve decreased to a greater extent and in all regions of the curve after long-term spaceflights. The fatigue index averaged 0.90 ± 0.03 at baseline and remained much the same, 0.90 ± 0.04, after a short-term spaceflight. However, after a long-duration spaceflight, the fatigue index increased 14.1%.DISCUSSION: The finding that the contractile functions and work capacity of muscles decrease more after long-term than after short-term spaceflights in spite of the physical training program of a certain type gave grounds to assume that physical training employed in long-term spaceflights were insufficient to simulate the daily mechanical load that the cosmonauts had before a spaceflight.Koryak YA. Isokinetic force and work capacity after long-duration Space Station Mir and short-term International Space Station missions. Aerosp Med Hum Perform. 2020; 91(5):422-431.

Impaired Knee Muscle Capacity Is Correlated With Impaired Sagittal Kinematics During Jump Landing in Women With Patellofemoral Pain.

Nunes, GS, Barton, CJ, and Serrão, FV. Impaired knee muscle capacity is correlated with impaired sagittal kinematics during jump landing in women with patellofemoral pain. J Strength Cond Res 36(5): 1264-1270, 2022-Knee and hip muscle capacity is impaired in women with patellofemoral pain (PFP), but little is known about the rate of force development (RFD) at the knee. Impaired muscle capacity may contribute to reduced sagittal plane movement at the knee and hip during jump landing in women with PFP. This study aimed to (a) compare knee extensor muscle capacity (including RFD), and hip abductor and extensor muscle capacity between women with and without PFP; and (b) evaluate the relationship between hip/knee muscle capacity and sagittal kinematics during single-legged drop jump landing in women with PFP. Fifty-two physically active women (26 with PFP and 26 controls) participated. Rate of force development (in %/ms), isometric, concentric, and eccentric torque (in N·m·kg-1 × 100) were evaluated using isokinetic dynamometry, and knee and hip kinematics were evaluated using three-dimensional motion capture. Compared with the control group (CG), the PFP group (PFPG) presented lower isometric (12%, PFPG = 217.2 ± 46.0; CG = 246.5 ± 38.8; p = 0.02), concentric (21%, PFPG = 133.0 ± 42.6; CG = 169.2 ± 28.8; p < 0.01), and eccentric (17%, PFPG = 172.9 ± 56.7; CG = 208.4 ± 59.4; p = 0.03) knee extension torque; lower RFD until 30% (30%, PFPG = 0.57 ± 0.27; CG = 0.83 ± 0.37; p < 0.01) and 60% (31%, PFPG = 0.47 ± 0.24; CG = 0.67 ± 0.33; p = 0.01) of maximal isometric torque; and lower concentric hip abduction (13%, PFPG = 94.7 ± 19.1; CG = 108.4 ± 17.5; p = 0.01) and extension (17%, PFPG = 134.4 ± 34.3; CG = 162.6 ± 38.0; p < 0.01) torque. Significant correlations between reduced RFD for knee extension and reduced sagittal plane knee/hip range of motion during landing were identified (r = 0.39-0.49). In conclusion, women with PFP have impaired knee extensor isometric and dynamic strength, and RFD. Impaired knee extensor RFD is associated with a stiffer landing strategy (reduced movement).

Effect of concentric vs. eccentric variant of lower limbs plyometric training on biomechanical and biochemical parameters

The study aimed to compare the effectiveness of two variants of 4 weeks plyometric training involving jumping up (dominance of concentric muscle work, UP) and jumping down (dominance of eccentric muscle work, DOWN) the stairs. Twenty-six young men were divided into two groups: UP (n = 13) and DOWN (n = 13). Control measurements of the muscle torques, vertical jumps, and creatine kinase (CK) activity were performed every week. The training resulted in significant changes (p < 0.001) in the muscle torques of the hip extensors (Δ ≈ 20% in both groups) and plantar flexors (ΔUP = 25%, ΔDOWN = 33%), but in the muscle torques of the knee extensors a significant (p < 0.001) increase occurred only in the group jumping down the stairs (ΔDOWN ≈ 15%). Furthermore, a significant increase (p < 0.001) of the height of the vertical jump was noted in the study only in the group jumping down (ΔDOWN = 8%). Training with the dominance of eccentric work caused greater weekly changes in the activity of creatine kinase in the plasma. The study confirmed that the exercise involving jumping on the stairs is viable in plyometric training, as it is an effective means of training the strength of the muscles of the lower limbs and vertical jump height, with a greater share assigned to jumping down consecutive steps.

