Hip Torque Research Articles

Relative muscular effort in the older adults during the sit-to-stand task: Monitoring neuromuscular reserve and movement limitations

BackgroundDue to lower maximum strength, older adults purportedly need to exert greater muscular effort to stand up from a chair. This study investigated joint-specific muscular effort during a sit-to-stand by calculating relative-muscular-effort and investigating differences between healthy older and young adults. MethodsFifteen older (age: 69.9 ± 3.5 years) and 15 young (age: 22.2 ± 2.6 years) adults performed five self-paced sit-to-stand trials. Kinematic and kinetic data were collected and used to calculate inverse dynamics net joint moment. Peak isometric knee and hip extensor torques were measured and used as inputs to regression models that predicted angle- and velocity-dependent maximum potential net joint moment. Knee and hip relative-muscular-effort were calculated as the net joint moment during the task and their maximum capacity. FindingsKnee and hip extensor relative-muscular-effort did not differ between age groups during momentum-transfer and extension phases of the sit-to-stand. However, peak knee and hip moments during the sit-to-stand, knee and hip maximum potential moments as well as peak knee and hip torques were significantly lower in older adults compared to young adults. InterpretationAlthough there were age-related decreases in muscle strength and joint kinetics during the sit-to-stand task in older adults, the findings that older adults exhibited similar knee and hip relative-muscular-effort to young adults suggests that neither knee nor hip extensors operated close to their maximum capacity during this task. Therefore, neuromuscular reserve in knee and hip strength may not be a critical limiting factor for healthy older adults during the two phases of sit-to-stand.

Human foot force informs balance control strategies when standing on a narrow beam.

Despite the abundance of studies on the control of standing balance, insights about the roles of biomechanics and neural control have been limited. Previous work introduced an analysis combining the direction and orientation of foot-ground forces. The "intersection point" of the lines of actions of these forces exhibited a consistent pattern across healthy, young subjects when computed for different frequency components of the center of pressure signal. To investigate the control strategy of quiet stance, we applied this intersection point analysis to experimental data of 15 healthy, young subjects balancing in tandem stance on a narrow beam and on the ground. Data from the sagittal and frontal planes were analyzed separately. The task was modeled as a double-inverted pendulum controlled by an optimal controller with torque-actuated ankle and hip joints and additive white noise. To test our prediction that the controller that minimized overall joint effort would yield the best fit across the tested conditions and planes of analyses, experimental results were compared with simulation outcomes. The controller that minimized overall effort produced the best fit in both balance conditions and planes of analyses. For some conditions, the relative penalty on the hip and ankle joints varied in a way relevant to the balance condition or to the plane of analysis. These results suggest that unimpaired quiet balance in a challenging environment can be best described by a controller that maintains minimal effort through the adjustment of relative ankle and hip joint torques. NEW & NOTEWORTHY This study explored balance control in humans during a challenging task using the novel intersection point analysis, based on foot-ground force direction and point of application. Experimental data of subjects standing on a narrow beam in tandem stance were compared with modeling results of a double-inverted pendulum. The analysis showed that individuals minimized effort by adjusting ankle and hip torques, shedding light on the interplay of biomechanics and neural control in maintaining balance.

Are demographics, physical function and psychological response associated with return to sport at one year following ACL-reconstruction?

ObjectiveTo determine the relative contribution of each of the following aspects: demographics, physical function, and patient-reported outcome measures (PROMs), including both physical and psychological constructs, to return to sport (RTS) (any level) one-year post anterior cruciate ligament reconstruction (ACLR). DesignCross-sectional cohort study. MethodsWe included data for 143 participants (73 women, mean (SD) age 24 (5.8) years) ∼ one-year post-ACLR. Data comprised demographics, physical function (hop performance, hip and knee peak torque) and PROMs (Knee Osteoarthritis Outcome Score subscales, perceived stress, and ACL Return to Sport after Injury scale (ACL-RSI)). We then used a Z-normalized multivariable logistic regression model to establish the relative contribution of factors associated with RTS. ResultsSixty-four (45%) of the participants had returned to sport at one year post-ACLR. In the regression model, greater hip abduction peak torque (OR = 1.70, 95% CI; 1.01 to 2.84) and greater psychological readiness to RTS (OR = 2.32, 95% CI; 1.30 to 4.12) were the only variables associated with RTS (R2 = 0.352). ConclusionsThe significant contribution of hip abduction strength and psychological readiness to RTS was still relatively small, suggesting other potential factors explaining RTS which may not be captured by common RTS criteria.

