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Predicting Forearm Muscle Activity in Hand-Intensive Work Tasks

This study aims to develop predictive models of forearm muscle activity in manually intensive work using readily obtainable variables such as age, sex, pain history, maximum grip strength, and self-reported hand force. While previous research has shown moderate success in predicting physical exposures during computer-based tasks, limited attention has been given to modeling muscle activity in manually-intensive jobs, which may involve greater variability and distinct influencing factors. By incorporating both individual characteristics and task-specific demands, this study seeks to assess the accuracy of estimating muscle load without relying on electromyography (EMG), which can be resource-intensive and require specialized expertise. These models could support more scalable ergonomic assessments in field settings where direct measurement is impractical. Ultimately, the goal is to inform exposure assessment and injury prevention strategies in physically demanding work environments.

Comparison of Sampling Strategies to Accurately Quantify the Duration and Frequency of Hand Exertion

Sampling strategies may impact the accuracy of measuring hand exertion frequency and duration, which are critical factors for assessing musculoskeletal disorder (MSD) risk. Using video analysis software, we analyzed short video segments of tasks categorized by pace-type. Repetition rate and duty cycle were calculated across different time intervals and job types, to assess within-subject and between-subject variability

Environmental Conditions and Recovery Strategies on Physiological Responses and Heat Stress Symptoms among Wildland Firefighters in Chile

The research aims to understand how heat, air pollution, and terrain characteristics influence the risk of experiencing heat stress events among wildland firefighters. Wearable devices are used to measure physiological variables such as heart rate, sweating, and body temperature to identify strategies that optimize recovery and prevent heat stress events.  The ultimate goal is to prevent these events, contributing to developing policies that promote a safer and more efficient work environment for wildland firefighters.

AI-based Video Tracking System for Ergonomics Risk Assessment

This study aims to validate an AI-based video tracking system for assessing ergonomic risks. Participants from various job categories will be included. By evaluating the system’s accuracy, reliability, and user acceptance, the research will demonstrate its potential to improve workplace ergonomics and reduce musculoskeletal disorders (MSDs). The findings could support the broader adoption of AI technologies in occupational health, offering an effective and scalable solution to the ongoing issue of MSDs in the workplace.

Prediction of Occupational Physical Activities using Inertial Measurement Units and Deep Learning Models

Machine learning models are applied to inertial measurement unit (IMU) data to predict occupational physical activities to provide a more reliable, informative and cost-effective approach to quantifying the physical demands of a job.

Poultry & Pork Line Speed Evaluation Study (PULSE) 

In conjunction with the USDA FSIS, this study seeks to determine possible health effects to establishment workers of increased evisceration line speeds in young chicken and pork processing plants, including ergonomic hazards in the workplace, measurement of biomechanical risk factors for acute and cumulative work-related musculoskeletal disorders (WRMSDs), medical management, and respiratory hazards from antimicrobial use.

LINK to poultry report: Poultry Processing Line Speed Evaluation Study (PULSE)

(PDF file)

LINK to swine report: Swine Processing Line Speed Evaluation Study (PULSE)

Janitor Workload Study

Janitor Workload Study 

This research study aims to assess workers' experiences with COVID-19 prevention measures at the worksite and how the work rate of janitors has been impacted by the pandemic. The study will determine the impact of work rate on janitor's health and safe and effective workloads for California Janitors. The study includes a qualitative survey and quantitative workload measurements using IMUs, Lumbar Motion Monitor, heart rate monitor and ActivPAL activity monitor.

Find recorded webinars about this project: COEH & California Labor Lab - YouTube

Evaluation of Exoskeletons for Construction Work​

In conjunction with Virginia Tech, we evaluated the use of lower back and shoulder exoskeletons for use in construction work.  This study is presented in a webinar hosted by the Center for Construction Research and Training (CPWR).

ENGLISH RESOURCES:

WATCH a short video about the project (English)

WEBINAR:  45-minutes about this project with more details (English)

​SPANISH RESOURCES:

WATCH a short video about the project (Spanish)

Past Projects

StandUp Kids Project​

We are studying ways to improve health, wellness and physical activity in 4th graders during the COVID-19 pandemic. The research study includes education and coaching on healthful habits, computer ergonomics and increasing physical activity.  A systems approach is evaluated and student participant measures include cognitive function, academic performance, functional performance, cardio-metabolic health indicators, and physical and mental wellbeing. 

