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Vallery Neumann 2013

Balancing on Slacklines: Modeling and Empirical Evaluation

Tags: #slackline #dynamic_balance #control

Related: [[Improved postural control after slackline training is accompanied by reduced H-reflexes]] [[Rethinking Margin of Stability - Kazanski Et Al 2022]] [[The Condition for Dynamic Stability - Hof Et Al 2005]]

Key Definitions

  1. Ankle Strategy: Balance strategy where ankle movements move the location of the center of pressure (COP)
  2. Hip Strategy: Balance strategy where the hips move the upper body counter to the lower body
  3. Arm Strategy/Windmilling: Balance strategy where the arms change the bodies angular momentum
  4. Foot strategy: Balance Strategy where movement of the feet changes the placement of the base of support (BOS)

Key Takeaways

  1. Neuromechanical control strategies for slacklining aren't well understood
  2. The 4 control strategies used in rigid surface walking (defined above) can't all be used on the line
    1. The BOS and COP are limited by the slackline
    2. The arms play an important role
  3. An existing simple model does not explain interaction of body segments or compare predictions to physiological movements
  4. This paper assumes energy consumption is minimal and stability margin is maximal
  5. The slackline reaction force must go from the BOS to the fictional line of the anchor point, thus can only be changed by moving the leg
  6. Control strategies are extremely limited, but it is possible to alter the mediolateral forces acting on the body
  7. Proposed model hypothesizes balance is achieved by:
    1. Decoupling stance leg from upper body movements
    2. Using the stance leg to direct the slackline reaction force vector
    3. Using arms to control angular momentum
  8. Evidence was found for decoupling the stance leg and skilled slackliners using less energy, but not for the arms as dominant control mechanism for angular momentum

Limitations

  1. Over relies on Hof's Margin of stability - see [[Rethinking Margin of Stability - Kazanski Et Al 2022]]