BodyBalance as an exercise therapy for knee osteoarthritis in older women: a study protocol for a randomized controlled trial

Abstract

Background

Knee osteoarthritis (OA) is a prevalent degenerative condition among older women, frequently causing pain, decreased mobility, and reduced quality of life. As the global population ages, effective and accessible non-pharmacological interventions are urgently needed. This randomized controlled trial aims to evaluate the clinical and statistical effects of a 12-week BodyBalance exercise program on symptoms and complications associated with OA in older women.

Methods

A total of 40 older women aged 60–80 years with clinically diagnosed knee OA will be randomly assigned to either the intervention group or the control group. The intervention group will participate in a supervised BodyBalance training program, while the control group will maintain their usual activities without any structured exercise. Outcomes include evaluations of knee pain, balance, postural control, lower limb muscle strength, proprioception (knee and ankle), fear of falling, and overall quality of life.

Discussion

The study is expected to demonstrate that BodyBalance significantly improves balance, reduces pain, and enhances functional mobility in older women with OA compared to no intervention. These findings may support the clinical adoption of mind–body exercise as a cost-effective strategy for improving independence and well-being in the aging population.

Trial registration

https://irct.behdasht.gov.ir/trial/68467. Registered on 15 April 2023. Retrospectively registered.

Introduction

Background and rationale {6a}

Population aging is accelerating globally due to increased life expectancy and declining birth rates, leading to a higher prevalence of chronic musculoskeletal conditions, such as knee osteoarthritis (OA) [1, 2]. Knee OA is the most prevalent form of arthritis and accounts for approximately 61% of all OA cases [3, 4], affecting nearly 40% of men and 47% of women during their lifetime [5, 6]. In older women, particularly postmenopausal individuals, knee OA significantly impairs physical function, balance, and quality of life, while increasing the risk of falls and dependence [7–9]. The economic burden is also substantial, with treatment and disability-related costs projected to double by 2030 [4].

Common management approaches for knee OA include pharmacotherapy, physiotherapy, surgical interventions, and exercise therapy [10, 11]. Among these, exercise therapy is widely recognized as a safe and effective method for reducing symptoms, enhancing joint function, and delaying disease progression [11–13]. Exercise improves muscle strength, proprioception, and joint stability, slows disease progression, and enhances functional independence. Regular exercise has been shown to reduce OA-related disability by up to 47% and may even delay the need for joint replacement surgery [14–17]. However, there is still a lack of standardized exercise protocols specifically suitable for older women with knee OA.

In recent years, mind–body exercises, which integrate slow, controlled physical movement with breathing techniques and mental focus, have gained recognition for their dual benefits on physical and psychological health [18–20]. Modalities such as tai chi, yoga, and Pilates not only improve strength, flexibility, and proprioception but also reduce anxiety and increase relaxation [11, 21]. One such intervention is BodyBalance, a structured, low-intensity group exercise program developed with principles from yoga, tai chi, and Pilates [22–24]. From a sports rehabilitation perspective, BodyBalance promotes neuromuscular control, core stability, joint alignment, and flexibility, while also promoting relaxation, stress reduction, and body awareness. It is particularly suited to older women due to its emphasis on slow, controlled movements and adaptable intensity.

To date, only two studies have specifically investigated BodyBalance. Khan et al. (2008) reported that BodyBalance improves anthropometric, physiological, and psychological parameters, enhancing balance, flexibility, and reducing anxiety in adults [24]. Similarly, Nicholson et al. (2014) found that a 12-week BodyBalance program improved balance, physical performance, fear of falling, and quality of life in older adults (mean age 66 years) [23]. These preliminary findings suggest potential benefits of BodyBalance across diverse populations, including adults and older adults [23, 24]. However, evidence in specific clinical populations, such as individuals with knee OA, remains limited.

Justification for the study

Although physical exercise is a cornerstone in managing knee OA, there is still no consensus on the most effective exercise protocol specifically designed for older women. Most available programs are not tailored to the needs of this population and may lack long-term adherence due to high intensity or lack of enjoyment. Meanwhile, BodyBalance offers a feasible and scalable intervention with dual physical and mental health benefits, yet its effectiveness in patients with knee OA has not been sufficiently studied.

Given the potential benefits of BodyBalance and the limitations of current interventions, this study proposes to design and evaluate a 12-week BodyBalance-based exercise program specifically targeting older women with knee OA. This protocol aims to address modifiable risk factors, enhance neuromuscular control, reduce pain and stiffness, and enhance quality of life. The group-based and low-impact nature of BodyBalance is also expected to promote adherence, satisfaction, and long-term functional outcomes.

Objectives {7}

Main objective

To assess the efficacy of a 12-week BodyBalance-based exercise protocol in alleviating symptoms and enhancing functional outcomes in older women with knee osteoarthritis.

Specific objectives

• To assess changes in pain severity, fears and beliefs, postural control, and quality of life using the Visual Analogue Scale (VAS), Knee Osteoarthritis Fears and Beliefs Questionnaire (KOFBeQ), WOMAC (Western Ontario and McMaster Universities Arthritis Index), and the Timed Up and Go (TUG) Index.

• To analyze changes in static and dynamic balance using the Sharpened Romberg and Functional Reach tests.

