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Effects of dietary intervention and quadriceps strengthening exercises on pain and function in overweight people with knee pain: randomised controlled trial

BMJ 2009; 339 doi: (Published 19 August 2009) Cite this as: BMJ 2009;339:b3170
  1. Claire M Jenkinson, research associate1,
  2. Michael Doherty, professor of rheumatology2,
  3. Anthony J Avery, professor of primary care3,
  4. Anna Read, senior dietitian4,
  5. Moira A Taylor, associate professor of human nutrition5,
  6. Tracey H Sach, senior lecturer in health economics6,
  7. Paul Silcocks, clinical senior lecturer7,
  8. Kenneth R Muir, professor of epidemiology1
  1. 1Division of Epidemiology and Public Health, School of Community Health Sciences, University of Nottingham, Queen’s Medical Centre, Nottingham NG7 2UH
  2. 2Academic Rheumatology, University of Nottingham, Clinical Sciences Building, City Hospital, Nottingham NG5 1PB
  3. 3Division of Primary Care, School of Community Health Sciences, University of Nottingham, Queen’s Medical Centre, Nottingham NG7 2UH
  4. 4Department of Nutrition and Dietetics, Queen’s Medical Campus, Nottingham University NHS Trust, Queen’s Medical Centre, Nottingham NG7 2UH
  5. 5School of Biomedical Sciences, University of Nottingham, Queens’s Medical Centre, Nottingham NG7 2UH
  6. 6School of Chemical Sciences and Pharmacy, University of East Anglia, Earlham Road, Norwich NR4 7TJ
  7. 7Nottingham Clinical Trials Unit, School of Community Health Sciences, University of Nottingham, Queen’s Medical Centre, Nottingham NG7 2UH
  1. Correspondence to: C M Jenkinson claire.jenkinson{at}
  • Accepted 18 June 2009


Objective To determine whether dietary intervention or knee strengthening exercise, or both, can reduce knee pain and improve knee function in overweight and obese adults in the community.

Design Pragmatic factorial randomised controlled trial.

Setting Five general practices in Nottingham.

Participants 389 men and women aged 45 and over with a body mass index (BMI) of ≥28.0 and self reported knee pain.

Interventions Participants were randomised to dietary intervention plus quadriceps strengthening exercises; dietary intervention alone; quadriceps strengthening exercises alone; advice leaflet only (control group). Dietary intervention consisted of individualised healthy eating advice that would reduce normal intake by 2.5 MJ (600 kcal) a day. Interventions were delivered at home visits over a two year period.

Main outcome measures The primary outcome was severity of knee pain scored with the Western Ontario McMaster (WOMAC) osteoarthritis index at 6, 12, and 24 months. Secondary outcomes (all at 24 months) included WOMAC knee physical function and stiffness scores and selected domains on the SF-36 and the hospital anxiety and depression index.

Results 289 (74%) participants completed the trial. There was a significant reduction in knee pain in the knee exercise groups compared with those in the non-exercise groups at 24 months (percentage risk difference 11.61, 95% confidence interval 1.81% to 21.41%). The absolute effect size (0.25) was moderate. The number needed to treat to benefit from a ≥30% improvement in knee pain at 24 months was 9 (5 to 55). In those randomised to knee exercise improvement in function was evident at 24 months (mean difference −3.64, −6.01 to −1.27). The mean difference in weight loss at 24 months in the dietary intervention group compared with no dietary intervention was 2.95 kg (1.44 to 4.46); for exercise versus no exercise the difference was 0.43 kg (−0.82 to 1.68). This difference in weight loss was not associated with improvement in knee pain or function but was associated with a reduction in depression (absolute effect size 0.19).

Conclusions A home based, self managed programme of simple knee strengthening exercises over a two year period can significantly reduce knee pain and improve knee function in overweight and obese people with knee pain. A moderate sustained weight loss is achievable with dietary intervention and is associated with reduced depression but is without apparent influence on pain or function.

Trial registration Current Controlled Trials ISRCTN 93206785.


  • We thank staff in the general practices and x ray departments. We thank Jonathan Webber for advice on the protocol design; Amanda Ingham, Gail Faulkner, Mary Chapman, Sarah Fisher, Roxanne McNaughton, and Holly Blake for visiting participants and providing dietary and exercise advice; Sandra Barratt for data management; and Tina Smith for study administration. We also thank the trial steering committee, the data monitoring committee, and J Prutton of 4 D Rubber Co, Heanor, Derbyshire, for donating 230 latex rubber exercise bands. We especially thank all the participants.

  • Contributors: KRM, MD, and AJA contributed to the development of the protocol. All authors except PS were involved with the conduct of the study. AR was responsible for the design and delivery of the dietary intervention. CMJ coordinated the trial, contributed to the analyses, and drafted the paper. PS carried out the analyses based on multiple imputation. All authors were involved with the revision of the paper. KRM was the principal investigator. MD is guarantor.

  • Funding: The study was funded by the Arthritis Research Campaign (grant Nos 13550 and 17375). The funder monitored the trial progress through a trial steering committee chaired by Richard Keen. Trial data were monitored by a data monitoring committee subgroup chaired by Ian Harvey. The study sponsor was the University of Nottingham.

  • Competing interests: None declared.

  • Ethical approval: The study was approved by Nottingham research ethics committee (Q1090219), and informed consent was given by all participants.

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