title: Indoor mobility-related fatigue and muscle strength in nonagenarians: a prospective longitudinal study.
abstract: OBJECTIVE
  Mobility-related fatigue is an important indicator of functional decline in old age, however, very little is known about fatigue in the oldest old population segment. The aim of this study was to examine the association between indoor mobility-related fatigue and muscle strength decline in nonagenarians.
  
  
  METHODS
  The study is based on a prospective longitudinal study of all Danes born in 1905 and assessed in 1998, 2000 and 2003, and includes 92- to 93-year-old persons who were independent of help in basic indoor mobility at baseline (n = 1,353). Fatigue was assessed at baseline and defined as a subjective feeling of fatigue when transferring or walking indoors. The outcome measure, maximum grip strength, was measured at each measurement point.
  
  
  RESULTS
  Grip strength declined throughout the study in participants with and without fatigue, but those reporting fatigue had significantly (P < .001) lower muscle strength during the entire study period. Longitudinal analyses indicated slightly slower decline in muscle strength among participants with fatigue compared to those without; however, observed selective dropout of participants with fatigue and poor performance at baseline needs to be considered when interpreting the results. Accordingly, participants without fatigue had significantly higher chances of being alive and having muscle strength above gender-specific median at first (RR 1.32, 95 % CI 1.07-1.58), second (RR 1.51, 1.06-1.96) and third (RR 1.39, 1.01-1.97) measurement points.
  
  
  CONCLUSIONS
  Indoor mobility-related fatigue in advanced later life should not merely be considered as an unpleasant symptom, but rather an indicator of physical impairment, and consequently declined physiological reserve.
authors.affiliation: Section of Social Medicine, Department of Public Health, University of Copenhagen, Øster Farimagsgade 5, P.O. Box 2099, 1014, Copenhagen K, Denmark, mrma@sund.ku.dk.
authors.forename: Minna
authors.initials: M
authors.lastname: Mänty
authors.forename: Anette
authors.initials: A
authors.lastname: Ekmann
authors.forename: Mikael
authors.initials: M
authors.lastname: Thinggaard
authors.forename: Kaare
authors.initials: K
authors.lastname: Christensen
authors.forename: Kirsten
authors.initials: K
authors.lastname: Avlund
mesh_terms: D000203:Activities of Daily Living; D000367:Age Factors; D000369:Aged, 80 and over; D005221:Fatigue / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D011446:Prospective Studies; D016138:Walking / Q000502:physiology*