Relationship between jump height and lower limb joint kinetics and kinematics during countermovement jump in elite male athletes

ABSTRACT This study aims to identify the relationship between jump height and the kinetic and kinematic parameters of the hip, knee, and ankle joints during countermovement jump (CMJ) in elite male athletes. Sixty-six elite male athletes from various sports (strength and power, winter downhill, combat, ball game, and aquatic) performed maximal effort CMJs with hands and arms crossed against their chests on force platforms. Jumping motion in the sagittal plane was recorded using video analysis and the peak torque, power, and angular velocity of the right hip, knee, and ankle joints were calculated during the propulsive phase. Correlations between the CMJ height and kinetic and kinematic parameters were investigated using Pearson’s product-moment coefficient (r) and Spearman’s rank correlation coefficient (ρ). CMJ height was highly correlated with peak hip power (ρ = 0.686, p < 0.001) and peak knee angular velocity (r = 0.517, p < 0.001), and moderately correlated with peak hip angular velocity (r = 0.438, p < 0.001) and peak hip torque (r = 0.398, p = 0.001). These results indicate that notable hip torque and power can contribute to increased angular velocity in both the knee and hip joints, ultimately increasing the CMJ height in elite male athletes.

Human–robot mechanics model using hip torque identification with a dual-arm nursing-care transfer robot

In response to the growing demand for robotic interventions to mitigate the profound physical strain experienced by caregivers during transfers, dual-arm robotic systems have emerged as a focal point of interest in the caregiving community due to their adaptability and versatility. However, the accuracy of existing human–robot mechanics model is insufficient, impacting the execution of transfer tasks. To enhance the model’s precision, an improved model is proposed, integrating hip torque identification. This proposed methodology involves the simplification of the human structure based on the kinematic attributes associated with the embrace of individuals by robotic arms and the subsequent computation of its inertial parameters. Accordingly, the application of D’Alembert’s principle is employed to analyze the impact of embracing motion, human posture, and the position of human–robot contact on the forces exerted on the human. This culminates in the establishment of a model. Considering the static indeterminacy predicament inherent in the model, a biomechanical data set is curated for the dual-arm transfer scenario. Leveraging this data set, a deep neural network utilizing multilayer perceptron is trained to accurately identify hip torque, thereby improving the model. Accordingly, a robotic transfer platform featuring dual arms is developed and trailed on six subjects with varying anatomical profiles. The results show that the constructed model has high accuracy. This study provides critical mechanics insights for dual-arm transfer tasks, offering potential application value in the field of nursing and rehabilitation.

Reduced trunk movement control during motor dual-tasking in older adults

Older adults have a decreased trunk movement control which is linked to their higher fall risk. While motor/cognitive dual-tasking deteriorates balance and walking in older adults, there is limited understanding on how trunk kinematics and kinetics are affected by dual-tasking in scenarios where falls can occur. Therefore, the purpose of the study was to determine the impacts of a challenging motor dual-task, specifically obstacle avoidance during walking, on trunk and lower-body kinematics and kinetics of older adults compared to young adults. The study captured three-dimensional kinematic and kinetic data from 12 young adults and 10 older adults as they walked on a treadmill and stepped over an obstacle with both legs. The study analyzed trunk, hip, knee, and ankle angles and torques. Trunk torque was further broken down to trunk muscle torque, gravitational torque, and inertia torque. A linear mixed effects model was used to investigate the difference in each variable between the two groups. Older adults exhibited significantly increased trunk flexion angle and trunk extension muscle torque compared to young adults, with the trunk being the only segment/joint showing differences in both kinematics and kinetics. Trunk torque breakdown analysis revealed that larger trunk flexion led to a larger gravitational torque, which contributed to an increased compensatory trunk muscle torque. Moreover, older adults' less controlled trunk flexion during weight shifting from trail leg to the lead leg, necessitated a compensatory trunk deceleration during trail leg obstacle avoidance which was achieved by generating additional increase in trunk muscle torque. The study demonstrated that motor dual-tasking has the most negative effects on trunk control in older adults compared to young adults. This exposes older adults to a higher fall risk. Therefore, future work should focus on supporting trunk control during daily multi-tasking conditions where falls can occur.

