Experimental study on the role of the ankle push off in the walk-to-run transition by means of a powered ankle-foot-exoskeleton

Malcolm, Philippe; Fiers, Pieter; Segers, Veerle; Caekenberghe, Ine Van; Lenoir, Matthieu; Clercq, Dirk De

doi:10.1016/j.gaitpost.2009.06.002

Cited by 35 publications

(26 citation statements)

References 29 publications

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“…Ultrasound imaging of the gastrocnemius (Farris and Sawicki, 2012) has shown that the walk-run transition produces favorable length and velocity changes that optimize force production at a given activation level. However, manipulating the demand of specific muscle groups only had limited effects on the walk-run transition speed (Segers et al, 2007;Bartlett and Kram, 2008;Malcolm et al, 2009).…”

Section: Preferred Walk-run Transition Speed Tracks the Optimal Neuromentioning

confidence: 99%

Neuromuscular effort predicts walk-run transition speed in normal and adapted human gaits

Stenum

Choi

2016

Journal of Experimental Biology

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Often, humans and other animals move in a manner that minimizes energy costs. It is more economical to walk at slow speeds, and to run at fast speeds. Here, we asked whether humans select a gait that minimizes neuromuscular effort under novel and unfamiliar conditions, by imposing interlimb asymmetry during splitbelt treadmill locomotion. The walk-run transition speed changed markedly across different gait conditions: forward, backward, hybrid (one leg forward, one leg backward) and forward with speed differences (one leg faster than the other). Most importantly, we showed that the human walk-run transition speed across conditions was predicted by changes in neuromuscular effort (i.e. summed leg muscle activations). Our results for forward gait and forward gait with speed differences suggest that human locomotor patterns are optimized under both familiar and novel gait conditions by minimizing the motor command for leg muscle activation.

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Section: Preferred Walk-run Transition Speed Tracks the Optimal Neuromentioning

confidence: 99%

Neuromuscular effort predicts walk-run transition speed in normal and adapted human gaits

Stenum

Choi

2016

Journal of Experimental Biology

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“…However, the design philosophy of this system may provide a significant insight into the development of rehabilitation orthosis systems and improve rehabilitative procedures for paraplegic patients. [38]; and (c) powered ankle-foot exoskeleton [39].…”

Section: It Was Developed In 2006 As Shown Inmentioning

confidence: 99%

“…In 2009, Malcom et al developed a powered ankle-foot exoskeleton, which investigated the role of the tibialis anterior (TA) in the walk-to-run condition, as shown in Figure 5c [39][40][41][42]. The pneumatic muscles are used to provide the dorsiflexion and plantar-flexion torques through the assisting orthosis for incomplete SCI patients during assist and resist conditions.…”

Section: It Was Developed In 2006 As Shown Inmentioning

confidence: 99%

Recent Trends in Lower-Limb Robotic Rehabilitation Orthosis: Control Scheme and Strategy for Pneumatic Muscle Actuated Gait Trainers

2014

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Abstract:It is a general assumption that pneumatic muscle-type actuators will play an important role in the development of an assistive rehabilitation robotics system. In the last decade, the development of a pneumatic muscle actuated lower-limb leg orthosis has been rather slow compared to other types of actuated leg orthoses that use AC motors, DC motors, pneumatic cylinders, linear actuators, series elastic actuators (SEA) and brushless servomotors. However, recent years have shown that the interest in this field has grown exponentially, mainly due to the demand for a more compliant and interactive human-robotics system. This paper presents a survey of existing lower-limb leg orthoses for rehabilitation, which implement pneumatic muscle-type actuators, such as McKibben artificial muscles, rubbertuators, air muscles, pneumatic artificial muscles (PAM) or pneumatic muscle actuators (PMA). It reviews all the currently existing lower-limb rehabilitation orthosis systems in terms of comparison and evaluation of the design, as well as the control scheme and strategy, with the aim of clarifying the current and on-going research in the lower-limb robotic rehabilitation field.

