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Updated: Jun 10, 2026
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A Modified Lean and Release Technique to Emphasize Response Inhibition and Action Selection in Reactive Balance
Published on: March 19, 2020
A new sledge jump system that allows almost natural reactive jumps
A Kramer1, R Ritzmann, A Gollhofer
1Department of Sport and Sport Science, University of Freiburg, Germany. andreas_kramer@web.de
Journal of Biomechanics
|July 21, 2010
Summary
A new ultra-light sledge jump system (SJS) allows for reactive jumps comparable to natural movements. This system enables better study of the stretch-shortening cycle (SSC) under controlled conditions.
Area of Science:
- Biomechanics
- Human Movement Science
- Exercise Physiology
Background:
- Sledge jump systems (SJS) are used to study the stretch-shortening cycle (SSC) by varying impact velocity and energy.
- Existing SJS have long ground contact times, limiting comparability to natural jumps and preventing effective kinetic energy storage.
Purpose of the Study:
- To evaluate if a newly developed ultra-light SJS, designed for minimal joint restriction, can produce jumps comparable to natural jumps.
Main Methods:
- Compared ground reaction forces, kinematics, and electromyographic (EMG) data between normal hopping (NH) and hopping in the custom-built SJS (SH).
- Data collected from 21 healthy subjects.
Main Results:
- Sledge hopping (SH) showed prolonged ground contact times (+22%) compared to NH.
- Peak ground reaction forces (-21%) and muscle preactivity (soleus and gastrocnemius medialis, -20% to -22%) were reduced in SH.
- Leg stiffness was reduced (-21%) in SH, with no significant changes in short-latency EMG responses or joint range of motion.
Conclusions:
- The new SJS facilitates reactive jumps that closely mimic natural jumps.
- This system is suitable for investigating the stretch-shortening cycle under controlled yet near-natural conditions.
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