Maximum Pulling Force Research Articles

Assessing Inter-yarn Frictional Behavior of Jute Fabrics Impregnated with Corn Flour Particles-Based Shear Thickening Fluids

Recently naturally driven fabrics are gaining more attention to develop impact-resistive fabrics due to their cost-effectiveness and environment-friendly nature. The effectiveness of jute fabrics becomes more prominent when used with shear thickening fluids (STFs). The present study is focused on the assessment of inter-yarn frictional behavior of jute fabrics impregnated with natural corn flour particles-based STFs. The varying amount of corn flour particles of 10 and 13 µm were blended with deionized water, glycerol, and polyethylene glycol (PEG-400) to synthesize STFs. To the best of our knowledge, first time the stability and rheological performance of corn flour particles-based STFs under varying shear rates in different dispersion mediums have been investigated. The peak viscosity of STF consisting 50% particles (10 µm) in glycerol was found significantly higher compared to the STF consisting same size and concentration of particles with deionized water. The yarn pull-out test was conducted to evaluate the materials’ inter-yarn frictional resistance behavior. The maximum pulling force was observed for jute fabric impregnated with glycerol-based STF. Thus, the developed STFs can be vital for developing better impact-resistive fabrics.

Application of temperature-dependent and steered molecular dynamics simulation to screen anti-dengue compounds against Marburg virus

Marburg virus infections are extremely fatal with a fatality range of 23% to 90%, therefore there is an urgent requirement to design and develop efficient therapeutic molecules. Here, a comprehensive temperature-dependent molecular dynamics (MD) simulation method was implemented to identify the potential molecule from the anti-dengue compound library that can inhibit the function of the VP24 protein of Marburg. Virtual high throughput screening identified five effective binders of VP24 after screening 484 anti-dengue compounds. These compounds were treated in MD simulation at four different temperatures: 300, 340, 380, and 420 K. Higher temperatures showed dissociation of hit compounds from the protein. Further, triplicates of 100 ns MD simulation were conducted which showed that compounds ID = 118717693, and ID = 5361 showed strong stability with the protein molecule. These compounds were further validated using Δ G binding free energies and they showed: −30.38 kcal/mol, and −67.83 kcal/mol binding free energies, respectively. Later, these two compounds were used in steered MD simulation to detect its dissociation. Compound ID = 5361 showed the maximum pulling force of 199.02 kcal/mol/nm to dissociate the protein-ligand complex while ID = 118717693 had a pulling force of 101.11 kcal/mol/nm, respectively. This ligand highest number of hydrogen bonds with varying occupancies at 89.93%, 69.80%, 57.93%, 52.33%, and 50.63%. This study showed that ID = 5361 can bind with the VP24 strongly and has the potential to inhibit its function which can be validated in the in-vitro experiment. Communicated by Ramaswamy H. Sarma

Interaction of biomolecules with anatase, rutile and amorphous TiO2 surfaces: A molecular dynamics study.

The adhesion of biomolecules to dental and orthopedic implants is a fundamental step in the process of osseointegration. Short peptide motifs, such as RGD or KRSR, carried by extracellular matrix proteins or coated onto implant surfaces, accelerate cell adhesion and tissue formation. For this reason, understanding the binding mechanisms of adhesive peptides to oxidized surfaces of titanium implants is of paramount importance. We performed molecular dynamics simulations to compare the adhesion properties of 6 peptides, including the tripeptide RGD, its variants KGD and LGD, as well as the tetrapeptide KRSR, its variant LRSR and its truncated version RSR, on anatase, rutile, and amorphous titanium dioxide (TiO2) surfaces. The migration of these molecules from the water phase to the surface was simulated in an aqueous environment. Based on these simulations, we calculated the residence time of each peptide bound to the three different TiO2 structures. It was found that the presence of an N-terminal lysine or arginine amino acid residue resulted in more efficient surface binding. A pulling simulation was performed to detach the adhered molecules. The maximum pulling force and the binding energy were determined from the results of these simulations. The tri- and tetrapeptides had slightly greater adhesion affinity to the amorphous and anatase structure than to rutile in general, however specific surface and peptide binding characters could be detected. The binding energies obtained from our simulations allowed us to rank the adhesion strengths of the studied peptides.

