Loading and Knee Flexion Post-Stroke: Less Does Not Equal More

My project is a research-oriented Capstone culminating in a manuscript that will eventually be published. The research looks at the relationship between limb loading and muscle activity with an effort to evaluate the effect of body weight support (BWS) on stiff-knee gait (SKG) in subjects affected by stroke.  We anticipate submitting the manuscript to Clinical Rehabilitation, as the research addresses a clinical question with neurophysiology and caters to clinicians. My over-arching personal goals for this project were to develop a better understanding of the research process and experience scientific writing first-hand.

 

Prior to UNC, I had no experience with the research environment and sought out an experience that would address some of my weaknesses and curiosities.  While the IRB approval was finished prior to my involvement, I had a hand in most everything else due to the Capstone or my research work study position. For my work study position, I screened potential subjects and did the scheduling. For the Capstone, I did the data collections with Mike, processed and analyzed data, and wrote the manuscript.

 

 

Data collection took about 2- 2 1/2 hours per subject. Most of that time was spent at the Cybex recording muscle responses of the quadriceps to fast knee flexion with and without ankle loading. A custom ankle loader had previously been built to apply loading exclusively at the ankle. EMG activity was recorded from rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM) and medial hamstrings (MH). We used 2 different speeds and 3 different loads for a total of 6 different conditions and each condition was repeated 6 times. I manned the computer responsible for recording EMG activity while Mike worked the Cybex.  After completing the isolated reflex testing, subjects walked on the treadmill at 0, 20 and 40% BWS. Kinematics and muscle activity was recorded for the three conditions.

 

By November, we had collected half of the subjects we needed (n=5). Unfortunately, recruitment of new subjects came to a standstill and it wasn’t until March 16^th that the last data collection was finally completed. We also ran into issues with clear EMG signals and had one subject come in to re-do the EMG data during BWS on the treadmill. Despite this, we had to leave out some subject data for VL and RF during analysis due to noisy signals.

 

In the meantime, I stumbled my way (with Mike’s patient guidance) through data processing using LabView programs, C-Motion, and Vicon. In Vicon, I made sure all of the reflective markers were labeled correctly and filled any gaps caused by conflicting camera information. In Labview, subject information and files were combined and a script file was written to direct C-Motion on how to look at the data. C-Motion then used the script file to create cute little walking skeletons based on each of the subjects.  Another LabView program was used to process the stretch data and some more of the gait data to ultimately create Excel files that would later be combined and used in SPSS.

 

Once we finally had our n=10 and the data was processed, it was time to analyze the data. We used SPSS and I refreshed my memory of ANOVAs, Pearson coefficients, and so many other statistical tests. This allowed us to see what relationships existed and if they were significant (p=0.05).

 

What we found is that the use of BWS did not influence knee kinematics or the muscle activity during late stance/early swing phase of gait in individuals post-stroke.  Muscle excitability with a simulated ankle load correlated directly to knee extensor excitability during gait.  This information shows that load has little role on knee extensor excitability during late stance/early swing and based on this, adjusting loading is not an effective tool to address stiff-knee gait.

 

Since “health literacy” didn’t readily apply to my project, I instead learned how to use RefWorks.  I utilized the Write-N-Cite tool for the in-text citations and bibliography to allow me to organize my references and make changes easily. RefWorks has literally saved me hours upon hours of work- I cannot believe people actually wrote anything that required citations before programs like RefWorks existed.

 

Overall, I have had 8 versions of the manuscript. Version 1 (turned in on March 11th) included the introduction and methods while versions 2-4 were revisions of those sections.  Version 5 (turned in on April 3rd) added in the results. Version 6 (turned in April 8th) included the discussion with version 7 being revisions to the discussion. With version 8 (turned in April 12th), I tried out my hand with the abstract and title.

 

For EBP II, my lit review was related to the clinical question of if body weight support improves (stiff-knee) gait. Additional literature reviewed for the background of the manuscript looked at research related to the impact of loading on muscle activity in animal models and humans (infants and people post-SCI) and early research on BWS treadmill training. Overall, I utilized 22 resources while putting together the introduction of the manuscript.  For the entire manuscript, almost 40 sources were included. Unfortunately, since the manuscript has yet to be published, it’s not appropriate for me to put it on here but trust me, it’s amazing.

 

Adventures encountered along the way:

• Equipment malfunctions- Let’s just say that the air compressor was on its last (very loud) breath by the time we finished.
• Reacquainted myself with the wonders of Excel: graph-making, spreadsheet organization, etc.
• Switching the ankle loader from a L foot to a R foot using tools I don’t know the names of (not because they’re rare tools- I just don’t use tools very much).
• Reading through script files to find mistakes by channeling my inner computer genius.
• Learning how to use terminology like “exteroceptive input,” “heteronymous reflexes,” and “linear envelope” in a sentence correctly.
• Manuscript writing- It takes so little time to tear apart an article when reading it but soooo long to compose even a poorly written manuscript.

 

 

A little reflection…

Beyond the intellectual knowledge I gained from this project, I learned that research can be time-consuming, tedious, frustrating, challenging and of course, rewarding. I learned how to do things I never thought I would and now have an even deeper respect for the talented people who take part in research.  I absolutely would have been lost without the guidance and help of Mike Lewek and cannot possibly thank him enough!

 

If you are interested in this research, I would be happy to send you the manuscript via email but please be aware that this is privileged information since it has not been published yet. Thank you!