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Evaluating how people with lower limb loss walk with their prostheses is crucial for comparing the effectiveness of various devices and treatments, as well as for tracking individual progress over time. Traditionally, the standard method for assessment has involved requiring individuals to walk continuously for six minutes or more. While this extended duration can provide reliable data, it can be physically demanding, especially for those dealing with mobility limitations, fatigue, or underlying health issues. Recognizing these challenges, a new study published in PLOS ONE explores whether shorter walking tests could offer equally valuable insights, potentially making assessments more accessible and less strenuous for patients.
The researchers aimed to determine if quick walking evaluations could accurately reflect the amount of energy prosthetic leg users expend while walking. Typically, energy expenditure is assessed by measuring oxygen uptake over a prolonged walking period, allowing the individual's breathing and energy use to stabilize into a steady state. However, such long tests may not be practical in clinical settings or for patients who get tired quickly. This prompted the investigators to consider whether a brief test, like a two-minute walk, could yield results comparable to those of traditional, longer-duration tests.
The study
In this study, 30 adults participated, divided equally into three groups: 10 individuals with below-knee amputations, 10 with above-knee amputations, and 10 individuals without amputations who served as the comparison group. Each participant completed three distinct walking tests in a controlled environment. The first test consisted of a two-minute treadmill walk, after which there was a mandatory 10-minute rest period. The second test was a six-minute treadmill walk; for this test, the researchers focused specifically on the data collected from minutes two to four. Finally, participants completed an overground two-minute walk test, which involved covering as much distance as possible within two minutes on a flat surface, outside the treadmill setting. Throughout all tests, the team measured the amount of oxygen consumed by the participants, using this data to calculate energy expenditure during each walking phase.
Key findings
The results revealed that certain short-duration tests can be surprisingly effective, while others may fall short in reliability. Notably, the two-minute treadmill test stood out for its ability to provide a good estimation of energy expenditure. Researchers assessed recovery following the test—a phenomenon known as excess post-exercise oxygen consumption (EPOC)—and found that this method could reliably reflect how much energy the body used during walking. This outcome is significant, suggesting that shorter testing durations, when properly analyzed, can yield accurate and clinically valuable information.
In addition, the two-to-four-minute segment of the six-minute treadmill test produced results that closely matched traditional, steady-state measures. This further supports the idea that clinicians may not always need longer, resource-intensive tests to gain meaningful insights into a patient’s walking efficiency and endurance.
Conversely, the overground two-minute walk did not deliver the same level of reliability. The test results from the outdoor walk were more variable and inconsistently aligned with gold-standard measures. This inconsistency may be attributed to greater difficulty in standardizing walking speeds and surface conditions outside the clinical treadmill environment.
Why this study matters
Measuring energy expenditure during walking is critical for several reasons: it informs the fitting and adjustment of prosthetic devices, guides rehabilitation goal setting, aids in selecting optimal prosthetic components, and helps clinicians monitor patients’ progress over time. If assessment protocols are too demanding, however, they may not be feasible for everyone, leading to missed opportunities for care or inaccurate evaluations.
The findings from this study indicate that shorter, more accessible treadmill-based walking tests, such as a simple two-minute walk followed by monitoring the recovery period, can provide clinicians with practical and valuable data without overburdening patients. This approach could significantly benefit people who experience fatigue, have limited endurance, or struggle to fit longer tests into their schedules, ultimately making essential evaluations more widely available.
Important points to consider
Before replacing longer, established assessment methods with shorter alternatives, several important factors should be kept in mind:
Trustworthiness of overground tests. Although overground walking tests may seem more representative of a person’s natural movement, they frequently yield less reliable data due to uncontrollable variables like changes in walking speed, the terrain's nature, and intermittent pauses or turns.
Short tests are estimates, not replacements. While short assessments offer a helpful glimpse into a person’s functional ability, they should be regarded as screening tools or supplementary measures. They do not replace comprehensive, steady-state tests when in-depth and precise data are needed for diagnosis or treatment planning.
Individual factors matter. Energy used while walking with a prosthesis can be influenced by numerous factors, including the type and fit of the device, individual walking abilities, and the level of limb loss. Therefore, assessment protocols should remain flexible, tailored to each patient’s unique circumstances, rather than taking a one-size-fits-all approach.
What’s next
This research highlights an important step towards creating more accessible, patient-friendly assessments for people with limb loss. It contributes to ongoing efforts to design clinical evaluation methods that are practical, sensitive to the needs and abilities of prosthesis users, and grounded in evidence. As further studies explore and refine these shorter protocols, it’s becoming increasingly clear that thoughtfully designed, brief walking tests can allow a greater number of people to receive essential feedback and care—no long, exhausting walks required.