Performa of SCARA based intelligent 3 axis robotic soft gripper for enhanced material handling

Soft robotic gripper is a model and intensively investigated area of soft robotics which is frequently motivated by nature. Human anatomical fingers are used as grippers in the current research. Robotic soft silicon grippers are constructed using hollow chambers that can be controlled by varying the pneumatic pressure inside the chambers. The soft gripper is made using casting, 3D printing, and molds. End-effectors made from flexible and soft components may frequently grasp or operate a greater variety of items with complicated geometries as compared to rigid grippers. Such grippers are an illustration of morphological computation, where mechanical compliance and material softness significantly reduce control complexity.The improved genetic (IG) and enhanced Cosserat (EC) algorithms carry out the grasping function. The actuator is made of shape memory alloy(SMA) and has configurable degrees of freedom (DoF).The proposed soft finger was prototyped using 3D printing and silica-reinforced polysiloxane cross-linked polymer, and it was then simulated using ANSYS software. The geometric advantage correlations of the prototyped finger's experimental input force against pressure and output stress, strain, and total deformation are in good agreement with the results of the simulation. The soft robotic gripper, which is based on the robotic operating system (ROS), is put on a 3-axis SCARA arm to show off its capacity to handle a variety of delicate things of different sizes and shapes, including eggs, fruits, vegetables, and glass objects. According to test results, the proposed end-effector gripper is capable of grabbing an object with a maximum weight of 401.9grams and a maximum diameter of 240mm. The suggested soft gripper's force and displacement at larger pressure are 12.5 psi, primary stiffness is 4.84 N/mm, and maximum load-bearing capacity is 36.4 N. The designed gripper model offers an improved object grasping with various curvatures of 213.65 pulling force of patterned at 35 kpa, 51.45 pulling force of non-patterned at 35 kpa, and 126.87 maximum pulling forces at 50 kpa, according to experimental validations and analysis of object grasping kinematic pulling force.During "pick and place" tasks, the versatile two-fingered robotic gripper must be able to recognize finger bending and stiffening. The humanistic grippers may substantially enhance the interaction between a gripper and exploitable materials.

Atomistic insights into migration mechanism of graphene-based membranes on soil mineral phases

Graphene-based membranes (GBM) will migrate in the soil and enter the groundwater system or plant roots, which will eventually pose potential risks to human beings. The migration mechanism of GBM depends on the interface behavior of complex soil components. Herein, we use molecular dynamics (MD) simulations to probe the interface behavior between GBM and three type minerals (quartz, calcite and kaolinite). Based on the investigation of binding energy, maximum pulling force and barrier energy, the order of the difficulty of GBM adsorption and desorption on the three minerals from small to large is roughly: quartz, calcite and kaolinite respectively. The graphene-oxide (GO), improves the binding energy and energy barrier, making GBM difficult to migrate in soil. Remarkably, a larger GBM sheet and high velocity external load improve GBM migration in soil to a certain extent. These investigations give the dynamic information on the GBM/mineral interaction and provide nanoscale insights into the migration mechanisms of GBM in soil.

A novel multi objective constraints based industrial gripper design with optimized stiffness for object grasping