• To evaluate improvements in muscle strength through a hand-held dynamometer.

• To assess knee and ankle proprioception using the digital photography method.

• To measure participants’ satisfaction, adherence, and perceived usefulness of the program.

• To explore the effective dosage and feasibility of implementing BodyBalance in community or clinical settings.

PICO question

In older women with knee osteoarthritis, does a structured BodyBalance-based training protocol alleviate symptoms and complications associated with OA compared to the control group?

Study hypothesis

We hypothesize that a 12-week structured BodyBalance-based intervention will significantly reduce pain and stiffness, enhance balance, muscle strength, and proprioception, and enhance quality of life in older women with knee osteoarthritis, compared to the control group.

Methods

Trial design {8}

This study is a two-arm, randomized controlled trial with a parallel-group design and a 1:1 allocation ratio. The trial will aim to assess whether the BodyBalance intervention yields greater improvements in clinical outcomes compared to no intervention in older women with knee osteoarthritis. The intervention will consist of a low-intensity, group-based BodyBalance exercise program that integrates elements of yoga, tai chi, and Pilates [25–27]. This protocol will be designed to address both the physical and psychological needs of older adult participants, focusing on enhancing overall well-being. The BodyBalance exercise sessions will target a variety of muscle groups, from small stabilizing muscles to larger muscle groups, to enhance strength, endurance, and flexibility [22, 23]. The program will incorporate flexibility exercises to address range of motion, as well as activities specifically designed to increase muscular strength and knee joint stability. The training will include meditation and relaxation techniques to enhance participants’ psychological and mental health in addition to the physical benefits. To further promote the psychological benefits of the intervention, group-based sessions will be conducted to foster emotional support and social interaction [22–24].

A total of 40 older women (aged 60 to 80 years) with knee OA will be recruited for this study. Participants will be screened and approved for inclusion by a specialist physician, based on the diagnostic criteria established by the American College of Rheumatology and specific inclusion and exclusion criteria. The total intervention period will be three months. Participants will be randomly assigned to either the BodyBalance group or a control group receiving no structured exercise intervention. Outcome assessments will be conducted at baseline (pre-test) and week 12 (post-test). Participants’ weight, height, and BMI will be measured at baseline using calibrated scales and stadiometers. Dietary intake will be assessed at both time points with a validated Food Frequency Questionnaire (FFQ) targeting anti-inflammatory foods and supplements (omega-3 fatty acids, glucosamine). Psychological factors will be assessed using the Knee Osteoarthritis Fears and Beliefs Questionnaire (KOFBeQ) at baseline and week 12 to capture fears and beliefs. Participants will be instructed to maintain their usual diet and physical activity patterns to minimize variability. These data will be used to control for confounding effects in statistical analyses, as detailed in the “Data Analysis” section.

The study protocol follows the SPIRIT 2025 statement recommendations (Fig. 1). Written informed consent will be obtained prior to enrollment, and participants may withdraw at any time without consequences.

Fig. 1.

SPIRIT timeline diagram

Study setting {9}

This trial will be conducted at the Rehabilitation Center of Bu-Ali Sina University in Hamedan, Iran. Participants will be recruited from local nursing homes and hospitals with the collaboration of medical personnel and caseworkers in geriatric and orthopedic departments.

Eligibility criteria {10}

Inclusion criteria

Participants must meet the following conditions:

• Women aged 60–80 years with grade II or III knee osteoarthritis, according to the Kellgren and Lawrence grading system, in at least one knee.

• Experiencing knee pain for at least three months.

• No intra-articular injections or physiotherapy within the past six months.

• No history of cardiorespiratory conditions.

• Absence of neurological disorders, such as Alzheimer’s, Parkinson’s, or other neurological conditions, including numbness or tremors.

• No history of fractures or surgeries involving the lower limb joints, particularly knee arthroscopy or arthroplasty.

• No participation in regular sports activities within the past six months.

Exclusion criteria

Participants will be excluded if they meet any of the following conditions:

• Being scheduled for knee replacement surgery.

• Having any contraindications to exercise therapy, as determined by the treating physician.

• Inability to comply with the study protocol or follow the exercise program instructions.

• Use of nonsteroidal anti-inflammatory drugs (NSAIDs) or analgesics during the study period.

• Experiencing worsening of pain or disease symptoms.

• Exhibiting consistent non-compliance with the exercise program (defined as two consecutive absences or three absences over the program duration).

• Voluntarily withdrawing from the exercise program.

Who will take informed consent? {26a}

Before the study begins, the research coordinator will explain the trial to eligible participants. Written informed consent will be obtained from each participant individually. Consent forms will be securely stored in sealed envelopes and confidentially filed.

Additional consent provisions for collection and use of participant data and biological specimens {26b}

This study will not involve the collection of biological specimens. No additional consent will be required for the use of participant data beyond what is specified in the main consent form.

Interventions

Explanation for the choice of comparators {6b}

The comparator was selected to reflect standard care. The control group will receive no structured exercise program, maintaining their regular daily routines. This will enable a clear comparison with the intervention group undergoing a structured BodyBalance exercise program.

