Congratulations to PoWeR Lab PhD students Jenny Leestma and Jonathan Gosyne with PoWeR Lab Postdoc Max Shepherd for being awarded the Black Biomechanists Outreach Grant for National Biomechanics Day. This funding will enable Jenny, Jonathan, and Max to put on an event for National Biomechanics Day in September 2021 to kindle a passion for biomechanics among Black students. Stay tuned for more details about the event!

In our everyday lives, we negotiate complex and unpredictable environments. Yet much of our knowledge regarding locomotion has come from studies conducted under steady-state conditions. We have previously shown that humans rely on the ankle joint to absorb energy and recover from perturbations, however, the muscle-tendon (MTU) behaviour and motor control strategies that accompany these joint-level responses are not yet understood. In this study, we determined how neuromuscular control and plantar flexor MTU dynamics are modulated to maintain stability during unexpected vertical perturbations. Participants performed steady-state hopping and, at an unknown time, we elicited an unexpected perturbation via rapid removal of a platform. In addition to kinematics and kinetics, we measured gastrocnemius and soleus muscle activations using electromyography and in vivo fascicle dynamics using B-mode ultrasound. Here, we show that an unexpected drop in ground height introduces an automatic phase shift in the timing of plantar flexor muscle activity relative to MTU length changes. This altered timing initiates a cascade of responses including increased MTU and fascicle length changes and increased muscle forces which, when taken together, enables the plantar flexors to effectively dissipate energy. Our results also show another mechanism, whereby increased co-activation of the plantar- and dorsiflexors enables shortening of the plantar flexor fascicles prior to ground contact. This co-activation improves the capacity of the plantar flexors to rapidly absorb energy upon ground contact, and may also aid in the avoidance of potentially damaging muscle strains. Our study provides novel insight into how humans alter their neural control to modulate in vivo muscle-tendon interaction dynamics in response to unexpected perturbations. These data provide essential insight to help guide design of lower-limb assistive devices that can perform within varied and unpredictable environments.

PoWeR Lab collaborator Dr. Massimo Sartori and PI Dr. Greg Sawicki are the authors of a new article currently in press entitled,  “Closing the loop between wearable technology and human biology: A new paradigm for steering neuromuscular form and function.” As opposed to simply trying to assist the body, they envision wearable robots and neuromodulation devices being used to steer a user’s physiology in different ways across timescales from seconds to years. This article will appear in the journal Progress in Biomedical Engineering.

Congratulations to Emily McCain lead author of, “Isolating the energetic and mechanical consequences of imposed reductions in ankle and knee flexion during gait” for her paper published in the Journal of NeuroEngineering and Rehabilitation. Her work focused on isolating energetic consequences of changes in ankle vs. knee range of motion during post-stroke walking. Using a healthy surrogate cohort, Emily used braces to impose a unilateral restriction on joint motion in a step-wise fashion — first locking only the ankle or knee and then locking both ankle and knee. She found that locking the ankle was worse than locking the knee suggesting that targeting the ankle may yield the best ‘bang for the buck’ for interventions in populations with unilateral impairments.

Luis Rosa, PhD student in the PoWeR Lab and Inan Research Lab, is first author on a preprint titled, “Machine learning to extract muscle fascicle length changes from dynamic ultrasound images in real-time.” This new method opens the door to the use of muscle lengths for biofeedback and control of wearable devices. Check it out here.

4th year PhD student Jordyn Schroeder was interviewed by the Georgia Tech George W. Woodruff School of Mechanical Engineering as a recipient of an NIH R01 Research Supplement! In the interview, she describes her research, goals for the future, and her commitment to building diversity in science and engineering. Check it out here!

3rd year BioEngineering PhD student Lindsey Trejo put on the first informational happy hour and social for Latinx in Biomechanix, a group which she helped to start! This group aims to promote inclusion and diversity by providing a safe space to embrace Latinx heritage while allowing people to support each other in life and research. You can find them on Instagram at @LATINXBIOMECH, on Twitter at @LATINXBIOMECH, and can contact the group by email at LATINXBIOMECH@gmail.com. The group has a slack channel which can be joined by emailing them!

Check out the Behind the Newsletter features on PI Gregory Sawicki and 4th year BioEngineering PhD student Pawel Golyski!