Soft gripper design is a rising area of research due of its great possibilities in automation. One difficult problem in robot design is the ability to grasp a broader variety of items with variable stiffness, forms, and sizes in a single gripper. An ideal soft robotic gripper design with variable stiffness was designed in this research as a grasping model. Its distinctiveness is found in the methods utilized for modelling actuators and in the shifting stiffness characteristics of silicon soft gripper. When modelling the actuator in this case, multi-objective functions like gripping displacement and force transmission ratio are taken into account, and the actuator functions are controlled by the MDF (multiple degrees of freedom). The precise stiffness needed to grasp the item is then chosen using an adaptive optimization method. This enhanced weight-based horse herd (IHH) optimization method carries out the stiffness adjustment based on actuation pressure. Additionally, the suggested soft robotic gripper with variable stiffness employs the adaptive level set (ALS) technique to build the gripping force model. Additionally, several validations are offered in relation to the outcomes for item gripping by the suggested soft gripper. This shown that the results of the created soft gripper excelled those of other methods. The developed ABBIRB 1410 robot gripper type may enhance the work cycle in industrial applications and performs object grabbing with dependability and speed. The experimental validations show that the developed gripper model provides an enhanced object grasp with a range of curvatures, delivering a maximum pulling force of 121.07 kPa at 50 kpa, 119.15 kPa for patterned pulling, and 45.05 kPa for non-patterned pulling. The designed gripper type has a curve with a minimum size of 1.1 mm and a maximum size of 218 mm. Additionally, the soft gripper for industrial applications is examined with variously sized and weighted items. The suggested gripper model achieved an RMSE performance of 2.9 and a Pearson correlation of 0.993.

The Pullout Mechanical Properties of Shrub Root Systems in a Typical Karst Area, Southwest China

Roots play a major role in reinforcing and stabilizing soil. The pullout mechanical characteristics of soil reinforcement and slope protection of the root systems of dominant shrub species (Pyracantha and Geranium) were estimated by in-situ pullout tests in a karst area, in which roots were pulled out from soil to reliably test the pulling force. The goals of this study were to discover the pullout mechanical properties of roots in karst areas and to try to analyse the impact of the root system on landslide control. The F–s curves were multipeak curves with a noticeable main peak and main double peaks. The curves showed a linear increasing trend at the initial stage of drawing and decreased rapidly after reaching the peak. The F–s curves of root systems inserted into rock cracks showed secondary fluctuations in the later stage of drawing, and rock cracks stimulated the tensile efficiency of the root system more effectively. Field in situ pullout results indicate that tree roots fail progressively rather than simultaneously. The maximum pulling force had a linear relationship with the increase in soil thickness and a disproportionate increasing trend with the increasing number of broken roots. The displacement of the maximum peak was different between the two tree species and was concentrated at 5–15 cm and 5–25 cm for Pyracantha and Geranium, respectively. The maximum pulling force of Geranium was 1.29 times that of Pyracantha, and the root system of Geranium had strong pullout resistance. We concluded that the peak distribution of the F–s curves was affected by broken roots and rock cracks, while soil thickness and the number of broken roots had positive effects on the maximum pulling force, all of which is helpful in understanding the effect of root pullout mechanical properties on landslides in karst areas.

Effects of Axial Relative Ground Movement on Small Diameter Polyethylene Piping in Loose Sand

Small diameter (42 mm) medium density polyethylene (MDPE) pipes are widely used in the gas distribution system in Canada and other countries. They are sometimes exposed to ground movements resulting from landslides or earthquakes. The current design guidelines for evaluating the pipes subjected to ground movement were developed for steel pipes of larger diameters and may not apply to flexible MDPE pipes. This paper evaluates 42 mm diameter MDPE pipes buried in loose sand under axial relative ground movement for developing a design method for the pipes. MDPE is a viscoelastic material; therefore, the behaviour of MDPE pipes exposed to landslides would depend on the rate of ground movements. In this research, full-scale laboratory tests were conducted to investigate the responses of buried pipes under various rates of relative axial displacement. Finite element modelling of the tests was used to interpret the observed behaviour using the continuum mechanics framework. The study revealed that the pulling force on the pipe depends on the rate of relative ground displacement (pulling rate). The nondimensional pulling force possessed a nonlinear relationship with the pulling rate. A rate-dependent interface friction angle could be used to calculate the maximum pulling forces using the conventional design guidelines for the pipes in loose sand. Based on the pulling force, the pipe wall strains can be estimated using the methods available for larger diameter pipes.

