Power Training Post-stroke
Condition: Stroke
MeSH terms: Stroke
Study type: Interventional
Phase: Phase 2

Summary: 
      Hemiparesis, strictly defined as (muscular) weakness affecting one side of the body, is seen
      in three-quarters of individuals following stroke. Weakness in this population results from
      both neural and muscular factors which include, respectively, the ability to activate
      skeletal muscle as well as the force generating capacity of the muscle. The overall goal is
      to improve walking in persons post-stroke by training subjects with an intervention that
      specifically targets existing neural and muscular impairments, thereby facilitating locomotor
      recovery.
    

Detailed description: 
      A primary impairment associated with post-stroke hemiparesis is the failure to make rapid
      graded adjustment of muscle force (i.e. muscle power) within the context of purposeful
      complex synergies (e.g., coordination during walking). Not surprisingly, the impact of stroke
      on walking is significant, with less than 50% of survivors progressing to independent
      community ambulation. Even among those who achieve independent ambulation, significant
      residual deficits persist in balance and gait speed, with ~75% of persons post-stroke
      reporting limitations in mobility related to walking. Muscle weakness is the most prominent
      motor consequence among the nearly 6 million survivors of stroke living in the United States
      and the strongest predictor of functional disability in this large clinical cohort. To date,
      the physiological mechanisms that contribute to muscle dysfunction in hemiparetic subjects
      are largely unstudied. Moreover, evidence regarding the efficacy of interventions aimed at
      attenuating impaired muscle function and the ensuing functional consequences in the
      post-stroke population is equivocal and viable therapeutic options to remediate hemiparetic
      muscle weakness remain among the most pressing challenges for biomedical research. The
      investigators propose that impaired muscle power (the product of muscle strength and
      velocity) generation is causal of functional (walking) disability post-stroke. In addition,
      coordination deficits are also critical determinants of functional performance. The
      investigators have developed a comprehensive theoretical framework that defines and measures
      the factors underlying disordered muscle function and coordination and will apply this
      framework to Post-stroke Optimization of Walking using Explosive Resistance (POWER) training.
      The investigators' goals over the four year funding period are to 1) quantify neural and
      muscular adaptations that contribute to impaired muscle power generation post-stroke; 2)
      assess effects of POWER training on neural and muscular adaptations in paretic and
      non-paretic muscle; and 3) determine the relationship between changes in neural and muscular
      adaptations following POWER training and locomotor improvements. Innovative aspects of the
      proposed work include the novel training intervention; the advanced magnetic resonance
      assessments; as well as the unique measure of the coordination that the investigators
      propose. It is the investigators' belief that: a) neural and muscular adaptations following
      stroke are associated with impaired muscle power generation as well as locomotor ability, b)
      POWER training attenuates functional deficits by addressing the underlying neural and
      muscular elements and c) functional improvements following training are predicated on
      improving the most prominent neural and muscular contributors to muscle power generation. If
      correct, the data generated will provide an entirely new level of evidence regarding the
      effectiveness of this novel intervention strategy on improving functional performance as well
      as the importance of peripheral muscle properties as predictors of locomotor ability
      post-stroke.
    

Intervention name(s): POWER training
Intervention type(s): Behavioral
Intervention description(s): Individuals with chronic post-stroke hemiparesis will undergo training to improve muscle power generation for 24 sessions (3 times/week) that includes both resistive and task-specific elements. Session duration will be ~90 minutes/day (inclusive of rest intervals). Training will include five distinct resistance activities aimed at improving muscle power-- each previously reported to contribute to improved walking
Other intervention name(s): strength training
Intervention model: Single Group Assignment
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Treatment
Keywords: exercise; rehabilitation; walking