Contribution of the Medial Iliofemoral Ligament to Hip Stability After Total Hip Arthroplasty Through the Direct Anterior Approach

BackgroundDislocation after total hip arthroplasty (THA) is a primary reason for THA revision. During THA through the direct anterior approach (DAA), the iliofemoral ligament, which provides the main resistance to external rotation (ER) of the hip, is commonly partially transected. We asked: (1) what is the contribution of the medial iliofemoral ligament to resisting ER after DAA THA? and (2) how much resistance to ER can be restored by repairing the ligament? MethodsA fellowship-trained surgeon performed DAA THA on 9 cadaveric specimens. The specimens were computed tomography scanned before and after implantation. Prior to testing, the ER range of motion of each specimen to impingement in neutral and 10° of extension was computationally predicted. Each specimen was tested on a 6-degrees-of-freedom robotic manipulator. The pelvis was placed in neutral and 10° of extension. The femur was externally rotated until it reached the specimen’s impingement target. Total ER torque was recorded with the medial iliofemoral ligament intact, after transecting the ligament, and after repair. Torque at extremes of motion was calculated for each condition. To isolate the contribution of the native ligament, the torque for the transected state was subtracted from both the native and repaired conditions. ResultsThe medial iliofemoral ligament contributed an average of 68% (range, 34 to 87) of the total torque at the extreme of motion in neutral and 80% (58 to 97) in 10⁰ of extension. The repaired ligament contributed 17% (1 to 54) of the total torque at the extreme of motion in neutral and 14% (5 to 38) in 10⁰ of extension, restoring on average 18 to 25% of the native resistance against ER. ConclusionsThe medial iliofemoral ligament was an important contributor to the hip torque at the extreme of motion during ER. Repairing the ligament restored a fraction of its ability to generate torque to resist ER.

Effects of attentional focus strategy on drop jump for athletes with different experience levels: Performance, kinetics and kinematics

The attentional focus strategy (AFS) affects drop jump (DJ) performance; however, its effects on DJ kinetics and kinematics are unclear. This study examines the effects of AFS on DJ performance, kinetics and kinematics. Forty collegiate males were divided into a DJ experienced group and a DJ inexperienced group, and they performed two trials of DJs after listening to instructions designed to elicit internal (INT), external (EXT) or neutral (NEUT) focus of attention. In the experienced group, the reactive strength index (RSI) was larger with the NEUT than with the INT. Hip joint torque and positive hip joint power in the concentric phase was smaller with the NEUT than with the INT, and the hip joint angle at the lowest centre of mass was larger with the NEUT than with the INT ( p &lt; .05). In the inexperienced group, RSI was larger with the EXT than with the INT. Further, the hip joint torque in the concentric phase was smaller with the EXT than with the INT; positive ankle joint power was larger with the EXT than with the INT; and the hip joint angles at the lowest centre of mass and take-off were larger with the EXT than with the INT ( p &lt; .05). These results showed that the AFS affected the DJ performance, kinetics and kinematics and suggested that effective DJ training may be achieved with the NEUT for DJ experienced and with the EXT for DJ inexperienced.

Three-dimensional kinematics of the trunk, pelvis, hip, and knee during the single-leg squat and hip torque in subjects with isolated patellofemoral osteoarthritis compared to individually matched controls: Preliminary results.