Unique steel belt press technology for high strength papers from high yield pulp

The dry strength properties of hot-pressed moist paper improved as stiff high-yield pulp fibers soften and the sheet density increased. Very high wet strength was also achieved without adding strengthening agents. This research focuses on a new hot-pressing methodology based on a steel belt-based pilot cylinder press with infrared heating. The heated steel belt transports the moist paper into the cylinder nip with two adjacent steel rollers with adjustable nip pressure. The temperature ranges up to 300 °C, maximum speed is 5 m/min, maximum pulling force from the steel belt is 70 kN and the line load in the two press nips is 15 kN/m each. High peak pressures are possible due to the hard press nip between steel rolls and steel belt, allowing a good heat transfer to the paper. The long dwell time allows strained drying of the paper which results to high density and high wet strength. Paper samples from high-yield pulps were tested at different nip pressures, temperatures and machine speeds while the dry content was kept constant at about 63%. High nip pressure showed the largest effect on densification and dry strength. While high temperature and long dwell time seem to be most important in achieving high wet strength.

A paper fortune teller-inspired reconfigurable soft pneumatic gripper

Soft pneumatic grippers (SPGs) have shown great grasping performances for various objects due to their simplicity, adaptability and rapid response. However, there are few SPGs that can grasp both flat and non-planar targets robustly. A reconfigurable mechanism that can transform the gripper into different states for grasping varied objects is desired by such versatile SPGs. Paper fortune teller (PFT) is a distinctive origami with 2D/3D shape switchability and 3D shape reconfigurability. In this paper, we propose a novel reconfigurable SPG which is inspired from PFT and augmented with an indirect vacuum adhesion (IVA) mechanism. The resultant gripper can not only lift flat-surface objects such as a piece of square glass (278 g) with the IVA force in its pad shape, but also pick up non-planar objects such as an orange (151 g) in a traditional grasping way in its four-converging-fingered shape. The experimental results reveal that our gripper can produce a maximum IVA force of about 4.24 N on acrylic plates and a maximum pulling force of about 2.10 N on 3D-printed non-planar objects respectively. The gripper’s traditional grasping robustness is also demonstrated when non-planar objects are placed irregularly (allowing up to 55 mm multi-orientation offsets or 20° multi-orientation drift angles). This new SPG design realizes the multi-function nature of origami transformation and is expected to promote the application of origami and soft gripper technologies.

Effect of combined treatment with pulsed electromagnetic field stimulation and sclerostin monoclonal antibody on changes in bone metabolism and pedicle screw augmentation in rabbits with ovariectomy-induced osteoporosis.

Both pulsed electromagnetic field (PEMF) stimulation and sclerostin monoclonal antibody are useful for treating osteoporosis, but whether the two therapies have synergistic effects on both screw fixation quality and bone metabolism of ovariectomy-induced osteoporosis has not been reported. We used ovariectomy to create a rabbit model of postmenopausal osteoporosis. Then, specimens were fixed with pedicle screws in the L4 vertebral body. Rabbits were randomly divided into an OVX control group, PEMF group, Scl-Ab group, and PEMF+Scl-Ab group. The PEMF group was given PEMF magnetic therapy, the Scl-Ab group was administered a subcutaneous Scl-Ab injection, and the PEMF+SclAb group received both therapies. The OVX group was injected subcutaneously with the same dose of saline instead. After eight weeks of treatment, the bone metabolism index, bone mineral density (BMD), and bone microstructural, biological, and biomechanical parameters were evaluated. BMD significantly decreased six months post-ovariectomy. Compared with that of the OVX group, the BMD of the PEMF, Scl-Ab, and PEMF+Scl-Ab groups increased by 20.3%, 19.9%, and 35.0%, respectively. The maximum pulling force of pedicle screws increased by 14.0%,15.0% and 19.1%, and the maximum failure power consumption of pedicle screws increased by 27.9%, 27.2% and 33.6%, respectively; these differences were statistically significant (P<0.05). The bone metabolism index and bone microstructure parameters of the PEMF+Scl-Ab group were more optimal than those in the single treatment group. Both Scl-Ab and PEMF therapy can enhance the BMD and the mechanical strength of pedicle screws in osteoporotic bones of rabbits with postmenopausal osteoporosis. However, combination of the two measures has achieved even better results, yielding potential clinical application value.

