Hip Extensor Research Articles

Computational Modeling of Gluteus Medius Muscle Moment Arm in Caviomorph Rodents Reveals Ecomorphological Specializations.

Vertebrate musculoskeletal locomotion is realized through lever-arm systems. The instantaneous muscle moment arm (IMMA), which is expected to be under selective pressure and thus of interest for ecomorphological studies, is a key aspect of these systems. The IMMA changes with joint motion. It’s length change is technically difficult to acquire and has not been compared in a larger phylogenetic ecomorphological framework, yet. Usually, proxies such as osteological in-levers are used instead. We used 18 species of the ecologically diverse clade of caviomorph rodents to test whether its diversity is reflected in the IMMA of the hip extensor M. gluteus medius. A large IMMA is beneficial for torque generation; a small IMMA facilitates fast joint excursion. We expected large IMMAs in scansorial species, small IMMAs in fossorial species, and somewhat intermediate IMMAs in cursorial species, depending on the relative importance of acceleration and joint angular velocity. We modeled the IMMA over the entire range of possible hip extensions and applied macroevolutionary model comparison to selected joint poses. We also obtained the osteological in-lever of the M. gluteus medius to compare it to the IMMA. At little hip extension, the IMMA was largest on average in scansorial species, while the other two lifestyles were similar. We interpret this as an emphasized need for increased hip joint torque when climbing on inclines, especially in a crouched posture. Cursorial species might benefit from fast joint excursion, but their similarity with the fossorial species is difficult to interpret and could hint at ecological similarities. At larger extension angles, cursorial species displayed the second-largest IMMAs after scansorial species. The larger IMMA optimum results in powerful hip extension which coincides with forward acceleration at late stance beneficial for climbing, jumping, and escaping predators. This might be less relevant for a fossorial lifestyle. The results of the in-lever only matched the IMMA results of larger hip extension angles, suggesting that the modeling of the IMMA provides more nuanced insights into adaptations of musculoskeletal lever-arm systems than this osteological proxy.

The effects of foot orthosis and low-dye tape on lower limb joint angles and moments during running in individuals with pes planus

BackgroundPes Planus or Flat feet is one of the most common lower limb abnormalities. When runners with this abnormality participate in recreational running, interventional therapies could help in pain alleviation and enhance performance. To determine the most effective treatment, however, a biomechanical examination of the effects of each treatment modality is required. Research questionThe aim of the present study was to investigate the effects of Foot Orthoses (FOs) and Low-Dye Tape (LDT) on lower limb joint angles and moments during running in individuals with pes planus. Methodskinematic and kinetic data of 20 young people with pes planus were measured during running in three conditions: (1) SHOD (2) with shoes and FOs (3) with shoes and LDT. One-way repeated measure ANOVA was used to investigate the impacts of the FOs and LDT on the lower limb joint angles and moments throughout the stance phase of the running cycle. ResultsThe results showed that FOs reduced ankle eversion compared to SHOD and LDT (P < 0.001) and decreased the dorsiflexion angle (P = 0.005) and the plantarflexor moment compared to the SHOD (P < 0.001). FOs increased knee adduction angle (P = 0.021) and knee external rotator moment (P < 0.001) compared to both conditions and increased knee extensor and abductor moments compared to SHOD (P < 0.001). At the hip joint, FOs only increased hip external rotation compared with the LDT condition (P = 0.031); and LDT increased hip extensor moment compared to SHOD and FOs (P = 0.037) and also increased hip adduction angle compared to SHOD (P = 0.037). SignificanceFOs with a medial wedge appears to increase the external knee adduction moment and knee adduction angles, which are risk factors for the development and progression of knee osteoarthritis. Further, usage of FOs seems to reduce the ankle joint role in propulsion as it impacts the ankle sagittal angles and moments.