Objectives: This study aimed to compare three-dimensional kinematic of the trunk, pelvis, hip, and knee during the single-leg squat and hip torque in individuals with and without isolated patellofemoral osteoarthritis (PFOA). Patients and methods: This cross-sectional study evaluated trunk, pelvis, hip, and knee kinematics at 30°, 45°, and 60° knee flexion during the single-leg squat using the Vicon motion capture and analysis system, the Nexus System 2.1.1, and 3D Motion Monitor software. Sixteen individuals (8 males, 8 females; mean age: 49.3±6.2 years; range 40 to 61 years) participated in the study, of which eight were PFOA patients and eight were healthy controls. Isometric hip abductor, extensor, and external rotator torques were evaluated using a handheld dynamometer. Results: The PFOA group exhibited greater hip adduction at 30° (p=0.008), 45° (p=0.005), and 60° (p=0.008) knee flexion in the descending phase of the single-leg squat, as well as at 60° (p=0.009) and 45° (p=0.03) knee flexion in the ascending phase. No significant differences were found between groups for other kinematic variables (p>0.05). The PFOA group exhibited lower isometric hip abductor (p=0.02), extensor (p <0.001), and external rotator (p=0.007) torques. Conclusion: Individuals with PFOA exhibited excessive hip adduction that could increase stress on the lateral patellofemoral joint at 30°, 45°, and 60° knee flexion during the single-leg squat and exhibited weakness of the hip abductors, extensors, and external rotators in comparison to healthy controls.

Identifying best fall-related balance factors and robotic-assisted gait training attributes in 105 post-stroke patients using clinical machine learning models.

Despite the promising effects of robot-assisted gait training (RAGT) on balance and gait in post-stroke rehabilitation, the optimal predictors of fall-related balance and effective RAGT attributes remain unclear in post-stroke patients at a high risk of fall. We aimed to determine the most accurate clinical machine learning (ML) algorithm for predicting fall-related balance factors and identifying RAGT attributes. We applied five ML algorithms- logistic regression, random forest, decision tree, support vector machine (SVM), and extreme gradient boosting (XGboost)- to a dataset of 105 post-stroke patients undergoing RAGT. The variables included the Berg Balance Scale score, walking speed, steps, hip and knee active torques, functional ambulation categories, Fugl- Meyer assessment (FMA), the Korean version of the Modified Barthel Index, and fall history. The random forest algorithm excelled (receiver operating characteristic area under the curve; AUC = 0.91) in predicting balance improvement, outperforming the SVM (AUC = 0.76) and XGboost (AUC = 0.71). Key determinants identified were knee active torque, age, step count, number of RAGT sessions, FMA, and hip torque. The random forest algorithm was the best prediction model for identifying fall-related balance and RAGT determinants, highlighting the importance of key factors for successful RAGT outcome performance in fall-related balance improvement.

An optimization model of tractor clutch pedal design parameters based on lower limb biomechanical characteristics

The design of tractor pedal affects operator's comfort, working efficiency, and occupational health. To optimize tractor clutch pedal design parameters, we conducted a single-factor experiment and a response surface experiment based on a biomechanical model. The experimental indicators included the biomechanical loads of major activated muscles and joints of the lower limb, and the experimental factors comprised pedal-seat horizontal distance L, pedal-seat vertical distance H, and pedal spring stiffness k. The results indicate that L and H mainly influence the loads of semitendinosus and hip. Semitendinosus activity and hip torque first decreased and then increased with increasing L (or H), reaching the lowest level at 82 cm of L (or 42 cm of H). The increase in k led to gradual decreases in iliopsoas activity and increases in semitendinosus, rectus femoris, soleus activities, and ankle torque, as well as a first decreasing and then increasing trend of hip and knee torques. The overall biomechanical loads of the lower limb first declined and then grew with increasing L, H, and k. The optimal range of clutch pedal design parameters was calculated to be {(L, H, k) | 36≤L ≤ 40, 72≤H ≤ 76, 14≤k ≤ 22} when using the response surface method. Within this range, muscle activity and joint torque were reduced by 14.2% and 51.6%, respectively, indicating effective alleviation of the lower limb biomechanical loads. This study provides important implications for the biomechanical analysis of tractor operator-pedal interaction system and lays a foundation for improving the design and comfort of tractors.