Intervention description {11a}

Overview of BodyBalance exercises

The BodyBalance exercise program will consist of a structured 60-min routine designed to engage all major muscle groups through 10 fundamental movement chains, referred to as “choreographie” [24]. These choreographies, which are detailed in Table 1, are grounded in the principles of yoga, tai chi, and Pilates and will form the basis of the exercise protocol used in this study. Each 60-min session will begin with tai chi movements to enhance flexibility and circulation, preparing the body for more intensive movements. The yoga sun salutations sequence will include strength and flexibility exercises that engage all muscle groups and will be a component of every choreography. The standing power chain will combine yoga and tai chi movements to strengthen lower body muscles. The fourth chain will focus specifically on improving balance. The fifth chain will include pelvic floor exercises to promote pelvic flexibility and strengthen the core muscles. The sixth chain will combine Pilates and yoga movements to target the abdominal muscles. Similarly, the seventh chain will strengthen the back, lumbar muscles, gluteus, and hamstrings, focusing on spinal erectors and posterior chain muscles. The eighth chain will involve yoga spinal rotations, while the ninth chain emphasizes forward bends derived from yoga. The final chain will conclude with relaxation and meditation, integrating yoga-based mindfulness techniques [24].

Table 1.

BodyBalance protocol study

Track	Origins	Set	Repetitions/Hold	Total time (min)	Level 1 (Weeks 1–3)	Level 2 (Weeks 4–6)	Level 3 (Weeks 7–9)	Level 4 (Weeks 10–12)
Tai chi warm-up	Tai chi	1	8–12 reps	10	-Wu Chi Position -Qi Gong Breathing Sequences -Arm Circles -Tiger Mouth And Chi Ball	-Qi Gong Breathing Sequences -Wide Wu Chi Position -Arm Circles -Tiger Mouth And Chi Ball - Chi Ball	-Qi Gong Breathing Sequences -Deep Tai Chi Arm Releases -Weight Transfers In Wide Wu Chi Position -Arm Circles -Tai Chi Hands Midline -Dan Bian	-Qi Gong Breathing Sequences -Weight Transfers In Wide Wu Chi Position -Deep Tai Chi Arm Releases -Arm Circles -Tai Chi Hands Midline -Dan Bian -Shield, And Block
Sun salutations	Yoga	1	4–10 reps	6.30	-Mountain Pose -Extended Mountain - To Swan Dive -To Forward Fold	-Mountain Pose -Extended Mountain - To Swan Dive -To Forward Fold -Down Dog	-Mountain Pose -Extended Mountain - To Swan Dive -To Forward Fold -Down Dog -Plank	Mountain Pose -Extended Mountain - To Swan Dive -To Forward Fold -Down Dog -Plank
Standing strength	Yoga, tai chi	1	10–12 reps	6.30	-Warrior One -Squat	-Warrior One -Warrior Two -Squat	-Warrior One -Warrior Two -Triangle -Squat	-Warrior One -Warrior Two -Triangle -Squat
Balance	Yoga, tai chi	1	10–30 s	5	-Knee To Chest -Star	-Knee To Chest -Star -Tree	-Knee To Chest -Star -Tree -Airplane	-Knee To Chest -Star -Tree -Airplane
Hip openers	Yoga, pilates	1	8–10 reps	5.40	-Quads & Abductor Stretch	-Quads & Abductor Stretch	-Quads & Abductor Stretch - Modified Frog lying on its back	-Quads & Abductor Stretch - Modified Frog lying on its back
Core – abdominals	Pilates, yoga	1	6–12 reps	6.30	-Toe Tap - Single Leg Lift - C Top Pulses -Leg Scoop	-Toe Tap - Single Leg Lift - C Top Pulses -Leg Scoop -Shoot Legs Out -Hundred	-Toe Tap -Leg Scoop -Shoot Legs Out -Hundred -Twisting Bicycles -Boat Pose	-Toe Tap -Leg Scoop -Shoot Legs Out -Hundred -Twisting Bicycles - Boat Pose
Core – back	Pilates, yoga	1	6–12 reps	4.30	-Upper Locust - Bridge -Side Leg Sequences	-Opposite Arm & Leg Raise - Bridge -Side Leg Sequences	-Upper Locust -Opposite Arm & Leg Raise - Bridge -Pointer -Side Leg Sequences	-Upper Locust -Opposite Arm & Leg Raise - Bridge -Pointer -Side Leg Sequences
Twists	Yoga, tai chi	1	10–20 S	2.20	-Supine Spinal Twists	-Seated Spinal Twists	-Supine Spinal Twists -Seated Spinal Twists	-Supine Spinal Twists -Seated Spinal Twists
Forward bends	Yoga, tai chi	1	10–30 S	4.30	-Stick -Supine Hamstring Stretch -Supine Adductor/Abductor Stretch	-Stick -Seated Forward Fold -Supine Hamstring Stretch -Supine Adductor/Abductor Stretch	-Stick -Seated Forward Fold -Supine Hamstring Stretch -Supine Adductor/Abductor Stretch -Happy Baby Pose	-Stick -Seated Forward Fold -Supine Hamstring Stretch -Supine Adductor/Abductor Stretch -Happy Baby Pose
Relaxation/meditation	Yoga, meditation	0	0	10	-	-	-	-

Experimental group {11a}

The intervention in this study will last 12 weeks and will include 36 BodyBalance training sessions over three months. The intervention group will participate in a supervised BodyBalance exercise program three times a week for 12 weeks, each session lasting 60 min. Each session will adhere to the guidelines of the American College of Sports Medicine and the principles of exercise science, consisting of three components: a 10-min warm-up, a 40-min exercise cycle (including core stability, balance, strength, and flexibility exercises), and a 10-min cool-down (Table 1). The exercises will begin at a basic level and will progress gradually to align with the overload principle. To ensure appropriate intensity, participants will complete the Borg Rating of Perceived Exertion scale at the end of each week’s third session. This feedback will be used to adjust exercise intensity accordingly (Supplement).

