Physically demanding occupations, such as manual materials handling and public safety, require the use of a variety of physical abilities to perform the job tasks. Because of the need for workers to meet the physical requirements of arduous jobs and the potential for injury, employers use physical performance tests to determine an individual’s physical capabilities to meet the job requirements. The physical abilities assessed by the tests are based on the essential tasks and functions, working conditions, and ergonomic parameters associated with a job. These abilities are defined in the following text:
- Muscular strength is the ability to exert force to lift, push, pull, or hold objects. The amount of force generated by a muscle contraction is dependent on the size of the muscles (cross-section) involved and muscle fiber type such as a fast twitch.
- Muscular endurance is the ability to exert force continuously over moderate to long time periods. The length of time a muscle can contract is dependent on the size of the muscles involved, the chemical composition of the muscle tissue, and the muscle fiber type such as a slow twitch.
- Aerobic capacity or cardiovascular endurance is the ability of the respiratory and cardiovascular systems to provide oxygen to the body systems for medium-to high-intensity tasks performed over a moderate time period. Aerobic tasks require continuous oxygen consumption.
- Anaerobic power is the ability to complete high-intensity, short-duration (e.g., 5-90 seconds) tasks. Anaerobic tasks are performed using stored energy in the form of adenosine triphosphate (ATP).
- Flexibility involves the range of motion at the joints including knees and shoulders to bend, stoop, rotate, and reach in all directions with the arms and legs. Flexibility at the joints is dependent on the extensibility of the ligaments, tendons, muscle, and skin.
- Equilibrium is the ability to maintain the center of gravity over the base of support such as feet. Equilibrium involves maintaining and recovering to a balanced position when outside forces, including gravity and slipping on ice, occur.
Combinations of different levels of these abilities are needed for all tasks in which muscular contraction, oxygen consumption, and energy expenditure are required. For example, low levels of muscular strength and muscular endurance in the abdominal and back muscles are required to sit in a chair. However, high levels of these two abilities are required to lift and carry thirty 70-pound boxes. Performance of arduous job tasks typically requires all six abilities, but to different extents. Lifting ten 90-pound boxes from a table and carrying them 100 yards to another table requires high levels of muscular strength and muscular endurance in the arms, legs, and torso, but only low levels of flexibility. The level of equilibrium needed is moderate because gravity is pulling downward as the box is carried forward. Similarly, to avoid falling over when picking up a weighted object, the base of support must be adjusted or widened, for example. This task also requires a moderate level of aerobic capacity because of the weight of the boxes, the distance they are carried, and the duration of the task. Therefore, the physical abilities interact at varying levels throughout performance of all arduous job tasks. The specificity of an ability can be determined through direct physiological measurement such as oxygen consumption, ergonomic measurement including force to torque bolts, or questionnaire data.
Physical performance tests are developed, validated, and implemented for purposes of applicant assessment, incumbent assessment and retention, and worker assessment for return to work after an injury. Physical tests are used for arduous jobs in the public (e.g., law enforcement, firefighter, emergency medical service), private (e.g., warehouse, manufacturing, longshoring, telecommunications, railroad, trades, electric, natural gas), and military sectors. Use of physical performance tests in the selection setting provides several benefits. First, individuals whose physical ability is commensurate with the demands of the job are identified. Second, physically qualified individuals have fewer injuries, which leads to lower worker compensation costs, increased productivity, and reduced turnover. Research in this area has shown reductions in injury rates of 10% to 20% for new hires who successfully completed a physical test screening when compared with individuals who did not take the test. Further, when workers were injured, those who passed the physical test had significantly lower injury costs than those who were not tested, for example, $4 million versus $12 million.
Types of Physical Performance Assessment Tests
There are numerous physical performance tests used by organizations to assess physical capabilities. However, these tests can be placed into one of two categories: basic ability tests and work/job simulations. Basic ability tests assess an individual’s physical ability including muscular strength and flexibility. Tests such as sit-ups (muscular endurance), the step test (aerobic capacity), arm ergometry (muscular endurance), and sit and reach (flexibility) are basic ability tests. Basic ability tests measure an ability required to perform job tasks.
Work/job simulation tests include components of the job being evaluated such as dragging a hose and climbing stairs. Work simulations require individuals to perform simulated job tasks or components and may require equipment or tools used on the job. A test requiring an individual to lift boxes and place them on shelves of various heights is considered a work simulation test. Law enforcement tests that simulate pursuing and restraining a suspect are also work simulation tests.
