Ankle resistance with a unilateral soft exosuit increases plantarflexor effort during pushoff in unimpaired individuals
Abstract Background Ankle-targeting resistance training for improving plantarflexion function during walking increases rehabilitation intensity, an important factor for motor recovery after stroke. However, understanding of the effects of resisting plantarflexion during stance on joint kinetics and...
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| Format: | Article |
| Language: | English |
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BMC
2021-12-01
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| Series: | Journal of NeuroEngineering and Rehabilitation |
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| Online Access: | https://doi.org/10.1186/s12984-021-00966-5 |
| _version_ | 1819283148713754624 |
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| author | Krithika Swaminathan Sungwoo Park Fouzia Raza Franchino Porciuncula Sangjun Lee Richard W. Nuckols Louis N. Awad Conor J. Walsh |
| author_facet | Krithika Swaminathan Sungwoo Park Fouzia Raza Franchino Porciuncula Sangjun Lee Richard W. Nuckols Louis N. Awad Conor J. Walsh |
| author_sort | Krithika Swaminathan |
| collection | DOAJ |
| description | Abstract Background Ankle-targeting resistance training for improving plantarflexion function during walking increases rehabilitation intensity, an important factor for motor recovery after stroke. However, understanding of the effects of resisting plantarflexion during stance on joint kinetics and muscle activity—key outcomes in evaluating its potential value in rehabilitation—remains limited. This initial study uses a unilateral exosuit that resists plantarflexion during mid-late stance in unimpaired individuals to test the hypotheses that when plantarflexion is resisted, individuals would (1) increase plantarflexor ankle torque and muscle activity locally at the resisted ipsilateral ankle, but (2) at higher forces, exhibit a generalized response that also uses the unresisted joints and limb. Further, we expected (3) short-term retention into gait immediately after removal of resistance. Methods Ten healthy young adults walked at 1.25 m s−1 for four 10-min discrete bouts, each comprising baseline, exposure to active exosuit-applied resistance, and post-active sections. In each bout, a different force magnitude was applied based on individual baseline ankle torques. The peak resistance torque applied by the exosuit was 0.13 ± 0.01, 0.19 ± 0.01, 0.26 ± 0.02, and 0.32 ± 0.02 N m kg−1, in the LOW, MED, HIGH, and MAX bouts, respectively. Results (1) Across all bouts, participants increased peak ipsilateral biological ankle torque by 0.13–0.25 N m kg−1 (p < 0.001) during exosuit-applied resistance compared to corresponding baselines. Additionally, ipsilateral soleus activity during stance increased by 5.4–11.3% (p < 0.05) in all but the LOW bout. (2) In the HIGH and MAX bouts, vertical ground reaction force decreased on the ipsilateral limb while increasing on the contralateral limb (p < 0.01). Secondary analysis found that the force magnitude that maximized increases in biological ankle torque without significant changes in limb loading varied by subject. (3) Finally, peak ipsilateral plantarflexion angle increased significantly during post-exposure in the intermediate HIGH resistance bout (p < 0.05), which corresponded to the greatest average increase in soleus activity (p > 0.10). Conclusions Targeted resistance of ankle plantarflexion during stance by an exosuit consistently increased local ipsilateral plantarflexor effort during active resistance, but force magnitude will be an important parameter to tune for minimizing the involvement of the unresisted joints and limb during training. |
| first_indexed | 2024-12-24T01:26:53Z |
| format | Article |
| id | doaj.art-1451cfe248734487baf241519cf140aa |
| institution | Directory Open Access Journal |
| issn | 1743-0003 |
| language | English |
| last_indexed | 2024-12-24T01:26:53Z |
| publishDate | 2021-12-01 |
