title: Effects of fear of falling on muscular coactivation during walking.
abstract: OBJECTIVE
  Increased fear of falling is associated with greater muscular coactivation during standing postural control. Excessive muscular coactivation reduces the performance of agonist muscles. Although several recent studies have observed increased muscular coactivation during walking in older adults, little is known about the relationship between fear of falling and muscular coactivation during walking. The purpose of this study was to compare muscular coactivation during walking between older adults with fear of falling and older adults without fear of falling.
  
  
  METHODS
  Thirty-eight healthy older adults (82.3 ± 6.8 years) participated in this study. Walking speed and step length were measured. Electromyography (EMG) data were collected from the tibialis anterior and soleus during walking to calculate the co-contraction index (CI). Subjects were divided into those with fear of falling and those without fear of falling, on the basis of a modified Falls Efficacy Scale (FES). Stepwise multiple regression analysis was used, with CI as the dependent variable, and fear of falling, experience of falling (during the past year), walking speed, step length, and age as independent variables.
  
  
  RESULTS
  Mean values of CI during walking, walking speed, and step length were 51.9 ± 11.7%, 0.90 ± 0.40 m/s, and 0.43±0.11 m, respectively. Eight subjects (21.1%) had fallen within the past year, and 19 subjects (50.0%) had fear of falling. All subjects without fear of falling had FES scores of 10 (maximum score). Subjects with fear of falling had a median FES score of 17 (interquartile range, 13 to 25). Stepwise multiple regression analysis revealed that fear of falling remained significantly associated with CI (p<0.01): CIs for subjects with fear and those without fear were 59.5 ± 12.2% and 46.7 ± 8.5%, respectively.
  
  
  CONCLUSIONS
  Individuals with a fear of falling have increased muscular co-activation at the ankle joint during walking, at least in a certain subgroup of older adults. Further research is needed to clarify negative and positive effects of muscular coactivation during walking in fearful subjects.
authors: Human Health Sciences, Graduate School of Medicine Kyoto University, 53, Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan. k.nagai@ky2.ecs.kyoto-u.ac.jp
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