Mechanism of quadriceps femoris muscle weakness in patients with anterior cruciate ligament reconstruction

Y. Konishi, T. Fukubayashi, D. Takeshita

Research output: Contribution to journalArticle

78 Citations (Scopus)


The purpose of this study was to investigate gamma loop function in the quadriceps femoris muscle in patients who with less than 6 month-history of anterior cruciate ligament (ACL) reconstruction. For this purpose, we compared the response to vibration stimulation in 10 patients with ACL repair and 12 normal healthy subjects, by measuring the maximal voluntary isometric contraction (MVC) and integrated electromyograms (I-EMG) of the quadriceps muscles. Pre-vibration data were obtained from each subject by measuring the MVC of the knee extension and the I-EMG from the vastus medialis, vastus lateralis, and rectus femoris muscles. Vibration stimulation was applied to the infrapatellar tendons, followed immediately by repeating the MVC and I-EMG recording. Prolonged vibration resulted in a significant decrease of both MVC and I-EMG in the control group. In contrast, the same stimulus failed to elicit changes in ACL-repair group. Our results suggest the presence of abnormal gamma loop function in the quadriceps femoris muscle of patients with ACL repair, which may explain the muscle weakness often described in such patients.

Original languageEnglish
Pages (from-to)371-375
Number of pages5
JournalScandinavian Journal of Medicine and Science in Sports
Issue number6
Publication statusPublished - 2002
Externally publishedYes



  • ACL reconstruction
  • EMG
  • Reflex inhibition
  • Vibration stimulation

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Physical Therapy, Sports Therapy and Rehabilitation
  • Orthopedics and Sports Medicine

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