Electromyographic differences of the gluteus maximus, gluteus medius, biceps femoris, and vastus lateralis between the barbell hip thrust and barbell glute bridge

ABSTRACT Hip extensor muscles are critical to sport performance as events requiring sprinting and forceful landings are highly dependent on these muscles. Despite biomechanical differences between the barbell hip thrust (BHT) and the barbell glute bridge (BGB), both are biomechanically efficient ways to load this musculature for training purposes. Research investigating the differences in muscular activity between the BHT and BGB has yet been conducted. The aim of this study was to investigate, through surface electromyography, if one exercise is more optimal than the other in producing greater muscle activation for specific hip extensor muscles. Ten male participants completed a two-part study protocol. Results revealed the BHT elicited significantly greater muscle activity within the vastus lateralis for peak and mean outcomes; however, the BGB elicited significantly greater muscle activity in the upper and lower gluteus maximus for peak and mean outcomes and mean outcome in the gluteus medius. Current findings suggest, the BGB is, at minimum, a superior substitute for the BHT for eliciting a larger magnitude of activity in the gluteus maximus. Future studies between the two exercises are warranted to discern which produces greater hypertrophy and whether adaption of the BHT or BGB transfers more optimally to sport performance.

Effect of Alternative Therapeutic Exercise on the Older Adults – A Pilot Study

IntroductionRegular physical activity is essential for sedentary older adults (aged 65 years and above) who are at the risk for multiple comorbidities. By performing physical activity, older adults can maintain or improve their physical function and mobility that may help them to be independent for a long time and delay the occurrence of disability in the future.ObjectiveTo assess the effect of the eccentric exercises prior to tai chi and yoga performance in the activities of daily living (ADL), balance and gait, and muscle strength in older adults.MethodsNine sedentary independent older adults aged between 60 and 90 were recruited. The study included the medical pre‐protocol assessment, the eccentric (ECC) exercise protocol with and without tai chi and yoga, subjective (Health activities of daily living (ADL) difficulty scale), and objective (Tinetti balance and gait, muscle strength) assessments, and medical post‐protocol assessment.ResultsThe functional limitations, Tinetti balance and gait score, manual muscle strength testing, and active range of motion (AROM) were improved in the medical post‐protocol assessment. Muscle strength showed statistically significant differences on the shoulder abductors (P=0.035), the elbow extensors (P=0.046), the hip abductors (P=0.028) and the hip extensors (P=0.03).ConclusionsOur findings show low perceived exercises (ECC) prior to tai chi and yoga training are well suited to the sedentary independent older adults with chronic conditions.

Energetic costs of hindlimb‐dominated locomotion in sifakas (Propithecus verreauxi)

Human bipedal locomotion is unique, requiring a suite of musculoskeletal adaptations that were acquired gradually throughout hominin evolution. For example, lordotic lumbar spines move the center of mass over the hip joint and resists axial compression, short, laterally‐oriented iliac blades increase the leverage of the hip extensors and abductors, and the adducted hallux facilitates weight transfer during a propulsive toe‐off. Sifakas and other primates occasionally move bipedally in the wild, especially in terrestrial settings, but because they lack specialized anatomy, bipedal locomotion should be less efficient. In this study we test the hypothesis that energy costs differ among sifaka locomotor modes and predict that terrestrial bipedal locomotion is associated with greater energy expenditure than their more habitual mode of arboreal locomotion, vertical clinging and leaping. Bipedal (n=77) and vertical clinging and leaping (n=74) gait cycles were filmed in nine sifakas at the Duke Lemur Center. Locomotor data (stride length, peak body height of the cycle, and velocity) were measured from these videos using ImageJ and used to calculate energy expenditure using published equations. Linear mixed models were used to statistically test the differences in energy expenditure between locomotor modes while accounting for the effects of velocity and repeatedly measuring the same individuals. Results demonstrate that the cost of bipedalism is significantly greater than that of vertical clinging and leaping (p&lt;0.0001). This result supports the idea that the locomotor adaptations in the hominin musculoskeletal system reduce the cost of locomoting bipedally. Furthermore, because sifakas rely on bipedal locomotion in terrestrial settings, these results have conservation implications for understanding the energetic demands of sifaka locomotion in deforested habitats.

