The rung of a ladder was never meant to rest upon, but only to hold a man's foot long enough to enable him to put the other somewhat higher.
- Thomas Huxley
Humans typically engage with enclosed physical environments by walking between places, climbing stairs, and by standing and sitting at workstations, and by transiting between different environments by means of the outside world. Even if a worker is seated and sedentary, or who does not need to move, or cannot walk, the lower limbs of a worker are always engaged. In a seated position, for example, the seat of the chair upon which a worker sits takes the weight of the body by supporting the worker’s backside and their thighs, with their shins supported through the contact of the feet on the ground (Eklund, 1986). Where the chair is so high as to change the contact of the feet with the ground, or so low as to change how the backside and thighs rest on the chair, problems arise (Kroemer, 1971). While a human’s arms articulate with the world in front of and around them, the lower limbs are responsible for navigation, postural maintenance, loadbearing, and postural alteration. Humans begin walking upright from the age of fourteen months as individuals, and began walking upright between six to three million years ago as a species. The lower limbs are perpetually loaded in some way throughout the day, managing the duties of balancing the upper body and the torso, walking, sitting, kneeling, crouching, climbing, mantling, and engaging in movements as diverse and as important as those undertaken by the upper limbs. The pedals of cars, the controls of dental chairs, pressure-plate control systems and stops all rely on movements from the feet, which are themselves positioned by the knees, the thighs, and the hips. The toes, feet, ankles, calves, knees, thighs, hips, waist, and lower back are all potential points of discomfort whose irritation and injury can have immediate personal and performance impacts. Repetitive kneeling, squatting, walking, standing, sitting, and driving can cause discomfort, all of which can be aggravated by load, sustained force, sustained activity, and vibration (Health and Safety Executive, n.d.).
In Australia, in the 2022-2023 reporting period, lower limb injuries comprised 22.2% of all serious injury claims ordered by body location, and had the second-longest median time lost following injury out of those reporting groups (Safe Work Australia [SWA], 2024a). That same report noted that the two most common mechanisms of injury for serious claims were body stressing and falls. Body stressing has previously been defined as a collective term covering a broad range of health problems associated with repetitive and strenuous work. Body stressing occurs when muscles, tendons, ligaments or bones are placed under stress and this can arise from a single traumatic event or multiple events over time (SWA, 2016). This notion is corroborated by the Australian Bureau of Statistics (ABS) which reported that in the 2021-2022 reporting period, sprains, strains or dislocations, chronic joint or muscle conditions, and cuts or open wounds were the most common types of work related injuries, and that the most common causes of work-related injuries were lifting, pushing, pulling, or bending as well as falls (ABS, 2023). In the 2022-2023 reporting period, hip and leg injuries represented one-fifth of all hospitalisations by main body part injured (Australian Institute of Health and Welfare, 2024). While those statistics are skewed due to over-representation of fractures and falls as injuries and presentations as a function of including all-population statistics, those figures serve to underscore the importance of healthy lower limb function and the severity of any performance or pathological effect that follows damage to those structures. Injuries to the lower limbs can affect the bones of the legs including the thighs, the shins, and the bones of the feet as well as the points where those bones meet - the knee and the hip are highly represented with respect to occupational injury of the lower limb. More generally, the soft tissues of the lower limbs including the join capsules, ligaments, tendons and muscles are all irritable across the short or long term as well, and may also experience irritation, injury, or pathological change depending on their loading, exposure, and dosage.
