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Estimating in vivo passive forces of the index finger muscles: exploring model parameters.

Qin J; Lee D; Li Z; Chen H; Dennerlein JT
J Biomech Eng 2010 May; 43(7):1358-1363
We compared predicted passive finger joint torques from a biomechanical model that includes the exponential passive muscle force-length relationship documented in the literature with finger joint torques estimated from measures in ten adult volunteers. The estimated finger joint torques were calculated from measured right index fingertip force, joint postures, and anthropometry across 18 finger and wrist postures with the forearm muscles relaxed. The biomechanical model predicting passive finger joint torques included three extrinsic and three intrinsic finger muscles. The values for the predicted passive joint torques were much larger than the values calculated from the fingertip force and posture measures with an average RMS error of 7.6Ncm. Sensitivity analysis indicated that the predicted joint torques were most sensitive to passive force-length model parameters compared to anthropometric and postural parameters. Using Monte Carlo simulation, we determined a new set of values for the passive force-length model parameters that reduced the differences between the joint torques calculated from the two methods to an average RMS value of 0.5Ncm, a 94% average improvement of error from the torques predicted using the existing data. These new parameter values did vary across individuals; however, using an average set for the parameter values across subjects still reduced the average RMS difference to 0.8Ncm. These new parameters may improve dynamic modeling of the finger during sub-maximal force activities and are based on in vivo data rather than traditional in vitro data.
Biomechanical-modeling; Biomechanics; Equipment-operators; Ergonomics; Force; Laboratory-techniques; Laboratory-testing; Motor control; Musculoskeletal-system; Physiological-response; Posture; Statistical-analysis; Work-analysis; Work-performance; Work-practices; Author Keywords: Index finger; Passive muscle force; Joint torque; Musculoskeletal model; Monte Carlo simulation
Jack T. Dennerlein, Department of Environmental Health, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115
Publication Date
Document Type
Journal Article
Funding Type
Fiscal Year
Identifying No.
Grant-Number-R01-OH-008373; Grant-Number-T42-OH-008416
Issue of Publication
Priority Area
Services; Wholesale and Retail Trade
Source Name
Journal of Biomechanical Engineering
Performing Organization
Harvard University School of Public Health
Page last reviewed: October 22, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division