Control group

Participants assigned to the control group will not receive any structured exercise intervention during the study period. They will be instructed to maintain their usual daily routines and to avoid initiating any new exercise programs. To monitor adherence and identify potential co-interventions, participants will be asked to complete self-reported activity logs and may also be contacted for brief structured interviews throughout the study period. In accordance with ethical standards and to preserve equipoise, access to the supervised BodyBalance program will be offered to control group participants after the post-test phase.

Criteria for discontinuing or modifying allocated interventions {11b}

The intervention will be modified or discontinued if persistent discomfort, adverse reactions, or participant withdrawal requests arise. All adverse events, whether physical or psychological, will be recorded in a dedicated log and reported promptly to the Ethics Committee of Bu-Ali Sina University.

Strategies to improve adherence to interventions {11c}

Participant adherence will be monitored through attendance tracking at each of the three weekly sessions by the exercise trainer. Participants will complete weekly self-reports to document engagement and experiences. A researcher will monitor protocol adherence weekly by directly observing sessions and reviewing documentation to ensure fidelity. A qualified exercise therapist will deliver the intervention to maintain consistency.

Relevant concomitant care permitted or prohibited during the trial {11d}

Physiotherapy or other concurrent treatments will not be permitted. Participants must not initiate any new exercise programs or rehabilitation during the trial period.

Provisions for post-trial care {30}

After the trial concludes, participants in the control group will be offered access to the BodyBalance intervention. No invasive procedures or high-risk interventions are involved, so no additional post-trial medical care is anticipated to be required.

Outcome {12}

Knee pain and fear of movement will be the primary outcomes, selected to align with the study’s hypothesis on pain alleviation and psychological barriers in knee osteoarthritis. Postural control, balance, strength, and proprioception will be secondary outcomes. Measurements will be conducted using standardized methods at two time points under controlled conditions to ensure consistency.

Pain severity measurement

The Visual Analogue Scale (VAS) will be used to assess pain severity for its simplicity, reliability, and ease of administration (ICC = 0.97) [28]. This scale comprises a horizontal or vertical line, typically 10 cm in length, with endpoints representing “no pain” (0) and “worst imaginable pain” (10). Participants will be asked to mark a point on the line corresponding to their perceived pain level. The distance from the “no pain” endpoint to the marked point will be measured to quantify pain severity.

Fears and beliefs measurement

The Knee Osteoarthritis Fears and Beliefs Questionnaire (KOFBeQ) will be used to assess the fears and beliefs of patients with knee osteoarthritis. This tool will aim to capture psychological factors that may influence the management and progression of the condition. The English version of KOFBeQ has demonstrated reliability (ICC = 0.81) [29]. Since a psychometrically validated Persian version is not currently available, we will administer the English version and will conduct a pilot test to ensure comprehension and cultural relevance among our Persian-speaking population.

The questionnaire consists of 11 items, divided into four domains: 1) Fears and beliefs about daily living activities (3 items), 2) Fears and beliefs about physicians (4 items), 3) Fears and beliefs about the disease (2 items), and 4) Fears and beliefs about sports and leisure activities (2 items). Scoring will be based on a Likert scale, with higher scores indicating more negative fears and beliefs about knee osteoarthritis.

Postural control and quality of life measurement

WOMAC (Western Ontario and McMaster Universities Arthritis Index) and the Timed Up and Go (TUG) test will be employed to evaluate quality of life, physical performance capacity, and postural control.

The WOMAC questionnaire is a validated and reliable tool (ICC = 0.63–0.94) for assessing pain, joint stiffness, and physical function limitations in individuals with knee or hip osteoarthritis [30, 31]. It consists of 24 questions divided into three sections: pain, joint stiffness, and physical function.

• Pain: Participants will report the severity of pain during activities, such as walking, using stairs, sleeping, sitting or lying down, and standing.

• Joint Stiffness: This section evaluates the degree of stiffness or reduced ease of movement in the joints.

• Physical Function: Participants will report their functional limitations during tasks such as using stairs, rising from a chair, standing, bending, walking, entering or exiting a car, shopping, putting on or removing socks, getting in and out of bed, lying in bed, entering or exiting the bathroom, sitting, using the toilet, performing heavy household chores, and completing light household tasks.

Responses will be scored on a Likert scale (0–4), and the total score will be calculated by summing the responses across all sections. A score of 0 indicates no limitations, while a score of 96 represents the highest level of disability [30].

