Kryztopher D. Tung PhD
Kryztopher D. Tung PhD
Faculty Mentor: Shawn C. Roll PhD, OTR/L, RMSKS, FAOTA, FAIUM
Kryztopher Tung currently acts as a postdoctoral researcher in the USC Chan Division of Occupational Science and Occupational Therapy. He is a researcher on the RO1 grant to investigate the risk factors associated with carpal tunnel syndrome in the profession of dental hygiene. Previously, he received his PhD in Mechanical Engineering from the University of Utah in 2018 for his work on predictive methods for heat illness potential utilizing wearable biosensors. Prior to this, he received his MS and BS in Mechanical Engineering from the University of Colorado, Boulder. His research interests lie in the prevention of upper extremity musculoskeletal disorders (UEMSD’s) in various working populations.
Doctor of Philosophy (PhD)
in Mechanical Engineering/ Ergonomics and Safety Focus
2018 | University of Utah, Salt Lake City
Master of Science (MS)
in Mechanical Engineering/ Bioengineering Focus
2012 | University of Colorado at Boulder
Bachelor of Science (BS)
in Mechanical Engineering/ Bioengineering Focus
2010 | University of Colorado at Boulder
Roll, S. C., Tung, K. D., Chang, H., Sehremelis, T. A., Fukumura, Y. E., Randolph, S., & Forrest, J. L. (2019). Prevention and rehabilitation of musculoskeletal disorders in oral health care professionals: A systematic review. The Journal of the American Dental Association, 150(6), 489-502. https://doi.org/10.1016/j.adaj.2019.01.031 Show abstract
Background. The authors’ objective in this systematic review was to describe the evidence for preventive and rehabilitative interventions for musculoskeletal disorders in oral health care.
Types of Studies Reviewed. The authors conducted systematic search, screening, and eligibility processes to identify experimental, quasiexperimental, observational, and survey research studies in which the investigators either directly evaluated or predicted the effects of preventive or rehabilitative interventions on the reduction of musculoskeletal symptoms in oral health care professionals.
Results. The authors identified and screened 3,571 unique abstracts, assessed 256 full-text articles for eligibility, and included 34 articles in the review. Investigators in 17 experimental studies described the results of preventive or rehabilitation interventions and in 17 survey research studies predicted or correlated preventive or protective techniques to a reduction in musculoskeletal symptoms. The primary techniques evaluated in the studies included equipment modification, ergonomic training, and physical exercise.
Conclusions and Practical Implications. The evidence suggests that magnification loupes and indirect-vision techniques have a positive effect on the reduction of musculoskeletal symptoms. In terms of evaluating intervention efficacy, other techniques have mixed evidence or are limited by low-level study design.
Keywords. Ergonomics; injury prevention; musculoskeletal disorders; dentists; dental hygienists
Tung, K. D., Shorti, R. M., Downey, E. C., Bloswick, D. S., & Merryweather, A. S. (2015). The effect of ergonomic laparoscopic tool handle design on performance and efficiency. Surgical Endoscopy, 29(9), 2500-2505. https://doi.org/10.1007/s00464-014-4005-9 Show abstract
Background. Many factors can affect a surgeon’s performance in the operating room; these may include surgeon comfort, ergonomics of tool handle design, and fatigue. A laparoscopic tool handle designed with ergonomic considerations (pistol grip) was tested against a current market tool with a traditional pinch grip handle. The goal of this study is to quantify the impact ergonomic design considerations which have on surgeon performance. We hypothesized that there will be measurable differences between the efficiency while performing FLS surgical trainer tasks when using both tool handle designs in three categories: time to completion, technical skill, and subjective user ratings.
Methods. The pistol grip incorporates an ergonomic interface intended to reduce contact stress points on the hand and fingers, promote a more neutral operating wrist posture, and reduce hand tremor and fatigue. The traditional pinch grip is a laparoscopic tool developed by Stryker Inc. widely used during minimal invasive surgery. Twenty-three (13 M, 10 F) participants with no existing upper extremity musculoskeletal disorders or experience performing laparoscopic procedures were selected to perform in this study. During a training session prior to testing, participants performed practice trials in a SAGES FLS trainer with both tools. During data collection, participants performed three evaluation tasks using both handle designs (order was randomized, and each trial completed three times). The tasks consisted of FLS peg transfer, cutting, and suturing tasks.
