title: Exercise therapy for bone and muscle health: an overview of systematic reviews.
abstract: BACKGROUND
  Musculoskeletal conditions (MSCs) are widely prevalent in present-day society, with resultant high healthcare costs and substantial negative effects on patient health and quality of life. The main aim of this overview was to synthesize evidence from systematic reviews on the effects of exercise therapy (ET) on pain and physical function for patients with MSCs. In addition, the evidence for the effect of ET on disease pathogenesis, and whether particular components of exercise programs are associated with the size of the treatment effects, was also explored.
  
  
  METHODS
  We included four common conditions: fibromyalgia (FM), low back pain (LBP), neck pain (NP), and shoulder pain (SP), and four specific musculoskeletal diseases: osteoarthritis (OA), rheumatoid arthritis (RA), ankylosing spondylitis (AS), and osteoporosis (OP). We first included Cochrane reviews with the most recent update being January 2007 or later, and then searched for non-Cochrane reviews published after this date. Pain and physical functioning were selected as primary outcomes.
  
  
  RESULTS
  We identified 9 reviews, comprising a total of 224 trials and 24,059 patients. In addition, one review addressing the effect of exercise on pathogenesis was included. Overall, we found solid evidence supporting ET in the management of MSCs, but there were substantial differences in the level of research evidence between the included diagnostic groups. The standardized mean differences for knee OA, LBP, FM, and SP varied between 0.30 and 0.65 and were significantly in favor of exercise for both pain and function. For NP, hip OA, RA, and AS, the effect estimates were generally smaller and not always significant. There was little or no evidence that ET can influence disease pathogenesis. The only exception was for osteoporosis, where there was evidence that ET increases bone mineral density in postmenopausal women, but no significant effects were found for clinically relevant outcomes (fractures). For LBP and knee OA, there was evidence suggesting that the treatment effect increases with the number of exercise sessions.
  
  
  CONCLUSIONS
  There is empirical evidence that ET has beneficial clinical effects for most MSCs. Except for osteoporosis, there seems to be a gap in the understanding of the ways in which ET influences disease mechanisms.
authors.affiliation: National Resource Centre for Rehabilitation in Rheumatology, Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway. k.b.hagen@medisin.uio.no
authors.forename: Kåre Birger
authors.initials: KB
authors.lastname: Hagen
authors.forename: Hanne
authors.initials: H
authors.lastname: Dagfinrud
authors.forename: Rikke Helene
authors.initials: RH
authors.lastname: Moe
authors.forename: Nina
authors.initials: N
authors.lastname: Østerås
authors.forename: Ingvild
authors.initials: I
authors.lastname: Kjeken
authors.forename: Margreth
authors.initials: M
authors.lastname: Grotle
authors.forename: Geir
authors.initials: G
authors.lastname: Smedslund
mesh_terms: D005081:Exercise Therapy; D006801:Humans; D009140:Musculoskeletal Diseases / Q000628:therapy*; D012196:Review Literature as Topic