New insights into lumbar flexion tests based on inverse and direct kinematic musculoskeletal modeling

Measurement of maximal lumbar flexion is considered to be a crucial element in the assessment of lumbar spine mechanics in situations as diverse as physiotherapy, orthopaedics, ergonomics, sport or aging. However, currently, there is no consensus on a reference test.This study aims to characterise five maximal lumbar flexion tests (four classical tests and a new, specifically-developed test designed to constrain pelvic retroversion) based on a three-dimensional, participant-specific musculoskeletal model.Twenty-six male and female participants performed the five tests. Movements were modelled in OpenSim to estimate change in length in lumbar, hamstring and gluteus muscles, together with lumbar flexion and pelvic tilt. These so-called “inverse” kinematic results were compared using a two-way ANOVA (sex×test). In a second step, lumbar muscle change in length was computed using a direct kinematic method.Lumbar flexion and lumbar muscle change in length were found to be greater when participants were in seated postures, with little pelvic retroversion. Female participants were observed to have less lumbar flexion than male participants (77±14° and 91±12°, respectively). Hip extensor muscles (hamstrings and gluteus) were fully stretched during each of the five tests. Our results highlight the specific roles of hamstrings, gluteus and lumbar muscles into reaching maximal lumbar flexion.Coupling inverse and direct kinematic methods proved to be a useful tool to enhance our knowledge of lumbar tests. Our findings help to characterise the role of the muscles involved in lumbar flexion, and we propose some recommendations for improving and standardising these tests.

A short communication on the relationships betweenthe barbell hip thrust and change-of-direction speed in college-aged women

Objectives: To determine the relationships between the one-repetition maximum barbell hip thrust (1RM BHT) with change-of direction (COD) speed measured by the 505 in college-aged, recreationally-trained women. Design and Methods: Twenty college-aged women completed two testing sessions. In session 1, participants completed a 1RM BHT to measure absolute and relative lower-body strength, with an emphasis on the hip extensors. In Session 2, participants completed four trials (two per leg) of the 505 COD speed test. The mean of the two trials per leg was analyzed; the leg with the fastest 505 time was termed the dominant leg. Pearson’s correlations (p < 0.05) and regression scatter plots were used to calculate relationships between absolute and relative BHT strength and the 505 measured from the dominant and non-dominant leg. Results: There were significant relationships between relative strength measured by the 1RM BHT and the 505 from the domi nant (r = -0.473, p = 0.035) and non-dominant (r = -0.452, p = 0.046) legs, with ~21-22% explained variance. There were no significant relationships between absolute BHT strength and the 505 (r = -0.291 to -0.309, p = 0.184-0.213). Conclusions: Relative maximal hip extensor strength could be an important contributor to faster COD as measured by the 505 in college-aged, recreationally-trained females. The correlation strength and explained variance indicates that there are likely other factors beyond relative strength measured by the BHT that would contribute to a faster 505. Nonetheless, the results of this short communication provide support for developing hip extensor strength in females, as this could benefit COD speed in actions similar to those in the 505.

RECOVERY FOLLOWING ACL RECONSTRUCTION IN MALE VS. FEMALE ADOLESCENTS: A MATCHED, SEX-BASED COHORT ANALYSIS OF 543 PATIENTS

