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Development of an automated method to detect sitting pivot transfer phases using biomechanical variables: toward a standardized method.

Desroches G, Vermette M, Gourdou P, Gagnon D - J Neuroeng Rehabil (2012)

Bottom Line: In order to better teach this task to those individuals and to improve performance, a better biomechanical understanding during the different SPT phases is a prerequisite.The definition of the phases of the SPT, along with the events characterizing these phases, will facilitate the interpretation of biomechanical outcome measures related to the performance of SPTs as well as strengthen the evidence generated across studies.The mean duration of the pre-lift, upper arm loading, lift-pivot and post-lift phases were 0.74 ± 0.29 s, 0.28 ± 0.13 s, 0.72 ± 0.24 s, 0.27 ± 0.14 s whereas their relative contributions represented approximately 35%, 15%, 35% and 15% of the overall SPT cycle, respectively.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Rehabilitation, University of Montreal, Montreal, Canada. guillaume.desroches@umontreal.ca

ABSTRACT

Background: Sitting pivot transfer (SPT) is one of the most important, but at the same time strenuous at the upper extremity, functional task for spinal cord injured individuals. In order to better teach this task to those individuals and to improve performance, a better biomechanical understanding during the different SPT phases is a prerequisite. However, no consensus has yet been reached on how to depict the different phases of the SPT. The definition of the phases of the SPT, along with the events characterizing these phases, will facilitate the interpretation of biomechanical outcome measures related to the performance of SPTs as well as strengthen the evidence generated across studies.

Methods: Thirty-five individuals with a spinal cord injury performed two SPTs between seats of similar height using their usual SPT technique. Kinematics and kinetics were recorded using an instrumented transfer assessment system. Based on kinetic and kinematic measurements, a relative threshold-based algorithm was developed to identify four distinct phases: pre-lift, upper arm loading, lift-pivot and post-lift phases. To determine the stability of the algorithm between the two SPTs, Student t-tests for dependent samples were performed on the absolute duration of each phase.

Results: The mean total duration of the SPT was 2.00 ± 0.49 s. The mean duration of the pre-lift, upper arm loading, lift-pivot and post-lift phases were 0.74 ± 0.29 s, 0.28 ± 0.13 s, 0.72 ± 0.24 s, 0.27 ± 0.14 s whereas their relative contributions represented approximately 35%, 15%, 35% and 15% of the overall SPT cycle, respectively. No significant differences were found between the trials (p = 0.480-0.891).

Conclusion: The relative threshold-based algorithm used to automatically detect the four distinct phases of the SPT, is rapid, accurate and repeatable. A quantitative and thorough description of the precise phases of the SPT is prerequisite to better interpret biomechanical findings and measure task performance. The algorithm could also become clinically useful to refine the assessment and training of SPTs.

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Related in: MedlinePlus

Schematic reconstruction of one subject. (a) at rest before SPT, (b) at the start of the pre-lift phase, (c) at the start of the upper-limb loading phase, (d) at the start of the lift-pivot phase, (e) at the start of the post-lift phase and (f) at the end of the SPT cycle.
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Figure 3: Schematic reconstruction of one subject. (a) at rest before SPT, (b) at the start of the pre-lift phase, (c) at the start of the upper-limb loading phase, (d) at the start of the lift-pivot phase, (e) at the start of the post-lift phase and (f) at the end of the SPT cycle.

Mentions: The mean (± 1 SD) absolute time for all phases of each of the two SPT trials as well as the mean for both SPT trials combined are summarized in Table 1. The relative phase duration (i.e., percentages) of each phase are also presented in Table 1. Similar phase duration (p > 0.05) across the two SPT trials was confirmed. The two longest phases are the pre-lift and lift-pivot phases (0.74 s and 0.72 s) and, on average, correspond to 37% and 36% of the entire SPT cycle, respectively. The upper limb-loading phase, i.e., the new phase introduced in this paper, lasts on average 0.28 ± 0.13 s and typically represents 14% of the entire SPT. Figure 3 shows the position of one subject for each time event.


