Comparison of muscle loadings between power and pinch grip tasks (original) (raw)
Related papers
A musculoskeletal model of the hand and wrist: model definition and evaluation
Computer Methods in Biomechanics and Biomedical Engineering, 2018
To improve our understanding on the neuromechanics of finger movements, a comprehensive musculoskeletal model is needed. The aim of this study was to build a musculoskeletal model of the hand and wrist, based on one consistent data set of the relevant anatomical parameters. We built and tested a model including the hand and wrist segments, as well as the muscles of the forearm and hand in OpenSim. In total, the model comprises 19 segments (with the carpal bones modeled as one segment) with 23 degrees of freedom and 43 muscles. All required anatomical input data, including bone masses and inertias, joint axis positions and orientations as well as muscle morphological parameters (i.e. PCSA, mass, optimal fiber length and tendon length) were obtained from one cadaver of which the data set was recently published. Model validity was investigated by first comparing computed muscle moment arms at the index finger metacarpophalangeal (MCP) joint and wrist joint to published reference values. Secondly, the muscle forces during pinching were computed using static optimization and compared to previously measured intraoperative reference values. Computed and measured moment arms of muscles at both index MCP and wrist showed high correlation coefficients (r ¼ 0.88 averaged across all muscles) and modest root mean square deviation (RMSD ¼ 23% averaged across all muscles). Computed extrinsic flexor forces of the index finger during index pinch task were within one standard deviation of previously measured in-vivo tendon forces. These results provide an indication of model validity for use in estimating muscle forces during static tasks.
Journal of Biomechanics, 2005
Risk factors for activity-related tendon disorders of the hand include applied force, duration, and rate of loading. Understanding the relationship between external loading conditions and internal tendon forces can elucidate their role in injury and rehabilitation. The goal of this investigation is to determine whether the rate of force applied at the fingertip affects in vivo forces in the flexor digitorum profundus (FDP) tendon and the flexor digitorum superficialis (FDS) tendon during an isometric task. Tendon forces, recorded with buckle force transducers, and fingertip forces were simultaneously measured during open carpal tunnel surgery as subjects (N ¼ 15) increased their fingertip force from 0 to 15 N in 1, 3, and 10 s. The rates of 1.5, 5, and 15 N/s did not significantly affect FDP or FDS tendon to fingertip force ratios. For the same applied fingertip force, the FDP tendon generated more force than the FDS. The mean FDP to fingertip ratio was 2.470.7 while the FDS to tip ratio averaged 1.571.0 (po0:01). The fine motor control needed to generate isometric force ramps at these specific loading rates probably required similar high activation levels of multiple finger muscles in order to stabilize the finger and control joint torques at the force rates studied. Therefore, for this task, no additional increase in muscle force was observed at higher rates. These findings suggest that for high precision, isometric pinch maneuvers under static finger conditions, tendon forces are independent of loading rate. r
A Musculoskeletal Model of the Hand for Biomechanical and Ergonomic Analyses of Manual Tasks
Consideration of hand biomechanics is essential during industrial manual tasks to minimize discomfort, prevent musculoskeletal disorders, and costs associated thereto. However, only limited data on muscles and joints are available for specific practical situations such as grasping. This study aims to develop a musculoskeletal model of the hand in order to evaluate not only the hand kinematics but also joint loads and muscular activities during a particular manual task. Movements of the hand and forearm are captured with an optoelectronic motion capture system (VICON system with T160 cameras recording 43 markers of 3mm-size). As example, a subject was asked to perform a 25mm-diameter cylinder grasping task. Using a modeling software (Adams.Msc with LifeMOD plug-in), a musculoskeletal model of the hand composed of 20 segments, 19 joints and 36 muscle/tendon units is designed and structured with 21 degrees of freedom. Raw motion capture data are then imported into the modeling software and accommodated to the musculoskeletal model. An inverse dynamics simulation is computed which permits to record joint angulations and muscle shortening/lengthening patterns. These elements are used to calculate internal and external forces (joint torques, muscle forces, gravity, etc.) necessary to guide the musculoskeletal model during a forward dynamics simulation. Muscle force results show that extensor digitorum muscles present a maximal production of force during the cylinder grasping task. Moreover, joint loads appear higher for metacarpophalangeal articulations during the movement. These results can be used in a clinical application to drive rehabilitation systems. Thus, this study demonstrates the relevance of the musculoskeletal modeling of human segments for biomechanical and ergonomic analyses of industrial tasks.
Comparison of tendon tensions estimated from two biomechanical models of the thumb
Journal of Biomechanics, 2009
Despite the paramount function of the thumb in daily life, thumb biomechanical models have been little developed and studied. Moreover, only two studies provided quantitative anthropometric data of tendon moment arms. To investigate thumb tendon tensions, biomechanicians and clinicians have to know the performances and the limits of these two data sets. The aim of this study was thus to compare the results of these two models and evaluate their performances in regard to prior electromyographic measurements (EMG).