Analysis of Musculoskeletal Biomechanics of Lower Limbs of Drivers in Pedal-Operation States

In this study, to establish the biomechanical characteristics of commercial vehicle drivers’ muscles and bones while operating the three pedals, a driver pedal-operation simulator was built, and the real-life situation was reconstructed in OpenSim 3.3 software. We set up three seat heights to investigate the drivers’ lower limbs, and the research proceeded in two parts: experiment and simulation. Chinese adult males in the 95th percentile were selected as the research participants. In the experiment, Delsys wireless surface electromyography (EMG) sensors were used to collect the EMG signals of the four main muscle groups of the lower limbs when the drivers operated the three pedals. Then, we analyzed the muscle activation and the degree of muscle fatigue. The simulation was based on OpenSim software to analyze the driver’s lower limb joint angles and joint torque. The results show that the activation of the hamstrings, gastrocnemius, and rectus femoris muscles were higher in the four muscle groups. In respect of torque, in most cases, hip joint torque &gt; knee joint torque &gt; ankle joint torque. The knee joint angles were the largest, and the ankle joint angles changed the most. The experimental results provide a reference for improving drivers’ handling comfort in commercial vehicles and provide theoretical bases for cab design and layout optimization.

Dynamic Optimization of Mechanism Parameters of Bipedal Robot Considering Full-Range Walking Energy Efficiency

Mechanism parameters of bipedal robots are crucial for achieving efficient locomotion in complex environments. Inspired by the human energy-efficient walking style, this paper proposes a novel concept of full-range walking energy efficiency and explores the optimal linkage mechanism within certain ranges of step length and walking speed for bipedal robots. First, a bipedal model incorporating an upper body is established for dynamic analysis. Next, an optimal walking gait subject to walking constraints is solved by considering the full-range energy efficiency. Further, an optimal linkage mechanism is investigated, and the influence of dynamic parameters on energy efficiency is analyzed. Finally, the push-off impulse, minimum ground support force, and walking torque features are discussed. It shows that the full-range walking energy efficiency can be lowered by reducing the ratio of leg mass, concentrating mass at the hip joint, decreasing the length of the upper body, or increasing the center of mass of the leg. In addition, efficient walking motion can be achieved by designing the coordination of positive hip joint torque and push-off impulse at the ankle. This paper can be used to guide the mechanism parameter optimization and efficient walking gait design of bipedal robots.

The Effects of Fatigue on the Lower Limb Biomechanics of Amateur Athletes during a Y-Balance Test.

The Y-Balance Test (YBT) is a reliable tool for assessing the dynamic balance of athletes' lower limbs. This study aimed to compare the effects of the YBT on lower limb biomechanics before and after fatigue. Sixteen adult male recreational athletes were recruited for the study, and motion capture in combination with a force plate was used to collect kinematic, dynamics, and center of pressure (COP) data of the dominant leg during YBT testing before and after fatigue. Based on the research findings, there were significant statistical differences in the distances reached during the YBT in three directions before and after fatigue. After fatigue, there is a significant decrease in the ROM of the hip and knee joints in all three directions. Also, there is a significant increase in hip joint torque in the anterior- and posterior-lateral directions, while a significant decrease in hip and ankle joint torque is observed in the posterior-medial direction. Moreover, there is an increasing trend in positive and negative joint work for the hip, knee, and ankle joints in all three directions after fatigue. The range of COP displacement also increases following fatigue. The decline in YBT scores demonstrates the detrimental impact of fatigue on the dynamic balance of the lower limbs of adult male amateur athletes. We hope that these results can provide information for athletes and coaches to better understand the effects of fatigue on the dynamic balance of lower limbs, so as to carry out targeted lower limb balance training and prevent sports injuries.

Lower extremity muscle volume in females with patellofemoral pain and its relationships to hip and knee torque: A cross-sectional study

ObjectivesCompare lower extremity muscle volume in females with patellofemoral pain (PFP) to a cohort of pain-free females and investigate the relationship between thigh and hip muscle volume and torque. DesignCross-sectional. ParticipantsTwenty-one females, 13 with PFP and 8 pain-free controls. Main outcome measuresWe quantified normalized lower extremity muscle volume (cm3/kg*m) via magnetic resonance imaging and isometric hip and thigh torque (Nm/kg) via a multimodal dynamometer. ResultsVersus pain-free individuals, females with PFP had smaller muscle volume of the anterior hip (P < 0.019; d = 0.97–2.42), deep external rotators (P < 0.006; d = 1.0–3.93), hamstrings (P < 0.009; d = 1.09–2.12), rectus femoris (P < 0.001; d = 1.79), and vastus intermedius (P < 0.001; d = 1.88). There was no difference in muscle volume of the gluteus maximus (P = 0.311; d = 0.22), gluteus medius (P = 0.087; d = 0.87), vastus lateralis (P = 0.22; d = 0.39), and vastus medialis (P = 0.47; d = 0.04). Gluteus maximus volume was moderately correlated to hip abduction torque (r = 0.60; P = 0.03). Vasti muscles and semitendinosus volume were moderately correlated to knee extension (r = 0.57–0.69; P < 0.05) and flexion (r = 0.66; P = 0.01) torque, respectively. ConclusionFemales with PFP present with lesser thigh and hip muscle volumes, with variability in volumetric profiles across participants. Lower extremity knee extension and hip abduction strength are moderately associated with the vasti and gluteus maximus muscle volume, respectively.