Given the number of structures in the lower limbs, their sustained and lifelong use, and their necessity, there are diverse means by which the lower limbs can become injured. Walking for more than two miles a day as well as driving, stair climbing, and awkward postures are all risk factors for osteoarthritis of the knee and hip, as well as meniscus lesions and bursitis of the knee (Okunribidio & Lewis, 2010). There is evidence of a relationship between kneeling, heavy lifting, and the emergence of knee osteoarthritis in an occupational context, and the combination of kneeling, squatting, and heavy lifting was a stronger, if clinically moderate, association (Jensen, 2008). As the legs are also responsible for bearing the weight of the body, the likelihood of developing knee osteoarthritis as a consequence of repetitive occupational lifting increases with the weight of the worker (Coggon et. al., 2000). Given that most workers undertaking prolonged standing experience increased risk of work-related musculoskeletal disorders (Halim et. al., 2011), the risk of lower limb irritation, injury, or other discomfort may be affected by a worker’s footwear (Anderson et. al., 2021). However, the footwear a worker uses may be dictated by their job role and be out of their control, meaning that workers may be exposed to stereotyped risk profiles depending on the protective equipment they are obliged to wear. The interface between the load of the human body and the floor is further complicated by flooring composition. Warehouses are typically concreted, construction can take place outside on gravel, grass or on slabs. Surgical spaces are typically upholstered in vinyl and plastic for infection control, commercial kitchens may be tiled, and hospitality venues are infinitely diverse. Walking, standing, lifting and taking steps transmits reaction load force through a worker’s footwear into the soft and hard tissues of their feet as well as their limbs, and so these exposures can be altered by changing the flooring or the worker’s interaction with that flooring (Anderson et. al., 2017) as well as worker foot posture (Neal et. al., 2014), which may be more or less practical depending on the environmental control of workers’ job tasks. For example, when considering roofing workers, roof slope, work posture, and occupational ergonomics including dynamic kneeling, transferring, and shuffling can increase the risk of knee symptoms in those workers (Breloff et. al., 2019), which can again be modified by footwear, task, and body composition.
Workers may be more or less at risk of lower limb injuries depending on their job tasks. Workers in more physically involved roles are at increased risk of both acute and chronic injury (Safe Work Australia, 2016). Labourers, community and personal service workers, machinery operators and drivers experienced a higher proportional percentage of reported claims compared with professionals and administrative workers relative to their working populations. In the 2020-2021 reporting period, the knee was the most highly represented region of the lower limb with respect to body stressing, and the knee and ankle were the most commonly injured regions in falls, trips and slips (Safe Work Australia, 2022). Again, the incidence of these injuries is higher in roles where the work is more physical, posturally diverse, or where the worker needs to move around. While walking long distances, manual handling, and sustained standing are risk factors for lower limb pain, sustained sitting is also a risk factor for the incidence of hip pain (Pope et. al., 2003). Where workers are obliged to maintain sustained sedentary postures for the time of their shifts, such as in office work, technical services, and in the professions, adjustable seating may be effective in improving worker comfort (Corlett, 2006; Zeverdegani et. al., 2022), where if the task cannot be adjusted to fit the worker, then the worker’s interface with the task may be adjusted to promote their comfort and sustainable participation. However, in job roles like truck and plant driving, or when seated or standing on vibrating equipment, wholebody exposure to vibration can increase the risk of lower limb as well as core discomfort and injury, either due to direct structural irritation or owing to referred pain (Hoy et. al., 2005; Bovenzi, 2010). To this end, a whole-work-task analysis should be undertaken to assess worker limb loading in the context of working posture, environmental exposure, and force exposure as a comprehensive whole (D’Souza et. al., 2005; Reid et. al., 2010a). Increased loading, lifting, and carrying again intensifies the risk of hip and knee-related lower limb discomfort, where loaded weight increased the joint contact forces for lifting and carrying, transiting stairs and ascending and descending a ladder, and even as well as sitting (Varady et. al., 2015). The force vector through the hip naturally changes as the movement of the load changes, where repetitive small-amplitude movements subject the lower limbs and joints to lower doses of strain when compared with large amplitude movements that might be one-offs. The greater the load, the greater the risk (Bergmann et. al., 2017)
