Pulling Tasks Research Articles

Algorithmic assessment of shoulder function using smartphone video capture and machine learning

Tears within the stabilizing muscles of the shoulder, known as the rotator cuff (RC), are the most common cause of shoulder pain—often presenting in older patients and requiring expensive advanced imaging for diagnosis. Despite the high prevalence of RC tears within the elderly population, there is no previously published work examining shoulder kinematics using markerless motion capture in the context of shoulder injury. Here we show that a simple string pulling behavior task, where subjects pull a string using hand-over-hand motions, provides a reliable readout of shoulder mobility across animals and humans. We find that both mice and humans with RC tears exhibit decreased movement amplitude, prolonged movement time, and quantitative changes in waveform shape during string pulling task performance. In rodents, we further note the degradation of low dimensional, temporally coordinated movements after injury. Furthermore, a logistic regression model built on our biomarker ensemble succeeds in classifying human patients as having a RC tear with > 90% accuracy. Our results demonstrate how a combined framework bridging animal models, motion capture, convolutional neural networks, and algorithmic assessment of movement quality enables future research into the development of smartphone-based, at-home diagnostic tests for shoulder injury.

Effect of Load on Upper Extremity Muscles of Agricultural Workers of West Bengal

Introduction: Agricultural fields like weed management and horticultural operations are the most common and labor-intensive. Most of these tasks are completed with the help of push-pull-type agricultural machinery. The push-pull tasks are mainly done using agricultural machinery (push-pull weeders, manually operated rice transplanters or seeders, long-handled agricultural tools, etc.) by farm workers. Since these are manually operated machinery, long working hours in awkward positions are expected, which causes physical stress and musculoskeletal disorders in the operators. An electromyography study for agricultural workers during push and pull operations was conducted in this study. Methods: To evaluate muscle activity, a laboratory test setup was developed based on the ergonomic criteria of the uniform force application. Four loads (50, 100, 150, and 200 N) and the four most used upper body muscles (middle deltoid MD, triceps brachii TR, brachioradialis BR, and biceps brachii BI) during push-pull operations were selected for an electromyographic study on twelve medically fit agricultural workers as subjects. This study attempted to minimize muscle activity, thereby reducing overexertion injuries. Results: The most activated muscles during the pushing and pulling operations were TR and BR, respectively. The muscle activity of the TR during the pushing task was found to be 109 µV, 135 µV, 178 µV and 195 µV at loads of 50 N, 100 N, 150 N, and 200 N, respectively. During the pulling task, the muscle activity of the BR was 51 µV, 66 µV, 80 µV, and 126 µV at loads of 50 N, 100 N, 150 N, and 200 N, respectively. Conclusion: For all subjects, a load of 200 N was found difficult to operate compared to other selected loads during push and pull operations. Muscle activation was found to increase with increasing load for each of the selected muscles.

Effects of using passive back- and arm-support exoskeletons for cart pushing and pulling

Though studies have shown both BSEs and ASEs are effective in reducing physical demands for various manual material handling tasks, limited evidence is currently available on their effects in pushing and pulling tasks. We evaluated the impacts of using a passive back-support (BSE) and an arm-support exoskeleton (ASE) on trunk kinematics, and the back and arm musculature for pushing and pulling of a moderately loaded (100 kg) cart. Fourteen volunteers performed cart the tasks, each of whom was randomly assigned one of the exoskeletons (BSE or ASE). Wearing the BSE substantially reduced lumbar muscle activity during both pushing (up to ~39%) and pulling (up to ~35%) compared to not wearing EXOs, while wearing an ASE had no significant impacts. For the anterior deltoid muscle, neither BSE nor ASE had beneficial impacts. Findings from the current study help to understand the effects of BSEs and ASEs in pushing and pulling tasks.

