title: The relationship between muscle fatigue and balance in the elderly.
abstract: OBJECTIVE
  To investigate the effect of gastrocnemius muscle fatigue on postural control ability in elderly people.
  
  
  METHODS
  Twenty-four healthy elderly people participated in this study. The postural control ability of single leg standing was evaluated with Health Improvement & Management System (HIMS) posturography before and after fatiguing exercises. After evaluating initial postural control ability, the maximal voluntary contraction (MVC) of ankle plantarflexion was assessed using a surface electromyogram from the medial belly of the gastrocnemius muscle. After a 5-minute resting period, subjects began submaximal isometric ankle plantarflexion (40% MVC) until 40% of MVC was dropped below 95% for 5 seconds, or subject couldn't continue working out due to muscle fatigue. And postural control ability was assessed after fatiguing exercise. The mean deviation of center of pressure (COP), length of COP movement, occupied area of COP were measured, and analyzed by paired t-test.
  
  
  RESULTS
  Mediolateral deviation, length of COP movement, and area of COP occupied were increased after fatiguing exercise of the gastrocnemius muscle. Anteroposterior deviation and length of COP movement were also increased, but had low statistical significance.
  
  
  CONCLUSIONS
  These findings suggest that the gastrocnemius muscle fatigue affects mediolateral stability and accuracy during single leg standing in elderly people. Therefore muscle endurance training is necessary to prevent falls in elderly people.
authors.affiliation: Department of Rehabilitation Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea.
authors.forename: Hee Seung
authors.initials: HS
authors.lastname: Nam
authors.forename: Dong Sik
authors.initials: DS
authors.lastname: Park
authors.forename: Dong Hyun
authors.initials: DH
authors.lastname: Kim
authors.forename: Hyun Jung
authors.initials: HJ
authors.lastname: Kang
authors.forename: Dong Hun
authors.initials: DH
authors.lastname: Lee
authors.forename: Sang Hun
authors.initials: SH
authors.lastname: Lee
authors.forename: Jin Gang
authors.initials: JG
authors.lastname: Her
authors.forename: Ji Hea
authors.initials: JH
authors.lastname: Woo
authors.forename: Seung Yeon
authors.initials: SY
authors.lastname: Choi
keywords: Ankle; Balance; Elderly; Fatigue; Posture