Adaptation in Gait to Body-Weight Unloading
Round 1
Reviewer 1 Report
The manuscript: ‘Adaptation in Gait to Body Weight Unloading’ presents an interesting investigation about the effects of walking at a reduced body weight on the weight sensation, lower limb kinematics and myoelectric activity on walking, standing and seating. Despite a relatively complex acquisition protocol the results are clearly presented and the interpretation looks clear and reasonable. Few minor point need to be amended:
Line 57: .. LBPP is regarded as one of the superior methods of unweighting when compared to upper body harness..
and again:
Line 61:… and is thus considered superior…if this is the opinion of the authors this should be explicitly stated, otherwise these sentences should be supported by references
Line 92: PAR-Q…is there any reference for this questionnaire?
Line 96: here it is not clear whether each subject was analyzed three times in different days or if all subjects were analyzed in three days. Please clarify
Line 97:… was assessed during one of the three sessions before, during and after two different adaptation sessions. Again, unclear: why three sessions and only one was used to assess gait performance? Are the three sessions corresponding to the three days of acquisition? Was there a difference in the three sessions or they were just a repetition of the same procedure?...the whole procedure should be described more clearly
103: …were counterbalanced across the participants… what does it mean?
Line 114-line 115: the two sentences: ‘walked inside the chamber at normal (100%) body weight’ and: ‘during both the control and unloading conditions’…seem in contradiction. What is the true? Isn’t the control condition corresponding to 100% body weight?
Figure 2. The numbers in the chart shuld have units (-2 min, +3 min…+10 min)
Figure 3. The meaning of the ‘*’ should me mentioned
Figure 6 and Figure 9. As in the other figures it could be expected that the control data were unchanged along time, either before, during and after the adaptation sessions. Changes that are so evident in these figures should be commented
Line 354: …swing time which was significantly increased during unloaded walking…the explanation which follows maybe acceptable, but also we may wonder whether the LBPP device itself can affect the swing phase. The doubt should be addressed…
Line 404:…dorsal extension…better to say 'plantar flexion'!
Line 502:…he has provided valuable...what?
Author Response
Please see attachment
Author Response File: 
Author Response.docx
Reviewer 2 Report
The paper presents an investigation on the short term changes in body weight perception and lower limb kinematics adaptations due to bodyweight unloading.
Bodyweight unloading is a common method used in gait rehabilitation. The investigation of its effects on the sensory input of the user and the related kinematic changes in gait can be very helpful in designing rehabilitation programs and understanding their outcomes. Such investigations can also be helpful in developing countermeasures or training programs for spaceflight as the authors suggest.
However, for the purpose of understanding the gait changes and body weight perception related to spaceflight long term adaptations are of more interest, thus the reviewer suggests focusing on rehabilitation programs were users experience bodyweight unloading for shorter periods of time. Otherwise, the relationship between short and long term adaptations should be addressed and discussed.
The methods are well designed and well presented. The randomization of the participants and the consequent measurements at periods of interest yield clear results as to what gait variables change and when they return to normal.
The paper is well written and clear to the point. English is very good.
The organization of the paper is very good in general. Especially the results and discussions. However, there is no conclusion section. Please consider a conclusion section in the revised manuscript.
Minor comments:
Adding a picture or an illustration of the LBPP anti-gravity chamber might be helpful to understand its function.
p.7. during unloading walking -> during unloaded walking
p.11. in the following section -> in this section
p.12. L.366-376
This argument is logical to some degree. However, even though the anti-gravity chamber eliminates the risk of falling mechanically, it does not necessarily translate to the risk of falling perceived by the user, who might be still attempting to compensate for the perceived body loading condition. e.x. people still can get great fear of height even when firmly supported by the equipment.
p.12. L.386
kinematic changes observed after unloading are the true adaptive effects of unloading and not caused by muscular fatigue. ->
kinematic changes observed after unloading are not caused by muscular fatigue.
P.12 L. 395
might represent the true after effects of adaptation ->
might represent the pure after effects of adaptation
(using true might be understood as: other methods yield “untrue” results)
P.14 L. 501
.. providing valuable “comments?” during ..
Author Response
Please see attachment.
Author Response File: Author Response.docx