Randomized controlled trial on application of negative pressure materials of polyvinyl alcohol and polyurethane in full-thickness burn wounds after escharotomy

Randomized controlled trial on application of negative pressure materials of polyvinyl alcohol and polyurethane in full-thickness burn wounds after escharotomy

A New Type of Rotary Magnetic Actuator System Using Electromagnetic Vibration and Wheel

In recent years, large structures, such as bridges, which are a type of social infrastructure, have been constructed with increasing traffic volume. For this reason, inspection and maintenance of social infrastructures, such as large bridges and tanks, is important. In the present paper, a magnetic wheel actuator system capable of movement using a new principle of locomotion was proposed and tested. The experimental results indicated a maximum pulling force of 1.6 N. By on-off control of the attractive force of the magnetic wheel, the actuator system was demonstrated to be able to move on a step having a height of 10 mm. Furthermore, the proposed actuator system could freely rotate in horizontal and vertical planes of over angles of 360°.

Measuring Forces in Suture Techniques for Wound Closure

BackgroundThe use of sutures remains the first choice for wound closure. However, incorrect use of a suture technique can lead to impaired healing. Many techniques are described for high-tension wounds, but not much is known about their mechanical properties. Complications of excessive tension include dehiscence, infection, and ischemic necrosis and could be prevented. This study aimed to compare forces in five techniques (single, horizontal mattress, vertical mattress, pulley, and modified pulley suture) in a standardized wound tension model. Materials and methodsA standardized neoprene wound model was developed on the ForceTRAP system (MediShield B.V., Delft, The Netherlands) to mimic a 5 Newton (N) wound. Five different suture techniques were each repeated 10 times by a student, resident dermatology, and dermsurgeon. The pulling force of the suture's first throw was measured with the Hook-in-Force sensor (Technical University Delft, The Netherlands). Changes in wound tension were measured by the ForceTRAP system. The ForceTRAP is a platform measuring forces from 0 to 20 N in three dimensions with an accuracy of 0.1 N. The Hook-in-Force is a force sensor measuring 0-15 N with an accuracy of 0.5 N. Maximum and mean forces were calculated for each suture technique and operator. ResultsMean maximum pulling force: 5.69 N (standard deviation [SD], 0.88) single, 7.25 N (SD, 1.33) vertical mattress, 8.11 N (SD, 1.00) horizontal mattress, 3.46 N (SD, 0.61) pulley, and 4.52 N (SD, 0.67) modified pulley suture. The mean force increase on the skin (substitute) ranged between 0.80 N (pulley) and 0.96 N (vertical mattress). ConclusionsThe pulley suture requires less pulling force compared with other techniques. The mechanical properties of sutures should be taken in consideration when choosing a technique to close wounds.

Decohesion of a rigid flat punch from an elastic layer of finite thickness

Interfacial bond strength is a crucial mechanical property of solid adhesive joints that plays an important role in a wide range of applications. A common way of quantifying mechanical strength of an adhered interface is to measure the apparent adhesion strength by finding the maximum pulling force in a tensile bond test and dividing it by the area. Despite the simplicity of this method, there is growing evidence suggesting that the measured quantity is not necessarily an intrinsic attribute of the interface but depends on thickness of the adhesive film and size of the interface. In this work, the critical pull-off force of a flat rigid punch adhered to an elastic film of finite thickness is studied via asymptotic analysis as well as finite element (FE) simulations. The decohesion behavior is found to be governed by two dimensionless parameters η and φ: the former represents the deformation of the interface relative to the interaction distance of interfacial forces, while the latter denotes a correction factor due to finite thickness of the film. As η changes from 0 to infinity, the interface decohesion would take place from uniform detachment (DMT-like) to crack-like propagation (JKR-like). The transition behavior can be well described by an empirical solution, which suggests a new rational procedure to consistently characterize the intrinsic adhesion properties of an adhered interface from tensile bond tests. Finally, the general empirical solution and the adhesion characterization procedure are directly validated by a series of experiments via detaching a stainless-steel flat punch from adhesive Polydimethylsiloxane (PDMS) films. This work not only offers a clear and explicit solution to capture the transition behavior of interface decohesion but also provides a guideline for modulating adhesion performance via geometry rather than chemistry of the adhesives.