Background:The subject of sex-based differences in postoperative recovery after anterior cruciate ligament reconstruction (ACLR) between males and females has been incompletely investigated, with no published comparative analyses specifically in adolescent sub-populations, which represent those most affected by ACL injury.Purpose/Hypothesis:To compare the 6-month postoperative functional recovery following ACLR between adolescent males and females. We hypothesized that significant differences in postoperative strength, dynamic balance, and functional hop test performance would be seen between the sexes.Methods:All adolescent athletes with closed or closing growth plates who underwent ACLR at a single institution between May 2014 and May 2018 and who underwent functional return-to-sport (RTS) testing between 5-8 months post-operatively were considered for inclusion in this IRB-approved study. To control for potential graft-based rehabilitation differences or donor site morbidity as confounders, only primary ACLRs performed with hamstring autograft were included. Exclusions were previous knee surgery (contralateral or ipsilateral knee), concomitant injury other than meniscus tear, allograft supplementation, and incomplete medical records. Limb Symmetry Indexes (LSI) for strength (quadriceps, hamstrings, hip abductors, hip extensors), dynamic Y-balance (anterior, posterolateral and posteromedial distance), and functional hopping (single hop, triple hop, and cross-over hop for distance, and 6-meter timed hop) were compared between groups. To account for differences in physical characteristics between the sexes, one-way between group multivariate analysis of covariance (MANCOVA) was used, with p = 0.05.Results:Amongst 543 subjects (211 male, 332 female), there was no significant difference in age, BMI, incidence of concomitant meniscal pathology, use of regional anesthesia blocks, or time to functional testing between cohorts. However, height and weight differences were incorporated in the MANCOVA model. Females demonstrated a statistically significant greater deficit in quadriceps strength LSI compared to males (Table 1). Both males and females demonstrated 33% hamstring strength deficits, with no statistically significant sex-based differences in dynamic balance or functional hop testing, though single leg hop deficits were less severe in males, which trended towards significance (-4% vs. -8%, p=0.062).Conclusion:Females demonstrated greater quadriceps strength deficits than males at 6 months post-ACLR with hamstring autograft, which may translate into greater functional hop testing deficits. Severe hamstring strength deficits persist in both males and females at this time point, underscoring the potential importance of mitigating risk of ACL re-tear by delaying return to play until a later time point with more normalized, symmetric, performance-based metrics.Table 1.Strength, balance, and functional hop testing deficits in quadriceps, hamstrings, hip abductors, and hip extensorsGroupsMales(N = 211)Females(N = 332)P-valuesQuadriceps Strength: Uninvolved limb4.57±1.2 (4.40, 4.73)4.27±1.0 (4.16, 4.39)ACLR limb4.61±1.2 (4.44, 4.78)4.11±1.1 (4.00, 4.23)Deficits (LSI%)+3.4 (+0.5, +6.3)-2.3 (-5.0, +0.4)0.011Hamstrings Strength: Uninvolved limb2.31±0.7 (2.21, 2.41)2.17±0.6 (2.10, 2.24)ACLR limb1.48±0.6 (1.40, 1.57)1.40±0.6 (1.33, 1.46) Deficits (LSI%)-33.0 (-38.0,-28.0)-33.2 (-37.9, -28.6)0.943Hip abductor Strength: Uninvolved limb1.90±0.6 (1.81, 2.00)1.85±0.7 (1.76, 1.93) ACLR limb1.94±0.6 (1.86, 2.03)1.92±0.8 (1.83, 2.01)Deficits (LSI%)+3.8 (-0.8, +8.4)+6.2 (+1.9, +10.5)0.490Hip extensor Strength: Uninvolved limb3.36±1.2 (3.19, 3.53)3.25±1.0 (3.14, 3.36) ACLR limb3.41±1.3 (3.23, 3.59)3.27±1.1 (3.15, 3.38) Deficits (LSI%)+4.2 (-1.5, +9.9)+2.2 (-3.1, +7.5)0.637Anterior Reach: Uninvolved limb61.9±7.8 (60.8, 63.0)59.5±6.5 (58.8, 60.2) ACLR limb60.3±7.5 (59.3, 61.3)57.9±6.3 (57.2, 58.6) Deficits-0.7 (-3.1, +1.6)-0.9 (-3.1, +1.2)0.905Posteromedial Reach: Uninvolved limb101.6±11.2 (100.1, 103.1)94.2±8.8 (93.2, 95.2) ACLR limb101.2±11.5 (99.6, 102.7)92.9±10.6 (91.8, 94.1) Deficits+0.5 (-0.1, +0.2)+0.1 (-1.3, +1.5)0.718Posterolateral Reach: Uninvolved limb96.5±11.3 (95.0, 98.0)91.1±8.7 (90.1, 92.0) ACLR limb96.3±11.4 (94.7, 97.8)90.3±9.4 (89.3, 91.3) Deficits+0.8 (-1.1, +2.7)-0.5 (-2.3, +1.2)0.334Composite Score: Uninvolved limb95.5±8.7 (94.2, 96.9)96.6±7.3 (95.6, 97.5) ACLR limb94.8±8.8 (93.4, 96.1)95.6±8.0 (94.5, 96.6) Deficits+0.3 (-0.9, +1.4)-0.6 (-1.7, +0.5)0.319Single Hop: Uninvolved limb1.29±0.27 (1.25, 1.34)1.07±0.21 (1.04, 1.10) ACLR limb1.22±0.28 (1.18, 1.27)0.97±0.23 (0.94, 1.00) Deficits-4.0 (-6.9, -1.0)-8.1 (-10.9, -6.9)0.062Triple Hops: Uninvolved limb4.40±0.77 (4.27, 4.53)3.55±0.58 (3.47, 3.63) ACLR limb3.13±1.21 (2.92, 3.33)2.84±0.68 (2.75, 2.94) Deficits-27.0 (-32.9, -21.1)-20.0 (-25.5, -14.5)0.117Cross-over Hops: Uninvolved limb3.82±0.84 (3.68, 3.97)3.04±0.60 (2.95, 3.13) ACLR limb3.62±0.80 (3.48, 3.76)2.85±0.61 (2.75, 2.94) Deficits-4.5 (-7.0, -2.0)-5.8 (-8.1, -3.5)0.5016 meter Timed Hop: Uninvolved limb2.12±0.47 (2.04, 2.20)2.45±0.44 (2.39, 2.51) ACLR limb2.21±0.49 (2.12, 2.29)2.57±0.50 (2.50, 2.64) Deficits-1.7 (-3.9, +0.4)-3.6 (-5.7, -1.6)0.244Values are mean ± standard deviation with 95% confidence interval.* p < 0.05.Strength was measured in newton/kg.LSI = Limb Symmetry IndexDynamic balance reach was measured in centimeters.Single, triple, and crossover hop distance was measured in meters. 6 meter timed hop was measured in seconds.

