title: Physical activity increases gains in and prevents loss of physical function: results from the lifestyle interventions and independence for elders pilot study.
abstract: BACKGROUND
  Physical activity (PA) appears to have a positive effect on physical function, however, studies have not examined multiple indices of physical function jointly nor have they conceptualized physical functioning as a state rather than a trait.
  
  
  METHODS
  About 424 men and women aged 70-89 were randomly assigned to complete a PA or a successful aging (SA) education program. Balance, gait speed, chair stand performance, grip strength, and time to complete the 400-m walk were assessed at baseline and at 6 and 12 months. Using hidden Markov model, empiric states of physical functioning were derived based on these performance measures of balance, strength, and mobility. Rates of gain and loss in physical function were compared between PA and SA.
  
  
  RESULTS
  Eight states of disability were identified and condensed into four clinically relevant states. State 1 represented mild disability with physical functioning, states 2 and 3 were considered intermediate states of disability, and state 4 severe disability. About 30.1% of all participants changed states at 6 months, 24.1% at 12 months, and 11.0% at both time points. The PA group was more likely to regain or sustain functioning and less likely to lose functioning when compared with SA. For example, PA participants were 20% more likely than the SA participants to remain in state 1.
  
  
  CONCLUSIONS
  PA appears to have a favorable effect on the dynamics of physical functioning in older adults.
authors.affiliation: Department of Biostatistical Sciences, Wake Forest University School of Medicine, Medical Center Blvd., WC23, Winston-Salem, NC 27157, USA. eip@wakehealth.edu
authors.forename: Edward H
authors.initials: EH
authors.lastname: Ip
authors.forename: Timothy
authors.initials: T
authors.lastname: Church
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Marshall
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Marsh
authors.forename: Jack
authors.initials: J
authors.lastname: Guralnik
authors.forename: Abby C
authors.initials: AC
authors.lastname: King
authors.forename: W Jack
authors.initials: WJ
authors.lastname: Rejeski
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D004185:Disability Evaluation; D006233:Persons with Disabilities / Q000193:education / Q000534:rehabilitation; D005081:Exercise Therapy / Q000193:education / Q000379:methods; D005260:Female; D005684:Gait; D018737:Hand Strength; D006801:Humans; D008297:Male; D009043:Motor Activity; D010353:Patient Education as Topic / Q000379:methods*; D004856:Postural Balance; D015397:Program Evaluation; D011597:Psychomotor Performance; D012720:Severity of Illness Index; D013997:Time Factors; D016138:Walking