Comparison of single bout effects of bicycle training versus locomotor training on paired reflex depression of the soleus H-reflex after motor incomplete spinal cord injury.

Department of Physical Therapy, University of Florida, Gainesville, FL, USA.
Archives of physical medicine and rehabilitation (Impact Factor: 2.18). 08/2009; 90(7):1218-28. DOI: 10.1016/j.apmr.2009.01.022
Source: PubMed

ABSTRACT To examine paired reflex depression changes post 20-minute bout each of 2 training environments: stationary bicycle ergometer training (bicycle training) and treadmill with body weight support and manual assistance (locomotor training).
Pretest-posttest repeated-measures.
Locomotor laboratory.
Motor incomplete SCI (n=12; mean, 44+/-16y); noninjured subjects (n=11; mean, 30.8+/-8.3y).
All subjects received each type of training on 2 separate days.
Paired reflex depression at different interstimulus intervals (10 s, 1 s, 500 ms, 200 ms, and 100 ms) was measured before and after both types of training.
(1) Depression was significantly less post-SCI compared with noninjured subjects at all interstimulus intervals and (2) post-SCI at 100-millisecond interstimulus interval: reflex depression significantly increased postbicycle training in all SCI subjects and in the chronic and spastic subgroups (P<.05).
Phase-dependent regulation of reflex excitability, essential to normal locomotion, coordinated by pre- and postsynaptic inhibitory processes (convergent action of descending and segmental inputs onto spinal circuits) is impaired post-SCI. Paired reflex depression provides a quantitative assay of inhibitory processes contributing to phase-dependent changes in reflex excitability. Because bicycle training normalized reflex depression, we propose that bicycling may have a potential role in walking rehabilitation, and future studies should examine the long-term effects on subclinical measures of reflex activity and its relationship to functional outcomes.

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