Osteoarthritis (OA) is the most prevalent degenerative joint disease globally, affecting approximately 595 million people and projected to rise substantially as populations age and physical inactivity increases.[1] While exercise is widely recommended as a first-line intervention for managing OA symptoms, the majority of existing research targets elderly or already-diagnosed populations, leaving working-age sedentary adults aged 30–60 largely understudied. This proposal presents a two-group randomized controlled trial examining the effect of a 12-week structured low-impact exercise program on joint health and physical function in sedentary adults aged 30–60 who meet at least one established OA risk criterion. Approximately 50 participants will be recruited and randomly assigned to either a supervised exercise intervention (three sessions per week of resistance training and moderate aerobic exercise) or a sedentary control condition. Primary outcomes will be measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC),[2] the Timed Up and Go test (TUG),[3] and a 6-minute walk test (6MWT).[4] A two-way repeated-measures ANOVA will assess between-group and within-subject differences across three timepoints. Qualitative data from structured weekly surveys and exit interviews will complement quantitative findings. This study aims to generate early-intervention evidence that may inform clinical practice guidelines and workplace wellness policy for a currently underserved population.
What is the effect of a 12-week structured low-impact exercise program, combining resistance training and aerobic exercise, on joint health and physical function in sedentary adults aged 30–60 who are at risk of osteoarthritis?
Osteoarthritis is the most prevalent degenerative joint disease worldwide, currently affecting approximately 595 million people and representing 7.6% of the global population.[1] Characterized by the gradual breakdown of articular cartilage and surrounding joint tissue, OA leads to chronic pain, progressive loss of mobility, and a substantially diminished quality of life. Critically, it currently has no known cure, making prevention and early symptom management a public health priority.[1]
While OA cannot be fully prevented, physical inactivity has been identified as one of its most significant modifiable contributing factors. Sedentary behavior causes progressive muscle atrophy around key joints, particularly the knee and hip, removing a primary source of structural support for the joint.[5] Without adequate muscular support, articular cartilage is exposed to increased mechanical stress during everyday movement, which may accelerate the degenerative cascade.[6] Importantly, this relationship between inactivity and joint deterioration is not confined to older adults, evidence indicates that cartilage begins showing measurable degenerative changes in sedentary individuals as early as the fourth decade of life.[7]
Research has consistently demonstrated that low-impact exercise, including resistance training, aerobic exercise, and mobility training, can help preserve cartilage health, strengthen periarticular musculature, and reduce systemic inflammation associated with OA progression.[8] However, the overwhelming majority of exercise intervention studies have been conducted in populations already diagnosed with OA, predominantly aged 60 and above. The evidence base for exercise as an early intervention strategy in preclinical, working-age sedentary adults aged 30–60 remains an area of limited consensus in the existing literature.[9]
This research proposal aims to address that gap by examining whether a structured, supervised low-impact exercise program can produce measurable improvements in joint health and physical function in adults aged 30–60 who are sedentary and carry at least one established OA risk factor, but have not yet received a clinical diagnosis. It should be acknowledged that a potential limitation of this study is the relatively short intervention duration of 12 weeks, which may limit the ability to capture long-term effects on osteoarthritis progression. Additionally, the broad age range of 30–60 represents a recognized limitation, as exercise response and baseline joint health may differ considerably across this window; future research with larger sample sizes should consider age stratification.
