Strength Training for Skeletal Muscle Adaptation After Stroke

Active, not recruiting

Phase N/A Results

Trial Description

Chronically disabled stroke survivors experience accelerated skeletal muscle atrophy and other detrimental changes to muscle and surrounding tissues on the paretic side. This unilateral tissue-level damage contributes to worsening disability and insulin resistance. This VA Merit Award will advance the investigators' understanding of the potential for strength training (ST) to reverse stroke-related muscle abnormalities to improve metabolic health, strength, and function. It will be the first study to thoroughly investigate the effects of ST on muscle atrophy, intramuscular fat, muscle fiber characteristics, capillary density and insulin sensitivity after stroke.

Detailed Description

This study investigates the hypothesis that a novel, high intensity, high repetition ST program will improve abnormalities in paretic and non-paretic leg muscle volume and composition compared to an attention-matched control regimen of supervised stretching over a 3-month intervention period in those disabled by stroke. The investigators further hypothesize that ST-induced skeletal muscle adaptation will translate into improved insulin sensitivity, strength, and function in this population. The specific objectives are to: 1) Determine the effects ST compared to a control intervention on paretic and non-paretic abnormalities in skeletal muscle volume, intramuscular fat, muscle fiber distribution, muscle capillary density, and muscle inflammation in chronically disabled stroke survivors. 2) Determine the effects ST compared to a control intervention on insulin sensitivity in stroke survivors, and whether structural and cellular skeletal muscle mechanisms contribute to improvements in insulin sensitivity after ST. 3) Determine the effects ST compared to a control intervention on physical function (strength, walking speed and balance) in stroke survivors, and whether structural skeletal muscle mechanisms predict ST-induced functional improvement.
The project design consists of 4 phases over 5 months for stroke participants enrolled in either of the two intervention arms (ST vs. CONTROL). During phase 1 the investigators will screen and consent chronic stroke patients with residual gait deficits. Phase 2 (3 weeks) will consist of baseline testing that includes dual energy X-ray absorptiometry (DEXA) scanning, bilateral CT scanning of the legs, bilateral vastus lateralis muscle biopsies, strength testing, timed walks, balance measurements, oral glucose tolerance testing, and hyperglycemic clamp testing. Following completion of baseline testing, volunteers are to be randomized to ST or the CONTROL group. Phase 3 (Intervention Phase, 3 months) will begin with 2 sessions of acclimatization for those assigned to the ST group. ST will then be progressed to 2 sets of 20 repetitions on each leg on each machine (Keiser Leg Press, Leg Extension, Leg Curl) with gradual increases in resistance over 3 months. Those in the CONTROL group will receive equal exposure to health care personnel in the Baltimore VA Exercise facility, performing a full battery of upper and lower body passive and active stretching exercises at each intervention session. In Phase 4 all baseline testing and laboratory analyses will be repeated.
Developing evidence-based therapies to combat skeletal muscle deterioration is highly relevant for chronically disabled stoke survivors. There is mounting evidence that current models of post-stroke rehabilitation are not optimal for maximizing recovery of muscle mass, strength, and metabolic health. The proposed research will develop new insight into the utility of progressive ST for reversing detrimental changes to gross muscle composition, muscle molecular phenotype, muscle inflammation, and muscle capillarization. Changes to any or all of these muscle parameters should have measurable impact on both whole body insulin sensitivity and function. Collectively, the results from this trial may change the current standard of care for stroke survivors by providing evidenced reasons for augmenting physical therapists' treatments, allowing more intense and diverse therapy sessions for maintenance of skeletal muscle.

Conditions

Interventions

  • Exercise- Strength Training Other
    Intervention Desc: 3x per week lower-extremity ST lasting approximately 45 minutes to 1 hour.
    ARM 1: Kind: Experimental
    Label: 1
    Description: Participants in this group undergo lower-extremity strength training on three pneumatic resistance machines (Keiser Leg Press, Keiser Leg Extension, and Keiser Leg Curl). Training sessions happen 3 times per week (M,W,F) and last approximately 45 minutes to 1 hour. Participants in this group exercise each limb individually to account for the large discrepancies in strength between legs in stroke survivors.
    ARM 2: Kind: Experimental
    Label: Arm 1
    Description: Participants in this group undergo lower-extremity strength training on three pneumatic resistance machines (Keiser Leg Press, Keiser Leg Extension, and Keiser Leg Curl). Training sessions happen 3 times per week (M,W,F) and last approximately 45 minutes to 1 hour. Participants in this group exercise each limb individually to account for the large discrepancies in strength between legs in stroke survivors.
  • Exercise- Stretching Control Other
    Intervention Desc: 3x per week upper and lower body stretching mixed with active and passive range of motion exercises
    ARM 1: Kind: Experimental
    Label: 2
    Description: Participants in this group receive equal exposure to study staff compared with the experimental ST group (approximately 45 minutes to 1 hour 3 times per week). Exercise sessions for this group involve a full battery of active and passive...upper and lower body.. stretching and range of motion exercises performed on raised padded tables.
    ARM 2: Kind: Experimental
    Label: Arm 2
    Description: Participants in this group receive equal exposure to study staff compared with the experimental ST group (approximately 45 minutes to 1 hour 3 times per week). Exercise sessions for this group involve a full battery of active and passive...upper and lower body.. stretching and range of motion exercises performed on raised padded tables.