In individuals with patellofemoral osteoarthritis, function but not strength was lower compared to matched controls

Purpose: In individuals with patellofemoral (PF) osteoarthritis (OA), it is currently unclear to what extent functional performance and strength are impaired. Lack of matching of PFOA and controls on body mass index (BMI) or physical activity levels make prior cross-sectional studies difficult to interpret. Limited evidence suggests individuals with PFOA may perform worse on a timed up and go test, and they may have lower hip abductor strength, but not lower hip extensor strength, than asymptomatic controls.

Ankle, knee, and hip contribution to ambulatory support moment and MRI-detected structural worsening 2 years later in knee OA

Purpose: During walking, extensor moments generated at the ankle, knee and hip are responsible for vertically supporting the body and advancing the body center of mass forward. Support moment (SM) is the sum of ankle, knee, and hip extensor moments when the limb accepts full body weight during gait (Figure 1). To maintain adequate SM, lower moment at one joint may be compensated by greater moment at the other. Cross-sectional studies have shown that persons with knee OA, compared to healthy controls, have increased ankle and decreased knee contribution to the total SM during walking.

Different Lower-Limb Setup Positions Do Not Consistently Change Backstroke Start Time to 10 m.

Backstroke starts involve the athlete starting from a flexed position with their feet against the pool wall and then extending their ankles, knees, hips and back to push off; however, swimmers can start in different positions. The purpose of this study was to evaluate the performance impact of different knee extension angles in the setup position for a backstroke start. Ten backstroke swimmers completed maximum-effort starts in each of two setup positions: one with the knees maximally flexed, and one with the knees less flexed. The start handles and touchpad were instrumented with multi-axial force sensors. Activity of major hip and knee extensors was measured using surface electromyography. Body position in the sagittal plane was recorded using high-speed cameras. There was no overall difference in time to 10 m between the two conditions (p = 0.36, dz = 0.12), but some participants showed differences as large as 0.12 s in time to 10 m between start conditions. We observed that starts performed from a setup position with less knee flexion had an average 0.07 m greater head entry distance (p = 0.07, dz = 0.53), while starts from a setup position with maximal knee flexion had an average 0.2 m/s greater takeoff velocity (p = 0.02, dz = 0.78). Both head entry distance and takeoff velocity are related to start performance, suggesting each position may optimize different aspects of the backstroke start. Coaches should assess athletes individually to determine which position is optimal.

Muscular Activity Modulation During Post-operative Walking With Hybrid Assistive Limb (HAL) in a Patient With Thoracic Myelopathy Due to Ossification of Posterior Longitudinal Ligament: A Case Report.