Effects of a proprioceptive focal stimulation (Equistasi®) on reducing the biomechanical risk factors associated with ACL injury in female footballers.

Football presents a high rate of lower limb injuries and high incidence of Anterior Cruciate Ligament (ACL) rupture, especially in women. Due to this there is the need to optimize current prevention programs. This study aims to verify the possibility to reduce the biomechanical risk factors associated with ACL injury, through the application of proprioceptive stimulation by means of the Equistasi® device. Ten elite female footballers were enrolled and received the device for 4 weeks (5 days/week, 1h/day). Athletes were assessed directly on-field at four time points: T0 and T1 (evaluation without and with the device), T2 (after 2 weeks), T4 (after 4 weeks) while performing two different tasks: Romberg Test, and four sidestep cutting maneuvers bilaterally. Seven video cameras synchronized with a plantar pressure system were used, thirty double colored tapes were applied on anatomical landmarks, and three dimensional coordinates reconstructed. Vertical ground reaction forces and center of pressure data were extracted from the plantar pressure insoles. Hip, knee, and ankle flexion-extension angles and moments were computed as well as abd-adduction joint torques. From the Romberg Test both center of pressure descriptive variables and frequency analysis parameters were extracted. Each variable was compared among the different time frames, T1, T2 and T4, through Friedman Test for non-parametric repeated measures (p<0.05); Wilcoxon Signed Rank Test was used for comparing variables between T0 and T1 (p<0.05) and across the different time frames as follows: T1-T2, T2-T4 and T1-T4. Statistically significant differences in both posturographic and biomechanical variables between the assessment at T0 and T1 were detected. Reduced hip and knee abduction torques were revealed in association with reduced both ground reaction forces and ankle dorsiflexion torque from T1 up to T4. The proprioceptive stimuli showed to have the potential to improve cutting biomechanics mainly with respect to the ligament and quadriceps dominance theories. Results of the present study, even if preliminary and on a small sample size, could be considered promising towards the inclusion of proprioceptive training in injury prevention programs.

Positioning of pivot points in quadrupedal locomotion: limbs global dynamics in four different dog breeds.

Dogs (Canis familiaris) prefer the walk at lower speeds and the more economical trot at speeds ranging from 0.5 Fr up to 3 Fr. Important works have helped to understand these gaits at the levels of the center of mass, joint mechanics, and muscular control. However, less is known about the global dynamics for limbs and if these are gait or breed-specific. For walk and trot, we analyzed dogs' global dynamics, based on motion capture and single leg kinetic data, recorded from treadmill locomotion of French Bulldog (N = 4), Whippet (N = 5), Malinois (N = 4), and Beagle (N = 5). Dogs' pelvic and thoracic axial leg functions combined compliance with leg lengthening. Thoracic limbs were stiffer than the pelvic limbs and absorbed energy in the scapulothoracic joint. Dogs' ground reaction forces (GRF) formed two virtual pivot points (VPP) during walk and trot each. One emerged for the thoracic (fore) limbs (VPPTL) and is roughly located above and caudally to the scapulothoracic joint. The second is located roughly above and cranially to the hip joint (VPPPL). The positions of VPPs and the patterns of the limbs' axial and tangential projections of the GRF were gaits but not always breeds-related. When they existed, breed-related changes were mainly exposed by the French Bulldog. During trot, positions of the VPPs tended to be closer to the hip joint or the scapulothoracic joint, and variability between and within breeds lessened compared to walk. In some dogs, VPPPL was located below the pelvis during trot. Further analyses revealed that leg length and not breed may better explain differences in the vertical position of VPPTL or the horizontal position of VPPPL. The vertical position of VPPPL was only influenced by gait, while the horizontal position of VPPTL was not breed or gait-related. Accordingly, torque profiles in the scapulothoracic joint were likely between breeds while hip torque profiles were size-related. In dogs, gait and leg length are likely the main VPPs positions' predictors. Thus, variations of VPP positions may follow a reduction of limb work. Stability issues need to be addressed in further studies.

