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Relationship Between Number of Different Lower‐Limb Resistance Exercises Prescribed in a Program and Exercise Outcomes in People With Knee Osteoarthritis: A Systematic Review With Meta‐Regression

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Arthritis Care & Research
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Objective We determine whether there is a relationship between the number of different lower‐limb resistance exercises prescribed in a program and outcomes for people with knee osteoarthritis. Methods We used a systematic review with meta‐regression. We searched the Cochrane Central Register of Controlled Trials, MEDLINE, and Embase up to January 4, 2024. We included randomized controlled trials that evaluated land‐based resistance exercise for knee osteoarthritis compared with nonexercise interventions. We conducted meta‐regressions between number of different exercises prescribed and standardized mean differences (SMDs) for pain and function. Covariates (intervention duration, frequency per week, use of resistance exercise machine[s], and comparator type) were applied to attempt to reduce between‐study heterogeneity. Results Forty‐four trials (3,364 participants) were included. The number of resistance exercises ranged from 1 to 12 (mean ± SD 5.0 ± 3.0). Meta‐regression showed no relationship between the number of prescribed exercises and change in pain (slope coefficient: −0.04 SMD units [95% confidence interval {95% CI} −0.14 to 0.05]) or self‐reported function (SMD −0.04 [95% CI −0.12 to 0.05]). There was substantial heterogeneity and evidence of publication bias. However, even after removing 31 trials that had overall unclear/high risk of bias, there was no change in relationships. Conclusion There was no relationship between the number of different lower‐limb resistance exercises prescribed in a program and change in knee pain or self‐reported function. However, given that we were unable to account for all differences in program intensity, progression, and adherence, as well as the heterogeneity and overall low quality of included studies, our results should be interpreted with caution.
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REVIEW ARTICLE
Relationship Between Number of Different Lower-Limb
Resistance Exercises Prescribed in a Program and Exercise
Outcomes in People With Knee Osteoarthritis: A Systematic
Review With Meta-Regression
Belinda J. Lawford,
1
Kim L. Bennell,
1
Libby Spiers,
1
Alexander J. Kimp,
1
Andrea DellIsola,
2
Alison R. Harmer,
3
Martin Van der Esch,
4
Michelle Hall,
3
and Rana S. Hinman
1
Objective. We determine whether there is a relationship between the number of different lower-limb resistance
exercises prescribed in a program and outcomes for people with knee osteoarthritis.
Methods. We used a systematic review with meta-regression. We searched the Cochrane Central Register of
Controlled Trials, MEDLINE, and Embase up to January 4, 2024. We included randomized controlled trials that evalu-
ated land-based resistance exercise for knee osteoarthritis compared with nonexercise interventions. We conducted
meta-regressions between number of different exercises prescribed and standardized mean differences (SMDs) for
pain and function. Covariates (intervention duration, frequency per week, use of resistance exercise machine[s], and
comparator type) were applied to attempt to reduce between-study heterogeneity.
Results. Forty-four trials (3,364 participants) were included. The number of resistance exercises ranged from 1 to
12 (mean ± SD 5.0 ± 3.0). Meta-regression showed no relationship between the number of prescribed exercises and
change in pain (slope coefcient: 0.04 SMD units [95% condence interval {95% CI} 0.14 to 0.05]) or self-reported
function (SMD 0.04 [95% CI 0.12 to 0.05]). There was substantial heterogeneity and evidence of publication bias.
However, even after removing 31 trials that had overall unclear/high risk of bias, there was no change in relationships.
Conclusion. There was no relationship between the number of different lower-limb resistance exercises prescribed
in a program and change in knee pain or self-reported function. However, given that we were unable to account for all
differences in program intensity, progression, and adherence, as well as the heterogeneity and overall low quality of
included studies, our results should be interpreted with caution.
INTRODUCTION
Knee osteoarthritis (OA) affects >654 million people aged
40 years worldwide.