The global burden of osteoarthritis has grown substantially over the past three decades. The Global Burden of Disease Study 2021 reported approximately 595 million cases of OA worldwide in 2020, reflecting a 132.2% increase since 1990, and projected a further 74.9% increase in knee OA cases by 2050.[1] OA is now recognized as a leading cause of disability in adults aged 40 and older, imposing significant healthcare costs and reducing workforce participation globally.[1] The prevalence of OA is consistently higher in females and increases steeply with age, though emerging evidence confirms that OA is not exclusively a disease of aging, modifiable lifestyle factors, including physical inactivity and obesity, contribute significantly to its onset and progression across the adult lifespan.[9]
A growing body of evidence has established a dose-response relationship between sedentary behavior and the severity of OA-related joint deterioration.[9] Physical inactivity leads to progressive atrophy of the periarticular musculature, with quadriceps weakness identified as a core pathological factor in knee joint instability and cartilage degeneration.[5] Reduced muscle support increases compressive forces on articular surfaces, disrupting the synovial fluid dynamics essential for cartilage nutrition and waste clearance.[7]
A Mendelian randomization study by examining the causal relationship between physical activity, sedentary behaviors, and OA risk found that light physical activity significantly decreased the risk of overall OA and knee OA, supporting a causal protective role of movement on joint health.[10] Furthermore, research in both animal and human models has demonstrated that cartilage degeneration is more closely associated with inactivity than with moderate exercise, with sedentary conditions leading to reduced proteoglycan content and compromised chondrocyte viability.[6]
Exercise is now recommended as a first-line, non-pharmacological intervention for OA management by multiple international guidelines, including those from the European League Against Rheumatism (EULAR), the American College of Rheumatology (ACR), and the Osteoarthritis Research Society International (OARSI).[9] A 2024 systematic review and meta-analysis by Nayab et al., encompassing 12 randomized controlled trials and 4,920 participants, found that aerobic training, resistance exercises, and multimodal programs all produced significant improvements in pain, physical function, and quality of life in individuals with knee and hip OA.[11]
A network meta-analysis by Mo et al. (2023) comparing five exercise modalities, aquatic exercise, stationary cycling, resistance training, traditional exercise, and yoga, found that resistance training and stationary cycling produced the most consistent improvements in WOMAC pain and stiffness subscale scores across included randomized controlled trials.[12] These findings provide strong justification for incorporating both resistance training and aerobic exercise components within the proposed intervention design.
Huffman et al. (2024) conducted a narrative review in The Journal of Rheumatology confirming that as little as 150 minutes per week of moderate-intensity activity produces significant benefits for joint health in adults with knee and hip OA, with additional gains observed from supplementary strengthening exercise on two or more days per week.[8] These dosage parameters directly inform the proposed exercise prescription in the current study.
Despite the substantial evidence supporting exercise for OA management, the literature is heavily weighted toward populations aged 60 and above, or those already carrying a clinical diagnosis. The preclinical window, adults aged 30–60 who are sedentary, carry established risk factors, but have not yet developed diagnosable OA, represents a largely neglected target for intervention research.[9] This gap is particularly significant given that muscle weakness and early cartilage changes precede symptomatic OA by years or decades, suggesting that earlier intervention may delay or attenuate disease onset.[6] The current proposal directly addresses this gap by targeting adults within the 30–60 age range who are sedentary and at risk, using a controlled experimental design with validated clinical outcomes.
This study is grounded in the biopsychosocial model of musculoskeletal health, which conceptualizes joint health as the product of interacting biological, psychological, and social factors rather than purely structural pathology. Within this framework, physical inactivity is understood not merely as an absence of movement but as an active contributor to a cascade of biological changes, including muscle atrophy, synovial dysfunction, and low-grade inflammation, that collectively increase vulnerability to degenerative joint disease.
Complementary to this is the exercise-cartilage loading hypothesis, which posits that moderate, cyclical mechanical loading of articular cartilage, as produced by structured low-impact exercise, stimulates chondrocyte activity, promotes the synthesis of extracellular matrix components, and maintains cartilage integrity.[6] This model predicts that even short-duration exercise programs will produce measurable improvements in joint-related outcomes in sedentary populations, providing the theoretical basis for the 12-week intervention design.
Together, these frameworks predict that systematic exposure to structured low-impact exercise will disrupt the sedentary-deterioration cycle, producing improvements in self-reported joint symptoms and objective physical function that are meaningfully greater in the intervention group than in the sedentary control group.
