PUBLICATIONS

Selected Publications

Beck ON, Shepherd MK, Rastogi R, Martino G, Ting LH, Sawicki GS, (In Press) “Exoskeletons need to react faster than physiological responses to improve standing balance”. Sci. Robot. Feb 15. (2023). PAPER • COVER ARTICLE • LINK TO ARTICLE • News from Georgia Tech • Highlighted in “The Conversation”

Beck ON, Schroeder JN, Trejo LH, Franz JR, Sawicki GS, “Shorter muscle fascicle operating lengths increase the metabolic cost of cyclic force production”. J Appl Physiol. (1985). Jul 14; 133 (3), 524-533 (2022). • PAPER

Golyski PR, Sawicki GS “Which lower-limb joints compensate for destabilizing energy during walking in humans?”. J R Soc Interface. 19 (191) (2022). • PAPER

Dick TJM, Clemente CJ, Punith LK, Sawicki GS, “Series elasticity facilitates safe soleus muscle-tendon shock absorption during perturbed human hopping”. Proc Biol Sci. Mar31; 288 (1947): 20210201 (2021). • PAPER

Nuckols RW, Sawicki GS “Impact of elastic ankle exoskeleton stiffness on neuromechanics and energetics of human walking across multiple speeds“. Journal of NeuroEngineering and Rehabilitation. (2020). • Supplementary Data • Supplementary Information • PAPER

2024

Beck ON, Schroeder JN, Sawicki GS, “Habitually wearing high heels may improve user walking economy in any footwear”. Journal of Applied Physiology (2024). PAPER

2023

Sponberg S, Abbott E, Sawicki GS, “Perturbing the muscle work loop paradigm to unravel the neuromechanics of unsteady locomotion”. Journal of Experimental Biology (2023). PAPER

Leestma JK, Golyski PR, Smith CR, Sawicki GS, Young AJ, “Linking whole-body angular momentum and step placement during perturbed walking”. Journal of Experimental Biology (2023). PAPER *Early Career Researcher (ECR) spotlight interview selection.

Boyer KA, …. Sawicki GS, …. Kent JA, (In Press) “Age-related changes in gait biomechanics: Impact on the metabolic cost of walking: Report from a National Institute on Aging workshop”. Exp. Gerontol. (2023).

Williamson JL, Lichtwark GA, Sawicki GS, Dick TJM, (In Press) “The influence of elastic ankle exoskeletons on lower limb mechanical energetics during unexpected perturbations”. R. Soc. Open Sci. (2023).

2022

Pan YT, Kang I, Joh J, Kim P, Herrin KR, Sawicki GS, Kesar TM, Young AJ, “Effects of bilateral assistance for hemiparetic gait post-stroke using a powered hip exoskeleton”. Annals of Biomedical Engineering. 1-12 (2022). • PAPER

Rabani S, Mizrachi S, Sawicki GS, Riemer R, “Parametric equations to study and predict lower-limb joint kinematics and kinetics during human walking and slow running on slopes”. PLoS One.17 (8) e0269061 • PAPER

Shafer B, Young AJ, Sawicki GS “Emulator-based optimization of a semi-active hip exoskeleton concept: Sweeping impedance across walking speeds”. IEEE Trans Biomed Eng. Jul 5; 70 (1), 271-282 (2022). • PAPER

Rubenson J, Sawicki GS, “Running birds reveal secrets for legged robot design”. Sci Robot. 7 (64) eabo2147 Mar 16; (2022). *Invited Perspective • PAPER

Shepherd MK, Molinaro DD, Sawicki GS, Young AJ, “Deep learning enables exoboot control to augment variable-speed walking”. IEEE Robotics and Automation Letters (RA-L) 7 (2), 3571-3577 (2022). • PAPER

Golyski PR, Sawicki GS “Which lower-limb joints compensate for destabilizing energy during walking in humans?”. J R Soc Interface. 19 (191) (2022). • PAPER

