Original Article

European Journal of Applied Physiology

, Volume 113, Issue 6, pp 1395-1403

Muscle–tendon interaction and EMG profiles of world class endurance runners during hopping

  • K. SanoAffiliated withOsaka University of Health and Sport Sciences Email author 
  • , M. IshikawaAffiliated withOsaka University of Health and Sport Sciences
  • , A. NobueAffiliated withOsaka University of Health and Sport Sciences
  • , Y. DannoAffiliated withOsaka University of Health and Sport Sciences
  • , M. AkiyamaAffiliated withOsaka University of Health and Sport Sciences
  • , T. OdaAffiliated withHyogo University of Teacher Education
  • , A. ItoAffiliated withOsaka University of Health and Sport Sciences
  • , M. HoffrénAffiliated withLikes Research Center, University of Jyväskylä
  • , C. NicolAffiliated withAix-Marseille University
    • , E. LocatelliAffiliated withInternational Association of Athletics Federations
    • , P. V. KomiAffiliated withLikes Research Center, University of Jyväskylä

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Abstract

The present study examined the muscle–tendon interaction of ten international level Kenyan runners. Ultrasonography and kinematics were applied together with EMG recordings of lower limb muscles during repetitive hopping performed at maximal level. The ten Kenyans had longer gastro Achilles tendon at rest (p < 0.01) as compared with ten control subjects matched in height. Conversely, the stretching and shortening amplitudes of the tendinous tissues of the medial gastrocnemius (MG) muscle were significantly smaller in the Kenyans than in controls during the contact phase of hopping. This applied also to the fascicle length changes, which were smaller and more homogeneous among Kenyans. These limited musculo-tendinous changes resulted in higher maximal hopping height and in larger power despite their reduced body weight. The associated finding of a greater shortening to stretching ratio of the MG tendinous tissues during contact could imply that the Kenyan MG muscle–tendon unit is optimized to favor efficient storage and recoil of elastic energy, while operating at optimal muscle fascicle working range (plateau region).

Keywords

Stretch-shortening cycle Elastic energy Running economy Ultrasound Stiffness