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“…Many key “determinants,” or factors that appear to drive the walk-to-run transition have been identified over the years, including: metabolic energy minimization (Minetti et al, 1994), kinetic factors (Raynor et al, 2002), critical flexor muscle activations during the swing phase of gait (Hreljac et al, 2001; Malcolm et al, 2009b; Prilutsky and Gregor, 2001; Segers et al, 2007), a critical angular velocity of the ankle to protect dorsiflexors (Hreljac, 1995), and pendular dynamics of the center of mass (Kram et al, 1997). Some have proposed the idea that a combination of these factors contributes to the walk-to-run transition (Bartlett and Kram, 2008; Malcolm et al, 2009a). More recently, work has pointed to plantar flexor force production as a major determinant of the walk-to-run transition (Arnold et al, 2013; Farris and Sawicki, 2012; Malcolm et al, 2009a; Neptune and Sasaki, 2005).…”

Section: Introductionmentioning

confidence: 99%

“…Some have proposed the idea that a combination of these factors contributes to the walk-to-run transition (Bartlett and Kram, 2008; Malcolm et al, 2009a). More recently, work has pointed to plantar flexor force production as a major determinant of the walk-to-run transition (Arnold et al, 2013; Farris and Sawicki, 2012; Malcolm et al, 2009a; Neptune and Sasaki, 2005). Modeling of the soleus, medial gastrocnemius, and lateral gastrocnemius, and in vivo measurement of the medial gastrocnemius have demonstrated that as walking speed increases, so do the plantar flexor fascicle shortening velocities.…”

Section: Introductionmentioning

confidence: 99%

Biomechanics of the human walk-to-run gait transition in persons with unilateral transtibial amputation

Giest

Chang

2016

Journal of Biomechanics

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Propulsive force production (indicative of intrinsic force-length-velocity characteristics of the plantar flexor muscles) has been shown to be a major determinant of the human walk-to-run transition. The purpose of this work was to determine the gait transition speed of persons with unilateral, transtibial amputation donning a passive-elastic prosthesis and assess whether a mechanical limit of their intact side plantar flexor muscles is a major determinant of their walk-to-run transition. We determined each individual’s gait transition speed (GTS) via an incremental protocol and assessed kinetics and kinematics during walking at speeds 50, 60, 70, 80, 90, 100, 120, and 130% of that gait transition speed (100%:GTS). Unilateral, transtibial amputees transitioned between gaits at significantly slower absolute speeds than matched able-bodied controls (1.73±0.13 and 2.09±0.05m/s respectively, p<0.01). Peak anterior-posterior propulsive force increased with speed in controls until 100% of the preferred gait transition speed and decreased at greater speeds. A significant decrease in anterior-posterior propulsive force production was found at 120%GTS (110%: 0.27±0.04 > 120%: 0.23±0.05BW, p<0.05). In contrast, amputee subjects’ intact side generated significantly higher peak anterior-posterior propulsive forces while walking at speeds above their preferred gait transition speed (100%: 0.28±0.04 < 110%: 0.30±0.04BW, p<0.05). Changes in propulsive force production were found to be a function of changes in absolute speed, rather than relative to the walk-to-run transition speed. Therefore, the walk-to-run transition in unilateral, transtibial amputees is not likely dictated by propulsive force production or the force-length-velocity characteristics of the intact side plantar flexor muscles.

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Experimental study on the role of the ankle push off in the walk-to-run transition by means of a powered ankle-foot-exoskeleton

Cited by 35 publications

References 29 publications

Neuromuscular effort predicts walk-run transition speed in normal and adapted human gaits

Neuromuscular effort predicts walk-run transition speed in normal and adapted human gaits

Recent Trends in Lower-Limb Robotic Rehabilitation Orthosis: Control Scheme and Strategy for Pneumatic Muscle Actuated Gait Trainers

Biomechanics of the human walk-to-run gait transition in persons with unilateral transtibial amputation

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