Muscles co-activation and wrist position during sustained grip in healthy subjects
Objective -To evaluate surface electromyography activity (SEMG) of extensor carpi radialis (ECR) in relation to flexor digitorum superficialis muscles (FDS) during power sustained gripo task and to correlate this activity with wrist range of motion (ROM). Methods -Healthy female university students, right-handed students (N=34), mean age 23 years. The task was three grips with maximal isometric force using Jamar TM dynamometer. Results -Main outcome measures, we used surface electromyograpy and considered 100% maximum voluntary contractrion to represent the amplitude of electromyographic activity. ROM was measured with electrogoniometer Miotec TM . Mean percentages of FDS and ECR activity were 92.41 (±4.84%) and 82 (±14.79%), respectively. Rate between FDS and ECR activation was 1:0.89. Mean ROM wrist extension during task was 13.92±9.18°. There was no significant correlation between ROM and SEMG activity for forearm muscles. Conclusion -The high EMG activity of extensor muscles found in this study reinforces its important synergistic role during a power sustained hand grip. The normality parameters can be considered in preventive and rehabilitation programs. The findings also suggest that there are different strategies of wrist extension ROM during grip.
The effects of posture on forearm muscle loading during gripping
Ergonomics, 2003
The purpose of this study was to quantify the response of the forearm musculature to combinations of wrist and forearm posture and grip force. Ten healthy individuals performed five relative handgrip efforts (5%, 50%, 70% and 100% of maximum, and 50 N) for combinations of three wrist postures (flexed, neutral and extended) and three forearm postures (pronated, neutral and supinated). 'Baseline' extensor muscle activity (associated with holding the dynamometer without exerting grip force) was greatest with the forearm pronated and the wrist extended, while flexor activity was largest in supination when the wrist was flexed. Extensor activity was generally larger than that of flexors during low to mid-range target force levels, and was always greater when the forearm was pronated. Flexor activation only exceeded the extensor activation at the 70% and 100% target force levels in some postures. A flexed wrist reduced maximum grip force by 40 -50%, but EMG amplitude remained elevated. Women produced 60 -65% of the grip strength of men, and required 5 -10% more of both relative force and extensor activation to produce a 50 N grip. However, this appeared to be due to strength rather than gender. Forearm rotation affected grip force generation only when the wrist was flexed, with force decreasing from supination to pronation (p 5 0.005). The levels of extensor activation observed, especially during baseline and low level grip exertions, suggest a possible contributing mechanism to the development of lateral forearm muscle pain in the workplace.
Dynamic assessment of finger joint loads using kinetic and kinematic measurements
Assessing finger joint loading is essential for the prevention of musculoskeletal disorders of the hand, wrist and forearm. Due to the technical and invasive nature of direct measurement, biomechanical modeling is necessary to evaluate finger joint forces. Most existing finger models have used maximum grip strength in order to quantify joint loads, although it is unlikely that these forces are routinely experienced in typical daily tasks. The purpose of this investigation was to assess finger joint forces continuously during submaximal tasks using an inverse dynamics approach. Eight participants performed a series of finger movements while pressing on a six-degree of freedom force transducer with the index finger. Participants were asked to maintain a 10 N vertical force with the distal phalanx of the finger during the movement while receiving visual feedback. Simultaneously, kinematic data were obtained using an optoelectronic motion capture system at 60 Hz. The index finger (digit 2) was instrumented with 20 reflective markers (4 mm in diameter). The data were used to model the metacarpals and phalanges based on an innovative segment definition technique. Forces were applied to the distal segment of the finger model to calculate joint reaction forces. The finger movements used in this study included isolated flexion/extension of the distal interphalangeal, proximal interphalangeal and metacarpophalangeal joints of the index finger. Results provided by the current model were promising in comparison with the literature. Using an inverse dynamics approach, joint reaction forces were determined continuously during each finger movement providing joint force profiles for each task which were normalized to the external fingertip force. While the current detailed methodology is limited to the laboratory, a refined and simplified model could be used for ergonomic analysis of manual tasks in the workplace. The current model will be integrated with musculotendinous structures to better assess musculoskeletal implications of finger movements and to further understand the link between fingertip loading and hand pathologies.
Hand kinematics: Application in clinical practice
Indian Journal of Plastic Surgery, 2011
Pathological conditions of the hand consequent to injuries, paralysis, disease, arthritis and congenital difference results in loss or limitation of function, deformities, stiffness, inadequate power and poor position for pinch. The pathogenesis of deformities is influenced by bio-mechanical principles of joints and muscle function. The crippling impact of secondary changes due to edema, soft tissue contractures, muscle shortening and functional adaptations also have a mechanical basis. For clinicians and hand therapists, it is necessary to understand these fundamental principles of biomechanics to plan treatment modalities. Interpretation of mechanics of hand deformities in rheumatoid arthritis and paralysis will enable the treating team to identify the appropriate interventions of splinting, therapy and surgical procedures. Basic knowledge of the principles of hand clinical biomechanics will help the beginner to sail through the multitude of tendon transfers described in the text books of hand surgery and find the best solution for a particular clinical presentation. Similarly, knowledge of bio-mechanics will provide solutions to an experienced surgeon to plan treatment protocols for complex situations. The article presents a concise summary of the basic principles of hand bio-mechanics for common hand conditions seen in clinical practice. Understanding and applying these principles will help clinicians in planning and devising treatment options for common and complex hand conditions.