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| spelling | doaj.art-1451cfe248734487baf241519cf140aa2022-12-21T17:22:29ZengBMCJournal of NeuroEngineering and Rehabilitation1743-00032021-12-0118111710.1186/s12984-021-00966-5Ankle resistance with a unilateral soft exosuit increases plantarflexor effort during pushoff in unimpaired individualsKrithika Swaminathan0Sungwoo Park1Fouzia Raza2Franchino Porciuncula3Sangjun Lee4Richard W. Nuckols5Louis N. Awad6Conor J. Walsh7John A. Paulson School of Engineering and Applied Sciences, Harvard UniversityJohn A. Paulson School of Engineering and Applied Sciences, Harvard UniversityJohn A. Paulson School of Engineering and Applied Sciences, Harvard UniversityJohn A. Paulson School of Engineering and Applied Sciences, Harvard UniversityJohn A. Paulson School of Engineering and Applied Sciences, Harvard UniversityJohn A. Paulson School of Engineering and Applied Sciences, Harvard UniversitySargent College of Health and Rehabilitation Science, Boston UniversityJohn A. Paulson School of Engineering and Applied Sciences, Harvard UniversityAbstract Background Ankle-targeting resistance training for improving plantarflexion function during walking increases rehabilitation intensity, an important factor for motor recovery after stroke. However, understanding of the effects of resisting plantarflexion during stance on joint kinetics and muscle activity—key outcomes in evaluating its potential value in rehabilitation—remains limited. This initial study uses a unilateral exosuit that resists plantarflexion during mid-late stance in unimpaired individuals to test the hypotheses that when plantarflexion is resisted, individuals would (1) increase plantarflexor ankle torque and muscle activity locally at the resisted ipsilateral ankle, but (2) at higher forces, exhibit a generalized response that also uses the unresisted joints and limb. Further, we expected (3) short-term retention into gait immediately after removal of resistance. Methods Ten healthy young adults walked at 1.25 m s−1 for four 10-min discrete bouts, each comprising baseline, exposure to active exosuit-applied resistance, and post-active sections. In each bout, a different force magnitude was applied based on individual baseline ankle torques. The peak resistance torque applied by the exosuit was 0.13 ± 0.01, 0.19 ± 0.01, 0.26 ± 0.02, and 0.32 ± 0.02 N m kg−1, in the LOW, MED, HIGH, and MAX bouts, respectively. Results (1) Across all bouts, participants increased peak ipsilateral biological ankle torque by 0.13–0.25 N m kg−1 (p < 0.001) during exosuit-applied resistance compared to corresponding baselines. Additionally, ipsilateral soleus activity during stance increased by 5.4–11.3% (p < 0.05) in all but the LOW bout. (2) In the HIGH and MAX bouts, vertical ground reaction force decreased on the ipsilateral limb while increasing on the contralateral limb (p < 0.01). Secondary analysis found that the force magnitude that maximized increases in biological ankle torque without significant changes in limb loading varied by subject. (3) Finally, peak ipsilateral plantarflexion angle increased significantly during post-exposure in the intermediate HIGH resistance bout (p < 0.05), which corresponded to the greatest average increase in soleus activity (p > 0.10). Conclusions Targeted resistance of ankle plantarflexion during stance by an exosuit consistently increased local ipsilateral plantarflexor effort during active resistance, but force magnitude will be an important parameter to tune for minimizing the involvement of the unresisted joints and limb during training.https://doi.org/10.1186/s12984-021-00966-5Resistance trainingGait biomechanicsSoft exosuitLocomotor adaptation |
| spellingShingle | Krithika Swaminathan Sungwoo Park Fouzia Raza Franchino Porciuncula Sangjun Lee Richard W. Nuckols Louis N. Awad Conor J. Walsh Ankle resistance with a unilateral soft exosuit increases plantarflexor effort during pushoff in unimpaired individuals Journal of NeuroEngineering and Rehabilitation Resistance training Gait biomechanics Soft exosuit Locomotor adaptation |
| title | Ankle resistance with a unilateral soft exosuit increases plantarflexor effort during pushoff in unimpaired individuals |
| title_full | Ankle resistance with a unilateral soft exosuit increases plantarflexor effort during pushoff in unimpaired individuals |
| title_fullStr | Ankle resistance with a unilateral soft exosuit increases plantarflexor effort during pushoff in unimpaired individuals |
| title_full_unstemmed | Ankle resistance with a unilateral soft exosuit increases plantarflexor effort during pushoff in unimpaired individuals |
| title_short | Ankle resistance with a unilateral soft exosuit increases plantarflexor effort during pushoff in unimpaired individuals |
| title_sort | ankle resistance with a unilateral soft exosuit increases plantarflexor effort during pushoff in unimpaired individuals |
| topic | Resistance training Gait biomechanics Soft exosuit Locomotor adaptation |
| url | https://doi.org/10.1186/s12984-021-00966-5 |
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