Percorrer por autor "Moniz-Pereira, Vera"
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- Construct validity of markerless three-dimensional gait biomechanics in healthy older adultsPublication . Carvalho, Andreia; Vanrenterghem, Jos; Cabral, Sílvia; d'Assunção, Ana M.; Carnide, Filomena; Veloso, António P.; Moniz-Pereira, VeraBackground and aim: Gait changes due to aging can result in functional limitations and a higher risk of falls, with older adults showing alterations in joint angles and moments. Marker-based gait analysis is not widely used in clinical settings due to its complexity and discomfort, especially in older adults. Recent advances in markerless motion capture, such as Theia3D, offer a promising alternative. This study aims to assess the construct validity of a markerless motion capture system for gait analysis in healthy older adults. Methods: A cross-sectional study included 30 healthy community-dwelling older adults. Gait data were collected using marker-based and markerless motion capture systems in randomized order, with participants wearing tight-fitting minimal clothes plus 46 reflective markers attached, or their usual clothes, respectively. Joint kinematics (including range of motion) and kinetics were analyzed, and correlations between methods (Rxy) were assessed. Bland-Altman analysis was used to measure agreement. Root-mean-square differences (RMSD) were computed. Acceptable thresholds were set at ≤ 5º for kinematics and at ≤ 10 % of signal amplitude for kinetics. Results: Strong correlations (Rxy≥0.7) were found between the systems for sagittal plane kinematics (except for the pelvis), particularly for knee and ankle joints. A low agreement was detected in sagittal plane hip and pelvis kinematics, along with RMSD exceeding 5º. Weaker correlations and poor agreement were observed for transverse and frontal plane motions. Overall, strong correlations were found for kinetics, except for the joint ankle inversion-eversion moment, and poor agreement for the frontal and transverse planes. Conclusion: Overall, markerless motion capture demonstrated good construct validity for measuring sagittal plane gait lower-limb gait kinematics (excluding pelvis) and kinetics in healthy older adults. However, considering the agreement between methods and the results for the other movement planes, further validation is required before markerless and marker-based systems can be used interchangeably in gait assessments.
- How many strides are needed for reliable markerless gait analysis?Publication . Carvalho, Andreia; Vanrenterghem, Jos; Pataky, Todd C.; Robinson, Mark A.; Veloso, António P.; Moniz-Pereira, VeraBackground/aim: Markerless motion capture is an emerging tool for gait analysis. In some populations, e.g., older adults, traditional gait analysis poses practical challenges, such as reduced assessment tolerance, and the number of strides collected can be limited. This study aimed to investigate the influence of the number of strides on test-retest reliability and measurement error of markerless gait biomechanics in older adults. Methods: Twenty strides were extracted from 29 healthy older adults for each of two sessions. Lower-limb kinematics and kinetics were computed. Subsequently, non-consecutive random subsets of k = 2-19 strides were averaged within-subjects and within-sessions, including scenarios with unequal k between sessions. Integrated Intraclass Correlation Coefficients (iICCA,k) and Standard Errors of Measurement (SEM) were calculated for trajectory data. ICCA,k [Confidence Intervals] were computed for the range of motion and peaks. Two arbitrary thresholds for the minimally acceptable number of strides were combined: (1) the smallest k that yielded an ICC within 10 % of the maximum ICC across all k, and (2) an absolute ICC threshold of 0.75. SEM≤ 2º was deemed suitable for kinematics, and SEM%≤ 5 % for kinetics. Results: For joint angles and moments, iICC dropped less than 10 % from the highest iICC when using ≥ 7 strides with an equal number of strides across sessions, attaining iICCs≥ 0.75. Reducing the number of strides in one session had less impact than reducing both equally. Lower Confidence intervals were generally ≥ 0.75 for discrete parameters. Kinematic SEM rarely exceeds 2º. Globally, 4 strides are needed to have a kinetics SEM%≤ 5 %. Conclusion: A minimum of 7 strides contributing to the average observation is generally sufficient to achieve reliable markerless kinematics and kinetics in older adults. These results have particular relevance to populations who may experience limited tolerance for lengthy assessments. Allowing flexibility in stride number collected across sessions, while maintaining reliability, contributes to optimizing data collection strategies.
- Markerless three-dimensional gait analysis in healthy older adults: test–retest reliability and measurement errorPublication . Carvalho, Andreia; Vanrenterghem, Jos; Cabral, Sílvia; Assunção, Ana; Fernandes, Rita; Veloso, António P.; Moniz-Pereira, VeraIn older adults, gait analysis may detect changes that signal early disease states, yet challenges in biomechanical screening limit widespread use in clinical or community settings. Recently, a markerless method from multi-camera video data has become accessible, making screenings less challenging. This study evaluated the test-retest reliability and measurement error of markerless gait kinematics and kinetics in healthy older adults. Twenty-nine healthy older adults performed gait analysis on two occasions, at preferred walking speed, using their everyday clothes. Lower limb angles and moments were averaged from 8 gait cycles. Integrated pointwise indices [Intraclass Correlation Coefficient (ICCA,K) and Standard Error of Measurement (SEM)] were calculated for curve data, as well as ICCA,K, and SEM [95 % confidence intervals] for selected peaks. Generally, kinematic ICCs were good (>0.75) and reasonably stable throughout the gait cycle, except for the hip kinematics during the swing phase in the sagittal plane and pelvis tilt and rotation. The integrated and peaks SEM were <2.4°. The reliability of kinetics was similar (ICC>0.75), except for the transverse hip moment and abduction peak, fluctuating more during the swing than through the stance phase. SEM were < 0.07Nm/Kg. In conclusion, these results showed good overall test-retest reliability for markerless gait kinematics and kinetics for the hip, knee, and ankle joints, moderate for the pelvis angles, and error levels of ≤5°, and SEM%≤5% for the sagittal plane. This supports this method's use in assessing gait in healthy older adults, including kinetics, for which reliability data from markerless systems is difficult to find reported.