Managing workplace psychosocial factors to help prevent musculoskeletal injuries

Credit: Adobe Stock/Jacob Lund.

It’s dawn on an early May morning in Northern Ontario, and the tree planting season is just starting. You wake up in a bush camp to below-zero temperatures and a dusting of snow on the ground. You unzip your sleeping bag, dress quickly in layers of damp, dirty clothes and lace up your steel-toed boots, still wet from days of rain. You pull on your mittens, your breath freezing as you head to the mess tent to eat breakfast and make lunch. You don’t have much time; by 6:00 a.m., you’re on an old school bus with your crew travelling across corduroy roads to the block where you’ll plant for the day. You’re dropped at a cache where you load your planting bags with 50 pounds of seedlings and fill your Nalgene with water, then you walk out to your piece of land. 

As the day goes on, the temperature rises quickly. Unlike the past three days of cold, hard rain, today the sun is beating down on you, and the black flies are gnawing persistently at your red, burnt skin. Your shovel hits rock time and again while poplar branches poke your scratched, bruised body as you bend over to throw trees in the ground every six feet. You’ve lost count of the number of times that you’ve fallen in nearly catastrophic but mostly comical ways. You ran out of water two hours ago. Apart from your crew boss – who you saw for five minutes six hours ago – you haven’t seen anyone all day, and you’re struggling to keep your thoughts from spiralling into existential nothingness.

By the end of the 10-hour workday, you’ve walked 20 kilometres and planted 3,000 trees. You fall asleep on the bus back to camp out of sheer exhaustion. You’re hungry, tired, sore and dirty. And you’re going to do it all over again tomorrow.     

Tree planting is arguably one of the toughest jobs in Canada. Young silviculture workers push themselves beyond reasonable physical and psychological limits, planting thousands of trees daily for piecework pay.

Given the gruelling pace and physical demands of the job, it’s no surprise that workers don’t often finish a season injury-free, and careers typically span no more than a few years. Musculoskeletal injuries are the most prevalent injury among tree planters and are often under-reported.

While it’s well understood that the primary causes of musculoskeletal injuries are overexertion (force), repetitive motions and awkward postures, evidence also suggests that psychosocial factors are key contributors.

Workplace psychosocial factors like high workload, monotonous tasks, low levels of job control, and poor supervisor support are associated with musculoskeletal disorders across multiple regions of the body, including the back, neck, shoulders, and the upper and lower extremities.[1] Why? Because psychosocial stressors can trigger physiological responses like muscle co-contraction and decreased blood flow.  Sustained exposure to psychosocial stressors leads to increased baseline loading of the musculoskeletal system, decreasing the threshold for physical injury.[1]

Knowing that workplace psychosocial factors are key contributors to musculoskeletal injuries, it’s important for employers to recognize, assess and control both physical and psychosocial exposures for injury prevention.

In silviculture work, physical exposures are easy to recognize. Thousands of shovel-strikes per day (force) increases the risk of injury in the hands, wrists, elbows, and shoulders, while repetitive bending and twisting can lead to back, hip, and knee injuries.[2], [3], [4] But what about psychosocial exposures?

In this piece-work occupation, compensation is linked directly to workload, working time and work pace.  Workers are alone in remote areas and have no contact with co-workers or supervisors during their shift.  There is no shelter from physical and environmental hazards and often no means of summoning immediate assistance in case of emergency.

An integrated approach to physical and psychosocial risk management is imperative for injury prevention and should be considered in workplace and job design. The CSA Z1004 standard for Workplace Ergonomics and CSA Z1003 standard for Psychological Health and Safety in the Workplace encourage work design and evaluation with consideration for physical, cognitive, and psychological job demands and the interaction of the worker with the workplace. Tools that take an integrated approach to physical and psychosocial assessment are a useful addition to an employer’s risk management toolkit.

When considering an integrated approach to injury prevention, it’s important to choose assessment methods and tools that are both reliable and practical. Interested in learning more?  Connect with a Canadian Certified Professional Ergonomist (CCPE). CCPEs are uniquely qualified within their scope of professional practice to help employers design work and the work environment to prevent injury. Visit cccpe.ca or find an ergonomist near you.

[1] Afsharian, A., Dollard, M.F., Glozier, N., Morris, R.W., Bailey, T.S., Nguyen, H., and Crispin, C. Work-related psychosocial and physical paths to future musculoskeletal disorders (MSDs).  Safety Science 164 (2023) 106177. 

[2] Slot, T., Dumas, G. Musculoskeletal Symptoms in tree planters in Ontario, Canada. Work. 36(1):67-75. (2010).

[3] Slot, T., Shackles, E., Dumas, G. Upper limb and trunk kinematics in tree planters during three load carriage conditions. Occupational Ergonomics 9(3): 169-182. (2010).

[4] Denbeigh, K., Slot, T., Dumas, G. Wrist postures and forces in tree planters during three tree unloading conditions. Ergonomics. 56(10):1599-1607. (2013).