MIPS Faculty

Jack Dennerlein

Associate Professor of Ergonomics and Safety
Department of Environmental Health

665 Huntington Avenue, SPH1-305
Boston MA 02115
phone: 1 617-432-2028
fax: 1 617-432-3468
Email: jax@hsph.harvard.edu
Other Affiliations:

Education

Research Interests:

    The goal of my research is the prevention of work-related musculoskeletal disorders and injuries, primarily those of the upper extremity, through developing neuromuscular biomechanical and exposure assessment methods uncovering the fundamental etiology of injury mechanisms. Musculoskeletal disorders are a huge public health burden with annual estimated cost of $50 billion a year in the United States alone.

    Upper extremity neuromuscular biomechanics

    A large thrust of our research is to determine how the dynamic loading of the tissues of the upper extremity varies between different possible interventions such as alternative keyboard designs, workstation arrangements, and typing styles. We have previously developed methods to investigate stresses in finger muscles in isometric and dynamic protocols. This previous research has defined the finger joint motions, torques, stiffness and work during a key strike as well as the temporal pattern of muscle activity of the extrinsic and intrinsic finger muscles. Our new research goal expands this research to include similar parameters within the larger framework of the complete kinematic chain of the fingers, wrist, forearm, elbow and upper arm.

    Exposure assessment of computer workers

    Another large thrust of our research is developing and testing a exposure assessment system that directly measured an office worker's exposure to forces applied to the keyboard and mouse (intensity), wrist postural dynamics (intensity) and temporal patterns of input device use via our computer usage monitor program (frequency and duration). With this system, assessment of duration and frequency of exposure can be automated and implemented on a large scale through computer usage monitoring software; however, force and postural dynamic measurements cannot be automated and as a result are costly and time consuming for epidemiologic studies. We are developing and validating a task-based exposure assessment tool that integrates individual duration and frequency of the exposure along with the subject's specific intensities of the exposure.

    Muscle fatigue and physiological changed during repetitive movements

    Repetitive tasks often require sub-maximum muscle contraction, but quantifying the exposure-dose response to these loads over the day is quite difficult. We have observed that a muscle's physiological response as measured through its response to electrical stimulation will change with exposure to sub-maximum repetitive work. We are exploring relationships between specific exposure parameters such as work and force-time integrals and muscle physiology such as low frequency muscle fatigue. We are also exploring how these physiological changes effect performance and may lead as surrogate measures of exposure.

    Acute injury prevention

    Our research examines several aspects of injury prevention, mainly surveillance of unstudied work populations and hazard recognition and control. For the unstudied populations we have been exploring injury rates and types of injuries among workers employed on bicycles. Injury rates among bicycle messengers within the City of Boston are quite high, 15 times higher than the national average. The other thrust is the development of tools and methods to evaluate and control injury hazards within the workplace, specifically the construction industry.

Publications:

    Barrero LH, Hsu YH, Terwedow H, Perry M, Dennerlein JT, Brain JD, Xu X. Prevalence and physical determinants of low back pain in a rural Chinese population. Spine, In Press, 2006.

    Chaumont Men?ndez C, Amick BC III., Jenkins M, Janowitz I, Rempel DM, Robertson M, Dennerlein JT, Chang CH, Katz JN. A Multi-Method Study Evaluating Computing-Related Risk Factors Among College Students. Work: A Journal of Prevention, Assessment, and Rehabilitation, In Press

    Dennerlein JT, Johnson PW. Changes in upper extremity biomechanics across different mouse positions in a computer workstation. Ergonomics, In Press

    Dennerlein JT, DiMarino MHJ. Forearm EMG changes with the use of a haptic force-feedback computer mouse. Human Factors, 48(1): 130-141, 2006.

    Balakrishnan AD, Jindrich DL, Dennerlein JT. Designing a keyswitch utilizing horizontal forces of the fingertip. Human Factors, 48(1): 121-129, 2006.

    Jindrich DL, Balakrishnan AD, Dennerlein JT. Finger joint impedance during tapping on a computer keyswitch, J. Biomechanics, 37(10):1589-96, 2004.

    Dennerlein JT, Ciriello VM, Kerin KJ, Johnson PW. Forearm muscles fatigue during repetitive ulnar deviation tasks. American Industrial Hygiene Association Journal. 64(6):799-805, 2003.

    Dennerlein JT, Meeker J. Injuries among Boston Bicycle Messengers. American Journal of Industrial Medicine, 42(6): 519-525, 2002.

    Dennerlein JT, Soumekh FS, Fossel AH, Amick BC, Keller RB, Katz JN. Longer Distal Motor Latency Predicts Better Outcomes of Carpal Tunnel Release. J Occup Environ Med, 44:176-183, 2002.

    Dennerlein JT, Yang MC. Haptic force-feedback devices for the office computer: Performance and musculoskeletal loading issues. Human Factors, 43(2):278-86, 2001.

    Dennerlein JT, Diao E, Mote CD Jr., Rempel DM. In vivo finger flexor tendon forces while tapping on a key switch. J. of Orthopaedic Research, 17(2) 178-184, 1999.

Current Students and Classes