Feedback based simulator training reduces superfluous forces exerted by novice residents practicing knot tying for vessel ligation

BackgroundTechnological advances have led to the development of state-of-the-art simulators for training surgeons; few train basic surgical skills, such as vessel ligation. MethodsA novel low-cost bench-top simulator with auditory and visual feedback that measures forces exerted during knot tying was tested on 14 surgical residents. Pre- and post-training values for total force exerted during knot tying, maximum pulling and pushing forces and completion time were compared. ResultsMean time to reach proficiency during training was 11:26 min, with a mean of 15 consecutive knots. Mean total applied force for each knot were 35% lower post-training than pre-training (7.5 vs. 11.54 N (N), respectively, p = 0.039). Mean upward peak force was significantly lower after, compared to before, training (1.29 vs. 2.12 N, respectively, p = 0.004). ConclusionsSimulator training with visual and auditory force feedback improves knot-tying skills of novice surgeons.

Force Barrier for Lipid Sorting in the Formation of Membrane Nanotubes

Abstract Understanding lipid sorting of multicomponent cell membranes associated with tubular deformation is of essential importance to many cell activities such as filopodial growth and protein-mediated vesiculation. Here, we conduct theoretical analysis to investigate how the membrane tubulation induced by an external pulling force over a finite region is regulated by the coupling between the lipid composition and the membrane bending rigidity and tension. It is shown that the presence of the lipid-disordered phase facilitates the nanotube formation by reducing the force barrier. As the pulling region size and the membrane tension increase, the membrane tubulation becomes discontinuous regardless of the coupling effect. The direct proportional relationships between the maximum pulling force and size of pulling region at different coupling scenarios are identified. Analytical solutions for the linear force-extraction relation and the membrane configurations in the early stage of the membrane extraction are obtained. Our results indicate that in the case of a relatively small pulling region, the coupling between the membrane composition and mechanical properties plays an important role in regulating the membrane extraction, and such an effect due to the phase separation diminishes gradually as the pulling region enlarges and the force barrier becomes dominated by a large pulling region.

Long Shape Memory Alloy Tendon-based Soft Robotic Actuators and Implementation as a Soft Gripper

Shape memory alloy (SMA) wire-based soft actuators have had their performance limited by the small stroke of the SMA wire embedded within the polymeric matrix. This intrinsically links the bending angle and bending force in a way that made SMA-based soft grippers have relatively poor performance versus other types of soft actuators. In this work, the use of free-sliding SMA wires as tendons for soft actuation is presented that enables large increases in the bending angle and bending force of the actuator by decoupling the length of the matrix and the length of the SMA wires while also allowing for the compact packaging of the driving SMA wires. Bending angles of 400° and tip forces of 0.89 N were achieved by the actuators in this work using a tendon length up to 350 mm. The tendons were integrated as a compact module using bearings that enables the actuator to easily be implemented in various soft gripper configurations. Three fingers were used either in an antagonistic configuration or in a triangular configuration and the gripper was shown to be capable of gripping a wide range of objects weighing up to 1.5 kg and was easily installed on a robotic arm. The maximum pulling force of the gripper was measured to be 30 N.

Estimating muscle activation patterns during overground walking for typically developing children and children with spastic cerebral palsy

