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    Physical workload

    Physical workload is the set of physical demands placed on a person throughout their workday, resulting from the muscular effort required by the tasks and the conditions under which they are performed. It manifests in two forms: static workload, associated with maintaining postures that require sustained muscle contraction without movement, and dynamic workload, associated with movements, displacements, and the handling of loads that involve successive contractions and relaxations with greater energy expenditure. INSST Technical Prevention Note 177 defines it as the set of physical requirements to which a person is subjected during the workday and proposes evaluating it based on energy consumption, heart rate, and analysis of postures and exertion. When the workload exceeds a person’s capacity or is maintained without sufficient recovery, physical fatigue sets in, reducing work capacity and attention, increasing errors and accidents, and, if it becomes chronic, contributing to musculoskeletal disorders of the back, shoulders, neck, and limbs. In Spain, physical workload is managed within the framework of Law 31/1995, which requires adapting work to the individual and assessing the risks of each job, Royal Decree 487/1997 on manual handling of loads and Royal Decree 486/1997 on workplaces, with the support of ergonomic assessment methods included in the INSST Prevention Technical Notes and in the technical standards of the UNE-EN ISO 11228 series on manual handling and UNE-EN 1005 on machine safety.

    In short

    The set of physical demands of the workday, in the form of static load (sustained postures) and dynamic load (movements, displacements, handling of loads, and exertion), conditioned by the task, the environment, the organization, and individual characteristics. Excessive demands lead to fatigue, decreased performance and attention, accidents, and musculoskeletal disorders. According to INSST Technical Note 177, it is assessed by measuring energy expenditure, heart rate, and analyzing postures and exertion, using specific methods for handling loads, postures, and repetitive movements. It is managed in accordance with Law 31/1995 and Royal Decrees 487/1997 and 486/1997 through job design, mechanization, organization, training, and health surveillance.

    Content
    1. Components and factors of physical load
    2. Effects and evaluation
    3. Preventive measures
    4. Organizational application: how to manage the physical load
    5. Limits and common mistakes
    6. Practical example
    7. Regulatory and reference framework
    8. Related concepts
    9. References

    A–Z dictionary →

    Components and factors of physical load

    • Static load. Sustained postures (standing without movement, sitting without support, arms raised, trunk flexed or turned) that compress blood vessels and fatigue the muscle quickly.
    • Dynamic load. Displacements, manual handling of loads, pushing and pulling, repetitive movements and application of forces, with energy consumption and general fatigue.
    • Task factors. Weight and characteristics of loads, frequency and duration of efforts, distances, heights, grips and tools.
    • Environmental factors. Available space, flooring, lighting, temperature and humidity, which modify effort and fatigue.
    • Organizational factors. Pace, breaks, rotation, shifts, working hours and time pressure.
    • Individual factors. Physical capacity, age, sex, training, health status and situations such as pregnancy, which require adapting the workload to the person.

    Effects and evaluation

    Excessive physical exertion leads to local and general muscle fatigue, resulting in decreased performance, accuracy, and attention; increased errors and accidents; and discomfort that can develop into musculoskeletal disorders of the back, neck, shoulders, and upper and lower extremities, as well as cardiovascular overload during intense and prolonged exertion. The assessment combines several approaches, as outlined in NTP 177: estimation of task energy expenditure using tables and activity classification; measurement of heart rate as a physiological indicator of dynamic load and environmental conditions; and analysis of postures and efforts using observational methods.

    For specific tasks, recognized methods are used: the INSST technical guide of Royal Decree 487/1997 for manual handling of loads, the REBA (NTP 601) and OWAS (NTP 452) methods for postures, the OCRA (NTP 629) and similar methods for repetitive movements , and the tables and standards for pushing and pulling. The assessment must consider the entire workday, critical tasks, and particularly vulnerable individuals, and its results are integrated into the risk assessment and preventive planning.

    Preventive measures

    • Workstation design. Suitable heights and reach, supports, adjustable seats and surfaces, ergonomic tools, and sufficient space to adopt neutral postures.
    • Mechanization and aids. Carts, lifting tables, pallet trucks, manipulators and exoskeletons to eliminate or reduce manual handling and effort.
    • Work organization. Recovery breaks appropriate to the intensity, rotation between tasks of different workloads, adjusted pace and distribution of the workload throughout the day.
    • Reduction of static load. Alternation of postures, arm and foot supports and design that avoids sustained and forced postures.
    • Training. Handling techniques, use of aids, recognition of fatigue and communication of discomfort.
    • Health monitoring and adaptation. Specific protocols for monitoring and adapting the workload to each person’s capabilities.