Assessing gait, balance, and muscle strength among breast cancer survivors with chemotherapy-induced peripheral neuropathy (CIPN): study protocol for a randomized controlled clinical trial

BackgroundChemotherapy-induced peripheral neuropathy (CIPN) is a common and understudied consequence of taxane chemotherapy for breast cancer treatment. CIPN symptoms include numbness combined with tingling sensations, persistent shooting, stabbing, or burning pain even in the absence of painful stimuli, lower extremity muscle weakness, and impaired balance. CIPN symptoms often persist for a long time after completion of chemotherapy, causing significant loss of functional abilities and increased risk of falls. Persistent CIPN caused by taxanes represents a therapeutic challenge due to the limited treatment options. Resistance exercise has shown promising results; however, the effect of exercise on CIPN remains understudied. This study aims to assess the effects of exercise on gait, balance, and lower extremity muscle strength after a 16-week home-based exercise program compared to an educational attention control condition.MethodsA sample of 312 women who completed taxane-based chemotherapy for breast cancer and have symptomatic neuropathy is recruited from a community-dwelling sample. Participants are randomized to either a 16-week Home-Based Physical Activity Intervention or an Educational Attention control group. The home-based intervention protocol consists of targeted lower extremity stretches, followed by 10 min each of gait/balance and 10 min of resistive training accessed by hyperlink or DVD. An Exercise Diary records quantitative exercise data. The gait assessment includes temporospatial parameters and lower extremity joint angles using APDM motion sensors. Participants’ balance is assessed using the Sensory Organization Test (SOT) performed using a NeuroCom Balance Master. Isometric strength of hip, knee, and ankle flexor and extensor muscles is assessed using an isokinetic dynamometer, Biodex BX Advantage. In addition, we assess neuropathy symptoms using the FACT-Taxane Additional Concerns Subscale and nerve conduction velocity of the sural and peroneal nerve action potentials. Outcomes are assessed at baseline (prior to randomization) and 16 weeks.DiscussionThere are currently no evidence-based interventions that address the functional declines associated with CIPN. If successful, this program is simple and easy to implement in the standard of care for individuals with CIPN. Gait and balance training have the potential to reduce physical dysfunction associated with CIPN and reduce the burden of disease in cancer survivors.Trial registrationClinicalTrials.gov NCT04621721. Registered on August 3, 2020. ClincialTrials.gov is a primary registry of the World Health Organization International Clinical Trials Registry Platform (WHO ICTEP) network and includes all items from the WHO Trial Registration data set in Trial registration.

Deep reinforcement learning coupled with musculoskeletal modelling for a better understanding of elderly falls.

Reinforcement learning (RL) has been used to study human locomotion learning. One of the current challenges in healthcare is our understanding of and ability to slow the decline due to muscle ageing and its effect on human falls. The purpose of this study was to investigate reinforcement learning for human movement strategies when modifying muscle parameters to account for age-related changes. In particular, human falls with modified physiological factors were modelled and simulated to determine the effect of muscle descriptors for ageing on kinematic behaviour and muscle force control.A 3D musculoskeletal model (8 DoF and 22 muscles) of the human body was used. The deep deterministic policy gradient (DDPG) method was implemented. Different muscle descriptors for ageing were integrated, including changes in maximum isometric force, contraction velocity, the deactivation time constant and passive muscle strain. Additionally, the effects of isometric force reductions of 10, 20 and 30% were also considered independently. An environment for the simulation was developed using the opensim-rl package for Python with the training process completed on Google Compute Engine. The simulation outcomes for healthy young adult and elderly falls under modified muscle behaviours were compared to experimental observations for validation.The result of our elderly simulation for multiple ageing-related factors (M_all) produced a walking speed of 0.26m/s for the two steps taken prior to the fall. The over activation of the hip extensors and inactivation of knee extensors led to a backward fall for this elderly simulation. The inactivated rectus femoris and right tibialis are main actors of the forward fall. Our simulation outcomes are consistent with experimental observations through the comparison of kinematic features and motion history evolution.We showed in the present study, for the first time, that RL can be used as a strategy to explore the effect of ageing muscle physiological factors on kinematics and muscle control during falls. Our findings show that the elderly fall model for the M_all condition more closely resembles experimental elderly fall data than our simulations which considered age-related reductions of force alone. As future perspectives, the behaviour preceding a fall will be studied to establish the strategies used to avoid falls or fall with minimal consequence, leading to the identification of patient-specific rehabilitation programmes for elderly people.