To compare changes in self-reported joint pain and stiffness scores (WOMAC pain and stiffness subscales)[2] between the intervention group and a sedentary control group at baseline (week 0), midpoint (week 6), and program completion (week 12).
To assess differences in functional mobility, using the Timed Up and Go test[3] and the 6-minute walk test,[4] between the intervention and control groups at baseline and program completion.
To evaluate participant adherence to the exercise program and identify key barriers and facilitators to sustained participation through structured weekly surveys and post-program exit interviews.
Sedentary lifestyles are a significant contributing factor to early joint deterioration in working-age adults. Physical inactivity causes progressive muscle atrophy around key joints (particularly the knee and hip), removing a primary source of structural support for the joint.[5] Without adequate muscular support, joint cartilage is exposed to increased stress during everyday movement, which may accelerate degradation over time.[6] Despite exercise being widely recommended for managing joint health, most intervention research focuses on elderly or already-diagnosed populations, leaving a meaningful gap in evidence for adults aged 30–60 who are at risk but have not yet received a clinical diagnosis.[9] For this study, "at risk" is defined as being sedentary (fewer than 150 minutes of moderate physical activity per week, per WHO guidelines)[13] and having at least one additional OA risk factor, such as a BMI over 25, a history of joint discomfort, or a family history of OA.
This study proposes a two-group randomized controlled design. A sample of approximately 50 participants (25 per group) will be recruited, based on a priori power analysis (see Section 08), to ensure sufficient statistical power to detect meaningful between-group differences. Eligible participants will be randomly assigned to either the intervention group or the control group following baseline assessment. The intervention group will complete a structured 12-week low-impact exercise program combining three sessions per week of resistance training (targeting lower-limb and core muscle groups) with moderate-intensity aerobic exercise such as cycling or walking, with each session lasting 45–60 minutes. Program intensity will be individually calibrated using the Modified Borg RPE Scale (CR10; 0–10).[14] The control group will maintain their current sedentary lifestyle for 12 weeks and will undergo identical assessments at the same timepoints. Ethical approval will be obtained prior to data collection, and all participants will provide written informed consent.
It is expected that participants in the intervention group will demonstrate significantly greater improvements in joint pain and stiffness scores (WOMAC index) and functional mobility on standardized assessments, compared to the control group after 12 weeks. These findings would contribute evidence supporting structured low-impact exercise as a scalable, cost-effective early intervention for improving joint health outcomes in working-age adults, with implications for public health guidelines and workplace wellness programming.
Sedentary adults aged 30–60 who are at risk of osteoarthritis and who complete a 12-week structured low-impact exercise program will show significantly greater improvements in joint pain scores, joint stiffness, and functional mobility compared to both their baseline measurements and a sedentary control group that receives no intervention, as measured by the WOMAC index and functional mobility tests (TUG and 6-minute walk test) at week 12.
This study will employ a two-arm, parallel-group randomized controlled trial (RCT) design with assessments at baseline (week 0), midpoint (week 6), and completion (week 12). Randomization will be performed using a computer-generated sequence with concealed allocation to minimize selection bias. The study will be conducted at a university gymnasium or equivalent supervised exercise facility.
The intervention group will complete three supervised exercise sessions per week for 12 weeks. Each session will consist of a 10-minute warm-up (light mobility work and low-intensity walking), 20–30 minutes of lower-limb and core resistance training (bodyweight and resistance band exercises including squats, lunges, leg press, and bridges), and 15–20 minutes of moderate-intensity aerobic exercise (stationary cycling or brisk walking). Sessions will conclude with a 5-minute cool-down and stretching. Program intensity will be progressed weekly using a linear periodization model, with the Modified Borg RPE Scale (CR10; 0–10) used to calibrate individual effort at a target of 3–5 (moderate) throughout.[14] Each session will be supervised by a trained kinesiologist to ensure safety, correct technique, and protocol adherence. The control group will receive no intervention during the 12-week period and will be asked to maintain their current lifestyle and activity levels.
