Farm machinery can expose operators to several hazards. Whole-body vibration (WBV) is known to be associated with back and hip disorders, but can also contribute to the risk of falls and collisions (‘accidents’). The years 1990 - 2008 averaged 104 Canadian farm fatalities/year and over 70% were related to agricultural machinery; during that period there were 38 fatalities specifically due to falls from agricultural machines. Driving itself also presents a health and safety risk. Between 2003 and 2007, 19.5% of all road fatalities were a result of heavy vehicle collisions/loss-of-control events, and a vast majority of crashes were attributed to driver error. Both fall risk and collision risk may be negatively affected by vibration exposure. The short-term effects of WBV include cognitive impairment, stress, loss of balance, reduced proprioception, and decrements in sensory and motor response. These effects can increase the risk of either a fall (due to disturbance of balance and proprioception), and increase the risk of a collision (due to impaired cognition, perturbed position sense, or errors of judgment). WBV is a thus contributing factor to fatal and non-fatal occupational injury resulting from accidents and errors, including equipment and machine-related injuries, falls, and vehicle crashes.
While engineering solutions such as vibration-dampening seating and engine isolation can reduce the whole body vibration levels associated with back pain, they do not mitigate the effects of extended static sitting. It is also not clear whether the frequencies of vibration reduced by specialized seating is the same ranges of the vibration spectrum which affect cognition, balance, and proprioception. Vibration-dampening seating is also very expensive (approximately $6000 USD per seat), limiting its feasibility for many producers. Alternatively, procedural controls such as rest breaks can be applied immediately without a cash investment. Advice commonly given to workers who are seated for extended periods is to get up and move around periodically to reduce musculoskeletal effects. For example, the Canadian Centre for Occupational Health and Safety recommends standing up and moving for 5-10 minutes out of every hour. There is also evidence that specific neck, arm, and leg movements performed after vibration can reduce vibration-related decrements in balance and proprioception. It may be that an appropriately-designed ‘alternate activity break’ can reduce the combined effects of seating and vibration, thereby reducing the risk of back and hip pain, egress injuries, and operator-error-related collisions.
The objective of this project is to develop a procedural control in the form of an intervention program appropriate for delivery to farmers. This project will involve the use of efficacy trials in the CCHSA Ergonomics Lab (https://research-groups.usask.ca/ergolab/), usability trials and user focus groups with farmers, followed by field testing for effectiveness.
Aims of Project
In order to deliver a procedural control and implementation plan suitable for wide-scale use or evaluation, this project will:
- Assemble a stakeholder advisory group of producers and other knowledge-users to help direct the study.
- Conduct a series of lab-based experiments to identify rest break activities that are most effective in reducing performance decrements associated with seated whole-body vibration (such as that found in tractor operation).
- Assemble the most effective activities into a single rest break protocol and test using farm-realistic exposure durations.
2019 - 2020 Year 1 Update
Producers and farmworkers are exposed to whole-body vibration (WBV) on a regular basis when operating farm machinery. Whole-body vibration is the mechanical vibration that, when transmitted to the whole-body, poses risks to the health and safety of operators. Exposure to WBV is cumulative over time. The goal of this project is to develop an evidence-based protocol for interspersing agricultural machinery operation with rest breaks to maximize the health and performance of workers while minimizing interruption of work that is applicable across all machinery-related agricultural tasks.
In Year 1, Activity 5 developed and pilot-tested protocols for lab-based testing of rest break activities. The project team was able to collect data during lab-based experiments where 20 experienced farm machinery operators were exposed to different vibration and rest conditions. These early tests provide preliminary data for planning WBV interventions on farms and analyses will remain ongoing.
Using the unique set of equipment available at the Canadian Centre for Rural and Agricultural Health’s Ergonomics Laboratory, vibration exposures programs based on real measurements made on-farm were developed so that a simulated tractor cab on top of a robotic vibration platform is able to produce realistic farm-type vibrations.
An additional investigation stream was added to Activity 5 to evaluate musculoskeletal effects of agricultural machinery operation using cadaveric mechanical testing and micro-computed tomographic (micro-CT) imaging to measure biomechanical damage at the vertebral end-plate. This additional study will extract vibration conditions from previously collected field studies to simulate agricultural machinery used in a controlled environment to simulate musculoskeletal damage related to low back pain in agricultural machinery users. Mechanical and image-based outcomes will be used to determine health effects, which will then be compared to current occupational vibration exposure standards. The mechanical testing and resulting damage will complement in-lab tests with human participants to help determine effective rest break timing related to musculoskeletal damage.
