New Study: Identifying When Additional Slip Resistance is Needed

According to the 2009 study conducted by the Center for Disease Control (CDC), over 26.7% of Americans self-reported themselves as obese.  Approximately over 72.5 million adults in the United States suffer the risk of serious health conditions such as heart disease, heart disease, hypertension, stroke, type-2 diabetes, and specific types of cancer.  Aside from aggravated health issues, obesity can be attributed to the propensity overweight employees to slip and fall accidents in the work place. In comparison to the frequency of accidents for people who weigh normally (15%), middle-aged and older obese adults fall as much as 27% in a given year (Fjeldstad, Fjeldstad, Acree, Nickel & Gardner, 2008).

Statistics suggest that over 85% of manufacturing employees are obese or overweight (Pollack, et al., 2007).  Because of these numbers, a study has been conducted to illuminate the visible correlation between weight and the risk of falling, and the causes by which these accidents occur.

Obesity impairs balance when walking

The study conducted by Dr. Jian Liu from the Center for Neuromotor and Biomechanics Research at the University of Houston postulates that while there are inconclusive findings regarding the correlation between Body Mass Index (BMI) and postural instability among the overweight, the risk of slip-induced accidents might lie with dynamic processes such as walking.  The purpose of their study is to detect the causation of the variance between normal-weighted individuals and the obese (Liu, 2010).

The laboratory study involved twelve young adults, ages ranging from 18-26.  Seven of which were considered normal weight by the CDC, and five were classified as overweight.  Several tests were performed including various postural stability checks.  Subjects were instructed to walk on an instrumental split-belt treadmill at their regular pace to measure friction demand (required coefficient of friction).

The required coefficient of friction (RCOF) pertains to the minimum amount of friction necessary between floors and shoes in order to support walking (Chang, Chang & Matz, 2010).  The number relates to the traverse shear component involved with the shoe and floor interface.  Slip and fall is initiated when the heel does not firmly make contact with the floor.

The results of the study prove that the overweight group, as a whole, required a 17.5% higher friction than their normal counterparts.   A higher BMI could mean that the traverse shear component increases as the heel meets the floor.  The higher RCOF quantifies the increased need of surer footing because of the pressure applied by the feet.  Because of the higher required coefficient of friction that is needed, the overweight are more likely to slip and fall on slippery surfaces.

In addition to the higher friction demand, computer simulations display that as body fat increases, the ankle torque necessary exponentially rises in proportion.  The higher body mass also multiplies the inertia on the ankle joint (Corbeil et al. 2001), which means that obese people will not be able to react as quickly during initiated slippage.

Ensure employee safety by using floor protective coverings

Help minimize premises liability for employees through investing in floor mats for safety. Adding floor mats will increase traction on surfaces and minimize traverse shear components, which will ensure surer footing for employees.

Investing in the commercial floor mats reduces the risk of falling by helping shoes adhere better to the floor surface at the point of interface.  Entrance mats in particular may minimize the amount of debris and moisture carried by shoes, thus removing another component that would lead to accidents.

Guaranteeing employee safety, regardless of their weight and condition, should be the top priority of any business.  Using floor mats, employers create a safe and clean environment in the workplace, and reduce the potential litigation costs of liability.


Resources for this special safety report include:

Center for Disease Control and Prevention. (2010). Vital Signs: State-Specific Obesity Prevalence Among Adults- United States, 2009. Morbidity and Mortality Weekly Report, August 3, 2010.

Chang, W., Chang, C., & Matz, S. (2010).  Role of Transverse Shear Force in Required Coefficient of Friction. Research  and Practice for Fall Injury Control in the Workplace, 44-47

Corbeil, P., Simoneau, M., & Rancourt, D. (2001). Increased risk for falling associated with obesity: mathematical modeling of postural control. IEEE trans neural Syst Rehabil Eng, 9, 126 – 136.

Finkelstein, E. A., Chen, H., Prabhu, M., Trogdon, J. G., & Corso, P. S. (2007). The relationship between obesity and injuries among US adults. [Article]. American Journal of Health Promotion, 21(5), 460-468.

Fjeldstad, C., Fjeldstad, A., Acree, L., Nickel, K., & Gardner, A. (2008). The influence of obesity on falls and quality of life. Dynamic Medicine, 7(1), 4.

Gronqvist, R., Chang, W. R., Courtney, T. K., Leamon, T. B., Redfern, M. S., & Strandberg, L. (2001). Measurement of slipperiness: Fundamental concepts and definitions. Ergonomics, 44(13), 1102-1117.

Hue, O., Simoneau, M., Marcotte, J., Berrigan, F., Dore, J., Marceau, P., et al. (2007). Body weight is a strong predictor of postural stability. [Article]. Gait & Posture, 26(1), 32-38.

Lockhart, T. E., Smith, J. L., & Woldstad, J. C. (2005). Effects of aging on the biomechanics of slips and falls. Human Factors, 47(4), 708-729.

Perkins, P. J. (1978). Measurement of slip between the shoe and ground during walking. American Society of Testing and Materials: Special Technical Publication, 649, 71-87.

Pollack, K. M., Sorock, G. S., Slade, M. D., Cantley, L., Sircar, K., Taiwo, O., et al. (2007). Association between body mass index and acute traumatic workplace injury in hourly manufacturing employees. [Article].American Journal of Epidemiology, 166(2), 204-211.

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