Metabolic cost adaptations during training with a soft exosuit assisting the hip joint.

Journal: Scientific reports
Published Date: Jul 5, 2019

Abstract

Different adaptation rates have been reported in studies involving ankle exoskeletons designed to reduce the metabolic cost of their wearers. This work aimed to investigate energetic adaptations occurring over multiple training sessions, while walking with a soft exosuit assisting the hip joint. The participants attended five training sessions within 20 days. They walked carrying a load of 20.4 kg for 20 minutes with the exosuit powered and five minutes with the exosuit unpowered. Percentage change in net metabolic cost between the powered and unpowered conditions improved across sessions from -6.2 ± 3.9% (session one) to -10.3 ± 4.7% (session five), indicating a significant effect associated with training. The percentage change at session three (-10.5 ± 4.5%) was similar to the percentage change at session five, indicating that two 20-minute sessions may be sufficient for users to fully adapt and maximize the metabolic benefit provided by the exoskeleton. Retention was also tested measuring the metabolic reduction five months after the last training session. The percent change in metabolic cost during this session (-10.1 ± 3.2%) was similar to the last training session, indicating that the adaptations resulting in reduced metabolic cost are preserved. These outcomes are relevant when evaluating exoskeletons' performance on naïve users, with a specific focus on hip extension assistance.

Authors

  • Fausto A Panizzolo
    John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA, 02138, USA.
  • Gregory M Freisinger
    Department of Civil and Mechanical Engineering, United States Military Academy, 752 Thayer Road, West Point, NY, 10996, USA. gregory.freisinger@westpoint.edu.
  • Nikos Karavas
    John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
  • Asa M Eckert-Erdheim
    John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA, 02138, USA.
  • Christopher Siviy
    John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA, 02138, USA.
  • Andrew Long
  • Rebecca A Zifchock
    Department of Civil and Mechanical Engineering, United States Military Academy, 752 Thayer Road, West Point, NY, 10996, USA.
  • Michael E LaFiandra
    United States Army Research Laboratory, Aberdeen Proving Ground, 4727 Deer Creek Loop, MD, 21005, Maryland, USA.
  • Conor J Walsh
    John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA, 02138, USA. walsh@seas.harvard.edu.

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