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Keller Et. Al. 2011

Improved postural control after slackline training is accompanied by reduced H-reflexes

Tags: Slackline

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Key Definitions

Hoffman Reflexes (H-Reflexes): "A monosynaptic reflex response that can be obtained from the soleus muscle after stimulation of the tibial nerve. Stimulation of afferent fibers in the tibial nerve triggers a reflex response in the motor nerves to the soleus via the spinal cord" [source](https://www.sciencedirect.com/topics/neuroscience/hoffmann-reflex#:~:text=The%20H%20reflex%20is%20

Key Takeaways

  1. How to explain the change from rapid swinging motions to stability while learning to slackline?
    1. Rapid swinging motions may be caused by muscle stretch reflexes exciting by the fast lateral movement of the line
    2. Speculation that experts suppress these reflexes to avoid overcompensating
  2. This study looks for spinal adaptations during slackline training
    1. Electrically evoked H reflex was used as a stand in for quantifying stretch reflex responses, which are hard to measure during activity
  3. Slacklining is significantly different from other balance training tasks
    1. The line moves in space, instead of being a static but unstable surface
    2. Slacklining activates the ankles, knees, and hips at the same time, instead of focusing primarily on the ankles.
  4. H Reflexes were evoked on the slackline and during other balance training tasks, before and after the 4 week slackline training program
    1. Postural control was assessed on a swinging platform to see if slackline training is transferable
  5. Found that slackline training significantly diminished H-reflexes without changing the background electromyography
    1. Neuromuscular adaptations are similar to other balance training
    2. Neural mechanisms are known to be able to influence the H reflex
  6. Seems to point to presynaptic rather than postsynaptic mechanisms

Limitations

  1. The SOL muscle where H reflexes were measured is not as active in the predominantly mediolateral movement of slacklining, but was chosen to compare slacklining to existing balance task research.
  2. Slacklining could alter motor control which alters H-reflex, instead of altering the h-reflex itself (which in this papers story would have altered motor control)

Additional Materials

SlacklineTrainingScheduleKellerEtAl2011