Effects of supervised high-intensity hardstyle kettlebell training on grip strength and health-related physical fitness in insufficiently active older adults: the BELL pragmatic controlled trial

The Ballistic Exercise of the Lower Limb (BELL) trial examined the efficacy and safety of a pragmatic hardstyle kettlebell training program in older adults. Insufficiently active men and women aged 59–79 years, were recruited to a 6-month repeated measures study, involving 3-months usual activity and 3-months progressive hardstyle kettlebell training. Health-related physical fitness outcomes included: grip strength [GS], 6-min walk distance [6MWD], resting heart rate [HR], stair-climb [SC], leg extensor strength [LES], hip extensor strength [HES], Sit-To-Stand [STS], vertical jump [CMVJ], five-times floor transfer [5xFT], 1RM deadlift, body composition (DXA), attendance, and adverse events. Sixteen males (68.8 ± 4.6 yrs, 176.2 ± 7.8 cm, 90.7 ± 11.0 kg, 29.2 ± 2.6 kg/m2) and sixteen females (68.6 ± 4.7 yrs, 163.9 ± 5.4 cm, 70.4 ± 12.7 kg, 26.3 ± 4.9 kg/m2) were recruited. Compliance with the supervised exercise program was very high (91.5%). Kettlebell training increased GS (R: MD = 7.1 kg 95% CI [4.9, 9.3], L: MD = 6.3 kg 95% CI [4.1, 8.4]), 6MWD (41.7 m, 95% CI [17.9, 65.5]), 1RM (16.2 kg, 95% CI [2.4, 30.0]), 30 s STS (3.3 reps, 95% CI [0.9, 5.7]), LES (R: MD = 61.6 N, 95% CI [4.4, 118.8]), HES (L: MD = 21.0 N,95% CI [4.2,37.8]), appendicular skeletal lean mass (MD = 0.65 kg, 95% CI [0.08, 1.22]), self-reported health change (17.1%, 95% CI [4.4, 29.8]) and decreased SC time (2.7 s, 95% CI [0.2, 5.2]), 5xFT time (6.0 s, 95% CI [2.2, 9.8]) and resting HR (7.4 bpm, 95% CI [0.7, 14.1]). There were four non-serious adverse events. Mean individual training load for group training sessions during the trial was 100,977 ± 9,050 kg. High-intensity hardstyle kettlebell training was well tolerated and improved grip strength and measures of health-related physical fitness in insufficiently active older adults.Trial registration: Prospectively registered: 20/08/2019, Australian New Zealand Clinical Trials Registry (ACTRN12619001177145).

Fast and ballistic contractions involve greater neuromuscular power production in older adults during resistance exercise

PurposeNeuromuscular power is critical for healthy ageing. Conventional older adult resistance training (RT) guidelines typically recommend lifting slowly (2-s; CONV), whereas fast/explosive contractions performed either non-ballistically (FAST-NB) or ballistically (FAST-B, attempting to throw the load) may involve greater acute power production, and could ultimately provide a greater chronic power adaptation stimulus. To compare the neuromechanics (power, force, velocity, and muscle activation) of different types of concentric isoinertial RT contractions in older adults.MethodsTwelve active older adult males completed three sessions, each randomly assigned to one type of concentric contraction (CONV or FAST-NB or FAST-B). Each session involved lifting a range of loads (20–80%1RM) using an instrumented isoinertial leg press dynamometer that measured power, force, and velocity. Muscle activation was assessed with surface electromyography (sEMG).ResultsPeak and mean power were markedly different, according to the concentric contraction explosive intent FAST-B > FAST-NB > CONV, with FAST-B producing substantially more power (+ 49 to 1172%, P ≤ 0.023), force (+ 10 to 136%, P < 0.05) and velocity (+ 55 to 483%, P ≤ 0.025) than CONV and FAST-NB contractions. Knee and hip extensor sEMG were typically higher during FAST-B than CON (all P < 0.02) and FAST-NB (≤ 50%1RM, P ≤ 0.001).ConclusionsFAST-B contractions produced markedly greater power, force, velocity and muscle activation across a range of loads than both CONV or FAST-NB and could provide a more potent RT stimulus for the chronic development of older adult power.