The Timed Up and Go (TUG) test is a widely used tool for assessing basic mobility and motor performance, particularly in older women and individuals with knee OA [32] (ICC = 0.95–0.97) [33]. It involves standing up from a chair, walking three meters, turning around, and returning to sit in the chair. The total time taken (in seconds) serves as the performance metric, with times exceeding 12 s indicating a high risk of falls. Each participant will perform two trials, and the average of the two will be recorded. The test will be conducted in a controlled and safe environment, with the option of using assistive devices if needed [34].

Balance measurement

This study will use the Sharpened Romberg Test and the Functional Reach Test (FRT) to assess static and dynamic balance, respectively.

Static balance—Sharpened Romberg Test

The Sharpened Romberg Test is a valid and reliable tool for evaluating static balance in individuals with knee osteoarthritis under eyes-open (validity = 0.79, reliability = 0.90–0.91) and eyes-closed (validity = 0.73, reliability = 0.76–0.77) conditions [35].

To perform the test, participants will stand in a tandem position, with the heel of one foot placed directly in front of the toes of the other foot, and the arms will be crossed over the chest. The test will be conducted twice: once with eyes open and once with eyes closed. The duration participants can maintain the position in each condition will be recorded, and the average will be calculated to determine the result.

Dynamic balance—Functional Reach Test (FRT)

The Functional Reach Test (FRT) is a highly valid and reliable method (ICC = 0.92) for assessing dynamic balance and fall risk, particularly in older individuals with OA [36].

In this test, participants will extend their dominant arm forward as far as possible without losing balance while keeping their feet stationary. The difference between the initial and final reach distance will be measured in centimeters. A reach distance of less than 15 cm indicates a high risk of falling [37].

Muscle strength measurement

The isometric strength of the knee flexors (ICC = 0.83) [38] and extensors (ICC = 0.95) [38], hip flexors (ICC = 0.96) [39], hip extensors (ICC = 0.97) [39], and hip abductors (ICC = 0.97) [39], muscle groups commonly affected by knee osteoarthritis, will be measured using a hand-held dynamometer (ICC = 0.78–0.95) [40] manufactured by North Coast (USA) [41].

Before the main assessment, participants will perform one or two submaximal contraction trials to familiarize themselves with the procedure and to warm up. During the main test, each muscle group will undergo two maximal isometric strength trials, each lasting five seconds. To prevent muscle fatigue, a 30-s rest period will be provided between repetitions, and a two-minute rest period will be provided between assessments of different muscle groups. Straps will be used to stabilize the limb and minimize unwanted movement during testing. The dynamometer will be positioned vertically and firmly against the targeted limb, and participants will be instructed to apply the maximum force gradually. Details such as participant positioning, joint angles, strap placement, and the dynamometer’s exact location are provided in Table 2 [42].

Table 2.

Participant positioning and dynamometer placement for measuring muscle strength

Muscle group	Subject position	Joint angle (at the start)	Location of stability	Strap placement
Knee flexors	Sitting	Knee flexion at 90 degrees	Pelvis, thigh	On the back of the calf, approximately 5 cm proximal to the ankle
Knee extensors	Sitting	Knee flexion at 90 degrees	Pelvis, thigh	On the anterior tibia, approximately 5 cm distal to the tibial tuberosity
Hip flexors	Sitting	Knee flexion to approximately 90 degrees (parallel to the surface or as close as possible)	Pelvis	On the anterior thigh, approximately 3 cm proximal to the patella
Hip extensors	Supine	Knee flexion between 60 and 90 degrees	Trunk, pelvis	On the posterior thigh, approximately 2 cm proximal to the popliteal fold
Hip abductors	Side-lying	Upper thigh slightly flexed, hip in neutral or slight abduction	Pelvis	On the side of the upper thigh, approximately 5 cm proximal to the knee

Before the test, participants will receive standardized instructions to “apply maximum force.” Verbal encouragement will be provided by the examiner throughout the test to ensure maximal effort. Isometric muscle strength will be recorded and normalized to body weight to facilitate comparisons across individuals. The final muscle strength values will be expressed in Newtons per kilogram of body weight. Individuals [43].

Measurement of proprioception

The proprioception of the knee and ankle joints will be assessed using a reliable method involving digital photography, angle reconstruction, and calculation of reconstruction error. This method demonstrates strong intra-rater reliability (ICC = 0.89–0.90) [44]. For this study, the affected knee joint (with osteoarthritis) will be selected as the target limb. All measurements will be conducted in a quiet, isolated environment to minimize auditory or visual distractions that could affect accuracy. Based on previous studies, the target angles for assessment will be 45° for knee flexion, 10° for ankle dorsiflexion, and 20° for ankle plantar flexion. Proprioception at these angles will be evaluated in this study [45].

Proprioception measurement of the knee joint

To evaluate knee joint proprioception, participants will be seated comfortably on a treatment table. Circular skin markers (2 cm in diameter) will be placed at four anatomical landmarks: (1) the greater trochanter, (2) the knee joint line, (3) the fibular neck, and (4) the lateral malleolus. A 16-megapixel Canon digital camera will be positioned 185 cm from the participant and 65 cm above the ground, with its lens aligned with the knee joint and perpendicular to the motion plane. A goniometer, visible only to the examiner, will be mounted on a wall near the participant. Participants will be seated with a 90° angle between the torso and thighs, with their legs hanging freely from the edge of the table. With eyes open, the participant’s leg will be passively moved to the target angle, and they will be asked to maintain and memorize the position. The leg will then be returned to the resting position, and participants will actively reconstruct the target angle with their eyes closed. The reconstructed angle will be recorded using digital photography and analyzed with AutoCAD software. This process will be repeated three times, and the average error across the three trials will be recorded as the proprioception error for the knee joint [44].