Golyski PR, Vazquez E, Leestma JK, Sawicki GS, “Onset timing of treadmill belt perturbations influences stability during walking”. J Biomech. 130, 110800 (2022). • PAPER

Krupenevich RL, Beck ON, Sawicki GS, Franz JR, “Reduced Achilles tendon stiffness disrupts calf muscle neuromechanics in elderly gait”. Gerontology. 68 (3), 241-251 (2022). • PAPER

2021

McCain EM, Berno M, Libera T, Lewek M, Sawicki GS, Saul K, “Reduced joint motion supersedes asymmetry in explaining increased metabolic demand during walking with mechanical restriction”. J Biomech. 126, 110621 (2021). • PAPER

Riemer R, Nuckols RW, Sawicki GS, “Extracting electricity with exosuit braking”. Science. May 28; 372(6545):909-911 (2021). *Invited Perspective • PAPER

Rosa L, Zia J, Inan O, Sawicki GS, “Machine learning to extract muscle fascicle length changes from dynamic ultrasound images in real-time”. PLoS One. May 26; 16 (5), e0246611 (2021). • PAPER

Shafer B, Philius S, Nuckols RW, Young AJ, Sawicki GS, “Neuromechanics and energetics of walking with an ankle exoskeleton using neuromuscular-model based control: a parameter study”. Front Bioeng Biotechnol – Bionics and Biomimetics. 9, 210 (2021). • PAPER

Dick TJM, Clemente CJ, Punith LK, Sawicki GS, “Series elasticity facilitates safe soleus muscle-tendon shock absorption during perturbed human hopping”. Proc Biol Sci. Mar31; 288 (1947): 20210201 (2021). • PAPER

Sartori M, Sawicki GS, “Closing the loop between wearable technology and human biology: A new paradigm for steering neuromuscular form and function”. Prog. Biomed. Eng. 3 (2) 023001 (2021). • PAPER

McCain EM, Libera T, Berno M, Sawicki GS, Saul K, Lewek M “Isolating the energetic and mechanical consequences of imposed reductions in ankle and knee flexion during gait”. J Neuroeng Rehabil. Feb 1;8(1):21 (2021). • PAPER

2020

Beck ON, Golyski PR, Sawicki GS “Adding carbon fiber to shoe soles may not improve running economy: a muscle level explanation“. Scientific Reports. (2020). • PAPER • SUPPLEMENTARY MATERIAL

Nuckols RW, Takahashi KZ, Farris DJ, Mizrachi S, Riemer R, Sawicki GS “Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons“. PloS One. (2020). • PAPER • SUPPLEMENTARY DATA • SUPPLEMENTARY MATERIAL

Beck ON, Gosyne J, Franz JR, Sawicki GS “Cyclically producing the same average muscle-tendon force with a smaller duty increases metabolic rate“. Proceedings of the Royal Society B: Biological Sciences. (2020). • Supplementary Data • Supplementary Material • PAPER

Krupenevich RL, Clark WH, Sawicki GS, Franz JR “Older adults overcome reduced triceps surae structural stiffness to preserve ankle joint quasi-stiffness during walking“. Journal of Applied Biomechanics. (2020). • PAPER

Nuckols RW, Sawicki GS “Impact of elastic ankle exoskeleton stiffness on neuromechanics and energetics of human walking across multiple speeds“. Journal of NeuroEngineering and Rehabilitation. (2020). • Supplementary Data • Supplementary Information • PAPER

Sawicki GS, Beck ON, Kang I, Young AJ “The exoskeleton expansion: Improving walking and running economy”. Journal of Neuroengineering and Rehabilitation. (2020). • PAPER

Nuckols RW, Dick TJ, Beck ON, Sawicki GS “Ultrasound imaging links soleus muscle neuromechanics and energetics during human walking with elastic ankle exoskeletons”. Scientific Reports. (2020). • Supplementary Data • Supplementary Analysis • Short Talk • PAPER

2019

Dick TJM, Punith LK, Sawicki GS “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). • PAPER • Supplementary Data • Correction

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

Abbott E, Nezwek T, Schmitt DO, Sawicki GS “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). • PAPER