1
All current clinical guidelines advocate exer-
cise for management of knee OA, irrespective of age, comorbidity,
pain severity, or disability.
26
Although numerous systematic
reviews support the effectiveness of exercise for knee OA, effect
sizes are small to moderate and decline over time.
7,8
New ways of
enhancing the effectiveness of exercise are needed, such as by
identifying the optimal content and dosage of exercise programs.
Muscle weakness is common in people with OA, often evi-
dent in muscles surrounding the affected joint,
911
and is associ-
ated with pain and physical dysfunction.
12
Improving muscle
strength via resistance training is therefore a common focus of
exercise for knee OA management and is hypothesized to be
one of the mechanisms by which exercise leads to improvements
in symptoms.
1316
The American College of Sports Medicine
(ACSM) provides specic recommendations for prescription of
resistance exercise programs for people with arthritis, including
the frequency, intensity, and duration of the program.
17
However,
Drs Bennell and Hinmans work was supported by the National Health
and Medical Research Council (grants 1174431 and 2025733).
1
Belinda J. Lawford, PhD, Kim L. Bennell, PhD, Libby Spiers, BPhysio, Alex-
ander J. Kimp, DPT, Rana S. Hinman, PhD: The University of Melbourne, Mel-
bourne, Victoria, Australia;
2
Andrea DellIsola, PhD: Lund University, Lund,
Sweden;
3
Alison R. Harmer, PhD, Michelle Hall, PhD: The University of Sydney,
Sydney, New South Wales, Australia;
4
Martin Van der Esch, PhD: Amsterdam
University of Applied Sciences, Amsterdam, The Netherlands.
Drs Hall and Hinman contributed equally to this work.
Additional supplementary information cited in this article can be found
online in the Supporting Information section (https://acrjournals.
onlinelibrary.wiley.com/doi/10.1002/acr.25476).
Author disclosures are available at https://onlinelibrary.wiley.com/doi/10.
1002/acr.25476.
Address correspondence via email to Belinda J. Lawford, PhD, at belinda.
lawford@unimelb.edu.au.
Submitted for publication July 1, 2024; accepted in revised form
November 22, 2024.
1
Arthritis Care & Research
Vol. 0, No. 0, Month 2025, pp 110
DOI 10.1002/acr.25476
© 2024 American College of Rheumatology
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Article
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Objective We wanted to determine if higher compliance with American College of Sports Medicine (ACSM) exercise prescription guidelines influences exercise outcomes in knee osteoarthritis (OA). Methods We conducted a systematic review. We searched the Cochrane Central Register of Controlled Trials, MEDLINE, and Embase up to January 4, 2024, for randomized controlled trials evaluating resistance and/or aerobic exercise for knee OA. Interventions were classified as higher compliance (meeting ≥60% of ACSM guideline recommendations for frequency, intensity, and duration) or lower compliance (meeting <60% of recommendations). Effects on pain and function were evaluated via meta‐analysis, stratified by compliance. Results Twenty‐five trials (3,290 participants) evaluated combined resistance and aerobic programs, with no differences in outcomes between those with higher and lower compliance (standardized mean difference [SMD] pain: −0.38 [95% confidence interval (CI) −0.59 to −0.17] vs −0.31 [95% CI −0.45 to −0.16], respectively; SMD function: −0.43 [95% CI −0.64 to −0.21] vs −0.36 [95% CI −0.58 to −0.14]). Sixty‐six trials (5,231 participants) evaluated resistance exercise, with no differences between interventions with higher and lower compliance (SMD pain: −0.60 [95% CI −0.81 to −0.39] vs −0.93 [95% CI −1.27 to −0.59]; SMD function: −0.64 [95% CI −0.83 to −0.44] vs −0.85 [95% CI −1.20 to −0.49]). Twelve trials (958 participants) evaluated aerobic exercise, with no differences between interventions with higher and lower compliance (SMD pain: −0.79 [95% CI −1.20 to −0.38] vs −1.00 [95% CI −2.52 to 0.53]; SMD function: −0.83 [95% CI −1.27 to −0.38] vs −0.76 [95% CI −2.02 to 0.50]). Conclusion Higher or lower compliance with ACSM exercise prescription guidelines did not influence exercise outcomes. Given there was substantial heterogeneity and many publications were at risk of bias, our results should be interpreted with caution.
