Applying good ergonomic principles to the design and undertaking of work tasks can reduce fatalities and absenteeism, address presenteeism, and improve productivity and quality of work. The expertise of occupational health is also key, explains Dr Aseni Wickramatillake.
Ergonomics is a scientific discipline and, in the occupational health setting, considers compatibility between the worker, their working environment and work tasks.
Applying good ergonomic principles to the design and undertaking of workplace tasks can reduce fatalities, perhaps as a result of human error and injuries, and can reduce the risk of exacerbating poor health conditions. It can reduce absenteeism, address presenteeism and improve productivity and quality of work.
The application of ergonomic principles can underpin the risk assessments required under health and safety legislation, including the general requirement under Regulation 3 of the Management of Health and Safety at Work Regulations (1999).
It can also be used for other more specific requirements for risk assessments within, but not restricted to, work, involving the use of display screen equipment, tasks involving manual handling and exposure to noise and or vibration.
Work-related musculoskeletal disorders (MSD) include any type of discomfort, at one end of the spectrum, to irreversible and disabling injury at the other. Motor organs, muscles, tendons, bones, cartilage, ligaments and nerves may all be affected (National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division, 2020).
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Work-related MSDs can be prevented by fitting the task to the physical and mental capabilities of the worker rather than expecting the worker to adjust to the task and workstation.
This approach reduces the primary risk factors, such as repetitive movement or awkward postures, including those that are static or require forceful exertion.
Frequency, prolonged work duration, contact stress, vibration, poor environmental temperature, illumination, noise and poor individual human conditions all can have a negative impact psychologically and on the musculoskeletal system.
According to the World Health Organization (2022) 1.71 billion people are suffering from MSK conditions worldwide, with it being the leading contributor to disability across the world.
With a rapidly ageing population, the disability and disease burden from non-communicable diseases is increasing (Cieza et al, 2020; Vos et al, 2020). MSK conditions are a leading contributor to disability and can place considerable demand on healthcare services for a longer period of a person’s life.
The costs may not be limited to healthcare, but the loss of services by the person to the workplace and society by a decline in functioning for longer periods can be substantial (World Health Organization, 2022).
In comparison to people without MSDs, those with MSDs are twice as likely to suffer from other chronic diseases (Williams et al, 2018). The peak age range of disability has been steadily increasing over the decades with the age range being between 50-54 years in 2019 (Liu et al, 2022).
Thermal environments and noise
Exposure to physical hazards such as challenging thermal environments, noise or vibration are ergonomic issues and may cause harm. Some work tasks such as those in fire and rescue services or within horticulture may be undertaken in very cold environments, particularly in a severe winter, or excessive hot and humid conditions within greenhouses or other horticultural hot houses.
These may impact the energy demands of muscles and organs, which may result in accelerated fatigue. Whole-body vibration (WBV) and hand and arm vibration (HAV) can contribute to significant and potentially disabling musculoskeletal injury (Krajnak, 2018).
Regular use of hand-held power tools such as drills and grinders can adversely affect muscles, joints, blood vessels and nerves in the hands and arms of which carpal tunnel syndrome (CTS) and vibration white finger (VWF) are common sequelae.
Tingling, numbness, reduced sensation and impaired blood circulation are common complaints of employees using vibratory tools. It is important to remember that the effects of vibration is not just restricted to those that use hand-held tools.
Whole-body vibration occurs as a result of vibration that is transmitted through the feet or seat of those whose work tasks involve flying helicopters or driving work vehicles over uneven surfaces. Large shocks and jolts may result in health risks including significant back pain (Upadhyay et al, 2021).
Large, sustained forces, high-power short-term repetitive contractions, or low-power sustained single/repetitive contractions over muscles, joints, ligaments, and tendons can increase fatigue or damage to the musculoskeletal system (National Research Council (US), 1999).
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When working using awkward postures for prolonged periods, the nerves continue to be entrapped for significant durations. Both reduced blood circulation (McNeil et al, 2015) and nerve entrapment can augment muscle fatigue and numbness in the musculoskeletal system (Langer et al, 2018).
Hence, the best practice to minimise health conditions associated with poor ergonomic design such as musculoskeletal strain and injury is to interchange between a few correct postures at regular intervals, so permitting the strained muscles to recover before fatigue builds up.
