Dietary protein intake and upper leg muscle strength in subjects with knee osteoarthritis: data from the osteoarthritis initiative
The aims of this study were (1) to describe dietary protein intake, and (2) to evaluate the association between dietary protein intake and upper leg muscle strength in subjects with knee osteoarthritis (OA). Baseline data from the OA was used, in a cross-sectional study. All subjects were diagnosed with symptomatic and radiographic knee OA. Daily dietary protein intake was measured with the Block Brief 2000 food frequency questionnaire (g/kg body weight). The sum of knee flexion and extension strength of the index knee (N/kg bodyweight) was assessed with the Good Strength chair test. Linear regression analysis was used to test the association between dietary protein intake and muscle strength, adjusting for relevant confounders. Data from 1316 subjects (mean age 61.4 ± SD 9.1 years, 57.0% female) were used. The mean daily protein intake was 0.72 ± SD 0.30 g/kg bodyweight, and 65.1% of the subjects had a protein intake lower than the recommended daily allowance of 0.8 g/kg bodyweight. The mean muscle strength was 5.4 ± SD 2.1 N/kg bodyweight. Lower protein intake was significantly associated with lower muscle strength (B = 0.583, 95% CI 0.230–0.936, p = 0.001). The majority of the subjects with knee OA had a dietary protein intake lower than the recommended daily allowance. Lower protein intake was associated with lower upper leg muscle strength. Longitudinal observational and interventional studies are needed to establish whether dietary protein intake has a causal effect on muscle strength in subjects with knee OA.
KeywordsKnee joint Osteoarthritis Muscle strength Protein intake Nutrition
The OAI is a public–private partnership comprised of five contracts (N01-AR-2-2258; N01-AR-2-2259; N01-AR-2-2260; N01-AR-2-2261; N01-AR-2-2262) funded by the National Institutes of Health, a branch of the Department of Health and Human Services, and conducted by the OAI Study Investigators. Private funding partners include Merck Research Laboratories; Novartis Pharmaceuticals Corporation, GlaxoSmithKline; and Pfizer, Inc. Private sector funding for the OAI is managed by the Foundation for the National Institutes of Health. This manuscript was prepared using an OAI public use data set and does not necessarily reflect the opinions or views of the OAI investigators, the NIH, or the private funding partners.
This study was funded by the Dutch Arthritis Association (Grant number 13-1-401).
Compliance with ethical standards
Conflict of interest
AH de Zwart declares that he has no conflict of interest, M van der Leeden declares that she has no conflict of interest, LD Roorda declares that he has no conflict of interest, M Visser declares that she has no conflict of interest, M van der Esch declares that he has no conflict of interest, WF Lems declares that he has no conflict of interest, J Dekker declares that he has no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
- 5.Culvenor AG, Ruhdorfer A, Juhl C, Eckstein F, Øiestad BE (2017) Knee extensor strength and risk of structural, symptomatic and functional decline in knee osteoarthritis: A systematic review and meta-analysis. Arthritis Care Res (Hoboken) 69:649–658. https://doi.org/10.1002/acr.23005 CrossRefGoogle Scholar
- 16.Bauer J, Biolo G, Cederholm T, Cesari M, Cruz-Jentoft AJ, Morley JE et al (2013) Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the prot-age study group. J Am Med Dir Assoc 14:542–559. https://doi.org/10.1016/j.jamda.2013.05.021 CrossRefGoogle Scholar
- 24.Nevitt M, Felson D, Lester G (2009) The osteoarthritis initiative. Protocol for the cohort study. Retrieved from: https://oai.epi-ucsf.org/datarelease/docs/studydesignprotocol.pdf
- 36.Bellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt LW (1988) Validation study of womac: a health status instrument for measuring clinically important patient relevant outcomes to antirheumatic drug therapy in patients with osteoarthritis of the hip or knee. J Rheumatol 15:1833–1840Google Scholar
- 38.Kleinbaum D, Kupper L, Nizam A, Rosenberg E (2013) Applied regression analysis and other multivariable methods. Nelson Education, TorontoGoogle Scholar
- 42.Tieland M, Dirks ML, van der Zwaluw N, Verdijk LB, van de Rest O, de Groot LC et al (2012) Protein supplementation increases muscle mass gain during prolonged resistance-type exercise training in frail elderly people: a randomized, double-blind, placebo-controlled trial. J Am Med Dir Assoc 13:713–719. https://doi.org/10.1016/j.jamda.2012.05.020 CrossRefGoogle Scholar
- 43.Morton RW, Murphy KT, McKellar SR, Schoenfeld BJ, Henselmans M, Helms E et al (2018) A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med 52:376–384Google Scholar