Proprioception measurement of the ankle joint

To assess ankle joint proprioception, participants will be seated on a chair with their trunk-thigh and thigh-knee angles adjusted to 90°, and their legs suspended off the ground. Circular skin markers will be placed at four specific landmarks: (1) the anterior edge of the fibular neck, (2) the lateral malleolus, (3) the lateral side of the heel, and (4) the head of the fifth metatarsal. During the test, the examiner will passively position the participant’s foot at the target angle (10° dorsiflexion or 20° plantar flexion) and will ask them to maintain the position. Participants, with their eyes closed, will then actively reconstruct the target angle after returning to the resting position. This procedure will be repeated three times, and the average reconstruction error will be recorded as the proprioception error for the ankle joint [46].

Participant timeline {13}

Participants will undergo a pre-test assessment before the intervention and a post-test assessment after 12 weeks of intervention. All assessments will be conducted at the same time of day and in a controlled environment to minimize external factors that could affect participants’ performance and to ensure measurement reliability. The assessments and interventions will take place at the sports science laboratory in Bu-Ali Sina University under standardized conditions.

Sample size {14}

The sample size was calculated using G*Power software for a repeated measures ANOVA, assuming an effect size of 0.33 (based on partial η² for group-by-time interaction of pain) [24], a significance level of 0.05, and a statistical power of 95%. Based on these parameters, the required sample size is 32 participants, with 16 participants in each group (intervention and control). To account for a potential dropout rate, the total sample size was increased by 25%, resulting in a recruitment target of 20 participants per group, for a total of 40 patients with knee OA.

Recruitment {15}

Recruitment will be conducted through three primary strategies:

1. Nursing Homes: Administrators and physicians in nursing homes will be contacted to secure their cooperation. Upon agreement, physicians will inform eligible patients with knee OA about the study and provide detailed information. Interested patients will be encouraged to contact the study team to register.

2. Hospitals: Recruitment will also take place in hospitals, particularly within orthopedic departments. Physicians will inform eligible patients with knee OA about the study and provide detailed information.

3. Advertisements and Brochures: Advertisements and brochures will be distributed in exercise rehabilitation centers and shared through the university’s social media platforms to increase public awareness and attract potential participants.

Interested participants will first undergo an initial screening via a telephone interview conducted by a nurse. Following the telephone screening, an in-person eligibility review will be conducted by a physician at the hospital, based on the study’s predefined inclusion and exclusion criteria. This structured process will ensure that all participants meet the eligibility criteria, thereby minimizing the risk of bias and enhancing the rigor of the study (Fig. 2).

Fig. 2.

Layout of the study design

Assignment of interventions: allocation

Sequence generation {16a}

Random allocation will be performed using a computer-generated randomization sequence created by an independent statistician not involved in the recruitment or assessment. The sequence will be generated using Random Number Generator software® with a 1:1 allocation ratio. Block randomization with a fixed block size of 4 will be applied to ensure balanced group sizes.

Allocation concealment mechanism {16b}

Allocation concealment will be ensured using sequentially numbered, opaque, sealed envelopes (SNOSE), prepared by a third party not involved in recruitment. The envelopes will be opened only after participant eligibility is confirmed.

Implementation {16c}

Eligible participants will be enrolled into the study by a research assistant not involved in the randomization or intervention delivery. The random allocation sequence will be maintained and managed by an independent researcher not involved in recruitment, assessment, or intervention.

Once eligibility is confirmed and informed consent is obtained, this independent researcher will assign participants to one of the two study groups based on the pre-generated allocation sequence. Baseline assessments will be conducted within one week of randomization.

Group allocation will be communicated to each participant via a mobile text message, including the session schedule and location. The intervention sessions will be conducted by a trained physiotherapist not involved in outcome assessments.

Assignment of interventions: blinding

Who will be blinded {17a}

Due to the nature of the exercise intervention, blinding of participants, instructors, and the principal investigator is not feasible. However, outcome assessors will remain blinded to group assignments. These assessors will only access coded clinical data and will be instructed not to ask participants about their allocation. Participants will also be asked not to disclose their assigned group to assessors.

Procedure for unblinding if needed {17b}

If unblinding of an outcome assessor becomes necessary, the incident will be documented and reported. The corresponding data will be handled with appropriate statistical methods during analysis to control for any introduced bias.

Data collection and management

Plans for assessment and collection of outcomes {18a}

Baseline and demographic information will be collected using standardized forms developed by the research team. All outcome assessors will be trained before the trial begins to ensure inter-rater reliability and protocol consistency. Pre-test assessments will be conducted within one week after randomization. Post-test assessments will take place in week 13, 48 h after the final session of the 12-week intervention, to minimize the influence of acute effects such as fatigue.