Altered Muscle Contributions are Required to Support the Stance Limb During Voluntary Toe-Walking.

Toe-walking characterizes several neuromuscular conditions and is associated with a reduction in gait stability and efficiency, as well as in life quality. The optimal choice of treatment depends on a correct understanding of the underlying pathology and on the individual biomechanics of walking. The objective of this study was to describe gait deviations occurring in a cohort of healthy adult subjects when mimicking a unilateral toe-walking pattern compared to their normal heel-to-toe gait pattern. The focus was to characterize the functional adaptations of the major lower-limb muscles which are required in order to toe walk. Musculoskeletal modeling was used to estimate the required muscle contributions to the joint sagittal moments. The support moment, defined as the sum of the sagittal extensive moments at the ankle, knee, and hip joints, was used to evaluate the overall muscular effort necessary to maintain stance limb stability and prevent the collapse of the knee. Compared to a normal heel-to-toe gait pattern, toe-walking was characterized by significantly different lower-limb kinematics and kinetics. The altered kinetic demands at each joint translated into different necessary moment contributions from most muscles. In particular, an earlier and prolonged ankle plantarflexion contribution was required from the soleus and gastrocnemius during most of the stance phase. The hip extensors had to provide a higher extensive moment during loading response, while a significantly higher knee extension contribution from the vasti was necessary during mid-stance. Compensatory muscular activations are therefore functionally required at every joint level in order to toe walk. A higher support moment during toe-walking indicates an overall higher muscular effort necessary to maintain stance limb stability and prevent the collapse of the knee. Higher muscular demands during gait may lead to fatigue, pain, and reduced quality of life. Toe-walking is indeed associated with significantly larger muscle forces exerted by the quadriceps to the patella and prolonged force transmission through the Achilles tendon during stance phase. Optimal treatment options should therefore account for muscular demands and potential overloads associated with specific compensatory mechanisms.

Biomechanical Research on Special Ability of Long Jump Take-Off Muscle Based on Multisource Information Fusion.

For athletes of different sports, their muscle activities in different sports will show different special characteristics according to different sports. The purpose of this paper is to study the technology of multi-information fusion and to study the athletes of the long jump competition. The relevant research on the muscle specific ability test methods of the athletes in the long jump competition is of great significance to the study of the long jump. This paper proposes a long jumper's special muscle ability experiment, using the now very popular multi-information fusion technology, to conduct in-depth research on the biomechanics of the long jumper's special ability of the take-off muscle, which can provide an effective scientific basis for the special ability level and special strength of the long jumper's take-off sports. The results of the study show that the hip joint of the take-off leg produces greater hip extensor torque during the take-off action of long jump, and the active contraction ability of the knee flexor group is very important for taking off and avoiding damage to the posterior femoral muscle group. The change range of the pressure center is between 51.26% and 74.35%, which has great application value in actual training.

Hip medial rotator action of gluteus medius in Japanese macaque (Macaca fuscata) and implications to adaptive significance for quadrupedal walking in primates.

The gluteus medius (GM) muscle in quadrupedal primates has long been thought to mainly act as a hip extensor. However, previous reports argue that it may be a prime hip medial rotator and functions to rotate the pelvis in the horizontal plane, suggesting the functional differentiation between the GM and other hip extensors as hamstrings. In this study, we aim to quantify the muscle actions of the GM and hamstrings using muscle moment arm lengths and discuss the functional differentiation among hip extensors. Muscle attachment sites of eight specimens of Japanese macaque (Macaca fuscata) were digitized, and musculoskeletal models were constructed. Flexor-extensor, abductor-adductor, and medial-lateral rotator moment arms were calculated as the models were moved following the experimentally acquired kinematic data during walking on a pole substrate. Using electromyography, we also recorded the pattern of muscle activation. The GM showed a larger medial rotator moment arm length than the extensor moment arm length when it was activated, suggesting this muscle acts mainly as a hip medial rotator rather than as a hip extensor. The medial rotator action of the GM in the early support phase may rotate the pelvis in the horizontal plane and function to help contralateral forelimb reaching as a previous study suggested and facilitate contralateral hindlimb swinging to place the foot near the ipsilateral forelimb's hand.