Organizations have used basic ability, work simulation, and a combination of both test types to assess candidate and incumbent physical capabilities. Both types of test have substantial validity that ranges from 0.45 to 0.85, depending on the type of criterion measure used in the validation study. However, regardless of the type of test used, significant gender differences in performance are typically present. These differences are attributed to the physiological differences between men and women such as larger muscle mass and greater lung volume.
Development and Validation of Physical Performance Assessment Tests
Both basic ability and work simulation tests must match the job in terms of the physical abilities or the job tasks being assessed. Job analysis data provides the input to select or design basic ability tests or to identify essential tasks that can be safely simulated. Ergonomic parameters (e.g., weights of tools and objects, forces to loosen nuts and bolts, distances walked, heights) and working conditions (e.g., temperature, surface, surface incline) related to the essential job tasks should be incorporated into the test development plan. In addition, when developing or selecting physical performance tests, the safety of the examinees must be considered; their health status and fitness level is usually unknown, and their age can range from 20 to 60 years old.
Design or selection of basic ability tests should include consideration of the tasks that require the abilities, and not just the relevant abilities. For example, if the job requires lifting 35-pound boxes to heights of 50 to 60 inches, a test of upper body muscular strength may be more appropriate than a lower body strength test. Similarly, if a job requires performing arduous tasks such as climbing stairs while wearing a protective nonbreathable suit with a respirator, a step test or treadmill test of aerobic capacity may be more appropriate than a bicycle test. Further, the duration of a basic ability test, such as muscular endurance, can be determined based on the time it takes to complete a physically demanding task or a series of tasks.
Consideration of these parameters will result in a testing process that is more specific to the job demands.
For work simulation tests, the job’s essential tasks are reviewed to determine which tasks are frequently performed and which tasks best represent the essence of the job demands. These tasks are evaluated to select which tasks can be simulated without using equipment or procedures that require on-the-job training. Use of working conditions and ergonomic parameters in the test development stage increases test fidelity. For example, a frequent and important task for firefighters is dragging a hose. This task can be safely simulated and requires no prior training, except for a demonstration of how to hold the hose. To increase the fidelity of this test component, ergonomic data such as the distances that hoses are dragged, size of the hose used, and use of assistance are evaluated to select hose size and distance parameters that are performed by one person. Other parameters related to the condition of the hose (e.g., filled with water or no water) are also examined. An example of a drag parameter that may not be included because it requires training would be opening the hose and spraying water at a target. Finally, the job analysis and working conditions information are used to ensure accurate ordering of test components, proper equipment usage, and appropriate durations for the test and its components.
The linking of job analysis and ergonomic parameters to test components provides the basis for establishing construct validity for basic ability tests and content validity for work simulations. Once the tests meet the conditions described earlier, a criterion-related validity approach can also be used to empirically establish the test validity and passing score(s).
Arduous jobs are found in numerous private (e.g., electric, telecommunications, natural gas, railroad, freight, warehousing) and public (e.g., fire, police) sector organizations. Identifying the demands of essential job tasks is paramount to development or selection of basic ability or work simulation tests. The ergonomic and working conditions parameters should be incorporated into the test development or selection to ensure that the test accurately represents the physical demands of the job. Careful attention to the details of the job task demands will ensure that the test is content or construct valid and will identify individuals who can perform arduous job tasks. Although design of physical performance tests involves different strategies than cognitive test development, most of the developmental and testing principles are similar.
- Gebhardt, D. L. (2000). Establishing performance standards. In S. Constable & B. Palmer (Eds.), The process of physical fitness standards development—State of the art report. Wright-Patterson AFB, OH: Human Systems Information Analysis Center (HSIAC-SOAR).
- Jackson, A. S. (2000). Types of physical performance tests. In S. Constable & B. Palmer (Eds.), The process of physical fitness standards development—State of the art report. Wright-Patterson AFB, OH: Human Systems Information Analysis Center (HSIAC-SOAR).
- Myers, D. C., Gebhardt, D. L., Crump, C. E., & Fleishman, E. A. (1993). The dimensions of human physical performance: Factor analyses of strength, stamina, flexibility, and body composition measures. Human Performance, 6(4), 309-344.
- Rayson, M. P., Holliman, D., & Belyavin, A. (2000). Development of physical selection procedures for the British Army. Phase 2: Relationship between physical performance tests and criterion tasks. Ergonomics, 43, 73-105.
- Sothmann, M. S., Gebhardt, D. L., Baker, T. A., Kastello, G. M., & Sheppard, V. A. (2004). Performance requirements of physically strenuous occupations: Validating minimum standards for muscular strength and endurance. Ergonomics, 47(8), 864-875.