Use of Instrumented Timed Up and Go in Adults with Traumatic Brain Injury

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study investigates the utility of the instrumented Timed Up and Go (iTUG) test in adults with moderate-to-severe traumatic brain injury (TBI), comparing their performance with healthy controls. The authors demonstrate that iTUG subcomponents (e.g., sit-to-stand velocity, turn angular velocity) reveal significant deficits in TBI patients not captured by total test time alone. The study fills a gap in the literature by extending prior pediatric TBI research to adults and provides valuable insights into functional mobility impairments post-TBI.
Strengths:
1. Novelty and Clinical Relevance:
2. 
The use of iTUG in adult TBI populations is understudied, and this work appropriately highlights the need for objective, subcomponent-specific measures to guide rehabilitation. The finding that sit-to-stand and turning deficits are more pronounced than total time alone has direct implications for targeted intervention design.
3. Methodological Rigor:
    * The study employs a matched control group (by age and sex), which strengthens between-group comparisons.
    * The use of a single IMU sensor (VN100 AHRS) with established reliability (via prior validation against Vicon systems) ensures consistency in data collection.
    * Reporting of technical challenges (e.g., initial Bluetooth interference, sensor placement) and subsequent mitigations (e.g., room relocation) demonstrates transparency in methodology.
4. Statistical Analysis:
5. 
The authors appropriately use paired t-tests/Wilcoxon tests and intraclass correlation coefficients (ICCs) to assess group differences and within-session reliability. The emphasis on subcomponent-specific reliability (e.g., excellent ICC for total iTUG time in both groups) provides a robust foundation for clinical applicability.
Areas for Improvement:
1. Sample Size and Demographic Differences:
    * The small sample size (n=15 per group) limits generalizability, particularly given the heterogeneity of TBI severity (GCS 3–12). Larger cohorts in future studies would strengthen statistical power and allow subgroup analyses (e.g., mild vs. severe TBI).
    * Demographic disparities (e.g., shorter stature, lower weight, less education in TBI group; Table 1) are noted but not discussed in relation to iTUG performance. While the study controls for age and sex, future work should explore whether factors like height or BMI influence subcomponent metrics (e.g., vertical acceleration during sit-to-stand).
2. Clinical Significance of Findings:
3. 
The study establishes statistical significance for subcomponent differences but does not address clinical relevance (e.g., minimal detectable change, correlation with functional outcomes like falls or independence in activities of daily living). Including patient-reported outcomes or long-term follow-up data would enhance the translational value of the work.
4. Technical and Methodological Refinements:
    * The algorithm’s reliance on smooth turning paths to detect temporal events (e.g., turn start) may introduce bias in TBI patients with erratic movements. Suggestions to improve this (e.g., manual waveform review as done here, or algorithm adjustments for non-smooth transitions) could be expanded in the Discussion.
    * The exclusion of data from two TBI and one HC participant due to unreliable turn subcomponent values (Section 3.1) highlights potential variability in sensor performance during complex movements. Clarifying whether this relates to sensor placement (e.g., sternum vs. other body sites) or participant factors (e.g., ataxia) would be useful.
5. Mechanistic Insights and Contextualization:
6. 
While the Discussion links turning deficits to cognitive-motor impairments (e.g., executive function), deeper exploration of TBI-specific pathophysiology (e.g., frontal lobe injury, white matter damage) and its relation to subcomponent performance would strengthen the narrative. Including measures of cognitive function (e.g., GOAT scores beyond PTA clearance) could establish direct correlations.
Recommendations for Revision:
* Expand Discussion on Demographic Impact: Acknowledge the observed demographic differences and hypothesize how they might influence results (e.g., lower weight affecting acceleration metrics).
* Address Clinical Utility: Propose how iTUG subcomponents could be integrated into rehabilitation protocols (e.g., targeting sit-to-stand velocity with strength training or turning efficiency with balance exercises).
* Enhance Methodological Transparency: Detail the criteria for defining "outliers" in waveform analysis (e.g., specific signal loss thresholds) and how manual adjustments were performed.
* Cite Related Adult Neurological Studies: While pediatric TBI and Parkinson’s disease comparisons are valuable, including research on adult stroke or multiple sclerosis populations (where iTUG has been used) would broaden the contextual framework.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear author 

I read with interest your manuscript 

• new and novel tool were tested to measure functionality in post TBI patients 
• Introduction is sufficiently covers the topic of the study
• Methods were clearly presented, in line 29 delete the word "both"
• in line 32, you mean instrumented timed up and go, if yes add the word instrumented before the abbreviation
• In result, I think it is of no importance to mention and compare tall, weight and educational status as you did not use them in comparison for the significancy, it is out of the purpose of the study 
• It is advisable to compare the iTUG between moderate and severe TBI (subgroups) also in mention in results the number of each of the (Moderate and severe) and the mean GCS for each 
• in discussion, better to avoid (we found) for example: use (important differences were found) and so on
• I congratulate authors for this well analyzed and well written work and I think that above noted may add a little to improve it   

best wishes 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The authors seek to determine whether the Timed Up and Go (iTUG) test detects differences in functional variability among adults with moderate to severe traumatic brain injury (TBI) and a group of healthy controls.

This is an observational, case-control pilot study involving a sample of 15 adults with moderate to severe traumatic brain injury (TBI) and 15 healthy controls, who are fully comparable in terms of age and gender. An inertial measurement unit (IMU) was used on the sternum. Total iTUG test time and detailed subcomponents (sit-to-stand, turn, stand-to-sit) were recorded.

The results confirm that the iTUG test detects deficits in dynamic movements in the TBI group that go beyond total time, especially in the sit-to-stand and turn phases.

It is undoubtedly a novel application that enables the measurement of differences that could have clinical applicability. The test allows the detection of differences that reach statistical significance.

However, the sample size is small, which can be interpreted as a pilot study, with only 15 subjects per group, limiting generalisation and statistical power. Not all results could be analysed, and confounding factors may exist.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The presented study is relevant and very interesting. The relevance of the chosen topic is determined by the limited number of diagnostic and therapeutic approaches in the treatment of pathological processes developing as a result of traumatic brain injury. In addition, to date there is a very limited number of studies of TBI conducted on patients. The authors of the article propose a new tool for diagnosing the consequences of TBI. The study is logically structured, there is a chapter Limitations, which determines not only some limitations of this work, but also outlines the path of its further development. I would like to advise the authors to pay attention to the study of mild traumatic brain injuries, since in this type of pathology, diagnostic approaches are practically absent. In my opinion, the study can be accepted for publication in the BioMed journal.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

None.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors 

Thanks for responding to my notes, I think your manuscript is now suitable to be published, I suggest acceptance with no further corrections are requires 

Best  

Reviewer 3 Report

Comments and Suggestions for Authors

I believe that the requested changes have been made and that it can be accepted for publication.

Comments on the Quality of English Language

I am not a native English speaker, but I believe that the language used is appropriate and easy to read.