Time Study for the Power Stow Rollertrack Conveyor for Airport Baggage Handling

A time study was conducted to evaluate the operation efficiency and the risk of musculoskeletal disorders (MSDs) for using the Power Stow Rollertrack Conveyor (PSRC) for baggage handling in the cargo holds of narrow-bodied aircrafts. The PSRC employs a retractable roller conveyor from a belt loader to provide powered transportation for loading and unloading baggage in the cargo holds. Thirteen baggage handlers at the Boston Logan International Airport participated in the data collection, which involved videotaping their work postures and methods during baggage handling operations in the cargo holds of the Boeing 737 and 757 aircrafts. Results showed that the PSRC provided improved efficiency in handling baggage, especially for unloading baggage by about 2 bags per minute. There was no significant difference in the total time spent on the risk factors for MSDs, such as lifting, pushing and pulling tasks per person for each bag between PSRC users and non-users.

Fatigue and Recovery of Muscles for Pulling Tasks.

Manual materials handling (MMH) contributes to musculoskeletal disorders (MSDs) in the workplace. The development and recovery of muscle fatigue are essential in work/rest arrangements for MMH tasks. A pulling experiment, including a muscle fatigue test and a muscle fatigue recovery test, was conducted. In the muscle fatigue test, the participant performed a pulling task on a treadmill with a walking velocity of 1 km/h until they could no longer do so. The load was either 30 or 45 kg. The maximum endurance time (MET) was recorded. The pull strength (PS) of the participant both before and after the pulling task was measured. The subjective ratings of muscle fatigue after the pulling task were recorded. In the muscle fatigue recovery test, the participant took a rest after performing the pulling task. The participants reported their subjective ratings of muscle fatigue on the CR-10 scale after taking a rest for a time period t, where t = 1, 2,…, 6 min. The PS of the participant was then measured again. It was found that the load significantly affected the MET for pulling tasks. The load was insignificant to the decrease of the PS, but was significant to the decrease rate (PS decrease per min) of the PS. The PS decrease rate for the 45 kg condition (30.8 ± 16.5 N/min) was significantly higher (p < 0.05) than that of the 30 kg condition (15.4 ± 5.5 N/min). The recovery time significantly affected the PS and CR-10. Two MET models were established to explore the development of muscle fatigue in pulling tasks. A PS model was constructed to describe the recovery of muscle force. A CR-10 model was proposed to show the subjective ratings of recovery. These models are beneficial for determining the work/rest allowance for pulling tasks.

Elbow-Height Handle and Staggered Stance Exhibited Greatest Force in Pushing and Pulling: A Study among Malaysian Adults

Introduction: Pushing and pulling activities are common in daily life and industrial workplaces. These activities are potentially contributing to muscle fatigue in the back and shoulder if not managed ergonomically. Therefore, this study aimed to quantify the maximum strength of Malaysian adults in horizontal symmetrical two-handed pushing and pulling with different handle heights and stances. Methods: Forty-seven participants of 24 males and 23 females were recruited in pushing and pulling experiments. The participants were assistant engineers and postgraduate students of a technical university. The dependent variable was the magnitude of push/ pull force. The independent variables consisted of action, handle height and stances. The experimental design was set for 2 actions, 3 handle heights and 2 stances, yielding 12 variables combinations. Results: Key findings of this study revealed that combination of pull action, handle height at elbow level and staggered stance exhibited greatest force. On the contrary, combination of push action, handle height at knuckle level and parallel stance resulted in lowest force. In pushing test, both male and female participants obtained greatest force of 233.3 N and 121.7 N, respectively, when the handle height was at elbow level and staggered stance. Similarly, in pulling test, males and females obtained highest force of 242.9 N and 152.4 N, respectively. Conclusion: This study concluded that handle height at elbow level and staggered stance exhibited greatest force in pushing and pulling activities. This study provides information to individuals who involved in pushing and pulling tasks with least force exertion to minimize muscle fatigue in the back and shoulder. Future studies should consider the following recommendations: 1) Participants of study should involve manufacturing industry workers. 2) To study the effect of pushing and pulling tasks on muscle activity.

