Exercise Training and Walking Ability After Chronic Stroke
Condition: Stroke
MeSH terms: Stroke
Study type: Interventional

Summary: 
      This study will investigate the efficacy of aerobic exercise and progressive resistance
      training (PRT), singularly and combined, on changes in walking endurance for
      mildly-to-moderately affected chronic stroke patients. Specifically, we will determine the
      relative importance of training induced changes in muscle strength versus aerobic fitness on
      increases in gait velocity and 6-min walking distance, and assess the concomitant functional
      and psychosocial impact of increased muscle strength, aerobic fitness and improved gait. This
      longitudinal study will be conducted as a double blinded factorial randomized controlled
      trial of exercise training for chronic stroke patients.
    

Detailed description: 
      The experimental hypotheses are:

        1. Participation in a 10-week exercise program consisting of aerobic, resistance or
           combined aerobic+resistance training will produce a 20% or greater increase of 6-min
           walking distance compared to controls.

        2. Aerobic fitness will increase equally in the combined aerobic+resistance program and
           aerobic program alone, greater than that in the resistance program only, where effect is
           measured in terms of maximal and submaximal cardiorespiratory exercise performance.

        3. Lower limb muscle strength will increase equally in the combined aerobic+resistance
           program and resistance program alone, greater than the increase in strength for aerobic
           training, where effect is measured in terms of measures of lower limb strength, power
           and endurance.

      Research Plan Synopsis:

      To determine treatment efficacy, a 2x2 factorial double-blinded randomized controlled trial
      will be conducted, the two factors being aerobic training and PRT. Forty-eight subjects will
      be randomly allocated to one of four groups comprising (i) aerobic exercise training
      [AEROBIC; n=12]; (ii) PRT [RESISTANCE; n=12]; (iii) combined aerobic training and PRT
      [AEROBIC+RESISTANCE; n=12], or (iv) control [CONTROLS; n=12]. AEROBIC and RESISTANCE groups
      will also include a "sham" treatment for the other factor, and the order of presentation of
      treatment versus "sham" will also be randomized within each exercise session. All subjects
      will attend 3 times per week for 10 weeks. Subjects will be recruited from various hospitals,
      peer support groups and previous participants of an acute stroke research project that we are
      now conducting. All will be screened by a medical practitioner for inclusion and exclusion
      criteria and then allocated to one of the four groups by the trial coordinator.

      Interventions:

      AEROBIC Training Group: These subjects will undertake 30 min of leg cycling per exercise
      session. Leg cycling will be performed at a pedaling cadence of 50 rev/min in the seated
      posture using a standard seated cycle ergometer to elicit a target heart rate equivalent to
      50% VO2peak - 70% VO2peak. Subjects in this group will also undertake 30-min of "sham"
      resistance training consisting of stretching and calisthenics lacking any strength
      development characteristics. Cycle ergometry will be used to develop aerobic fitness, rather
      than fast walking, because previous studies have shown that stroke patients do not have the
      capacity to walk at a sufficient pace to provide an adequate stimulus to the cardiovascular
      system.

      RESISTANCE Training Group: These subjects will undertake 30 min of PRT per exercise session
      using pneumatic resistance equipment and free weights. Standard PRT principles governing
      frequency, volume, duration, and intensity of exercise known to provide maximal adaptation in
      both healthy and frail adults will be followed. Legs will be trained unilaterally to maximize
      neural recruitment of the impaired side and prevent substitution of stronger muscles for
      weaker ones. Subjects will perform 3 sets of 8 repetitions at 80% of the one repetition
      maximum with each muscle group. Subjects in this group will also undertake 30-min of "sham"
      aerobic training consisting of motorized passive leg cycling.

      AEROBIC+ RESISTANCE Training Group: Subjects in the AEROBIC+RESISTANCE training group will
      undertake 30 min of leg cycling exercise as described for the AEROBIC group in addition to 30
      min of PRT as described for the RESISTANCE group per exercise session.

      CONTROL Group: Subjects in this group will undertake 30-min of "sham" aerobic training
      consisting of motorized passive leg cycling and 30-min of "sham" resistance training
      consisting of stretching and calisthenics lacking any strength development characteristics
      per session.

      Outcomes:

      Primary outcome: Subjects will undertake a 6 min walking test for maximum distance. The 6-min
      test has been selected as our primary outcome because walking distance is an important
      criteria for 'community ambulation', it avoids the problem of gait velocity being relevant
      only for short-distance ambulation and has a prior history of investigation in previous
      studies of low intensity aerobic and resistance training.

      Secondary outcomes:

      A. Cardiorespiratory Fitness will be assessed from cardiorespiratory variables collected
      during (i) a maximal effort cycle test, (ii) a multi stage submaximal exercise cycle test,
      and (iii) a dual stage treadmill walking test, performed on separate days.

      B. Lower limb Muscular Strength and Endurance will be assessed from maximal muscle force,
      maximal muscle power and muscle endurance using pneumatic resistance machines (leg press,
      knee extension) and free weights (hip abduction, ankle dorsiflexion).

      C. Mobility Variables:

      Temporal (velocity, step time, single support, double support) and spatial (step length and
      stride length) variables will be collected using a gait analysis system. Balance in standing
      and coordinated stability will be assessed using a sway-meter that measures displacements of
      the body at the level of the waist.

      D. Scales and Questionnaires:

      To provide an assessment of changes in the subjects' psychological and functional states, a
      stroke impact scale, a self-efficacy scale and the health-related quality of life
      questionnaire will be used.

      Data Analysis:

      Treatment efficacy for the primary and secondary outcomes will be analyzed using univariate
      and multivariate analysis of variance. Where within-group differences are found, appropriate
      multiple comparisons a posteriori analyses will be used. If significant multivariate effects
      are evident, the standardized discriminant function coefficients will be examined to give an
      indication of the relative importance of each variable in explaining the variance in the
      group by time effect. To allow for the possibility that all or some of these data may be
      covariates upon the primary outcome, multiple regression analysis will be utilized to explore
      the relative importance of aerobic fitness, muscle power, strength or endurance and mobility
      measures upon 6-min walk distance.
    

Intervention name(s): [A] Aerobic isokinetic cycling exercise; [B] Progressive Resistance Training; [A] + [B]
Intervention type(s): Procedure; Procedure; Procedure
Allocation: Randomized
Intervention model: Factorial Assignment
Masking: Double
Primary purpose: Treatment
Keywords: Stroke; Exercise; Aerobic; PRT; Walking ability