Progressively worsening poor postures and increased musculoskeletal discomfort can lead to a worker becoming less active and alert, further increasing the risk of incidents and errors (Soares et al, 2019).
Short-term discomforts can eventually lead to severe and chronic health problems, reducing productivity and increasing absenteeism. Hence, good workplace design and flooring; appropriate tools and machinery; appropriate work durations; improved cycle times; increased intervals; employee training and awareness; improved health of individuals; and improved environmental factors such as noise, air quality, temperature, illumination, will all assist in reducing the negative impact on the musculoskeletal system.
Working in a standing position on a regular basis for prolonged periods requires considerable muscular effort to keep the body upright. This reduces the blood supply to the loaded muscles (Waters and Dick, 2015).
Insufficient blood flow accelerates the onset of fatigue and causes pain, and even permanent damage to body tissues. This, along with forceful and repetitive work can have a synergistic effect on the strained musculoskeletal system.
Frequent changes of posture and job rotation enabling blood circulation and relaxation of the strained musculoskeletal system can minimise harm to the muscles and skeletal system.
Pacing and importance of micro breaks
Increased work pace under forceful and strained posture have a substantial impact on the musculoskeletal system. Hence, work cycles should be well paced, providing micro breaks in between to relax and recirculate the strained muscles.
Micro breaks are frequent short breaks, which can be taken by the individual worker between tasks. Frequent micro breaks provide the opportunity for recovery of muscles prior to becoming overly fatigued (Radwan et al, 2022).
Employees engaged in static postures, heavy manual work or working under adverse environmental conditions for prolonged periods can experience a greater adverse impact on the musculoskeletal health.
Prolonged work can also affect the general physical health, mental health as well general fatigue increasing the risk of accidents and injuries (Wong, Chan, and Ngan, 2019).
Excessive noise, poor illumination and other poor environmental conditions can lead to increased fatigue, stress and poor posture, which may contribute to the exacerbation of musculoskeletal injuries (MSI).
Excessive noise, poor illumination and other poor environmental conditions can lead to increased fatigue, stress and poor posture, which may contribute to the exacerbation of musculoskeletal injuries”
Poor air quality and exposure to particulate matter (PM2.5) is known to adversely impact the respiration and circulatory systems (Manisalidis et al, 2020). This can reduce the aerobic activity of the muscles.
Tasks conducted in hot and humid conditions can increase the energy demands of the muscles causing accelerated muscle fatigue (Magnavita et al, 2011). Hence, the work duration of employees should be significantly reduced with rotation between employees.
Both environmental and metabolic heat should be considered during heat exposures. Light, moderate, heavy and very heavy activity levels can influence metabolic heat. The duration of continuous work should be based on the heat exposure.
Environmental heat is more than just temperature. Factors that contribute to heat stress in workers are air temperature; humidity; radiant heat from sunlight or artificial heat sources; and air movement. In most situations, wind helps workers cool off.
Screen use causes strain on the eyes, including the eye muscles. Static use of the eyes by continuously focusing on a single object, working with reduced blinking causing dry eyes, repetitive movement of the eyes to focus and refocus, working under inappropriately illuminated environments, exposure to glare and many other causes can affect the general health of the eyes with adverse impact on the vision.
Blurred vision, dry eyes, eye irritation and headaches are some of the common symptoms of fatigued eyes. Therefore, maintaining good eye health of employees is particularly important (Kaur et al, 2022).
Ensuring task-appropriate illumination, avoiding glare and screen reflection, rearranging workstations and frequent breaks for the eyes can significantly reduce the strain on the eye, thus reduce visual problems. High-risk employees should have frequent eye testing and be enrolled in the proper medical surveillance programme to prevent further deterioration of their vision.
Loss of muscle mass is linked with the ageing process. Hence, older workers may experience more significant discomfort while engaging in strenuous activities (Wilkinson, Piasecki, and Atherton, 2018). Integrating sound ergonomic principles into the design of work processes and work equipment is important, particularly for this group.
Links between poor sleep and MSDs
Sleep and musculoskeletal fatigue are believed to be intrinsically linked. Sleep deprivation associated with the desynchrony of the circadian rhythm is known to cause metabolic disruption within the human body leading to obesity, diabetes and metabolic syndrome.