Emergence of Extreme Paw Accelerations During Cat Paw Shaking: Interactions of Spinal Central Pattern Generator, Hindlimb Mechanics and Muscle Length-Depended Feedback.

Cat paw shaking is a spinal reflex for removing an irritating stimulus from paw by developing extremely high paw accelerations. Previous studies of paw shaking revealed a proximal-to-distal gradient of hindlimb segmental velocities/accelerations, as well as complex inter-joint coordination: passive motion-dependent interaction moments acting on distal segments are opposed by distal muscle moments. However, mechanisms of developing extreme paw accelerations during paw shaking remain unknown. We hypothesized that paw-shaking mechanics and muscle activity might correspond to a whip-like mechanism of energy generation and transfer along the hindlimb. We first demonstrated in experiments with five intact, adult, female cats that during paw shaking, energy generated by proximal muscle moments was transmitted to distal segments by joint forces. This energy transfer was mostly responsible for the segmental velocity/acceleration proximal-to-distal gradient. Distal muscle moments mostly absorbed energy of the distal segments. We then developed a neuromechanical model of hindlimb paw shaking comprised a half-center CPG, activating hip flexors and extensors, and passive viscoelastic distal muscles that produced length/velocity-depended force. Simulations reproduced whip-like mechanisms found experimentally: the proximal-to-distal velocity/acceleration gradient, energy transfer by joint forces and energy absorption by distal muscle moments, as well as atypical co-activation of ankle and hip flexors with knee extensors. Manipulating model parameters, including reversal of segmental inertia distal-to-proximal gradient, demonstrated important inertia contribution to developing the segmental velocity/acceleration proximal-to-distal gradient. We concluded that extreme paw accelerations during paw shaking result from interactions between a spinal CPG, hindlimb segmental inertia, and muscle length/velocity-depended feedback that tunes limb viscoelastic properties.

Methodological considerations for assessing whole-body strength capacity through isometric dynamometry

ABSTRACT The present study aimed to explore the possibility of comprehensively assessing whole-body muscle strength by testing as few muscle groups as possible, using a single testing method (isometric or isokinetic dynamometry) and a single variable (maximal force or rate of force development). Knee, hip, shoulder and elbow extensors and flexors were evaluated in males with high (n = 26) and low strength levels (n = 32). The principal component analysis revealed three factors that explained 62.5% of the total variance, while the main factors were loaded by the different testing methods and strength variables for the muscles acting on the knee (first component), hip (second component) and arm joints (third component). These results were confirmed by a three-way ANOVA which revealed a significant factor of group (P < 0.001) and the interaction test type × group (P = 0.002), but not of test type (P = 0.644), muscle group (P = 0.999), or their interactions (P > 0.205). The correlations of strength outcomes across the muscles ranged from trivial to very large (r range = −0.17, 0.84), being generally higher for the antagonistic muscles. Overall, a comprehensive assessment of whole-body muscle strength can be obtained using isometric dynamometry and maximal force, but it should consider at least one muscle group from the antagonistic pair.

Explanatory factors of dynamic balance impairment in myotonic dystrophy type 1.