Effects of Pause Design on the Decline in Pulling Effort and the Evaluation of Perceived Effort in Pulling Tasks

Pulling is one of the manual material handling activities that could lead to work-related musculoskeletal disorders. The objectives of this study were to explore the development of muscular fatigue when performing intermittent pulling tasks and to establish models to predict the pull strength decrease due to performing the tasks. A simulated truck pulling experiment was conducted. Eleven healthy male adults participated. The participants pulled a handle with a load of 40 kg, which resulted in a pulling force of approximately 123 N. The pulling tasks lasted for 9 or 12 min with one, two, or three pauses embedded. The total time period of the embedded pauses was 3 min. The pull strength after each pull and rest was measured. Ratings of the perceived exertion on body parts after each pull were also recorded. The results showed insignificant differences regarding the development of muscular fatigue related to rest frequency. We found that the development of muscular fatigue for pulling tasks with embedded pauses was significantly slower than that for continuous pulls. The forearm had a higher CR-10 score than the other body parts indicating that the forearm was the body part suffering early muscle fatigue. An exponential model was developed to predict the pull strength of the pulling tasks with embedded pauses. This model may be used to assess the developing of muscular fatigue for pulling tasks.

Key indicators of repetitive overuse-induced neuromuscular inflammation and fibrosis are prevented by manual therapy in a rat model

BackgroundWe examined the effectiveness of a manual therapy consisting of forearm skin rolling, muscle mobilization, and upper extremity traction as a preventive treatment for rats performing an intensive lever-pulling task. We hypothesized that this treatment would reduce task-induced neuromuscular and tendon inflammation, fibrosis, and sensorimotor declines.MethodsSprague-Dawley rats performed a reaching and lever pulling task for a food reward, 2 h/day, 3 days/week, for 12 weeks, while simultaneously receiving the manual therapy treatment 3 times per week for 12 weeks to either the task-involved upper extremities (TASK-Tx), or the lower extremities as an active control group (TASK-Ac). Results were compared to similarly treated control rats (C-Tx and C-Ac).ResultsMedian nerves and forearm flexor muscles and tendons of TASK-Ac rats showed higher numbers of inflammatory CD68+ and fibrogenic CD206+ macrophages, particularly in epineurium, endomysium and epitendons than TASK-Tx rats. CD68+ and CD206+ macrophages numbers in TASK-Tx rats were comparable to the non-task control groups. TASK-Ac rats had more extraneural fibrosis in median nerves, pro-collagen type I levels and immunoexpression in flexor digitorum muscles, and fibrogenic changes in flexor digitorum epitendons, than TASK-Tx rats (which showed comparable responses as control groups). TASK-Ac rats showed cold temperature, lower reflexive grip strength, and task avoidance, responses not seen in TASK-Tx rats (which showed comparable responses as the control groups).ConclusionsManual therapy of forelimbs involved in performing the reaching and grasping task prevented the development of inflammatory and fibrogenic changes in forearm nerves, muscle, and tendons, and sensorimotor declines.

Assessing Behavioral Impairment after Doxorubicin Chemotherapy in Rats

Chemotherapy has been associated with deficits in cognition and memory, delayed processing speed and executive function which may remain in patients as a long-term neurological effects. In addition, it also causes the disruption of hippocampal cell proliferation and neurogenesis, increased oxidative stress, and disruption in white matter. The cellular mechanisms linked with these side effects are poorly understood until now. Doxorubicin is Anthracycline agent that adversely affects the hippocampal neurogenesis and induces apoptosis by increasing oxygen radicals. It is considered first line therapy treatment for the most common cancers like breast, ovarian, and bladder. Young adult female Long Evans Hooded rats were divided into Doxorubicin treated (6mg/kg IP injection; once weekly for 4 weeks) and control groups (IP injection of sterile 0.9% saline on same schedule). We utilized the string pulling task, skilled ladder rung walking task, and other standard cognitive tests. We also performed immunohistochemistry to examine markers of inflammation related to chemotherapy and the extent to which chemotherapy would affect the process of neurogenesis. The results of the experiment we performed will be presented at the meeting and represent preliminary data for future studies.