Primary outcomes: The WOMAC Pain and Stiffness subscales[2] will be administered as the primary patient-reported outcome instrument. The WOMAC, originally validated by Bellamy et al. (1988), comprises 24 items across three subscales, Pain (5 items), Stiffness (2 items), and Physical Function (17 items), scored on a Likert scale where higher scores indicate greater symptom burden. This study will use the Pain and Stiffness subscales specifically, as these are most relevant to the preclinical population being examined.
Secondary outcomes: The Timed Up and Go test (TUG)[3] will assess functional mobility by measuring the time required to rise from a chair, walk 3 metres, turn, return, and sit. The 6-Minute Walk Test (6MWT)[4] will assess submaximal functional exercise capacity by measuring the distance covered in six minutes on a standardized flat course, per ATS guidelines (American Thoracic Society, 2002).
Qualitative outcomes: Participants will complete brief structured weekly self-report surveys capturing perceived joint comfort (0–10 numeric scale), fatigue levels, and program experience. A 20-minute structured exit interview will be conducted at week 12 with each intervention group participant to explore barriers and facilitators to adherence, perceived benefits, and recommendations for program design.
Sample size was estimated a priori based on WOMAC pain subscale scores as the primary outcome. Drawing on Nayab et al. (2024),[11] who reported a pooled standardized mean difference (SMD) of approximately 0.60 for exercise versus control conditions in OA-adjacent populations, a medium effect size (Cohen's d = 0.60) was assumed. Using G*Power (version 3.1) with a two-way repeated-measures ANOVA model, a desired statistical power of 0.80, an alpha level of 0.05, and three measurement timepoints, the minimum required sample size was calculated at 42 participants (21 per group). To account for an anticipated attrition rate of approximately 15%, consistent with dropout rates reported in comparable 12-week exercise RCTs, a target of 50 participants (25 per group) will be recruited.[12]
It is acknowledged that this sample size is modest and may limit the generalizability of findings. This study is intended as a pilot RCT to establish preliminary effect estimates and feasibility data that could inform the design of a larger, adequately powered multi-site trial in future.
This study will employ a mixed-methods approach to develop a comprehensive understanding of both the measurable and experiential effects of the intervention.
Both groups will complete WOMAC,[2] TUG,[3] and 6MWT[4] assessments at weeks 0, 6, and 12. All assessors will be blinded to group allocation where possible. Data will be analyzed using a two-way repeated-measures ANOVA[15] to assess group × time interaction effects, with post-hoc pairwise comparisons corrected for multiple testing using Bonferroni adjustment. Statistical significance will be set at p < 0.05. Effect sizes will be reported as partial eta-squared (η²p).
Quantitative data is essential here because joint pain and physical function are inherently measurable phenomena. This allows for objective comparison between groups and makes the findings easier to replicate, strengthening the overall scientific validity of the study.
Participants in the intervention group will complete brief weekly surveys capturing perceived joint comfort, fatigue, and adherence. At week 12, semi-structured exit interviews (approximately 20 minutes each) will explore barriers, perceived benefits, and program improvement suggestions.
Interview data will be analyzed using thematic analysis following the Braun and Clarke (2006) framework, with themes reviewed by a second independent coder to ensure reliability. Qualitative data addresses dimensions that quantitative measures cannot capture, particularly the lived experience of participants and factors that would influence real-world program uptake.