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StandUp Kids Online Ergonomics Training - Free for public use

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ENGLISH RESOURCES:
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SPANISH RESOURCES:

Chair Design Study​

We are studying the impact of chair design on sitting behavior and usability during computer-based tasks over a prolonged bout of sitting.  Participants perform word processing, web browsing and PC gaming while sitting in two different chairs for three hours each. We measure pressure distribution and sitting behavior with Tekscan pressure mats and XSens IMUs, and gather performance data for PC tasks.  Subjective data about discomfort, usability and fatigue are collected with surveys.

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The Implementation and Impact of Prevention Measures on the Well Being of Grocery Workers during COVID-19

UC San Francisco/Berkeley is running a research study surveying people about working in food retail during the coronavirus outbreak.  This 10-minute survey will help to provide a better understanding of how to support and safeguard grocery workers during this time.

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Are you a grocery worker? Take the survey HERE

Drill Test Bench

A laboratory robotic system was designed and built that controls large hammer drills while they drill into concrete blocks. The system measures drilling speed and health related outcomes such as handle vibration, handle twist force, silica dust, and noise. The purpose is to compare drilling methods, bits and other factors on health and productivity. 

Video - Summary of Drill Comparison: Electric v. Pneumatic 

Video - Hazards of Jackleg drill

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[Funded by CPWR and NIOSH]

Concrete Dowel Drilling

Dowel and rod drilling involves drilling holes about 1 inch in diameter 1 - 2 feet deep into concrete in order to epoxy in rebar for structural upgrades. It is usually done manually with 30-lb pneumatic rock drills and is noisy and physically exhausting work. A Universal Drilling Jig is being developed and tested at commercial construction sites in the Bay Area. The goal is to improve productivity while reducing muscle loads, vibration exposure and exposure to silica dust. The Jig has also been used at several BART construction sites for drilling holes for large anchors as well as for setting anchors.  Read More

The Development and Application of Exposure Assessment Devices

Quantitative exposure assessment can be time consuming and expensive.  New technology such as inertial measuring units can change how we measure and monitor exposure for various applications on the job and individual level.  We are working on a variety of devices that measure, summarize and interpret physical exposures to improve how we measure, track and manage risk for MSDs.  These devices may be used to quantify job level exposures or track individual exposures for injured workers returning to work.

Biomechanical and Cardiovascular Strain in Hotel Room Cleaners

Studies have shown that hotel room cleaners are at risk for developing MSDs based on physical and psychosocial risk factors (Krause et al 2005 & 2009).  Our lab has studied whether certain interventions such as bed lift tools and fitted sheets reduce the workload associated with making beds.   We are also interested in whether the current workload leads to cardiovascular strain placing them at risk for cardiovascular disease.

Prospective studies of Carpal Tunnel Syndrome & related Work Disability

Prospective data on 3515 production workers, followed for up to 7 years, from 50 companies were pooled from 7 research groups [UC San Francisco, SHARP, U Utah, Wisconsin U, Washington U at St Louis, U Iowa, NIOSH](Dale 2013). The study is evaluating the association of personal, sports, hobby, workplace psychosocial and workplace biomechanical factors on predicting new cases of CTS (Harris et al 2015).  Currently, research is focused on adjusting for healthy worker survivor bias and identifying whether the predictors for those with work disability from CTS differ from those associated with the incidence of CTS.

The impact of Trunk and Upper Extremity Exoskeletons on Worker Fatigue, Productivity and Comfort

Risk factors contributing to upper extremity and spine MSDs include repetition, force and awkward posture. Overhead work, defined as working at or above the shoulder, has been identified as a category of tasks with especially high risk of WMSDs, and repetitive heavy lifting increases risk for the low back.  To mitigate risk of injury, force must be decreased, the duration of the task reduced, and/or amount of rest breaks increased. Exoskeleton technology has the potential to reduce exposure to force based risk factors, aid in return-to-work programs for injured individuals, and allow an aging workforce to remain in certain occupations.  Students involved with the design of 2 different exoskeletons are testing their effectiveness in a laboratory setting.  