Characterization of hand forces exerted during non-powered hospital bed pushing and pulling tasks

Accurate assessment of biomechanical risk associated with pushing/pulling tasks represents a challenging issue, especially in the health system where personnel are often required to maneuver beds and carts. Most studies in this field have been carried out in the laboratory, while few data have been collected under actual working conditions. This study aims to characterize the forces exerted during non-powered hospital bed maneuvering. Twenty participants were required to move a bed (equipped with a customized handlebar to measure exerted forces) along an actual hospital path including straight, turn and maneuver phases. The results show that higher forces are associated with the initial phase (peak and mean values 222 and 68 N) while the straight, turn and maneuvering phases required similar (lower) efforts. The combined effect of left, right and transversal forces suggests that the trunk of the operator might experience axial rotation, thus calling for further investigations of this aspect.

Kinematic and perceptual responses in heavy lifting and pulling: Are there differences between males and females?

This study investigated kinematic and perceptual differences between the sexes in a heavy lifting and pulling task. A 20 kg box was lifted from floor to chest height, and a 70 kg mannequin pulled across 20m. The effect of height, mass and average grip strength on kinematics and perceived workload was examined in 42 (19 females, 23 males) healthy individuals. A univariate linear regression analysis found females lifted with greater lumbar extension compared to males (p < 0.001), and adopted more hip (p = 0.006) and knee flexion (p = 0.036) in the pulling task. Females reported a greater perceived workload in both tasks (p < 0.001). After the multivariable analysis, only grip strength remained significant for perceived workload in the lift (p = 0.04), and height for knee flexion in the pull (p = 0.009). This highlights that height and strength are important factors driving kinematics and perceived workload. Clinicians may consider these factors in heavy manual tasks, more so than sex.

Blocking CCN2 preferentially inhibits osteoclastogenesis induced by repetitive high force bone loading

ABSTRACT Purpose/Aim: We recently found that blocking CCN2 signaling using a monoclonal antibody (FG-3019) may be a novel therapeutic strategy for reducing overuse-induced tissue fibrosis. Since CCN2 plays roles in osteoclastogenesis, and persistent performance of a high repetition high force (HRHF) lever pulling task results in a loss in trabecular bone volume in the radius, we examined here whether blocking CCN2 signaling would reduce the early catabolic effects of performing a HRHF task for 3 weeks. Materials and Methods: Young adult, female, Sprague-Dawley rats were operantly shaped to learn to pull at high force levels, before performing the HRHF task for 3 weeks. HRHF task rats were then left untreated (HRHF Untreated), treated in task weeks 2 and 3 with a monoclonal antibody that antagonizes CCN2 (HRHF+FG-3019), or treated with an IgG (HRHF+IgG), while continuing to perform the task. Non-task control rats were left untreated. Results: In metaphyseal trabeculae of the distal radius, HRHF Untreated and HRHF-IgG rats showed increased osteoblast numbers and other indices of bone formation, compared to controls, yet decreased trabecular bone volume, increased osteoclast numbers, and increased serum CTX-1 (a serum biomarker of bone resorption). HRHF+FG-3019 rats also showed increased osteoblast numbers and bone formation, but in contrast to HRHF Untreated and HRHF-IgG rats, showed higher trabecular bone volume, and reduced osteoclast numbers and serum CTX-1 levels (and statistically similar to Control levels). Conclusions: HRHF loading increased bone formation in each task group, yet blocking CCN2 dampened trabecular bone catabolism by reducing osteoclast numbers and activity.

The Effects of Ramp Gradients and Pushing-Pulling Techniques on Lumbar Spinal Load in Healthy Workers.

BackgroundMany tasks in industrial and health care setting are involved with pushing and pulling tasks up or down on a ramp. An efficient method of moving cart which reduces the risk of low back pain should be concerned. This study aimed to investigate the effects of handling types (HTs) and slope on lumbar spinal load during moving a cart on a ramp. We conducted a 2 × 2 × 4 factorial design with three main factors: 2 HTs, 2 handling directions of moving a cart and 4 degrees of ramp slope.MethodsThirty healthy male workers performed 14 tasks consist of moving a cart up and down on the ramp of 0°, 10°, 15°, and 20° degrees with pushing and pulling methods. Joint angles from a 3D motion capture system combined with subject height, body weight, and hand forces were used to calculate the spinal load by the 3DSSPP program.ResultsOur results showed significant effect of HT, handling directions and slope on compression and shear force of the lumbar spine (p < 0.001). When the ramp gradient increased, the L4/5 compression forces increased in both pushing and pulling (p < 0.001) Shear forces increased in pulling and decreased in pushing in all tasks. At high slopes, pulling generated more compression and shear forces than that of pushing (p < 0.01).ConclusionUsing the appropriate technique of moving a cart on the ramp can reduce the risk of high spinal load, and the pushing is therefore recommended for moving a cart up/down on ramp gradients.