People, regardless of whether they work or do not work, take force through and use their lower limbs from the moment they get out of bed to the moment they return to sleep. This includes individuals with diverse mobilities such as walking aid users who take the weight differently as a result of using a support like a crutch or a frame, as well as wheelchair users who may not be bearing weight through the long axes of their legs but by virtue of sitting on their thighs and backsides will need to balance their weight on the pan of the seat. Given the ubiquity of lower limb use with different occupations, management of risks to the legs and prevention of injuries and incidents involving the legs requires analysis of job tasks and work organisation first, both for a comprehensive assessment and to bring this consideration in line with current best practice (SWA, 2024b), and given the commonality of postural strain in physically intensive industries that gives rise to increased risk of musculoskeletal disorders (Reid et. al., 2010b). Given that general risk factors for occupational illness included lifting frequency, weight lifted per day, weight lifted per hour, the number of trunk flexions, twists, and motions per hour, the number of knee flexions per hour, and shoulder movement where specific factors included lifting frequency and lifted weight (Craig et. al., 2003), and that the lower limbs are involved in bending as a matter of necessity and in lifting as a matter of facilitation, minimising or otherwise eliminating worker exertion in these roles may be a good first step before considering the worker themselves or even their PPE. Decreasing the dose of force through the lower limbs by adjusting the necessary lifts and the necessary loads in work can decrease cumulative physical loading and thus be effective in minimising lower limb strain (Konito et . al., 2020), to the extent that hip osteoarthritis may be reasonably inferred to have an occupational component (Coggon et. al., 1998; Unverzagt et. al., 2022). Given that humans use their lower limbs for activities outside of working (citation needed) including sport, hiking, recreational weightlifting, walks, and in seated and relaxed postures at home, it is also worth considering a worker’s non-occupational body usage as well. Where possible, consideration should be given to workers’ smoking and alcohol consumption as well as their hobbies, all of which may affect or bias the development of lower limb discomfort as a result of non-occupational contributing factors (Craig et. al., 2006). When returning focus back to the workplace and workspace, specifically focusing on the most common point of physical interaction between the worker and that environment, being the feet, lower limb force exposure and position can be controlled using protective or situationally appropriate footwear, but care should be taken to ensure that that footwear is appropriate so as to not further irritate the ankles, feet, knees, hips and lower back, and should be appropriately fitted and worn in (Pereira-Barriga et. al., 2024). Protecting the lower limbs is a complicated endeavour given that people use their legs inside and outside of work, in a near-infinite series of postures, in a near-infinite diversity of tasks, exposed to a near-infinite combination of arrangements and loads, over the spans of their lives (Fransen et. al., 2011). This diversity of exposure is further complicated by diversities of age, body composition, physical conditioning, biological sex and anthropometry on the workers’ part as well - effective risk control is therefore targeted to the workplace and workspace and made as bespoke as possible to the worker where that is practicable (Varacallo & Knoblauch, 2017).
People of all ages and workers of all roles use their bodies to engage with, navigate through, and enjoy the world in which they live. The legs play a central role in this, allowing us to play as children, sport as adolescents, work as adults, and relax in our retirements. Injuries affecting the lower limbs affect mobility, balance, strength, flexibility, and comfort. All of these domains affect human dignity and occupational performance. Workers of all roles are obliged to use their bodies as tools and facilitators to engage with the duties of work, and in doing so, provide for themselves and their loved ones. Workers are obliged to use those same bodies in their recreation as they do in their occupation, subjecting them to stresses, exertions, and sustained activity. Workplaces, workspaces, and workers have opportunities to evaluate their work and the way it is done, to proactively protect themselves against accumulated and all-at-once doses of strain that can cause injury and disruption that they take home with them.
It’s on businesses and employers to put their best foot forward (I am sorry) to engage with and implement best practices that support the health, wellbeing, and dignity of their workers, so as to allow those workers to lead rich, full lives.
None of this information constitutes medical, legal, occupational health and safety, best guidance, standard, or other guidance, instruction, or prescription.
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References
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