The Association Between Heavy Load Carrying and Women's Health in Developing Countries

Musculoskeletal injuries comprise the largest burden of disease globally.  In fact, the 1990, 2005, and 2015 Global Burden of Disease studies listed low back pain (LBP) and neck pain as the primary contributor to years lost to disability (YLD) (GBD,2015), and “among the top ten causes of YLDs in every country” (GBD,2013). Musculoskeletal injuries such as LBP affect an individual’s capacity to carry out activities of daily living (ADLs), including the ability to work and care for children.  In low- and middle-income (LMIC) countries, this can have serious implications on livelihoods and household welfare.  As in many patriarchal developing countries, “domestic load-carrying” as a low-status activity and culturally assigned to females; thus women and children bear most of the carrying burden.   Our research explores the association between heavy load carrying and musculoskeletal pain and disability among women in Tanzania and Nepal.

Physical Exposures While Performing Colonoscopies

Gastroenterologists are at increased risk for developing recurrent thumb, hand, and elbow pain due to colonoscopy procedures.  We have evaluated forearm muscle loads and wrist postures during routine colonoscopy to understand distal upper extremity musculoskeletal risk factors associated with the 4 different subtasks of colonoscopy.  Currently we are testing various interventions to see if they reduce fatigue and discomfort among endoscopists during procedures.

Dental Hygiene - Pain is NOT in the job description

Many dental hygienists work in pain or know others suffering from musculoskeletal disorders, known as MSDs. Tendonitis, tennis elbow, carpal tunnel syndrome, and other MSDs are injuries caused by wear and tear to the tendons, nerves, muscles, and joints.  Dental hygienists and their employers can prevent MSDs by paying attention to ergonomics. Occupational Health Branch (OHB) of the California Department of Public Health partnered with the University of California, Berkeley, Ergonomics Program and the California Dental Hygienists’ Association (CDHA) to create videos on ergonomics by and for dental hygienists.  Watch videos

Hand Computer Interaction Studies using Hand Gestures

The use of standard input devices such as joysticks, keyboards and hand controllers to controlling self-travel and object selection in virtual reality is challenging due to the visual requirements of interacting with such devices and the visual constraints of VR.  Thus, hand gestures used to interact with the computer will be of increasing importance to improve the usability and acceptance of virtual reality. 

Tablet Design

Tablets and smart phones are used more and more for mobile business. Can the shape and texture of tablets be changed so that they are more secure and comfortable to hold in one hand? We are testing different tablet designs to evaluate their impact on productivity, comfort, and biomechanics. In the first study, 30 experienced users tested eight tablet prototypes while forearm electromyography, upper body posture, productivity and usability were evaluated. The study findings will be useful for designers of tablets and smart phones.

Palm Rejection During Direct Touch

The primary objective of this research is to quantify the effects of palm rejection on direct touch performance, shoulder loading, and discomfort. Subjects performed a series of tasks involving one, two, and three simultaneous touches on a touch display, both with and without palm rejection. Results suggest that palm rejection affords some performance (speed) and comfort benefits, but little benefit to shoulder unloading.

Keyboard Key Spacing

Surprisingly, the spacing of keys (e.g., 19 mm) on the conventional keyboards that we all use are based on 1950's conventions and not empirical data. Keyboards with smaller key spacing may be easier for people with smaller hands to use, could reduce the size and weight of laptops, and reduce the distance to reach to the mouse. We built and tested 8 keyboards with different key spacings on 89 experienced touch typists while measuring typing speed, error, forearm muscle activity, wrist posture and subjective preference. As it turns out, you can reduce key spacing without decreasing typing speed, even for typists with large hands.

Peripheral Trackpad Size

The primary objective of this research is to quantify the effects of desktop-trackpad size on performance, posture and discomfort. Subjects performed a series of drag-and-select target acquisition tasks using three trackpads (112X63 mm to 230 X130 mm) while the dependent variables were recorded. Results suggest that trackpads with a width between 112 and 178 mm and a depth between 63 and 100 mm may provide an appropriate balance between cost, footprint, performance, and comfort.