Sleep deprivation is a key factor in reduced alertness, which can lead to an increase in accidents and errors. Sleep deprivation is a significant cause of increased fatigue including musculoskeletal fatigue (Chun et al, 2018).
During the change from a daytime work-rest pattern to a night-time work-rest pattern, workers may be deprived of sleep for more than 20 hours. In studies, long-term sleep deprivation is considered equivalent to illegal levels of blood alcohol level (Williamson, 2000).
In some people, sleep deprivation might lead to a condition called shift work sleep deprivation (Schwartz and Roth, 2006). For most people, work shifts rotating forward through the day, afternoon and night may be less disruptive than backward rotation (in other words, night, afternoon and day).
When scheduling shift rotations one must consider the duration of the rotation, frequency of the rotation, starting and finishing time of the shift, number of days off work between rotations, age, gender, existing health conditions, home conditions and individual diurnal preferences.
Forward rotating shift (FRS) moves from a morning shift to an evening shift and then to a night shift. Backward rotating shift (BRS) (counterclockwise rotation) moves from a night shift to an evening shift and then to a morning shift (Di Muzio et al, 2021).
In comparison to FRS, the BRS is known to be associated with poorer health outcomes such as increased triglyceride, increase blood glucose, raised systolic blood pressure, increase general and muscle fatigue and poor immunity (Shon et al, 2016).
Chronic musculoskeletal pain (CMP) is characterised by continuous or repeated episodes of MSK pain with a duration of three months or more (Vellucci, 2012).
In comparison to patients without CMP, anxiety, depression (Storheim and Zwart, 2014), fatigue (McBeth et al, 2015) and insomnia (Generaal et al, 2016; Alföldi, Wiklund, and Gerdle, 2013) are reported significantly more in patients with CMP.
Not only is insomnia common among patients with CMP (Asih et al, 2014), but insomnia has also been identified as a contributor to the intensity of perceived pain (Generaal et al, 2016; Orenius et al, 2012). CMP creates a challenge to the daily functioning and quality of life of the sufferer (Silvestri 2016, Garnaes et al, 2022). Therefore, mental health of patients with CMP should be an imperative consideration in primary healthcare services (Björnsdóttir et al, 2012).
Myalgia, arthralgia, neuropathy and myopathy were observed in patients suffering from Covid-19 infection (Huang et al, 2020).
Inflammation has been linked to damage to the MSK system (White-Dzuro et al, 2020; Tao et al, 2020). A study revealed that nearly a third of the patients reported musculoskeletal complaints (Hoong et al, 2021).
The prevalence of persistent MSK symptoms was high among patients who recovered from Covid-19 infection (Azadvari et al, 2022). Patients suffering from MSK conditions resulting from acute, or post-Covid-19 may have to take adequate precautions when returning to work and engaging in activities using the MSK system.
Maintaining functional agility
Good MSK health is important for functional agility throughout the life course, enabling a pain-free and physically active retirement. It is also necessary for economic and social independence.
Changing or altering human behavioural practices to minimise MSD is a challenging task encountered at workplaces. Any change, despite beneficial consequences, can be initially frowned upon by the employees because of the natural resistance of human nature to change.”
When implementing control measures, always conform to the hierarchy of controls, as elimination, substitution, and engineering controls can safeguard greater number of employees. Administrative controls, too, can protect a larger number of employees.
However, implementation and compliance can vary on the management, employees’ attitudes and organisational culture.
Personal protective equipment can only protect one person and is significantly dependent on the compliance of the individual. Therefore, it is recommended to implement suitable control measures in accordance with the hierarchy.
Changing or altering human behavioural practices to minimise MSDs is challenging. Any change, despite beneficial consequences, can be initially frowned upon by the employees because of the natural resistance to change.
Change should be done with suitable awareness, training and supervision to maintain the good work practices until the correct behavior is established.
Finally, there is an important overlap between ergonomics and occupational psychology. Ergonomic principles should be integrated into the design of work equipment, work tasks and work environment.
Ergonomics also incorporates an appreciation of human factors and how these relate to functioning in the workplace, particularly in relation to designing out the potential for human error.
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