Knee pain, fear of movement, and quality of life will be assessed using VAS, KOFBeQ, and WOMAC questionnaires. Postural control and balance will be evaluated with TUG, Sharpened Romberg, and FRT tests. Strength and proprioception will be measured using a hand-held dynamometer and digital photography under controlled laboratory conditions. All assessments will be conducted at the Sports Science Laboratory of Bu-Ali Sina University, at the same time of day, under consistent environmental conditions to maximize reliability.

Plans to promote participant retention and complete follow-up {18b}

To minimize dropout and promote adherence throughout the 12-week intervention period, several strategies will be implemented: (1) weekly SMS reminders for upcoming sessions, (2) providing an exercise diary to track participation and enhance motivation, (3) consistent communication between participants and the trainer, (4) telephone calls during the study and after completion to confirm attendance at assessment. These steps aim to maximize participant retention, particularly for the final post-test assessment.

Data management {19}

All data will be recorded electronically using a double-entry method to reduce data entry errors. The raw data will be stored in password-protected databases accessible only to the principal investigator and authorized data managers.

Confidentiality {27}

To ensure data confidentiality, each participant will be assigned a unique study identification number. Personal identifiers will be removed, and all data will be anonymized before analysis. Only the study coordinator will have access to the master list linking identifiers to participant codes. Data will be stored securely in accordance with institutional and ethical guidelines.

Plans for collection, laboratory evaluation, and storage of biological specimens for genetic or molecular analysis {33}

No biological specimens will be collected or stored for genetic or molecular analysis in this study.

Statistical methods

Statistical methods for primary and secondary outcomes {20a}

Descriptive statistics will summarize demographic and baseline characteristics. The normality of continuous variables will be assessed using the Shapiro–Wilk test. Independent samples t-tests will compare baseline variables between groups. Analysis of covariance (ANCOVA) will compare post-intervention outcomes between the intervention and control groups, controlling for covariates including weight, body mass index BMI, dietary intake (assessed via a validated Food Frequency Questionnaire at baseline and week 12, targeting anti-inflammatory foods and supplements like omega-3 and glucosamine), and psychological factors (measured using the Knee Osteoarthritis Fears and Beliefs Questionnaire at baseline and week 12).

A mixed-model repeated measures ANOVA will be performed to examine the interaction between time (pre- and post-intervention) and group (intervention vs. control). The assumption of sphericity will be tested using Mauchly’s test. If sphericity is violated, the Greenhouse–Geisser correction will be applied. Bonferroni-adjusted post-hoc pairwise comparisons will be used to explore within-group changes over time.

Effect sizes will be reported using partial eta squared (η²), interpreted as small (0.01), medium (0.06), and large (0.14). In addition to statistical significance (p ≤ 0.05), clinically meaningful changes will be assessed using the minimal clinically important difference (MCID) and percentage change from baseline. All analyses will be conducted using SPSS software version 26.

To evaluate clinical changes and the effectiveness of the interventions, both the MCID and minimum detectable change (MDC) will be calculated. Using a 95% confidence level, MCID will be determined via a distribution-based approach, while MDC will be calculated using the standard error of measurement (SEM) and the following formulas [47]:

$$\mathrm{SEM}={\mathrm{SD}}_{\mathrm{pre}}\times \sqrt{1-ICC)}$$

$${\mathrm{MDC}}_{\%95}=1.96\times \sqrt{2}\times \mathrm{SEM}$$

$${\mathrm{MCID}}_{\mathrm{RCI}}=1.96\times {\mathrm{SD}}_{\mathrm{pre}}\left[\sqrt{(2\times (1-\text{ICC}))}\right]$$

Here, SD_pre refers to the standard deviation of the pre-test scores in the training group, ICC denotes the intraclass correlation coefficient, and MCID_RCI represents the minimum clinically important difference using the reliable change index.

Interim analyses {21b}

No interim analyses are planned due to the low-risk nature of the intervention. The trial will proceed as planned unless significant adverse events necessitate early termination, in which case the decision will be made by the principal investigator in consultation with the ethics committee.

Methods for additional analyses (e.g., subgroup analyses) {20b}

Subgroup analyses are not planned for this trial.

Methods in analysis to handle protocol non-adherence and any statistical methods to handle missing data {20c}

To address potential protocol non-adherence, the initial sample size will be increased by 25%. Missing data will be handled using an Intention-to-Treat (ITT) approach, including all randomized participants. Multiple imputation will be used for missing continuous outcomes using baseline data. Linear Mixed Models (LMM) will be applied for repeated measures ANOVA to manage missing data. Sensitivity analyses (Last Observation Carried Forward, LOCF) will be conducted to check the robustness of results.

Plans to give access to the full protocol, participant-level data, and statistical code {31c}

The full trial protocol will be published in a peer-reviewed journal. Anonymized participant-level data and statistical code will be made available upon reasonable request from the corresponding author, subject to data-sharing policies and ethical approvals.

Oversight and monitoring

Composition of the coordinating center and trial steering committee {5d}

This trial is coordinated by the principal investigator and a trained clinical research assistant. No formal trial steering committee has been established.

Composition of the data monitoring committee, its role, and reporting structure {21a}

Given the non-invasive nature of the exercise-based intervention and minimal risk involved, no independent Data Monitoring Committee (DMC) has been established. Oversight of safety, adherence, and data integrity will be conducted by the principal investigator in collaboration with the university ethics committee.