Myotonic dystrophy type 1 (DM1) is a neuromuscular disease affecting many systems and for which muscle weakness is one of the cardinal symptoms. People with DM1 also present with balance-related impairments and high fall risk. The aim of this study was to explore explanatory factors of dynamic balance impairment in the DM1 population. A secondary analysis of data collected as part of a larger study was performed. The Mini Balance Evaluation System Test (Mini-BESTest) was used to assess dynamic balance. Age, sex, and CTG repeat length in blood were retrieved from medical records and research files. The maximal isometric muscle strength of five lower limb muscle groups (hip flexors and extensors, knee flexors and extensors, and ankle dorsiflexors) was quantitatively assessed as well as fatigue. Standard multiple regression analysis was used. Fifty-two individuals (31 men) aged between 24 and 81 years were included. The final model explains 65.9% of the balance score; ankle dorsiflexor muscle strength was the strongest explanatory factor, followed by CTG repeat length, age and fatigue to a lesser extent. Dynamic balance is impaired in people with DM1. Results of this study suggest that rehabilitation interventions aimed at improving strength of the ankle dorsiflexors and managing fatigue could help to improve dynamic balance in this specific population.

Lower-limb muscle function in healthy young and older adults across a range of walking speeds

BackgroundPrevious studies have compared the functional roles of the individual lower-limb muscles when healthy young and older adults walk at their self-selected speeds. No age-group differences were observed in ankle muscle forces and ankle muscle contributions to support and progression. However, older adults displayed higher gluteus maximus (hip extensor) muscle forces and greater contributions to support during early stance. There are no data that describe the functions of the individual lower-limb muscles in healthy older adults for walking at speeds other than the self-selected speed. Research questionHow does walking speed affect the functional roles of the individual lower-limb muscles in healthy older adults? MethodsThree-dimensional gait data were recorded for 10 healthy young and 10 healthy older adults walking at slow, normal, and fast speeds (0.7 m/s, 1.4 m/s, and 1.7 m/s, respectively). Both groups walked at the same speed at each condition. The experimental data were combined with a full-body musculoskeletal model to calculate and compare muscle forces and muscle contributions to the vertical, fore-aft, and mediolateral ground reaction forces (support, progression, and balance, respectively) in both groups. ResultsLower-limb muscle function was similar in young and older adults when both groups walked at the same speed at each condition. The same five muscles - gluteus maximus, gluteus medius, vasti, gastrocnemius, and soleus – contributed most significantly to support, progression, and balance in both groups at all speeds. However, gluteus maximus generated greater support and braking forces during early stance and gastrocnemius contributed less to forward propulsion during late stance at all speeds in the older group. SignificanceThese results provide further insight into the functional roles of the individual lower-limb muscles of older adults during walking and could inform the design of exercise programs aimed at improving support and balance in those at risk of falling.

Identification of Sex Differences within Lunge Decelerations via Lower Extremity Support Moments; Implications for ACL Injury Disparity, Prevention, and Rehabilitation

Loading characteristics and lower extremity injury mechanisms, such as the non-contact mechanism of cruciate ligament injury, differ between sexes. The Limb Support Moment (LSM) quantifies hip, knee, and ankle moment contribution to the net moment required to prevent limb collapse during deceleration tasks. In total, 10 males and 10 females performed single limb deceleration landings within three knee flexion ranges: 0–25°, 25–50°, and 50–75°. Lower extremity joint moments and LSMs were calculated for all planes at initial contact (IC) through 50 ms. A two-way multivariate ANOVA compared LSMs and joint moments between sexes for all planes. Female LSMs were significantly greater at IC in the sagittal and transverse planes due to the generation of hip and ankle extensor moments and larger hip, knee, and ankle internal rotation moments. Males demonstrated significantly greater LSMs in the frontal plane due to the generation of hip abductor moments. Results suggest that females have a more rigid lower limb than males at landing, with less shock absorption capacity and greater potential for frontal plane collapse due to an unsupportive hip adductor moment. Quantifying the contribution of joint moments to limb support via LSMs suggests that there are landing characteristic sex differences, which may provide insight into injury disparity while guiding injury prevention/rehabilitation methodology.

The effects of spasticity on glucose metabolism and soft tissue body composition in patients with spinal cord injury.

