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Research Reports: Jeffrey F Israel, Donielle D Campbell, Jennifer H Kahn, and T George Hornby Metabolic Costs and Muscle Activity Patterns During Robotic- and Therapist-Assisted Treadmill Walking in Individuals With Incomplete Spinal Cord Injury PHYS THER 2006; 86: 1466-1478 [Abstract] [Full text] [PDF]

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"As much help as necessary, but as little as possible"

Anton Wernig, Sabine Mueller PT   (18 January 2007)

"As much help as necessary, but as little as possible" 18 January 2007
Anton Wernig, M.D., Ph.D. Univ.-Bonn & Clinic KKL, Germany, Sabine Mueller PT Send rapid response to journal: Re: "As much help as necessary, but as little as possible" anton.wernig{at}ukb.uni-bonn.de Anton Wernig, et al.	In their careful analysis, Israel et al(1) find that robot-assisted locomotor training on the treadmill of people with incomplete SCI is associated with less active contribution by the patient than training under manual guidance by therapists. As a consequence, the authors expect that the intended training effects will be more pronounced under therapist guidance. Such deficit can indeed be noticed(2) when comparing the functional improvements (walking over firm ground) in patients with a chronic condition who are trained with manual guidance(3) or in a robotic device (eg, Locomat)(4): 8 out of 9 nonambulating people with incomplete SCI became capable of independent walking over ground after “manually assisted training,” but none of the 4 comparable patients trained in a Locomat. The reasons for the poor outcome of robot-assisted training seem to be complex; in my mind, one can be traced to the relatively high amount of body-weight support continuously necessary with the robot(1,4). Reduced limb loading produces inappropriate proprioceptive signals to spinal cord circuitry, to the effect of less recruitment of spinal motor pools(5). Reduced voluntary effort by the patient means less activation of efferent motor paths, which will hinder activity-related learning at central and peripheral synapses(1,6). Moreover, it is rather unlikely that movements beyond voluntary control that can be facilitated or even elicited by proper limb settings (ie, active loading and de-loading of limbs, hyperextension in the hip joint; summarised as “rules of spinal locomotion”)(3,5,7) are at all supported, if not hindered, by robotic devices.(2) From our experience, we would like to add that suboptimal demand on the patient's active contribution can also occur under manual guidance by therapists: Even experienced therapists tend to provide more support than is necessary, in particular with high treadmill speeds. Consequently, the patient will tend to stop or reduce his/her own effort (see two accompanying videos at http://imbie.meb.uni-bonn.de/wernig/tocha/TOCHA-02.pdf). Clearly, therefore, the therapist’s intervention also ought to be “as much as necessary,(1) but as little as possible.” Such restricted manual aid includes help in completing a step and in proper setting of the foot with heel strike followed by early knee extension (demonstrated in the videos; for more details and training in other diseases, see www.meb.uni-bonn.de/wernig[8]). Israel et al(1) applied high treadmill speeds (around 3 km/h). We find that with severe paralyses and high speeds, therapists tend to provide less differentiated help, approaching unreflected “robot-like” help, which is bound to be less effective. Apart from this, such effort is indeed demanding on the physical condition of the therapists, as Israel et al note, and will also involve more therapists to assist a single patient than necessary at regular speeds (in video 2, a single therapist trains a nonambulating patient with SCI). Curiously, there is no scientific reason to apply such high speed other than it is approaching the regular walking speed of healthy persons; to the contrary, high speeds have not been proven to be as effective as speeds originally suggested (according to the needs of the patient between 0,1 and some 1,8 km/h)(7, 8, 9, 10, 11). References: 1 Israel JF, Campbell DD, Kahn JH, Hornby TG. Metabolic costs and muscle activity patterns during robotic- and therapist-assisted treadmill walking in individuals with incomplete spinal cord injury. Phys Ther. 2006 Nov;86:1466-1478. 2 Wernig A. “Ineffectiveness” of Automated Locomotor Training. Arch Phys Med Rehabil. 2005;86:2385-2386. Comment. 3 Wernig A, Müller S, Nanassy A, Cagol E. Laufband therapy based on 'rules of spinal locomotion' is effective in spinal cord injured persons. Eur J Neurosci. 1995;7:823-829. Erratum in: Eur J Neurosci 1995;7:1429. 4 Wirz M, Zemon DH, Rupp R, et al. Effectiveness of automated locomotor training in patients with chronic incomplete spinal cord injury: a multicenter trial. Arch Phys Med Rehabil. 2005;86:672-680. Comment in: Arch Phys Med Rehabil. 2005;86:2385-2386; author reply, 2386-2387. 5 Maegele M, Müller S, Wernig A, Edgerton VR, Harkema SJ. Recruitment of spinal motor pools during voluntary movements versus stepping after human spinal cord injury. J Neurotrauma. 2002;19:1217-1229. 6 Dorlochter M, Irintchev A, Brinkers M, Wernig A. Effects of enhanced activity on synaptic transmission in mouse extensor digitorum longus muscle. J Physiol. 1991;436:283-292. 7 Wernig A, Müller S. Laufband locomotion with body weight support improved walking in persons with severe spinal cord injuries. Paraplegia. 1992;30:229-238. 8 Wernig A, Müller S. Laufband (LB) Therapy. Available at: www.meb.uni-bonn.de/wernig/html/manual.htlm. Accessed January 18, 2007. 9 Norman K E, Pepin A, Ladouceur M, Barbeau H. A treadmill apparatus and harness support for evaluation and rehabilitation of gait. Arch Phys Med Rehabil. 1995;76:772-778. 10 Barbeau H, Blunt R. A novel interactive locomotor approach using body weight support to retrain gait in spastic paretic subjects. In: Wernig A, ed. Plasticity of Motorneuronal Connections. Philadelphia, Pa: Elsevier Science; 1991:461–474. 11 Dietz V, Colombo G, Jensen L, Baumgartner L. Locomotor capacity of spinal cord in paraplegic patients. Ann Neurol. 1995;37:574-582.