Disorders of the central nervous system sometimes cause severe sensory motor paralysis accompanied by gait impairment. Recently, there are several reports on the effectiveness of robot-assisted gait training for patients experiencing these issues. The purpose of this case report was to assess the neuromechanical effect of a wearable robot suit HAL (Hybrid Assistive Limb) during post-operative gait training in a patient with gait impairment due to compressive myelopathy caused by ossification of the posterior longitudinal ligament (OPLL). For this purpose, we compared lower limb muscular activities while the patient was walking with and without the robot through a course of treatment sessions by (i) gait phase-dependent muscle usage analysis, (ii) muscle synergy analysis, and (iii) muscle network analysis. The results show (i) enhanced activity of the extensor muscles for weight-bearing in the initial sessions by using HAL and reduced knee extensor and increased hip extensor activations for achieving larger steps and faster gait in the later sessions; (ii) involvement of a greater number of synergies during walking with HAL than without HAL; and (iii) modulated muscle network property during walking with HAL remaining until the next HAL session. The patient's gait was improved after completing HAL sessions, acquiring close to normal joint profile with greater range of joint movement, faster walking speed, and larger step length. We discuss that the muscular activity modulation during walking with HAL suggests altered control of the muscles by the central nervous system during post-operative walking. Activity-dependent sensorimotor augmentation by HAL is discussed in the context of recovery of gait control by the central nervous system. The relationship between the altered control and the achieved gait recovery requires further investigation.

Effects of age, speed, and step length on lower extremity net joint moments and powers during walking.

During walking older adults' gait is slower, they take shorter steps, and rely less on ankle and more on knee and hip joint moments and powers compared to young adults. Previous studies have suggested that walking speed and step length are confounds that affect joint moments and powers. Our purpose was to examine the effects of walking speed and step length manipulation on net joint moments and powers in young and older adults. Sixteen young and 18 older adults completed walking trials at three speeds under three step length conditions as marker position and force platform data were captured synchronously. Net joint moments were quantified using inverse dynamics and were subsequently used to compute net joint powers. Average extensor moments at each joint during the stance phase were then computed. Older adults displayed greater knee extensor moment compared to young adults. Older adults showed trends (p<.10) of having lower ankle and higher hip moments, but these differences were not statistically significant. Average ankle, knee, and hip extensor moments increased with speed and step length. At the fast speed, older compared to young adults generated lower average ankle power (p=.003) and showed a trend (p=.056) of exerting less average moment at the ankle joint. Age-associated distal-to-proximal redistribution of net joint moments was diminished and not statistically significant when the confounding effects of walking speed and relative step length were controlled. These findings imply that age-related distal-to-proximal redistribution of joint moments may influence the different speeds and step lengths chosen by young and older adults.

The influence of hip biomechanics on patellofemoral pain: Bibliographic Review

Patellofemoral pain can occur among young people even older sedentary ones, being more prevalent in young people. The characteristic symptoms are pain located in the anterior retropatellar and / or peripatellar region of the knee, presented during activities such as squatting, walking up / down trails, jumping and running. Muscle weakness in joints like the knee and the hip, has been shown to be symptomatic and developmental dysfunction modulators. The present literature aims to investigate the influence of hip biomechanics on symptoms of patellofemoral pain. This is a bibliographic review, including articles written in the English language, in the electronic databases LILACS, PubMed, SciELO and PEDro. A survey started in January 2020 and ended in February. As variables of interest, they were noted by one of the authors. In total, 15 articles were selected, excluding 6 items, including 9 in this review. The types of study were: Systematic Review (2), Meta-analysis (1), Cross-sectional descriptive study (1), Randomized Clinical Trial (4), Case-control study (1), with the total of final samples included in the sample 14 70 female and male individuals. Selected studies revealed that hip biomechanics directly influences the development of patellofemoral pain symptoms. The literature review shows that there is a direct relationship between femoral pain and hip biomechanics, which is excess adduction, internal rotation of the hip, muscle weakness of external rotators, hip extensors and abductors, enhancing the chance of showing the characteristic characters of the hip dysfunction.

Is There an Optimal Recovery Step Landing Zone Against Slip-Induced Backward Falls During Walking?

Recovery stepping in response to forward slips has the potential to not only rebuild the base of support to prevent backward falling, but also provide extra limb support to prevent downward falling. Hence, recovery stepping is often necessary for fall prevention following an unexpected slip. However, less is known about whether recovery foot placement could affect the likelihood of recovery following a slip. The purpose of this study was to determine whether there is an optimal recovery landing zone within which older adults have a higher likelihood of recovery. 195 participants experienced a novel, unannounced forward slip while walking on a 7-m walkway. The center of mass (COM) stability (computed from its position and velocity), vertical limb support (computed from change in hip kinematics), and recovery limb joint moments (computedfrom joint kinematics and ground reaction force) in the sagittal plane were analyzed. The results showed that a longer distance between recovery foot landing position and the projected COM position at recovery foot touchdown (relative recovery step placement) was conducive to stability improvement but adverse to limb support enhancement, and vice versa for a shorter distance. Relative recovery step placement could predict the recovery likelihood with an accuracy of 67.3%, and the recovery rate was greater than 50% when the distance between recovery foot and COM is less than 0.3 × foot length. This study also found more posterior stepping could be attributed to insufficient ankle plantar flexor and hip flexor moments in the pre-swing phase, while more anterior stepping was induced by insufficient hip and knee extensor moments in the following swing phase.