Results. Feedback from test participants indicated that they significantly preferred the ergonomic pistol grip in every category (p < 0.05); most notably, participants experienced greater degrees of discomfort in their hands after using the pinch grip tool. Furthermore, participants completed cutting and peg transfer tasks in a shorter time duration (p < 0.05) with the pistol grip than with the pinch grip design; there was no significant difference between completion times for the suturing task. Finally, there was no significant interaction between tool type and errors made during trials.
Conclusions. There was a significant preference for as well as lower pain experienced during use of the pistol grip tool as seen from the survey feedback. Both evaluation tasks (cutting and peg transfer) were also completed significantly faster with the pistol grip tool. Finally, due to the high degree of variability in the error data, it was not possible to draw any meaningful conclusions about the effect of tool design on the number or degree of errors made.
Keywords. Ergonomics, MIS tool design, Laparoscopy
Tung, K., Franz, J., & Kram, R. (2014). A test of the metabolic cost of cushioning hypothesis during unshod and shod running. Medicine & Science in Sports & Exercise, 46(2), 324-329. https://doi.org/10.1249/MSS.0b013e3182a63b81 Show abstract
Purpose. This study aimed to investigate the effects of surface and shoe cushioning on the metabolic cost of running. In running, the leg muscles generate force to cushion the impact with the ground. External cushioning (surfaces or shoes) may reduce the muscular effort needed for cushioning and thus reduce metabolic cost. Our primary hypothesis was that the metabolic cost of unshod running would decrease with a more cushioned running surface. We also hypothesized that because of the counteracting effects of shoe cushioning and mass, unshod running on a hard surface would have approximately the same metabolic cost as running in lightweight, cushioned shoes.
Methods. To test these hypotheses, we attached 10- and 20-mm-thick slats of the same foam cushioning used in running shoe midsoles to the belt of a treadmill that had a rigid deck. Twelve subjects who preferred a midfoot strike pattern and had substantial barefoot/minimalist running experience ran without shoes on the normal treadmill belt and on each thickness of foam. They also ran with lightweight, cushioned shoes on the normal belt. We collected V˙O2 and V˙CO2 to calculate the metabolic power demand and used a repeated-measures ANOVA to compare between conditions.
Results. Compared to running unshod on the normal belt, running unshod on the 10-mm-thick foam required 1.63% ± 0.67% (mean ± SD) less metabolic power (P = 0.034) but running on the 20-mm-thick foam had no significant metabolic effect. Running with and without shoes on the normal belt had similar metabolic power demands, likely because the beneficial energetic effects of cushioning counterbalanced the detrimental effects of shoe mass.
Conclusions. On average, surface and shoe cushioning reduce the metabolic power required for submaximal running.
Tung, K. D., Fukumura, Y. E., Baker, N. A., Forrest, J. L., & Roll, S. C. (2019). Identifying an optimal sampling method to estimate postural risk in a dynamic work task. Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 63(1), 1028-1033. https://doi.org/10.1177/1071181319631180 Show abstract
Introduction. The Rapid Upper Limb Assessment (RULA) is an ergonomic assessment tool used to screen for risk of musculoskeletal injury due to working posture. The RULA is traditionally applied once during a work task to approximate overall risk. No method exists for estimating a RULA score for work requiring frequent shifts in posture across an extended period of time.
Purpose. The goal of this study was to identify an optimal sampling method for applying the RULA across a long time-period that accurately represents overall risk.
Methods. Four right-handed female dental hygiene students were video recorded from three angles while performing hand scaling during patient clinic visits (88.97 minutes on average). RULA was continuously scored across the entire session, updating the score when a significant postural shift lasting for more than 15 seconds occurred. A time-weighted average (TWA) RULA score was calculated. Three sampling methods were evaluated: equivalent interval samples, random samples, and random samples selection weighted within “clock positions.” Each method was compared to the TWA using a paired samples t-test and percent difference.
Results. TWA RULA across the four students ranged from 3.4 to 4.3. Preliminary sampling averages using 10 samples were all within 0.2 of the TWA. Further iterations evaluating various sample sizes is ongoing.
Discussion. Preliminary results suggest that all three sampling methods provide a reasonably accurate approximation of the TWA score at the sampling rate tested. Future iterations of this analysis will be continued to identify the minimum required sampling rate to meet our TWA criterion.