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Ischemic conditioning increases strength and volitional activation of paretic muscle in chronic stroke: a pilot study. J Appl Physiol (1985) 2018 05 01;124(5):1140-1147

Date

02/09/2018

Pubmed ID

29420152

Pubmed Central ID

PMC6050199

DOI

10.1152/japplphysiol.01072.2017

Abstract

Ischemic conditioning (IC) on the arm or leg has emerged as an intervention to improve strength and performance in healthy populations, but the effects on neurological populations are unknown. The purpose of this study was to quantify the effects of a single session of IC on knee extensor strength and muscle activation in chronic stroke survivors. Maximal knee extensor torque measurements and surface EMG were quantified in 10 chronic stroke survivors (>1 yr poststroke) with hemiparesis before and after a single session of IC or sham on the paretic leg. IC consisted of 5 min of compression with a proximal thigh cuff (inflation pressure = 225 mmHg for IC or 25 mmHg for sham) followed by 5 min of rest. This was repeated five times. Maximal knee extensor strength, EMG magnitude, and motor unit firing behavior were measured before and immediately after IC or sham. IC increased paretic leg strength by 10.6 ± 8.5 Nm, whereas no difference was observed in the sham group (change in sham = 1.3 ± 2.9 Nm, P = 0.001 IC vs. sham). IC-induced increases in strength were accompanied by a 31 ± 15% increase in the magnitude of muscle EMG during maximal contractions and a 5% decrease in motor unit recruitment thresholds during submaximal contractions. Individuals who had the most asymmetry in strength between their paretic and nonparetic legs had the largest increases in strength ( r2 = 0.54). This study provides evidence that a single session of IC can increase strength through improved muscle activation in chronic stroke survivors. NEW & NOTEWORTHY Present rehabilitation strategies for chronic stroke survivors do not optimally activate paretic muscle, and this limits potential strength gains. Ischemic conditioning of a limb has emerged as an effective strategy to improve muscle performance in healthy individuals but has never been tested in neurological populations. In this study, we show that ischemic conditioning on the paretic leg of chronic stroke survivors can increase leg strength and muscle activation while reducing motor unit recruitment thresholds.

Author List

Hyngstrom AS, Murphy SA, Nguyen J, Schmit BD, Negro F, Gutterman DD, Durand MJ

Authors

Matt Durand PhD Associate Professor in the Physical Medicine and Rehabilitation department at Medical College of Wisconsin
David D. Gutterman MD Sr Associate Director, Professor in the Medicine department at Medical College of Wisconsin
Allison Hyngstrom PhD Associate Professor in the Physical Therapy department at Marquette University
Brian Schmit PhD Professor in the Biomedical Engineering department at Marquette University




MESH terms used to index this publication - Major topics in bold

Electromyography
Female
Humans
Ischemia
Knee
Knee Joint
Male
Middle Aged
Muscle Strength
Muscle, Skeletal
Paresis
Pilot Projects
Prospective Studies
Recruitment, Neurophysiological
Single-Blind Method
Stroke
Torque