Cooperation with closely bonded individuals reduces cortisol levels in long-tailed macaques.

Many animal species cooperate with conspecifics in various social contexts. While ultimate causes of cooperation are being studied extensively, its proximate causes, particularly endocrine mechanisms, have received comparatively little attention. Here, we present a study investigating the link between the hormone cortisol, cooperation and social bonds in long-tailed macaques (Macaca fascicularis). We tested 14 macaques in a dyadic cooperation task (loose-string paradigm), each with two partners of different social bond strength and measured their salivary cortisol before and after the task. We found no strong link between the macaques' cortisol level before the task and subsequent cooperative success. By contrast, we did find that the act of cooperating in itself led to a subsequent decrease in cortisol levels, but only when cooperating with closely bonded individuals. Two control conditions showed that this effect was not due to the mere presence of such an individual or the pulling task itself. Consequently, our study shows an intricate way in which the hypothalamic–pituitary–adrenal axis is involved in cooperation. Future studies should reveal whether and how our findings are driven by the anxiolytic effect of oxytocin, which has been associated with social bonding.

Between Two Rocks and in a Hard Place: Reflecting on the Biomechanical Basis of Shoulder Occupational Musculoskeletal Disorders.

The aim was to review the biomechanical origins of occupational shoulder damage, while considering the complexity of shoulder mechanics and musculoskeletal consequences of diverse task demands. Accessible measures of physical exposures are the primary focus of occupational shoulder assessments and analyses. This approach has led to guidelines and intervention strategies that are often inadequate for mitigating shoulder disorders amongst the complexity of modern workplace demands. Integration of complex shoulder mechanics into occupational assessments, analyses, and interventions is critical for reducing occupational shoulder injury risk. This narrative review describes shoulder biomechanics in the context of common injury mechanisms and consequent injuries, with a particular focus on subacromial impingement syndrome. Several modulators of shoulder injury risk are reviewed, including fatigue, overhead work, office ergonomics considerations, and pushing and pulling task configurations. Relationships between work requirements, muscular demands, fatigue, and biomechanical tissue loads exist. This review highlights that consideration of specific workplace factors should be integrated with our knowledge of the intricate arrangement and interpersonal variability of the shoulder complex to proactively evaluate occupational shoulder demands and exposures. A standard method for evaluating shoulder muscle exposures during workplace tasks does not exist. An integrated approach is critical for improved work design and prevention of shoulder tissue damage and accompanying disability. This review is particularly relevant for researchers and practitioners, providing guidance for work design and evaluation for shoulder injury prevention by understanding the importance of the unique and complex mechanics of the shoulder.

Individual and social factors affecting the ability of American crows to solve and master a string pulling task.

Crows and other birds in the family Corvidae regularly share information to learn the identity and whereabouts of dangerous predators, but can they use social learning to solve a novel task for a food reward? Here we examined the factors affecting the ability of 27 wild-caught American crows to solve a common string-pulling task in a laboratory setting. We split crows into two groups; one group was given the task after repeatedly observing a conspecific model the solution, the other solved in the absence of conspecific models. We recorded the crows' estimated age, sex, size, body condition, level of nervousness, and brain volume using DICOM images from a CT scan. Although none of these variables were statistically significant, crows without a conspecific model and large brain volumes consistently mastered the task in the minimum number of days, whereas those with conspecific models and smaller brain volumes required varying and sometimes a substantial number of days to master the task. We found indirect evidence that body condition might also be important for motivating crows to solve the task. Crows with conspecific models were no more likely to initially solve the task than those working the puzzle without social information, but those that mastered the task usually copied the method most frequently demonstrated by their knowledgeable neighbors. These findings suggest that brain volume and possibly body condition may be factors in learning new tasks, and that crows can use social learning to refine their ability to obtain a novel food source, although they must initially learn to access it themselves.