PoWeR Lab postdoc Owen Beck is first author of a paper describing how carbon fiber insoles may not improve running economy. Together with PI Greg Sawicki and 4th year PhD student Pawel Golyski he investigated a host of biomechanical variables spanning the joint and muscle levels, the only significant change induced by adding carbon fiber plates to running shoes was a longer ground contact time.  You can find the paper here!

Congratulations to 4th year PhD student Jordyn Schroeder and PI Greg Sawicki for their funded NIH R01 Research Supplement to their parent grant, “Dynamic imaging to guide wearable robotic intervention for enhanced mobility in aging!” This funding will support Jordyn’s research and conference travel for the next 2 years of her graduate studies. Jordyn’s specific project will be a comprehensive assessment of age-related changes in plantar flexor muscle-tendon structure and function. The data she collects will enable formal links between a user’s ankle structural properties and their exoskeleton, and accelerate translation of this technology out of the lab for daily use to increase mobility for our aging population.

The Diversity Virtual Event held at the 2020 Virtual American Society of Biomechanics Meeting has been posted and is available here. Jordyn Schroeder, 4th year PhD student in the PoWeR Lab and American Society of Biomechanics Diversity Committee Student Representative, kicked off the event in a statement on Systemic Racism in Academia. Her statement outlines the scope of systemic racism in academia and provides insight on how the entire scientific community should be tackling these issues.

Congratulations to 3rd-year PoWeR Lab PhD student Lindsey Trejo for winning a fellowship through the Sloan Minority Ph.D. Program (MPHD)! This award will fund her travel and professional development throughout her PhD program.

To better link muscle-tendon mechanics to energy expenditure, this investigation studied participants as they cyclically contracted their calf muscle in a manner that mimics key aspects of locomotion: constant cycle-average force and work. Overall, decreasing the fraction that the muscle is on per each on-off cycle (i.e., duty factor) caused greater tendon stretch and muscle fascicle shortening, leading to increased energy expenditure. Thus, by accounting for structural (e.g., tendon stiffness) and functional (e.g., duty factors) parameters during walking and running, researchers may better explain metabolic energy changes across locomotor tasks and animal species. Check out the accepted proof here!

Richard Nuckols, currently a postdoc at Harvard, and Greg Sawicki have published an article looking at the influence of unpowered ankle exoskeletons on metabolic cost across walking speeds. Check it out here!

Please read Jordyn’s statement on systemic racism. She tweeted about it here, and the statement itself can also be read here. Please stand with her and our lab in implementing the considerations and action items she put forward!

Congratulations to Lindsey Trejo for her awesome interview for 1 Million Women in STEM, whose goal is to provide role models for the next generation of girls! You can find the interview here.

Richard Nuckols, currently a postdoc at Harvard, has recently released a preprint describing the biological joint mechanics associated with walking and running across inclines. These results suggest different setting-specific approaches exoskeletons could use to make locomotion easier. Check out the preprint here!

Postdoc Owen Beck, PhD student Pawel Golyski, and PI Greg Sawicki have just released a preprint investigating the effects of carbon fiber shoe insoles on metabolic cost and ankle muscle mechanics. Spoiler: they didn’t find an appreciable effect of carbon fiber insoles on running economy or muscle mechanics… Read it here!

Richard Nuckols is first author on a new article in Scientific Reports looking at how ankle muscles change lengths during elastic ankle exoskeleton use. Check it out here!

PI Greg Sawicki, postdoc Owen Beck, EPIC lab PhD student Inseung Kang, and EPIC Lab PI Aaron Young recently published a review which explores the past, present, and future of exoskeletons in light of metabolic cost reductions. Check it out here!

Congratulations to Jordyn and Laksh for being featured in the Winter 2020 Partnership for an Advanced Computing Environment (PACE) newsletter! Both PhD students have used the Georgia Tech supercomputing resources for their projects. Laksh is interested in understanding how muscle-tendon properties lend themselves to moving on uneven terrain, while Jordyn’s project focused on simulating long term adaptation to exoskeleton use. Check out the article here.

