Human Factors & Ergonomics Program

Human Factors and Ergonomics Program (UCB / UCSF)

The HFE program provides specialized training in an HFE-related discipline like Environmental Health Sciences or Engineering (Mechanical, Industrial, Bioengineering), and trains tomorrow’s experts in exposure assessment and human-centered design to optimize performance and health.

Impact of Seat Material on Comfort, Preference and Performance During Computer-Based Tasks over a Prolonged Bout of Sitting

Melissa Afterman, MS-HFE, CPE
Frederick Houghton
Meg Honan, MS, CPE, PT
Alan Barr, MS
2022

Prolonged sitting time is associated with negative health outcomes, including physical discomfort. Chair design affects seat posture, micro-movement, and pressure distribution, which impacts the user experience. This study investigated the impact of mesh versus foam material, on comfort, preference, and subjective performance. Two chairs were used over a three-hour bout of sitting on two different days. Analysis showed no significant difference in pain, comfort, discomfort, or fatigue between chairs, but pain increased in both chairs during the last hour of sitting. The foam chair...

Comparison of the observer, single-frame video and computer vision hand activity levels

Robert Radwin
Yu Hen Hu
Oguz Akkas
Stephen Bao
Carisa Harris, PhD, CPE
Jia-Hua Lin
Alysah R Meyers
David Rempel
2022

Observer, manual single-frame video, and automated computer vision measures of the Hand Activity Level (HAL) were compared. HAL can be measured three ways: (1) observer rating (HALO), (2) calculated from single-frame multimedia video task analysis for measuring frequency (F) and duty cycle (D) (HALF), or (3) from automated computer vision (HALC). This study analysed videos collected from three prospective cohort studies to ascertain HALO, HALF, and HAL...

Hand Posture and Force Estimation Using Surface Electromyography and an Artificial Neural Network

Mengcheng Wang
Chuan Zhao
Alan Barr, MS
Hao Fan
Suihuai Yu
Jay Kapellusch
Carisa Harris, PhD, CPE
2021

Objective: The purpose of this study was to develop an approach to predict hand posture (pinch versus grip) and grasp force using forearm surface electromyography (sEMG) and artificial neural networks (ANNs) during tasks that varied repetition rate and duty cycle.

Background: Prior studies have used electromyography with machine learning models to predict grip force but relatively few studies have assessed whether both hand posture and force can be predicted, particularly at varying levels of duty cycle and repetition rate.

Method:...

Hand Posture and Force Estimation Using Surface Electromyography and an Artificial Neural Network

Mengcheng Wang
Chuan Zhao
Alan Barr, MS
Hao Fan
Suihuai Yu
Jay Kapellusch
Carisa Harris, PhD, CPE
2021

Objective: The purpose of this study was to develop an approach to predict hand posture (pinch versus grip) and grasp force using forearm surface electromyography (sEMG) and artificial neural networks (ANNs) during tasks that varied repetition rate and duty cycle.

Background: Prior studies have used electromyography with machine learning models to predict grip force but relatively few studies have assessed whether both hand posture and force can be predicted, particularly at varying levels of duty cycle and repetition rate.

Method:...

Analysis of the external acoustic meatus for ergonomic design: part II - anthropometric variations of the external acoustic meatus by sex, age and side in Chinese population

Hao Fan
Suihuai Yu
Mengcheng Wang
Mei Li
Xiao Zhao
Yihui Ren
Shuai Zhang
Dengkai Chen
Carisa Harris, PhD, CPE
2021

For devices worn inside the ear, detailed anthropometric data of the external acoustic meatus (EAM) is needed, yet lacking due to the complex and costly methodology associated with attaining such measurements. The purpose of this study was to provide the anthropometric characteristics of the EAM including variations by age group, sex, and side (right/left). 1400 external ears (700 Chinese subjects) were casted and scanned. A total of 23 EAM dimensions of length, width, angle, circumference and area were measured, most of which changed by age group, sex and side. 19 measurements were...

Movement Behavior and Health Outcomes among Sedentary Adults: A Cross-Sectional Study

Federico Arrippa
Athena Nguyen
Massimiliano Pau
Carisa Harris, PhD, CPE
2023

Background: Sedentary behavior, which is highly prevalent among office workers, is associated with multiple health disorders, including those of the musculoskeletal and cardiometabolic systems. Although prior studies looked at postures or physical activity during work or leisure time, few analyzed both posture and movement throughout the entire day.

Objective: This cross-sectional pilot study examined the movement behavior of sedentary office workers during both work and leisure time to explore its association with musculoskeletal discomfort (MSD)...

The Association Between Forceful Hand Exertions and Musculoskeletal Disorders of the Neck and Shoulder: A Prospective Cohort Study of US Manufacturing Workers

Alexa Zimbalist
David Rempel, MD, MPH
Lydia Feng
Carisa Harris, PhD, CPE
2022

Objective: The aim of this study was to estimate associations between biomechanical exposures and workplace neck and shoulder musculoskeletal disorders (NSMSDs) in a prospective cohort.

Methods: Manufacturing workers (N = 349) were followed for 28 months. Biomechanical exposures were collected on each individual, and physical examinations were performed every 4 months. Prevalent cases at baseline (n = 30) were excluded from the analysis.

Results: There were 18 incident cases of NSMSDs. Greater than 33% time in forceful hand...

Analysis of the external acoustic meatus for ergonomic design: part I - measurement of the external acoustic meatus using casting, scanning and rapid estimation approaches

Hao Fan
Suihuai Yu
Mengcheng Wang
Mei Li
Jianjie Chu
Yishu Yan
Shuai Zhang
Dengkai Chen
Carisa Harris, PhD, CPE
2021

Numerous ear-related wearables require precise measurements of the external acoustic meatus (EAM) to optimise function and comfort. The purpose of this study is to describe a novel methodology for measuring the EAM. A total of 23 measurement variables (18 novel) of the EAM from the entrance to the second bend were collected on 700 Chinese subjects (age: 15-83) using casting and 3D scanning over seven age spans: 10, 20, 30, 40, 50, 60 s and 70+. The ear horizontal plane was identified as a new reference plane for measurements and the medial concha was selected as the reference point...

Heavy Load Carrying and Symptoms of Pelvic Organ Prolapse among Women in Tanzania and Nepal: An Exploratory Study

Koyunco, Aybuke
Carisa Harris, PhD, CPE
Jillian Kadota
Agatha Mnyippembe
Prosper Njau
Tula Ram Sijali
Sandra McCoy
Michael Bates, PhD
Ndola Prata
2021

Heavy load carrying of water, firewood, and sand/stones is a ubiquitous activity for women living in developing countries. Although the intra-abdominal pressure associated with heavy load carrying is hypothesized to increase the risk of pelvic organ prolapse (POP) among women, relevant epidemiologic data are lacking. We conducted a comparative study involving two exploratory cross-sectional studies among convenience samples of women carrying heavy loads, with different characteristics: (1) as part of their activities for daily living, in Shinyanga region, Tanzania; and (2) working as...