Shoulder muscle activity in off-axis pushing and pulling tasks

Workspace design can often dictate the muscular efforts required to perform work, impacting injury risk. Within many environments, industrial workers often use sub-maximal forces in offset directions in to accomplish job tasks. The purpose of this research was to develop methods to estimate shoulder muscle activation during seated, static, sub-maximal exertions in off-axis (non-cardinal) directions. Surface EMG signals were recorded from 14 upper extremity muscles in 20 right-handed university aged, right-handed males (age: 22 ± 3 years, weight: 77.5 ± 11.1 kg, height 179.0 ± 7.0 cm) participated in this study. Each participant performed 60 submaximal exertions (40N) directed at 4 off-axis phase angles of 45° (45°, 135°, 225°, and 315°) in 3 planes (frontal, sagittal, and transverse) in 5 hand locations within a right handed reach envelope. The influence of hand location and force direction on muscle activity was evaluated with a forced-entry stepwise regression model. The ability of previously published on-axis prediction equations to predict muscle activity during these off-axis exertions was also evaluated. Within each muscle, activity levels were affected by both hand location and three-dimensional force direction and activation levels ranged from <1 to 37 %MVE. For each force direction there were 75 predictive equations selected and used, and the specific equation that best predicted activation depended on the muscle, exertion direction and hand location evaluated. This work assists ergonomic workplace design to minimize muscle demands during commonly performed off-axis exertions. These estimated demands can be employed to improve workplace design to reduce workplace injuries and enhance worker productivity.

Activation pattern of the upper extremity muscles during dynamic push and pull tasks

Manual pushing and pulling is a common occupational task that has been associated with the development of various work-related musculoskeletal disorders, but research regarding the biomechanics of sub-maximal pushing and pulling exertions has been limited. This study was conducted to evaluate the activation pattern of upper extremity and shoulder muscles during sub-maximum dynamic pushing and pulling exertions with varying horizontal and vertical loads. Twenty young healthy female participants performed repetitive pushing exertions and pulling exertions against horizontal resistance (1 kg, 2 kg, or 3 kg) while supporting vertical hand load (0.6 kg, or 1.3 kg). Myoelectric signal of the seven upper extremity and shoulder muscles were collected during the exertions to assess the activation level of the muscles. Results found that the anterior deltoid muscle was the main mover of the sub-maximal pushing and the elbow flexors were the main muscles of the sub-maximal pulling exertions. The analysis on the effect sizes of two loads showed that the activation of the muscles near the shoulder joint were more sensitive to the horizontal load, while the forearm muscles and the elbow flexors were more sensitive to the vertical load. Study findings showed how muscles of the upper extremity and the shoulder would respond differently to the changes of the vertical and horizontal hand loads during sub-maximal pushing and pulling exertions. Results could be used to understand the mechanism of injury of low-to-moderate exertion pushing and pulling tasks such as hand sawing and floor vacuuming.

Unimodal statistical learning produces multimodal object-like representations.

The concept of objects is fundamental to cognition and is defined by a consistent set of sensory properties and physical affordances. Although it is unknown how the abstract concept of an object emerges, most accounts assume that visual or haptic boundaries are crucial in this process. Here, we tested an alternative hypothesis that boundaries are not essential but simply reflect a more fundamental principle: consistent visual or haptic statistical properties. Using a novel visuo-haptic statistical learning paradigm, we familiarised participants with objects defined solely by across-scene statistics provided either visually or through physical interactions. We then tested them on both a visual familiarity and a haptic pulling task, thus measuring both within-modality learning and across-modality generalisation. Participants showed strong within-modality learning and 'zero-shot' across-modality generalisation which were highly correlated. Our results demonstrate that humans can segment scenes into objects, without any explicit boundary cues, using purely statistical information.

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.