Muscle and tendon relations in humans: Power enhancement in counter-movement exercise

Tetsuo Fukunaga*, Yasuo Kawakami, Tetsuro Muraoka, Hiroaki Kanehisa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


To clarify the mechanisms of power enhancement during counter-movement exercise, in vivo muscle fibre behavior during plantar flexion exercise was estimated by real time ultrasonography. Six healthy male subjects were requested to perform ankle plantar flexion exercise with counter-movement (CM, plantar flexion preceded by dorsiflexion) and without counter-movement (noCM, plantar flexion only) on a specially designed dynamometer. In CM, in the dorsiflexion phase, muscle fascicle length was initially lengthened, following which its length remained unchanged while the whole muscle-tendon unit was still lengthened, and decreased in the plantar flexion phase. In noCM, fascicle length decreased throughout the movement and it was longer at the onset of movement than in CM. During dorsiflexion phase in CM, muscle fascicles were not actively lengthened, but contracted isometrically at near optimum length of fibre; thus the increase in muscle-tendon unit length was taken up by elongation of the tendinous tissues. These results demonstrate that power enhancement during CM is due to higher force production by isometric contraction at optimal fibre length.

Original languageEnglish
Pages (from-to)501-505
Number of pages5
JournalAdvances in experimental medicine and biology
Publication statusPublished - 2002
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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