Gait rehabilitation after stroke: review of the evidence of predictors, clinical outcomes and timing for interventions.

The recovery of walking capacity is one of the main aims in stroke rehabilitation. Being able to predict if and when a patient is going to walk after stroke is of major interest in terms of management of the patients and their family's expectations and in terms of discharge destination and timing previsions. This article reviews the recent literature regarding the predictive factors for gait recovery and the best recommendations in terms of gait rehabilitation in stroke patients. Trunk control and lower limb motor control (e.g. hip extensor muscle force) seem to be the best predictors of gait recovery as shown by the TWIST algorithm, which is a simple tool that can be applied in clinical practice at 1week post-stroke. In terms of walking performance, the 6-min walking test is the best predictor of community ambulation. Various techniques are available for gait rehabilitation, including treadmill training with or without body weight support, robotic-assisted therapy, virtual reality, circuit class training and self-rehabilitation programmes. These techniques should be applied at specific timing during post-stroke rehabilitation, according to patient's functional status.

Associations of lower limb joint asymmetry with fatigue and disability in people with multiple sclerosis

BackgroundAn early symptom of multiple sclerosis is unilateral weakness, particularly in the lower limbs, which is associated with strength asymmetries. The purpose of this exploratory study was to examine strength asymmetries at the hip, knee, and ankle joints, and to investigate the associations between lower limb strength asymmetries and self-reported fatigue severity and disability in people with multiple sclerosis. MethodsSixteen mildly-disabled people with multiple sclerosis (females = 9) completed isokinetic maximal voluntary contractions of the hip extensors and flexors, knee extensors and flexors, and ankle plantar flexors and dorsiflexors. Asymmetry indices between the strength of the more- and less-affected lower limbs at each muscle group and the percent agreement between self-reported and objectively-determined more-affected lower limb were calculated. Patient Determined Diseases Steps and Fatigue Severity Scale were also completed. FindingsAll joints showed asymmetry (asymmetry indices ≥10%). Knee flexors (mean [SD]; 49.9 [37.8%]) and ankle plantar flexors (46.6 [35.5%]) had the largest asymmetry indices. Hip and knee extensors had the lowest asymmetry indices (21.1 [18.1%] and 30.1 [24.7%], respectively) and the highest agreement between self-reported and objectively-determined more-affected lower limb (93.3 and 93.8, respectively). The hip extensor asymmetry index was correlated with the Fatigue Severity Scale (r = 0.542, p = 0.037). InterpretationFor the assessment of strength asymmetries in people with multiple sclerosis, it is suggested to 1) include measures of hip, knee, and ankle strength asymmetries, 2) include subjective perceptions and objective measures of strength asymmetries concurrently, and 3) to include measures of sensory function (proprioception).

Acute Effects of Intermittent and Continuous Static Stretching on Hip Flexion Angle in Athletes with Varying Flexibility Training Background.

Τhis study examined changes in hip joint flexion angle after an intermittent or a continuous static stretching protocol of equal total duration. Twenty-seven female subjects aged 19.9 ± 3.0 years (14 artistic and rhythmic gymnasts and 13 team sports athletes), performed 3 min of intermittent (6 × 30 s with 30 s rest) or continuous static stretching (3 min) of the hip extensors, with an intensity of 80–90 on a 100-point visual analogue scale. The order of stretching was randomized and counterbalanced, and each subject performed both conditions. Hip flexion angle was measured with the straight leg raise test for both legs after warm-up and immediately after stretching. Both stretching types equally increased hip flexion angle by ~6% (continuous: 140.9° ± 20.4° to 148.6° ± 18.8°, p = 0.047; intermittent: 141.8° ± 20.3° to 150.0° ± 18.8°, p = 0.029) in artistic and rhythmic gymnasts. In contrast, in team sports athletes, only intermittent stretching increased hip flexion angle by 13% (from 91.0° ± 7.2° to 102.4° ± 14.5°, p = 0.001), while continuous stretching did not affect hip angle (from 92.4° ± 6.9° vs. 93.1° ± 9.2°, p = 0.99). The different effect of intermittent vs. continuous stretching on hip flexion between gymnasts and team sports athletes suggests that responses to static stretching are dependent on stretching mode and participants training experience.