Notes on Body Weight–Supported Treadmill Training and Robotic-Assistive Steppers

BWSTT and RAST

  • Body weight–supported treadmill training (BWSTT) and robotic-assisted step training (RAST) have not shown better outcomes than progressive over-ground training (OGT) for disabled individuals with various conditions.

  • Conceptual bases seemed plausible, but randomized clinical trials (RCTs) have been disappointing.

  • BWSTT and RAST should not replace OGT outside efficacy trials due to lack of evidence.

Central Pattern Generators (CPGs)

  • Animal models suggested lumbar CPGs enable hind-limb stepping on a treadmill (TM) via afferent input, even after spinal cord transection.

  • Human studies indicated BWSTT might tap into CPGs to aid walking in impaired patients.

  • CPGs alone are insufficient for bipedal over-ground gait; supraspinal inputs are necessary.

Task-Oriented Massed Practice

  • BWSTT and RAST aimed to facilitate massed practice of stepping, focusing on gait kinematics.

  • Motor learning stresses reusing affected neural networks.

  • Practice intensity is often modest in rehabilitation.

  • Task-oriented training isn't always task-specific; components need better description.

  • Treadmills and robotic devices may not fully replicate over-ground walking biomechanics.

  • Patient engagement and attention are crucial for learning during BWSTT and RAST.

Neuroplasticity

  • Skills practice and exercise induce neural network adaptations.

  • Cortical adaptations don't automatically prove training efficacy.

  • Plasticity isn't a direct substitute for functional gains.

Early Studies and Their Limitations

  • Initial pilot studies showed promise but had limitations:

    • Selection bias

    • Small sample sizes

    • Lack of active comparison groups

    • Varied outcome measures

    • Methodological variations

    • No blinded outcomes

RCT Findings and Current Status

  • SCILT and LEAPS trials found conventional OGT and home-based exercise had similar results to BWSTT.

  • RAST also showed equivalence to conventional therapy in RCTs.

  • Commercial BWS systems and robotic steppers are widely available despite limited evidence of superior efficacy.

Key Questions and Future Directions

  • How can devices enhance skill training and problem-solving for walking?

  • Can robotic algorithms allow errors for better motor learning?

  • How can patient engagement be ensured during device training?

  • Can gait deviations be improved during BWSTT and RAST?

  • Is there effective therapeutic bridging between device and OGT?

  • BWSTT and RAST may augment walking skills when combined with neural repair or stimulation but are currently expensive workhorses, not thoroughbreds.

The type of bias mentioned in the context is selection bias, which was one of the limitations found in initial pilot studies of BWSTT and RAST. This means that the participants in those studies may not have been representative of the broader population, potentially skewing the results and inflating the perceived benefits of the interventions.