European Journal of Applied Physiology

, Volume 114, Issue 11, pp 2341–2351 | Cite as

Enhancing performance during inclined loaded walking with a powered ankle–foot exoskeleton

  • Samuel Galle
  • Philippe Malcolm
  • Wim Derave
  • Dirk De Clercq
Original Article



A simple ankle–foot exoskeleton that assists plantarflexion during push-off can reduce the metabolic power during walking. This suggests that walking performance during a maximal incremental exercise could be improved with an exoskeleton if the exoskeleton is still efficient during maximal exercise intensities. Therefore, we quantified the walking performance during a maximal incremental exercise test with a powered and unpowered exoskeleton: uphill walking with progressively higher weights.


Nine female subjects performed two incremental exercise tests with an exoskeleton: 1 day with (powered condition) and another day without (unpowered condition) plantarflexion assistance. Subjects walked on an inclined treadmill (15 %) at 5 km h−1 and 5 % of body weight was added every 3 min until exhaustion.


At volitional termination no significant differences were found between the powered and unpowered condition for blood lactate concentration (respectively, 7.93 ± 2.49; 8.14 ± 2.24 mmol L−1), heart rate (respectively, 190.00 ± 6.50; 191.78 ± 6.50 bpm), Borg score (respectively, 18.57 ± 0.79; 18.93 ± 0.73) and \(\dot{V}{\rm O}_{2}\) peak (respectively, 40.55 ± 2.78; 40.55 ± 3.05 ml min−1 kg−1). Thus, subjects were able to reach the same (near) maximal effort in both conditions. However, subjects continued the exercise test longer in the powered condition and carried 7.07 ± 3.34 kg more weight because of the assistance of the exoskeleton.


Our results show that plantarflexion assistance during push-off can increase walking performance during a maximal exercise test as subjects were able to carry more weight. This emphasizes the importance of acting on the ankle joint in assistive devices and the potential of simple ankle–foot exoskeletons for reducing metabolic power and increasing weight carrying capability, even during maximal intensities.


Ankle–foot exoskeleton Locomotion Uphill walking Loaded walking Performance Exercise test Maximal exercise Exhaustion 



This research was supported by BOF10/DOC/288. The authors wish to thank Ing. Davy Spiessens for the technical support, Brecht Van Genabet and Hanneke Van Gucht for the support during data collection and Technische Orthopedie België for constructing the exoskeleton.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Samuel Galle
    • 1
  • Philippe Malcolm
    • 1
  • Wim Derave
    • 1
  • Dirk De Clercq
    • 1
  1. 1.Department of Movement and Sport SciencesGhent UniversityGhentBelgium

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