This study investigated the stepping boundary – the force that can be resisted without stepping – for force-controlled perturbations of different durations. Twenty-two healthy young adults (19–37 years old) were instructed to try not to step in response to 86 different force/time combinations of forward waist-pulls. The forces at which 50% of subjects stepped (F50) were identified for each tested perturbation durations. Results showed that F50 decreased hyperbolically when the perturbation’s duration increased and converged toward a constant value (about 10% BW) for longer perturbations (over 1500 ms). The effect of perturbation duration was critical for the shortest perturbations (less than 1 s).In parallel, a simple function was proposed to estimate this stepping boundary. Considering the dynamics of a linear inverted pendulum + foot model and simple balance recovery reactions, we could express the maximum pulling force that can be withstood without stepping as a simple function of the perturbation duration. When used with values of the main model parameters determined experimentally, this function replicated adequately the experimental results.This study demonstrates for the first time that perturbation duration has a major influence on the outcomes of compliant perturbations such as force-controlled pulls. The stepping boundary corresponds to a constant perturbation force-duration product and is largely explained by only two parameters: the reaction time and the displacement of the center of pressure within the functional base of support. Future work should investigate pathological populations and additional parameters characterizing the perturbation time-profile such as the time derivative of the perturbation.

Rescuing Sensorimotor Declines in a Rat Model of Musculoskeletal Disorders: Is Rest Best?

Overuse‐induced musculoskeletal disorders (MSDs) are a leading cause of pain and physical disability worldwide. Substance P (SubP) and its primary receptor, neurokinin‐1 (NK1R), are known for their role in pain perception, yet may also be involved in increasing tissue fibrosis. Fibrosis may be a key factor in motor dysfunction, discomfort and pain in patients with overuse‐induced MSDs. In this study, we pharmacologically targeted the SubP‐NK1R pathway in a clinically relevant operant rat model in which a high repetition, high force (HRHF) pulling task was performed.AimWe hypothesized that blocking the SubP‐NK1R pathway would reverse or at least reduce overuse‐induced sensorimotor declines.MethodsFemale Sprague‐Dawley rats pulled a lever bar at 48% their maximum pulling force (MPF) with self‐chosen variable force levels (+/− 10% of the 48% target) at high repetition rates. The HRHF task was performed for 12 wks (2 hrs/day, 3 days/wk). After 12 weeks, HRHF task rats were either: 1) euthanized; 2) rested 4 wks; or, 3) rested 4 wks while receiving a NK1R antagonist (NK1RA). Control rats were euthanized at matched time points as HRHF task rats. All rats were assayed every 3 weeks for reflexive grip strength and forepaw mechanical allodynia (von Frey filaments). A thermal sensitivity assay was performed in their final week before euthanasia. Serum and forelimb tissues were analyzed for fibrogenic proteins. Anti‐CD68 IHC was performed to assess macrophage infiltration in the median nerve.ResultsReflexive grip strength declined significantly in all HRHF task animals by week 12. Rest alone improved grip strength, although NK1RA rescued it. Forepaw mechanical sensitivity changes were not evident until HRHF task week 9 (hypersensitivity to a 0.4 gram sized filament). Interestingly, hyposensitivity to 6 and 8 gram sized filaments was also present in 12 week HRHF rats. Rest (+/− NK1RA) improved these sensory deficits. Hyposensitivity to noxious warm temperatures was observed in 12 week HRHF rats. The drug was anti‐nociceptive, as warm temperature hyposensitivity was enhanced in both control+NK1RA and HRHF+Rest+NK1RA rats. Only untreated HRHF rats showed increased muscle and serum fibrogenic proteins, and CD68‐positive cells in median nerve branches, compared to control rats.ConclusionPast results from our lab, in which rats pulled at 55% their MPF, resulted in early musculoskeletal and nerve tissue injury and sensorimotor deficits from which the rats did not recover, even with 12 weeks of rest. We found here, for the first time, that a 4 week rest was sufficient for recovery in rats performing a slightly lower HRHF task. This recovery was also observed in HRHF+Rest+NK1RA rats; however, similar findings in control+NK1RA rats suggest that the functional improvements may be due to a drug‐induced diminished ability to sense pain and discomfort. Although our hypothesis that blocking the SubP‐NK1R pathway rescues overuse‐induced sensorimotor declines was supported, we importantly demonstrated that rest alone was just as effective, suggesting that simply reducing force effort and rest may be the most appropriate therapy for this patient population.Support or Funding InformationNIH‐NIAMS: AR056019ASBMR Gap AwardThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.