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Many individuals do not participate in resistance exercise, with perceived lack of time being a key barrier. Minimal dose strategies, which generally reduce weekly exercise volumes to less than recommended guidelines, might improve muscle strength with minimal time investment. However, minimal dose strategies and their effects on muscle strength are still unclear. Here our aims are to define and characterize minimal dose resistance exercise strategies and summarize their effects on muscle strength in individuals who are not currently engaged in resistance exercise. The minimal dose strategies overviewed were: “Weekend Warrior,” single-set resistance exercise, resistance exercise “snacking,” practicing the strength test, and eccentric minimal doses. “Weekend Warrior,” which minimizes training frequency, is resistance exercise performed in one weekly session. Single-set resistance exercise, which minimizes set number and session duration, is one set of multiple exercises performed multiple times per week. “Snacks,” which minimize exercise number and session duration, are brief bouts (few minutes) of resistance exercise performed once or more daily. Practicing the strength test, which minimizes repetition number and session duration, is one maximal repetition performed in one or more sets, multiple days per week. Eccentric minimal doses, which eliminate or minimize concentric phase muscle actions, are low weekly volumes of submaximal or maximal eccentric-only repetitions. All approaches increase muscle strength, and some approaches improve other outcomes of health and fitness. “Weekend Warrior” and single-set resistance exercise are the approaches most strongly supported by current research, while snacking and eccentric minimal doses are emerging concepts with promising results. Public health programs can promote small volumes of resistance exercise as being better for muscle strength than no resistance exercise at all.
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Article
Background: Knee osteoarthritis (OA) is a major public health issue causing chronic pain, impaired physical function, and reduced quality of life. As there is no cure, self-management of symptoms via exercise is recommended by all current international clinical guidelines. This review updates one published in 2015. Objectives: We aimed to assess the effects of land-based exercise for people with knee osteoarthritis (OA) by comparing: 1) exercise versus attention control or placebo; 2) exercise versus no treatment, usual care, or limited education; 3) exercise added to another co-intervention versus the co-intervention alone. Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and two trial registries (ClinicalTrials.gov and World Health Organisation International Clinical Trials Registry Platform), together with reference lists, from the date of the last search (1st May 2013) until 4 January 2024, unrestricted by language. Selection criteria: We included randomised controlled trials (RCTs) that evaluated exercise for knee OA versus a comparator listed above. Our outcomes of interest were pain severity, physical function, quality of life, participant-reported treatment success, adverse events, and study withdrawals. Data collection and analysis: We used the standard methodological procedures expected by Cochrane for systematic reviews of interventions. Main results: We included 139 trials (12,468 participants): 30 (3065 participants) compared exercise to attention control or placebo; 60 (4834 participants) compared exercise with usual care, no intervention or limited education; and 49 (4569 participants) evaluated exercise added to another intervention (e.g. weight loss diet, physical therapy, detailed education) versus that intervention alone. Interventions varied substantially in duration, ranging from 2 to 104 weeks. Most of the trials were at unclear or high risk of bias, in particular, performance bias (94% of trials), detection bias (94%), selective reporting bias (68%), selection bias (57%), and attrition bias (48%). Exercise versus attention control/placebo Compared with attention control/placebo, low-certainty evidence indicates exercise may result in a slight improvement in pain immediately post-intervention (mean 8.70 points better (on a scale of 0 to 100), 95% confidence interval (CI) 5.70 to 11.70; 28 studies, 2873 participants). Moderate-certainty evidence indicates exercise likely results in an improvement in physical function (mean 11.27 points better (on a scale of 0 to 100), 95% CI 7.64 to 15.09; 24 studies, 2536 participants), but little to no improvement in quality of life (mean 6.06 points better (on a scale of 0 to 100), 95% CI -0.13 to 12.26; 6 studies, 454 participants). There was moderate-certainty evidence that exercise likely increases participant-reported treatment success (risk ratio (RR) 1.46, 95% CI 1.11 to 1.92; 2 studies 364 participants), and likely does not increase study withdrawals (RR 1.08, 95% CI 0.92 to 1.26; 29 studies, 2907 participants). There was low-certainty evidence that exercise may not increase adverse events (RR 2.02, 95% CI 0.62 to 6.58; 11 studies, 1684 participants). Exercise versus no treatment/usual care/limited education Compared with no treatment/usual care/limited education, low-certainty evidence indicates exercise may result in an improvement in pain immediately post-intervention (mean 13.14 points better (on a scale of 0 to 100), 95% CI 10.36 to 15.91; 56 studies, 4184 participants). Moderate-certainty evidence indicates exercise likely results in an improvement in physical function (mean 12.53 points better (on a scale of 0 to 100), 95% CI 9.74 to 15.31; 54 studies, 4352 participants) and a slight improvement in quality of life (mean 5.37 points better (on a scale of to 100), 95% CI 3.19 to 7.54; 28 studies, 2328 participants). There was low-certainty evidence that exercise may result in no difference in participant-reported treatment success (RR 1.33, 95% CI 0.71 to 2.49; 3 studies, 405 participants). There was moderate-certainty evidence that exercise likely results in no difference in study withdrawals (RR 1.03, 95% CI 0.88 to 1.20; 53 studies, 4408 participants). There was low-certainty evidence that exercise may increase adverse events (RR 3.17, 95% CI 1.17 to 8.57; 18 studies, 1557 participants). Exercise added to another co-intervention versus the co-intervention alone Moderate-certainty evidence indicates that exercise when added to a co-intervention likely results in improvements in pain immediately post-intervention compared to the co-intervention alone (mean 10.43 points better (on a scale of 0 to 100), 95% CI 8.06 to 12.79; 47 studies, 4441 participants). It also likely results in a slight improvement in physical function (mean 9.66 points better, 95% CI 7.48 to 11.97 (on a 0 to 100 scale); 44 studies, 4381 participants) and quality of life (mean 4.22 points better (on a 0 to 100 scale), 95% CI 1.36 to 7.07; 12 studies, 1660 participants) immediately post-intervention. There was moderate-certainty evidence that exercise likely increases participant-reported treatment success (RR 1.63, 95% CI 1.18 to 2.24; 6 studies, 1139 participants), slightly reduces study withdrawals (RR 0.82, 95% CI 0.70 to 0.97; 41 studies, 3502 participants), and slightly increases adverse events (RR 1.72, 95% CI 1.07 to 2.76; 19 studies, 2187 participants). Subgroup analysis and meta-regression We did not find any differences in effects between different types of exercise, and we found no relationship between changes in pain or physical function and the total number of exercise sessions prescribed or the ratio (between exercise group and comparator) of real-time consultations with a healthcare provider. Clinical significance of the findings To determine whether the results found would make a clinically meaningful difference to someone with knee OA, we compared our results to established 'minimal important difference' (MID) scores for pain (12 points on a 0 to 100 scale), physical function (13 points), and quality of life (15 points). We found that the confidence intervals of mean differences either did not reach these thresholds or included both a clinically important and clinically unimportant improvement. Authors' conclusions: We found low- to moderate-certainty evidence that exercise probably results in an improvement in pain, physical function, and quality of life in the short-term. However, based on the thresholds for minimal important differences that we used, these benefits were of uncertain clinical importance. Participants in most trials were not blinded and were therefore aware of their treatment, and this may have contributed to reported improvements.