Congratulations to Wendy Nevarez-Sanchez for winning a spot at the 2020 Internation Science and Engineering Fair held in Anaheim, CA!  A high schooler from South Atlanta High School, Wendy has been involved with Project ENGAGES since May of 2019. With the guidance of her mentor, 2nd year PoWeR Lab PhD student in Robotics, Ben Shafer,  Wendy is presenting her original research on how muscle activation can serve as a control signal for exoskeleton optimization.

2nd year PhD student Lindsey Trejo won the Executive Vice President of Research’s Travel Award for her poster presentation at the 2020 Career, Research, and Innovation Development Conference at Georgia Tech. Her poster describes how an elastic ankle exoskeleton could make walking less expensive in older adults. See it here!

Previous PoWeR Lab PhD student and current postdoctoral research fellow at Harvard, Richard Nuckols, is first author of a preprint that explores the interaction of ankle exoskeletons stiffness, muscle activation, and walking speed. Check it out here!

Previous PoWeR Lab PhD student and current postdoctoral research fellow at Harvard, Richard Nuckols, is first author of a preprint that dives into the mechanism by which elastic ankle exoskeletons may reduce the metabolic cost of walking. This work describes how changes in muscle length (measured using ultrasound) and muscle activation may explain why a moderate exoskeleton stiffness made walking less metabolically costly. Check it out here!

The PoWeR Lab and friends had a strong showing at this year’s Chomp and Stomp Chili Festival! Team PoWeR Chomp cooked 7.5 gallons of pork chili (Pork PoWeR-Up) and 12 gallons of mushroom chili (PoWeR Shroom). Jordyn’s mushroom chili was voted 5th best of the 16 chilis in the vegetarian category, and Pawel’s pork chili was voted 28th best out of the 99 meat chilis!

Congratulations to former PoWeR Lab Postdoc Taylor Dick and current PhD student Laksh Punith for their new paper on how limb mechanics help us deal with unexpected perturbations. Check out the paper here.

The PoWeR and EPIC labs have been featured in an article from the Woodruff School of Mechanical Engineering at Georgia Tech. The article highlights the different approaches of both labs as well as the wearable robots we develop and use. Check it out!

Three papers have been recently published by our lab. Postdoc Emily Abbott, Postdoc Owen Beck, and former Postdoc and now Lecturer at University of Queensland Taylor Dick are first authors of the following articles currently In Press:

Dick TJM, Punith LK, Sawicki GS (In Press) “Humans falling in holes: adaptations in lower-limb joint mechanics in response to a rapid change in substrate height during human hopping”. J. Royal Soc. Interface. (2019).

Beck ON, Punith LK, Nuckols RW, Sawicki GS (In Press) “Exoskeletons improve locomotion economy by reducing active muscle volume“. Exerc Sport Sci Rev. (2019).

Abbott E, Nezwek T, Schmitt DO, Sawicki GS (In Press) “Hurry up and get out of the way!: Exploring the limits of muscle-based latch systems for power amplification”. Journal of Integrative and Comparative Biology. (2019).

Congratulations to 3rd-year PoWeR Lab PhD student Jordyn Schroeder for winning a fellowship through the Sloan Minority Ph.D. Program (MPHD)! This award will fund her travel and professional development throughout her PhD program.

Congratulations to Dr. Owen Beck, a post-doctoral fellow in the PoWeR Lab, for being awarded an F32 (postdoctoral fellowship) from the National Institutes of Health! This award will fund Owen for 2 years while he performs his funded research project: “Linking muscle-tendon dynamics and energetics to inform exoskeleton design for improved locomotor economy in aging.”

Dr. Sawicki spoke with Rose Scott from Atlanta Public Radio about the PoWeR Lab’s research, the joint PoWeR and EPIC lab space, and the future of wearable robotics. Check it out here!

Congratulations to Dr. Greg Sawicki and Dr. Tim Cope for being awarded one of three 2019 Petit Institute Seed Grants! Their proposal, entitled “Modifying musculotendon neuromechanics to improve proprioception in aging,” aims to understand how changes with age in muscle “position-sense” can inform exoskeleton design to improve mobility in the elderly.

The PoWeR Lab had a great outcome from the NSF GRFP this cycle – second-year Mechanical Engineering PhD student Jordyn Schroeder received an Honorable Mention, and second-year BioEngineering PhD student Pawel Golyski received a Fellowship! Congratulations to both!