title: Is Soleus Muscle-Tendon-Unit Behavior Related to Ground-Force Application During the Sprint Start?
abstract: OBJECTIVE
  To describe the stretch-shortening behavior of ankle plantar-flexing muscle-tendon units (MTUs) during the push-off in a sprint start.
  
  
  METHODS
  Fifty-four male (100-m personal best: 9.58-12.07 s) and 34 female (100-m personal best: 11.05-14.00 s) sprinters were analyzed using an instrumented starting block and 2-dimensional high-speed video imaging. Analysis was performed separately for front and rear legs, while accounting for block obliquities and performance levels.
  
  
  RESULTS
  The results showed clear signs of a dorsiflexion in the upper ankle joint (front block 15.8° ± 7.4°, 95% CI 13.2-18.2°; rear block 8.0° ± 5.7°, 95% CI 6.4-9.7°) preceding plantar flexion. When observed in their natural block settings, the athletes' block obliquity did not significantly affect push-off characteristics. It seems that the stretch-shortening-cycle-like motion of the soleus MTU has an enhancing influence on push-off force generation.
  
  
  CONCLUSIONS
  This study provides the first systematic observation of ankle-joint stretch-shortening behavior for sprinters of a wide range of performance levels. The findings highlight the importance of reactive-type training for the improvement of starting performance. Nonetheless, future studies need to resolve the independent contributions of tendinous and muscle-fascicle structures to overall MTU performance.
authors.forename: Erik
authors.initials: E
authors.lastname: Schrödter
authors.forename: Gert-Peter
authors.initials: GP
authors.lastname: Brüggemann
authors.forename: Steffen
authors.initials: S
authors.lastname: Willwacher
mesh_terms: D000293:Adolescent; D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D012420:Running / Q000502:physiology*; D013710:Tendons / Q000502:physiology*; D055815:Young Adult
keywords: SSC; lower extremity; performance; stretch-shortening cycle