Objectives The aim of this study was to assess the effects of spasticity on glucose metabolism and percentage of fat-free mass (FFM%) in patients with spinal cord injury (SCI). Patients and methods A total of 33 patients (22 males, 11 females; mean age: 38.6±12.5 years; range, 20 to 64 years) with SCI defined by the American Spinal Injury Association Impairment Scale Grades A to D were included between September 2014 and May 2018. We assessed spasticity with the Modified Ashworth Scale (MAS) and evaluated spasms with the Penn Spasm Frequency Scale (PSFS). We assessed the glucose metabolism by calculating the Matsuda and HOMA-IR index, and measured FFM% by dual-energy X-ray absorptiometry. Results Fourteen patients had motor complete, and 19 had motor incomplete SCI. The neurological injury levels of the patients were C4-T12. There was a positive correlation between hip adductor muscle MAS and trunk, android, and gynoid FFM% and between hip extensor muscle MAS and android FFM% in patients with motor complete SCI. Hip extensor and knee flexor muscle MAS showed a negative correlation with the HOMA-IR. Hip adductor and extensor muscle MAS, as well as knee flexor and extensor muscle MAS, had a positive correlation with the Matsuda index in these patients. There was a positive correlation between knee extensor muscle MAS and gynoid FFM% and between PSFS and arms, trunk, gynoid, and total FFM% in patients with motor incomplete SCI. There was a negative correlation between hip adductor and extensor muscle MAS, PSFS, and level of fasting glucose in these patients. Conclusion This study supports the notion that spasticity has positive effects on the FFM% and glucose metabolism in patients with motor complete and incomplete SCI.

Deficits in eccentric antagonist/concentric agonist strength ratios: a comparative study of football players with and without osteitis pubis.

Dynamic hip stabilizers are essential for optimal performance in football players, particularly during kicking. Although the muscle strength deficits of hip muscles as an etiology of osteitis pubis (OP) in football players have not yet been well investigated, previous assessments give more attention to the concentric mode of strength for both hip flexor and extensor muscles. Functionally, the hip muscles interact in an eccentric/concentric pattern. This study aimed to compare the concentric, eccentric, and eccentric antagonist/concentric agonist ratios for hip flexor and extensor strength between football players with OP and healthy athletes. Thirty-four male footballers with OP and eighteen healthy footballers were tested using an isokinetic dynamometer at a speed of 180°/s. Football players with osteitis pubis demonstrated a significantly lower eccentric extensor/concentric flexor ratio and higher eccentric hip flexor/extensor ratio (p < 0.05) when compared with healthy participants. The present study demonstrated that football players with OP had a reduced capability to produce eccentric hip extension torque compared to healthy athletes. Consequently, the eccentric rather than the concentric weakness of hip extensors could be suggested as one of the intrinsic contributing factors for OP. Incorporating findings of the current study in clinical practice could afford critical information while evaluating the hip muscles in football players with OP for pre-screening, developing rehabilitation programs, and guiding the decision to return to sports after injury.

Distinct effects of trampoline-based stretch-shortening cycle exercises on muscle strength and postural control in children with Down syndrome: a randomized controlled study.

The aim of the study was to investigate the effect of a 3-month, trampoline-based stretch-shortening cycle (SSC) exercises on muscle strength and postural control in children with Down's syndrome (DS). Thirty-two children with DS aged between 7-9 years were enrolled and randomly assigned into the control group (n = 16); received standard physical therapy (sPT) or SSC group (n = 16); received sPT in addition to a 15-minute, trampoline-based SSC training program twice per week for 12 successive weeks. Lower limb muscle strength and postural stability [anterior/posterior stability index (A/P-SI), medial/lateral stability index (M/L-SI)], and overall stability index (O-SI) were assessed pre- and post-treatment. Strength of hip extensor (p=0.034) and adductor (p=0.015), knee extensor (p=0.028) and flexor (p=0.01), and ankle dorsi (p=0.033) and plantar flexor (p=0.007) muscles increased significantly in the SSC group when compared with the control group. Also, the A/P-SI (p=0.019), M/L-SI (p=0.002), and O-SI (p=0.021) decreased significantly in the SSC group when compared with the control group, suggesting better postural control. Twelve weeks of trampoline-based SSC exercises are likely effective for enhancing muscle strength and postural control in children with DS and should consequently be included in the rehabilitation programs for these children.