Enhancing Muscle Force and Femur Compressive Loads Via Feedback-Controlled Stimulation of Paralyzed Quadriceps in Humans

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• 作者：Shauna Dudley-Javoroski ; PhD ; PT ; Andrew E. Littmann ; MA ; PT ; Shuo-Hsiu Chang ; PhD ; PT ; Colleen L. McHenry ; BSE ; Richard K. Shields ; PhD ; PT ; ^{richard-shields@uiowa.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Electrical stimulation ; Fatigue ; Osteoporosis ; Rehabilitation ; Spinal cord injuries
• 刊名：Archives of Physical Medicine and Rehabilitation
• 出版年：2011
• 出版时间：February 2011
• 年：2011
• 卷：92
• 期：2
• 页码：242-249
• 全文大小：1173 K

文摘

Dudley-Javoroski S, Littmann AE, Chang S-H, McHenry CL, Shields RK. Enhancing muscle force and femur compressive loads via feedback-controlled stimulation of paralyzed quadriceps in humans.

Objective

To compare paralyzed quadriceps force properties and femur compressive loads in an upright functional task during conventional constant-frequency stimulation and force feedback-modulated stimulation.

Design

Crossover trial.

Setting

Research laboratory.

Participants

Subjects (N=13; 12 men, 1 woman) with motor-complete spinal cord injury.

Interventions

Subjects performed 2 bouts of 60 isometric quadriceps contractions while supported in a standing frame. On separate days, subjects received constant-frequency stimulation at 20Hz (CONST) or frequency-modulated stimulation triggered by a change in force (FDBCK). During FDBCK, a computer algorithm responded to each 10% reduction in force with a 20% increase in stimulation frequency.

Main Outcome Measures

A biomechanical model was used to derive compressive loads on the femur, with a target starting dose of load equal to 1.5 times body weight.

Results

Peak quadriceps force and fatigue index were higher for FDBCK than CONST (P<.05). Within-train force decline was greater during FDBCK bouts, but mean force remained above CONST values (P<.05). As fatigue developed during repetitive stimulation, FDBCK was superior to CONST for maintenance of femur compressive loads (P<.05).

Conclusions

Feedback-modulated stimulation in electrically activated stance is a viable method to maximize the physiologic performance of paralyzed quadriceps muscle. Compared with CONST, FDBCK yielded compressive loads that were closer to a targeted dose of stress with known osteogenic potential. Optimization of muscle force with FDBCK may be a useful tactic for future training-based antiosteoporosis protocols.