Lewis MJ, Williams KD, Langley T, Jarvis LM, Sawicki GS, Olby N, “Development of a novel gait analysis tool measuring center of pressure for evaluation of canine chronic thoracolumbar spinal cord injury”. J Neurotrauma. (2019). • PAPER

Lewek MD, Sawicki GS, “Trailing limb angle is a surrogate for propulsive limb forces during walking post-stroke”. Clinical Biomechanics. (2019). • PAPER

McCain EM, Dick TJM, Giest TN, Nuckols RW, Lewek MD, Saul KR, Sawicki GS, “Mechanics and energetics of post-stroke walking aided by a powered ankle exoskeleton with speed-adaptive myoelectric control”. J Neuroeng Rehabil. (2019). • PAPER • Supplementary Data

2017

Blau SR, Davis LM, Gorney AM, Dohse CS, Williams KD, Lim JH, Pfitzner WG, Laber E, Sawicki GS, Olby NJ, “Quantifying center of pressure variability in chondrodystrophoid dogs”. The Veterinary Journal. (2017). • PAPER

*Robertson BD, Sawicki GS “A benchtop biorobotic platform for in vitro observation of muscle-tendon dynamics with parallel mechanical assistance from an elastic exoskeleton “. J Biomech. Mar 21.(2017). • Supplementary Methods • PAPER

*This article was selected as the 2016 American Society of Biomechanics Journal of Biomechanics Award winner.

2016

Rosario MV, Sutton GP, Patek SN, Sawicki GS, “Muscle-spring dynamics in time-limited, elastic movements “. Proc Biol Sci. Sep 14; 283(1838) (2016). • PAPER

Danos N, Holt N, Sawicki GS, Azizi E, “Modeling age-related changes in muscle tendon dynamics during cyclical contractions in the rat gastrocnemius muscle”. J Appl Physiol (1985). Oct 1; 124(4): 1004-1012 Epub Aug 4 (2016). • PAPER

Takahashi KZ, Gross MT, van Werkhoven H, Piazza SJ, Sawicki GS, “Adding stiffness to the foot modulates soleus force velocity behaviour during human walking “. Nat Sci Rep. Jul 15; 6:29870 (2016). • PAPER

*Sawicki GS, Khan N, “A simple model to estimate plantarflexor muscle-tendon dynamics during walking with elastic ankle exoskeletons”. IEEE Trans Biomed Eng. May; 63(5):914-923. Epub 2015, Oct 15 (2016). • PAPER • Supplementary Methods • Model • Data • Readme

*Invited submission to a special issue.

Huang H, Crouch DL, Liu M, Sawicki GS, Wang D,”A cyber expert system for auto-tuning powered prosthesis impedance control parameters”. Ann Biomed Eng. May; 44(5) 1613-24. Epub 2015, Sep 25. (2016). • PAPER

2015

Sawicki GS, Sheppard P, Roberts TJ, “Power amplification in an isolated muscle-tendon unit is load dependent”. J Exp Biol. Nov; 218(Pt22):3700-9. (2015). • PAPER

Robertson BD, Sawicki GS, “Unconstrained muscle-tendon workloops indicate resonance tuning as a mechanism for elastic limb behavior during terrestrial locomotion”. Proc Natl Acad Sci USA. Oct 27; 112(43): E5891-8. (2015). • Supplementary Text • PAPER

Sawicki GS, Robertson BD, Azizi E, Roberts TJ, “Timing matters: Tuning the mechanics of a muscle-tendon unit by adjusting stimulation phase during cyclic contractions”. J Exp Biol. Oct; 218(Pt 19): 3150-9. Epub Jul 31. (2015). • PAPER

Collins SH, Wiggin MB, Sawicki GS,“Reducing the energy cost of human walking using an unpowered exoskeleton“. Nature. Jun 11; 522(7555): 212-5. Epub Apr 1. (2015). • PAPER

