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BioMed Research International
Volume 2014, Article ID 925762, 8 pages
Research Article

Gradually Increased Training Intensity Benefits Rehabilitation Outcome after Stroke by BDNF Upregulation and Stress Suppression

1Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong
2Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hong Kong
3College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou 310027, China

Received 28 February 2014; Revised 14 May 2014; Accepted 21 May 2014; Published 19 June 2014

Academic Editor: Yiwen Wang

Copyright © 2014 Jing Sun et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Physical training is necessary for effective rehabilitation in the early poststroke period. Animal studies commonly use fixed training intensity throughout rehabilitation and without adapting it to the animals' recovered motor ability. This study investigated the correlation between training intensity and rehabilitation efficacy by using a focal ischemic stroke rat model. Eighty male Sprague-Dawley rats were induced with middle cerebral artery occlusion/reperfusion surgery. Sixty rats with successful stroke were then randomly assigned into four groups: control (CG, ), low intensity (LG, ), gradually increased intensity (GIG, ), and high intensity (HG, ). Behavioral tests were conducted daily to evaluate motor function recovery. Stress level and neural recovery were evaluated via plasma corticosterone and brain-derived neurotrophic factor (BDNF) concentration, respectively. GIG rats significantly ( ) recovered motor function and produced higher hippocampal BDNF (112.87 ± 25.18 ng/g). GIG and LG rats exhibited similar stress levels (540.63 ± 117.40 nM/L and 508.07 ± 161.30 nM/L, resp.), which were significantly lower ( ) than that (716.90 ± 156.48 nM/L) of HG rats. Training with gradually increased intensity achieved better recovery with lower stress. Our observations indicate that a training protocol that includes gradually increasing training intensity should be considered in both animal and clinical studies for better stroke recovery.