Evaluation of maximum thigh angular acceleration during the swing phase of steady-speed running

ABSTRACT The hip joint and surrounding musculature must generate and withstand torque during the swing phase of running. Prior research has demonstrated that sagittal plane hip torque increases with speed, indicating that thigh angular acceleration likely increases in a similar manner and may be an important gait parameter. In this investigation, we modelled thigh angle vs. time data with a sine wave function, requiring inputs of thigh angular amplitude and stride frequency. This enabled a simple formula to model maximum thigh angular acceleration (αmax , rad/s2) during the swing phase of steady-speed running. A total of 40 participants (20 male, 20 female) completed submaximal and maximal 40 m running trials (n = 154 trials, speed range: 3.1–10.0 m/s), with kinematic data collected from 31–39 m. Thigh angle vs. time curves were well fit by a sine wave function (mean R2 > 0.94 across all trials) and modelled αmax was highly correlated with top speed (R2 = 0.81, p < 0.001). We conclude that thigh angular acceleration is an important parameter when examining running performance across a range of speeds and the simple method introduced here to model αmax may have practical utility for future examinations into high-speed running mechanics.

Immediate effects of Dynamic Tape™ on hip muscle activation and torque and on lower limb kinematics: A randomized controlled clinical trial

ABSTRACT This study aimed to evaluate the immediate effect of Dynamic TapeTM (DT) on hip muscle activation and torque and on lower limb kinematics. Forty-five healthy, recreationally active women were randomly assigned to three groups: 1) submitted to the application of DT in the active form in the gluteus medius (GMed) muscle (BG; n = 15), 2) submitted to the application of DT in the placebo form in the GMed muscle (PG; n = 15), and 3) not submitted to any intervention (CG; n = 15). Participants were evaluated for GMed and gluteus maximus (GMax) muscle activation in a maximal voluntary isometric contraction, simultaneously with the assessment of the hip abductor and extensor torques, as well as during two functional tasks – single leg squat (SLS) and jump landing + maximum vertical jump (VJ) – simultaneously with a 2-D kinematic assessment of the lower limb. After DT application in BG, there was a significant decrease in the hip abductor time to peak torque (P = 0.004), hip extensor torque (P = 0.02), excursion to hip adduction (P = 0.007), and to knee flexion (P = 0.02) during the SLS, as well as in GMed activation during VJ (P < 0.05). DT was able to reduce GMed activation and modify lower limb torque and kinematics.

Muscle co-activation in the elderly contributes to control of hip and knee joint torque and endpoint force

We investigated the coordinated activity patterns of muscles based on cosine tuning in the elderly during an isometric force exertion task. We also clarified whether these coordinated activity patterns contribute to the control of hip and knee joint torque and endpoint force as co-activation. Preferred direction (PD) of activity for each muscle in 10 young and 8 older males was calculated from the lower limb muscle activity during isometric force exertion task in various directions. The covariance of endpoint force (η) was calculated from the exerted force data using a force sensor. Relationship between PD and η was used to examine the effect of muscle co-activation on the control of endpoint force. Co-activation between rectus femoris and semitendinosus/biceps femoris increased with changes in muscle PD. Additionally, the η values were significantly low, suggesting that co-activation of multiple muscles may contribute to endpoint force exertion. The mechanism for cooperative muscle activity is determined by the cosine tuning of the PD of each muscle, which affects the generation of hip and knee joint torque and endpoint force exertion. Co-activation of each muscle’s PD changes with age, causing increased muscle co-activation to control torque and force. We demonstrated that co-activation in the elderly is a stabilizer of unsteady joints and a muscle control strategy for cooperative muscle activity.