Development of an automated method to detect sitting pivot transfer phases using biomechanical variables: toward a standardized method.

Desroches G, Vermette M, Gourdou P, Gagnon D - J Neuroeng Rehabil (2012)

Schematic reconstruction of one subject. (a) at rest before SPT, (b) at the start of the pre-lift phase, (c) at the start of the upper-limb loading phase, (d) at the start of the lift-pivot phase, (e) at the start of the post-lift phase and (f) at the end of the SPT cycle.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3298704&req=5

Figure 3: Schematic reconstruction of one subject. (a) at rest before SPT, (b) at the start of the pre-lift phase, (c) at the start of the upper-limb loading phase, (d) at the start of the lift-pivot phase, (e) at the start of the post-lift phase and (f) at the end of the SPT cycle.
Mentions: The mean (± 1 SD) absolute time for all phases of each of the two SPT trials as well as the mean for both SPT trials combined are summarized in Table 1. The relative phase duration (i.e., percentages) of each phase are also presented in Table 1. Similar phase duration (p > 0.05) across the two SPT trials was confirmed. The two longest phases are the pre-lift and lift-pivot phases (0.74 s and 0.72 s) and, on average, correspond to 37% and 36% of the entire SPT cycle, respectively. The upper limb-loading phase, i.e., the new phase introduced in this paper, lasts on average 0.28 ± 0.13 s and typically represents 14% of the entire SPT. Figure 3 shows the position of one subject for each time event.

Bottom Line: In order to better teach this task to those individuals and to improve performance, a better biomechanical understanding during the different SPT phases is a prerequisite.The definition of the phases of the SPT, along with the events characterizing these phases, will facilitate the interpretation of biomechanical outcome measures related to the performance of SPTs as well as strengthen the evidence generated across studies.The mean duration of the pre-lift, upper arm loading, lift-pivot and post-lift phases were 0.74 ± 0.29 s, 0.28 ± 0.13 s, 0.72 ± 0.24 s, 0.27 ± 0.14 s whereas their relative contributions represented approximately 35%, 15%, 35% and 15% of the overall SPT cycle, respectively.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Rehabilitation, University of Montreal, Montreal, Canada. guillaume.desroches@umontreal.ca

ABSTRACT

Background: Sitting pivot transfer (SPT) is one of the most important, but at the same time strenuous at the upper extremity, functional task for spinal cord injured individuals. In order to better teach this task to those individuals and to improve performance, a better biomechanical understanding during the different SPT phases is a prerequisite. However, no consensus has yet been reached on how to depict the different phases of the SPT. The definition of the phases of the SPT, along with the events characterizing these phases, will facilitate the interpretation of biomechanical outcome measures related to the performance of SPTs as well as strengthen the evidence generated across studies.

Methods: Thirty-five individuals with a spinal cord injury performed two SPTs between seats of similar height using their usual SPT technique. Kinematics and kinetics were recorded using an instrumented transfer assessment system. Based on kinetic and kinematic measurements, a relative threshold-based algorithm was developed to identify four distinct phases: pre-lift, upper arm loading, lift-pivot and post-lift phases. To determine the stability of the algorithm between the two SPTs, Student t-tests for dependent samples were performed on the absolute duration of each phase.

Results: The mean total duration of the SPT was 2.00 ± 0.49 s. The mean duration of the pre-lift, upper arm loading, lift-pivot and post-lift phases were 0.74 ± 0.29 s, 0.28 ± 0.13 s, 0.72 ± 0.24 s, 0.27 ± 0.14 s whereas their relative contributions represented approximately 35%, 15%, 35% and 15% of the overall SPT cycle, respectively. No significant differences were found between the trials (p = 0.480-0.891).

Conclusion: The relative threshold-based algorithm used to automatically detect the four distinct phases of the SPT, is rapid, accurate and repeatable. A quantitative and thorough description of the precise phases of the SPT is prerequisite to better interpret biomechanical findings and measure task performance. The algorithm could also become clinically useful to refine the assessment and training of SPTs.

Show MeSH
Related in: MedlinePlus