Trial Design

  • Allocation: Randomized
  • Masking: Open Label
  • Purpose: Treatment
  • Endpoint: Efficacy Study
  • Intervention: Parallel Assignment

Outcomes

Type Measure Time Frame Safety Issue
Primary Bilateral Thigh Muscle Area and Volume by CT scan baseline and 3 months (post intervention) No
Secondary Bilateral Thigh Intramuscular Fat by CT baseline and 3 months No
Secondary Histochemical analyses of fiber type and capillary density from Bilateral Thigh Muscle Biopsy samples baseline and 3 months No
Secondary Muscle Fiber proportion and mean cross sectional area by immunohistochemistry baseline and 3 months No
Secondary Myosin Heavy Chain Isoform expression by gel electrophoresis baseline and 3 months No
Secondary Skeletal Muscle TNF-alpha transcript expression by RT-PCR baseline and 3 months No
Secondary Muscle Inflammatory Infiltrates by Immunohistochemistry baseline and 3 months No
Secondary Oral Glucose tolerance Test baseline and 3 months No
Secondary Insulin Sensitivity by Hyperglycemic Clamp Test baseline and 3 months No
Secondary Bilateral Single Limb Strength Testing (Leg Extension and Leg Press) baseline and 3 months No
Secondary Timed Walks (10 meter and 6 minute walk tests baseline and 3 months No
Secondary Balance Testing using Berg Balance Scale baseline and 3 months No
Secondary Peak Fitness by graded treadmill VO2 peak testing baseline and 3 months No
Secondary Bilateral Single Limb Muscle Endurance (Static and Dynamic) baseline and 3 months No
Secondary Cognitive Function baseline and 3 months No
Secondary Balance during reaching task baseline and 3 months No
Primary Change in 1-RM Muscle Strength (Leg Press, Paretic Side) Baseline, 3 months No
Primary Change in 1-RM Muscle Strength (Leg Press, Non-Paretic Side) Baseline, 3 months No
Primary Change in 1-RM Muscle Strength (Leg Extension, Paretic Side) Baseline, 3 Months No
Primary Change in 1-RM Muscle Strength (Leg Extension, Non-Paretic Side) Baseline, 3 Months No
Primary Change in Leg Muscle Endurance (Paretic Side) Baseline, 3 Months No
Primary Change in Leg Muscle Endurance (Non-Paretic Side) Baseline, 3 months No
Primary Change in 6-minute Walk Distance Baseline, 3 Months No
Primary Change in 10 Meter Walking Speed (Self-Selected) Baseline, 3 months No
Primary Change in 10 Meter Walking Speed (Fastest) Baseline, 3 Months No
Primary Change in Peak Aerobic Capacity (VO2 Peak) Baseline, 3 Months No
Primary Change in Berg Balance Scale Baseline, 3 months No
Primary Change in Paretic Limb Step Time (Self-Selected) Baseline, 3 months No
Primary Change in Paretic Limb Step Time (Fastest) Baseline, 3 Months No
Primary Change in Non-Paretic Limb Step Time (Self-Selected) Baseline, 3 months No
Primary Change in Non-Paretic Limb Step Time (Fastest) Baseline, 3 Months No
Primary Change in Paretic Limb Step Length (Self-Selected) Baseline, 3 Months No
Primary Change in Paretic Limb Step Length (Fastest) Baseline, 3 months No
Primary Change in Non-Paretic Limb Step Length (Self-Selected) Baseline, 3 Months No
Primary Change in Non-Paretic Limb Step Length (Fastest) Baseline, 3 Months No
Primary Change in 1-repetition Maximum (RM) Muscle Strength (Leg Press, Paretic Side) Baseline, 3 months No

Sponsors