—Nature Press Release, Nature Podcast,
—NCSU Press Release, NCSU PoWeR Lab Promo Video, Sawicki – CMU RoboticsInstitute Lecture, NIH Press Release
—CMU Press Release, CMU Exp. Biomechatronics Lab Promo Video, Add’tl Carnegie Mellon Media Materials, NSF Press Release

Takahashi KZ, Lewek MD, Sawicki GS, “A neuromechanics-based powered ankle exoskeleton to assist walking post-stroke: A feasibility study”. J Neuroeng Rehabil. Feb 25;12:23 (2015). • PAPER

Farris DJ, Hampton AS, Lewek MD, Sawicki GS, “Revisiting the mechanics and energetics of walking in individuals with chronic hemiparesis following stroke: From individual limbs to lower-limb joints”. J Neuroeng Rehabil. Feb 27; 12(1): 24 (2015). • PAPER

Mahon C, Farris DJ, Sawicki GS, Lewek MD, “Individual limb mechanical analysis of gait following stroke”. J Biomech. Apr 12; 48(6): 984-9. (2015). • PAPER

Zelik K, Takahashi KZ, Sawicki GS, “Six degree-of-freedom analysis of hip, knee, ankle and foot provides updated understanding of biomechanical work during human walking”. J Exp Biol. Mar; 218(Pt 6): 876-86. (2015). • PAPER • Article featured on ‘Inside JEB’

2014

Farris DJ, Hicks J, Delp S, Sawicki GS, “Musculoskeletal modelling deconstructs the paradoxical effects of elastic ankle exoskeletons on plantar-flexor mechanics and energetics during hopping”. J Exp Biol. Nov 15; 217(Pt 22) 4018-28. (2014). • PAPER

Robertson BD, Farris DJ, Sawicki GS, “More is not always better: Modeling the effects of elastic exoskeleton compliance on underlying ankle muscle-tendon dynamics”. Bioinspir. Biomim. Nov 24; 9(4): 046018. (2014). • PAPER • FIGURE CORRECTION

Robertson BD, Sawicki GS, “Exploiting elasticity: Modeling the influence of neural control on mechanics and energetics of ankle muscle-tendons during human hopping“. J Theor Biol. Jul 21; 353: 121-32. Epub Mar 16. (2014). • PAPER • Equations for Metabolic Rate in Table 2 have errors in the inequalities. Should be Vce<0 for first line and Vce>=0 for second line

2013

Shamaei K, Sawicki GS, Dollar A, “Estimation of quasi-stiffness of the human hip in the stance phase of walking”. PLoS One. 8(12): e81841. Epub Dec 9. (2013). • PAPER

Matta P, Myers J, Sawicki GS, “The influence of available reaction time on ball-player impact probability in youth baseball”. Sports Health. Mar;7(2): 154-60. doi: 10.1177/1941738113498209. (2013). • PAPER

Farris DJ, Robertson BD, Sawicki GS, “Passive elastic exoskeletons reduce soleus muscle force but not work in human hopping”. J Appl Physiol. Sep 1; 115(5): 579-85 Epub Jun 20. (2013). • PAPER

Shamaei K, Sawicki GS, Dollar A,“Estimation of quasi-stiffness and propulsive work of the human ankle in the stance phase of walking“. PLoS One. 8(3): e59935. Epub Mar 21. (2013). • PAPER

Shamaei K, Sawicki GS, Dollar A,“Estimation of quasi-stiffness of the human knee in the stance phase of walking“. PLoS One. 8(3): e59935. Epub Mar 22. (2013). • PAPER

2012

Farris DJ, Sawicki GS, “Linking the mechanics and energetics of hopping with passive elastic ankle exoskeletons”. J Appl Physiol. Dec 15; 113(12): 1862-72. Epub Oct 11. (2012). • PAPER • FIGURE CORRECTION

Richards C, Sawicki GS, “Elastic recoil can either amplify or attenuate muscle-tendon power depending on inertial versus fluid dynamic loading”. J Theor Biol. Nov 21, 313:68-78. Epub Aug 8. (2012). • PAPER