Adverse event reporting and harms {22}

All adverse events will be systematically documented using pre-designed Excel-based templates developed by the research team. An adverse event will be defined as any musculoskeletal pain, injury, or physical complaint reported by participants during or following the exercise sessions. A clinical threshold of concern is set at an increase of more than 3 points on the VAS for pain intensity.

Monitoring of potential harms will be conducted through a dual approach: (1) weekly participant self-reports and (2) observations by trainers or supervising personnel during intervention sessions. All reported events will be reviewed weekly by the research team to assess severity, frequency, and potential causal relationships with the intervention. Appropriate actions, such as clinical referral or temporary suspension of participation, will be taken when necessary to ensure participant safety.

Frequency and plans for auditing trial conduct {23}

Trial conduct will be audited monthly by the principal investigator. Monitoring will include data completeness, adherence to protocol, and reporting of deviations or adverse events.

Plans for communicating important protocol amendments to relevant parties {25}

Major protocol amendments will be submitted for review and approval by the ethics committee and updated in the Iranian Registry of Clinical Trials (IRCT).

Dissemination plans {31a}

Findings from the trial will be submitted for publication in a peer-reviewed journal. Results will also be shared with study participants upon request. Authorship will follow the International Committee of Medical Journal Editors (ICMJE) guidelines, and the study team will not employ professional writers. Anonymized data and protocols will be shared based on data-sharing agreements.

Discussion

Future expectations of the study

This clinical trial protocol is designed to evaluate the effectiveness of a 12-week BodyBalance exercise program, an integrated regimen combining yoga, Pilates, and tai chi, in improving symptoms of knee OA among older women. The goal is to provide a comprehensive, evidence-based intervention that targets not only pain reduction but also quality of life, postural control, balance, muscle strength, and proprioception. Given the increasing prevalence of knee OA in aging populations, particularly among women, this intervention could offer a scalable and low-risk strategy to enhance quality of life and functional independence in this demographic.

BodyBalance exercises provide both biomechanical and psychological benefits. Biomechanically, strengthening lower limb and core muscles reduces stress on the knee joint and alleviates discomfort, while gentle mobility exercises enhance range of motion and joint alignment. Movements focused on balance and proprioception improve neuromuscular control and joint awareness, leading to better functional performance and reduced fall risk. Psychologically, the mind–body nature of BodyBalance may enhance motivation and self-efficacy, improve pain-coping strategies, and reduce anxiety or depressive symptoms commonly observed in individuals with chronic osteoarthritis [48–50].

If successful, the results of this trial may support the incorporation of mind–body exercise programs into routine OA management, particularly in community and clinical settings where medication or invasive interventions are ineffective or undesirable. Additionally, the holistic nature of BodyBalance may enhance adherence and self-management in chronic conditions, making it suitable for long-term implementation. These outcomes could influence rehabilitation policies and clinical guidelines for older adults with knee osteoarthritis.

Limitations

Several limitations of this study should be acknowledged: The study is limited to older women with knee OA, which restricts the generalizability of findings to male participants or other age groups. Sex-specific differences in biomechanics, pain perception, and responsiveness to exercise may limit broader applicability. Although the sample size is adequately powered to detect clinically significant changes, the relatively small sample size could limit the external validity of the results. Despite efforts to control for potential confounders (e.g., BMI, dietary intake, psychological factors) through statistical covariates, full standardization of these variables is not feasible. This may introduce residual variability in the outcomes. The protocol does not include a long-term follow-up phase, which limits the ability to determine whether the benefits of the intervention are maintained over time.

Strengths

This trial has several methodological and practical strengths. The randomized controlled trial design enhances internal validity and reduces selection bias. Adherence to international standards (SPIRIT) ensures transparency and reproducibility. BodyBalance exercise offers both biomechanical and psychological benefits, aligning with the multifactorial nature of osteoarthritis. Its low-impact nature makes it safe and suitable for older adults. By incorporating both statistical significance and clinically meaningful outcomes (e.g., MCID and MDC), the study aims to provide results that are statistically robust and practically applicable for physical therapists and patients. The use of standardized procedures and blinded assessors minimizes observer bias and measurement error. As global aging increases, the need for non-pharmacological interventions in chronic disease management grows. If proven effective, BodyBalance could become an affordable, accessible option for osteoarthritis rehabilitation worldwide.

Trial status

This study is registered with the Iranian Clinical Trial Registration Center (IRCT20230101057015N1).

Authors’ contributions {31b}

FS is the Chief Investigator; she conceived the study, led the proposal, and led protocol development. FR and LY contributed to the study design and to the development of the proposal. PS was the lead trial methodologist. All authors read and approved the final manuscript.

Funding {4}

This study has not received funding from any organization.

Data availability {29}

Data sharing does not apply to this article as no datasets were generated or analyzed during the current study.

Declarations

Ethics approval and consent to participate {24}

This research has been approved (IR.BASU.REC.1401.022) by the Ethics Committee of Bu-Ali Sina University.

Consent for publication {32}

Informed consent will be obtained from all participants prior to their involvement in the study.

Competing interests {28}

The authors declare that they have no competing interests.