2020 - 2021 Year 2 Update
Year 2 of the project was focused on developing specific methodologies for in-lab vibration and rest break activity testing, and continuing with ongoing image processing and analysis of the micro-CT scans of vertebral end-plates. The micro-CT scans are being evaluated to determine the damage to the vertebral endplate as a result of whole-body vibration exposure from agricultural machinery. Typically, when examining how WBV causes low back pain the focus is on the intervertebral discs. However, there is research that suggests that damage to the vertebral endplate, the surface between the vertebrae and intervertebral disk, is a red flag for disc damage and subsequent low back pain. The vertebral endplate is a delicate structure that is only millimeters thick and composed of porous bone, making it the weakest point in your spine, so it only makes sense that the vertebral endplate would be the first part of your back to show damage from exposure to WBV. Using lab simulations of farm machinery WBV and pig spine segments which are ‘shaken’ using biomechanical testing equipment and then examined using micro-computed tomography images to look at the structure of the spine for damage post-shake. Pig spine segments are used to model the human spine in these lab simulations. The vibration conditions used for these experiments are collected from agricultural machinery in order to provide an accurate simulation of musculoskeletal damage related to low back pain common among farm machinery operators.
Using the unique set of equipment available at the Canadian Centre for Rural and Agricultural Health’s Ergonomics Laboratory, the research team will be programming vibration exposures based on realistic, ecologically valid measurements made on farms, so that a simulated tractor cab on top of a robotic vibration platform will produce workplace-simulating vibrations. Participants will be tested before and after vibration to see the effect vibration exposure has on their balance, coordination, and joint loading as they exit the tractor cab. Using this design the team will be testing the impact of a series of different rest break protocols on time standardized exposure profiles.
To date, a series of requisite vibration exposure and rest break methodologies have been developed, including participant surveys for baseline data collection and participant interviews to guide the development of field test methodologies. These will be experimentally applied in a step-wise manner to volunteer participants in the Ergonomics Laboratory to determine which rest break activities have the strongest modulating effect on any recorded decrements in musculoskeletal and cognitive performance from field relevant and ecologically valid whole-body vibration exposures. This aspect of the project is currently awaiting further clarification and guidance from the University of Saskatchewan COVID pandemic advisory team on when face-to-face participant recruitment can begin.
The outcomes of this vibration exposure and rest break testing will be supplemented with the qualitative investigation of participant perceptions as to which rest break activity(s) would pragmatically have the greatest likelihood of workforce acceptance and feasible implementation in preliminary field trials. With the guidance of a recruited Stakeholder Advisory Group, the outcomes of these laboratory-based physical and qualitative investigations will create the framework for the fieldwork-based investigations that will be explored for the effect and practical implications of applying the final recommended intervention strategies.
2021 - 2022 Year 3 Update
WBV Rest Break Intervention Studies
Access to the in-lab vibration simulation equipment (Rotopod platform) was significantly delayed during Year 3 due to repair difficulties during the COVID-19 pandemic. Once the vibration platform service was complete, testing resumed quickly. So far, 5 study participants have completed one or more 1-hour vibration exposure and rest break intervention sessions. A total of 20 participants will be recruited for this study.
In addition to the in-lab controlled vibration exposure and rest breaks, the research team will also test rest break interventions in a realistic on-farm environment during in-field testing. This will provide further practicality and feasibility testing to the pre-determined rest break interventions and will provide further insight on feasible and practical guideline development. A portable force platform was acquired to carry out measurements in the field.
The WBV Smart-Device App
To empower agricultural machinery operators in understanding and managing vibration exposure, the research team is testing the feasibility and practicality of using a mobile smart-device application to measure in-field vibration exposure. Once installed, the new app utilizes the smart-device’s existing technology to monitor the user’s exposure to WBV. The device must therefore be placed on or near the body to provide adequate and representative data. By providing machinery operators with tools to aid in understanding and measuring their own vibration exposure, it will empower them to make feasible and practical decisions regarding rest break timing and what effective rest break activities will best suit their circumstances.
2022 - 2023 Year 4 Update
2023 - 2024 Year 5 Update
Burnett, W., Milosavljevic, S. 2021. Whole Body Vibration in Agricultural Machinery Use: Measurement and Mitigation Strategies. Presentation to Huskies Motorsports ¼-Scale Tractor Design Team in Engineering. March 2022. Saskatoon, SK.
Burnett, W., Milosavljevic, S. 2022. Methodological Development for In-Field Rest Break Activity Intervals to Reduce Occupational Whole-Body Vibration Exposure During Agricultural Machinery Use. Poster Presentation at School of Rehabilitation Science Virtual Research Meeting. March, 2022. Saskatoon, SK.
Burnett, W., Okpalauwaekwe, U. and Milosavljevic, S. 2022. Validation of a Portable Force Plate for In-Field Evaluation of Postural Sway. Presentation at School of Rehabilitation Science Virtual Research Meeting. March 2022. Saskatoon, SK.
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