Wutzke CJ, Sawicki GS, Lewek MD, “The influence of a unilateral fixed ankle on metabolic and mechanical demands during walking in unimpaired young adults“. J Biomech. Sep 21, 45(14): 2405-10. Epub Jul 25. (2012). • PAPER

Farris DJ, Sawicki GS, “Human medial gastrocnemius force-velocity behavior shifts with locomotion speed and gait“. Proc Natl Acad of Sci USA. Jan 17, 109(3): 977-82. Epub Jan 4. (2012). • PAPER

*Note: Units on velocity graphs from running in (Fig. 1F and Fig. S2E,F,G,H.) should be labeled mm/s, NOT m/s.

Farris DJ, Sawicki GS, “The mechanics and energetics of human walking and running: a joint-level perspective”. J R Soc Interface. Jan 7, 9(66): 110-8. Epub 2011 May 25. (2012). • PAPER

2009

Sawicki GS, Lewis CL, Ferris DP, “It pays to have a spring in your step”. Exerc Sport Sci Rev. 37(3):130-8 (2009). • PAPER

Sawicki GS, Ferris DP, “A pneumatically powered knee-ankle-foot orthosis (KAFO) with myoelectric activation and inhibition”. J Neuroeng Rehabil. 6(1):23 (2009). • PAPER

Sawicki GS, Ferris DP, “Mechanics and energetics of incline walking with robotic ankle exoskeletons”. J Exp Biol. 212(Pt 1):32-41 (2009). • PAPER

Sawicki GS, Ferris DP, “Powered exoskeletons reveal the metabolic cost of plantar flexor mechanical work during walking with longer steps at constant step frequency”. J Exp Biol. 212(Pt 1):21-31 (2009). • PAPER

2008

Sawicki GS, Ferris DP, “Mechanics and energetics of level walking with powered ankle exoskeletons”. J Exp Biol. 211(Pt 9):1402-1413 (2008). • PAPER • Article featured on ‘Inside JEB’

2007

Ferris DP, Sawicki GS, Daley, MA, “A physiologist’s perspective on robotic exoskeletons for human locomotion”. International Journal of Humanoid Robotics. 4(3):507-528 (2007). • PAPER

Domingo A, Sawicki GS, Ferris DP, “Kinematics and muscle activity of individuals with incomplete spinal cord injury during treadmill stepping with and without manual assistance”. J Neuroeng Rehabil. 4:32 (2007). • PAPER

2006

Sawicki GS, Domingo A, Ferris DP, “The effects of powered ankle-foot orthoses on joint kinematics and muscle activation during walking in individuals with incomplete spinal cord injury “. J Neuroeng Rehabil. 3:3 (2006). • PAPER

Gordon KE, Sawicki GS, Ferris DP, “Mechanical performance of artificial pneumatic muscles to power an ankle-foot orthosis”. J Biomech. 39(10):1832-41 (2006). • PAPER

Ferris DP , Gordon KE, Sawicki GS, Peethambaran A, “An improved powered ankle-foot orthosis using proportional myoelectric control”. Gait Posture. 23(4):425-8 (2006). • PAPER

2005

Ferris DP, Sawicki GS, Domingo A., “Powered lower limb orthoses for gait rehabilitation”. Top Spinal Cord Inj Rehabil. 11(2):34-49 (2005). • PAPER

Sawicki GS, Hubbard M, Stronge WJ, “Reply to Comment on “How to hit home runs: Optimum baseball swing parameters for maximum range trajectories”, by G. S. Sawicki, M. Hubbard, and W. J. Stronge [Am. J. Phys. 71(11):1152-62 (2003)]”. Am J Phys. 73(2):185-89 (2005). • PAPER

2003

Sawicki GS, Hubbard M, Stronge WJ, “How to hit homeruns: Optimum bat swing parameters for maximum range trajectories”. Am J Phys. 71(11):1152-62 (2003). • PAPER • Highlighted in ‘Science’ • Highlighted on NPR’s ‘Day to Day’ with Mike Pesca