    Organizational application: how to manage the physical load

    1. Identify the jobs and tasks with relevant physical workload (handling loads, sustained or forced postures, repetitive movements, efforts, displacements) and the people exposed, including those who are especially sensitive.
    2. Evaluate the load using methods appropriate to each task (technical guide for manual handling of loads, REBA, OWAS, OCRA, estimation of energy consumption) considering the full workday and the conditions of the environment.
    3. Prioritize design and mechanization measures that eliminate or reduce strain and awkward postures, and adjust the work environment.
    4. Organize the work with recovery breaks, rotation, adjusted pace and load sharing, with the participation of the people affected.
    5. Train staff in handling techniques, use of aids and recognition of fatigue, and establish a communication channel for complaints.
    6. Integrate specific health monitoring and adapt the workload to each person’s capabilities.
    7. Review the assessment in light of changes in tasks, equipment or pace, and with the results of health surveillance and records of discomfort and accidents.

    Preventive management software allows you to link jobs and tasks with ergonomic assessments and their methods, plan and follow design, mechanization and organization measures, record training and complaints, integrate health surveillance and analyze the evolution of musculoskeletal disorders by job.

    Limits and common mistakes

    1. Evaluate only the handling of loads and forget the static load of sustained postures and repetitive movements.
    2. Rely on training in lifting techniques as the primary measure instead of eliminating or reducing the load.
    3. Do not consider the full workday or the accumulation of tasks of different workload.
    4. Ignoring environmental and organizational conditions that aggravate fatigue.
    5. Not adapting the workload to particularly sensitive people, pregnant workers or older people.
    6. Do not review the evaluation after changes in pace, teams, or task distribution.

    The specific evaluation depends on each task and person; this sheet is for informational purposes only.

    Practical example

    Situation: A food distribution warehouse with manual order preparation is registering an increase in lower back and shoulder discomfort among picking staff.

    • Evaluation. The prevention service analyzes the entire workday, evaluates the handling of loads with the INSST technical guide and the postures with the REBA method, and estimates the energy consumption of the task, detecting heavy loads at low heights, frequent trunk twists and absence of breaks.
    • Measures. The heaviest items are relocated to intermediate heights, trolleys with adjustable platforms and lifting aids are incorporated at critical points, and the layout is redesigned to reduce turns and displacements.
    • Organization. Recovery breaks are established, rotation between zones of different load and a pace adjusted to the results of the evaluation, with practical training and a channel for communicating discomfort.
    • Follow-up. Health surveillance and the recording of complaints show a reduction in cases in the following months, and the evaluation is reviewed after new stock items are introduced.

    Regulatory and reference framework

    The UNE-EN ISO 11228 (manual handling) and UNE-EN 1005 (machinery safety, human physical performance) standards provide complementary technical criteria for the evaluation of physical load.

    Related concepts

    References

    1. Official State Gazette. Law 31/1995, of November 8, on Occupational Risk Prevention. 1995, current consolidated text. Official source
    2. Official State Gazette. Royal Decree 487/1997, of April 14, on minimum health and safety requirements for the manual handling of loads that pose risks, particularly to the lower back, for workers. 1997, current consolidated text. Official source
    3. Official State Gazette. Royal Decree 486/1997, of April 14, establishing the minimum health and safety requirements in the workplace. 1997, current consolidated text. Official source
    4. National Institute for Occupational Safety and Health. NTP 177: Physical workload: definition and evaluation. 1986. Official source
    5. National Institute for Occupational Safety and Health. NTP 601: Evaluation of working conditions: postural load. REBA (Rapid Entire Body Assessment) method. 2001. Official source
    6. National Institute for Occupational Safety and Health. NTP 452: Evaluation of working conditions: postural load. 1997. Official source
    7. National Institute for Occupational Safety and Health. Musculoskeletal Disorders. Thematic Portal. Official Source

    Editorial information

    Publication date: August 30, 2026 .

    Editorial Manager: Sabentis Editorial Team .

    Editorial review by Pablo Rodríguez LinkedIn

    Executive Vice President of the ORP International Foundation and Chief Financial Officer of Sabentis.

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