The study is planned over a total of 18 months, divided into four phases as outlined below.
| Phase | Activity | M1–3 | M4–6 | M7–12 | M13–18 |
|---|---|---|---|---|---|
| Phase 1, Preparation | Ethics, recruitment, screening | ||||
| Phase 2, Baseline Assessment | Week 0 data collection (all participants) | ||||
| Phase 3, Intervention | 12-week exercise program + midpoint assessment | ||||
| Phase 3, Final Assessment | Week 12 data collection + exit interviews | ||||
| Phase 4, Analysis & Write-up | Statistical analysis, qualitative coding, report |
The following provides an indicative budget for a standalone study of this scope. Costs would vary depending on institutional affiliation, existing facilities, and available equipment.
| Category | Item | Estimated Cost (CAD) |
|---|---|---|
| Personnel | Kinesiologist supervisor (12 weeks, 3 sessions/week) | $4,800 |
| Personnel | Research assistant for assessments and data entry | $2,400 |
| Equipment | Resistance bands, exercise mats, stopwatches | $600 |
| Participant | Participant honoraria (50 × $20 per assessment × 3 timepoints) | $3,000 |
| Materials | Printing, survey administration, data storage | $300 |
| Software | SPSS or G*Power license for statistical analysis | $500 |
| Recruitment | Community advertising, flyers, social media | $400 |
| Total Estimated Cost | $12,000 | |
| Risk | Level | Mitigation Strategy |
|---|---|---|
| Participant dropout (>15%) | High | Recruit 50 participants to allow for attrition; maintain contact via weekly check-ins; offer flexible scheduling for missed sessions |
| Exercise-related adverse event or injury | Medium | Pre-screening with PAR-Q+; trained kinesiologist supervision; progressive intensity loading; first-aid kit on site |
| Control group contamination (beginning exercise independently) | Medium | Weekly lifestyle monitoring surveys; participants instructed to maintain current activity; sensitivity analysis if contamination detected |
| Data loss or corruption | Low | Dual backup of all data (encrypted cloud storage and local drive); paper copies of all assessments retained |
| Recruitment shortfall | Medium | Multi-channel recruitment (university noticeboards, social media, community centers, workplace wellness programs); 3-month recruitment window |
This study will be submitted for review and approval by the relevant institutional research ethics board prior to any data collection. All participants will provide written informed consent following a full explanation of the study's purpose, procedures, potential risks, and their right to withdraw at any time without penalty. Participant data will be anonymized, stored securely on encrypted servers, and accessible only to the research team. Data will be retained for a minimum of seven years in accordance with standard research governance requirements. The study will be registered on a publicly accessible clinical trial registry (e.g., ClinicalTrials.gov) prior to participant recruitment, and results will be reported transparently regardless of outcome direction.
The exercise intervention poses minimal risk when conducted under qualified supervision and with appropriate pre-screening. The control condition does not withhold any active treatment from participants; those in the control group will be offered access to the exercise program on completion of the study.
Findings will be submitted for publication in peer-reviewed journals relevant to kinesiology and rehabilitation science, with target outlets including the Journal of Orthopaedic & Sports Physical Therapy, Arthritis Care & Research, or BMC Musculoskeletal Disorders. Results will also be presented at relevant academic conferences, such as the Osteoarthritis Research Society International (OARSI) annual congress or the American College of Sports Medicine (ACSM) annual meeting.
A plain-language summary of findings will be produced for dissemination to community health centers, workplace wellness coordinators, and public health stakeholders, ensuring that results are accessible to non-specialist audiences who may implement findings in practical settings. Participants will receive an individual summary of their results upon study completion.
Several limitations of this study should be acknowledged. First, the 12-week intervention duration, while sufficient to observe short-term changes in joint symptoms and physical function, does not permit conclusions about long-term effects on OA progression or disease onset. A longer longitudinal follow-up would be required to address this question. Second, the broad 30–60 age range introduces potential heterogeneity in baseline joint health and exercise response; future studies should consider age-stratified analyses. Third, blinding of participants to group allocation is not feasible in exercise RCTs, introducing the possibility of performance or expectation bias. Fourth, the modest sample size (approximately 50 participants) limits statistical power for subgroup analyses and reduces generalizability. This study should therefore be considered a pilot RCT, with findings used to power a larger future trial.