Altered squat jumping mechanics after specific exercise

Boris Ullrich, Kai Heinrich, Jan-Peter Goldmann, Gert-Peter Brüggemann

Publication: Contribution to journalJournal articlesResearchpeer-review

Abstract

This study examined squat jumping (SJ) mechanics following length restricted strength training regimens of the knee extensors and flexors. SJ from a 110 degrees knee joint angle starting position and isometric moment-knee angle relations of knee extensors and flexors were analysed in 16 athletes before and directly after 8 weeks of strength training regimens that were restricted to knee joint angles corresponding to long muscle-tendon unit (MTU) length for the knee extensors and flexors. SJ mechanics were studied using a two-dimensional kinematic model with three rigid bodies (upper leg, lower leg, foot) in combination with force plates measurements of ground reaction force in the right and left lower extremity. Centre of mass jumping height significantly (p<0.05) increased post training, but this was not explained by enhanced absolute power generation in the knee joint. However, post training small but significant (p<0.05) shifts to smaller knee joint angles occurred in the normalized [% Max.] knee joint angle dependent power generation in the right and left knee joint during SJ. The isometric moment-knee angle relation of the knee extensors was also significantly (p<0.05) shifted to longer MTU lengths of knee extensors. Length restricted strength training may alter the mechanical situation during both isometric contractions and dynamic athletic movements.

Original languageEnglish
JournalInternational journal of sports medicine
Volume31
Issue number4
Pages (from-to)243-250
Number of pages8
ISSN0172-4622
DOIs
Publication statusPublished - 01.04.2010

Research areas and keywords

  • Arthrometry, Articular
  • Biomechanical Phenomena
  • Exercise
  • Female
  • Humans
  • Isometric Contraction
  • Knee Joint
  • Leg
  • Male
  • Muscle Strength
  • Muscle, Skeletal
  • Posture
  • Resistance Training
  • Sports
  • Statistics as Topic
  • Time Factors
  • Young Adult

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