The Effect of TRX vs. Aquatic Exercises on Self-Reported Knee Instability and Affected Factors in Women with Knee Osteoarthritis: A Randomized Controlled Trial



Background Knee Instability (KI) is described as a sense of the knee buckling, shifting, or giving way during the weight bearing activities. High prevalence (65%) has been reported for KI amongst the patients with knee osteoarthritis (KOA). So, we studied the effect of two interventions on self-reported KI and affected factors.Methods In this single blind, randomized, and controlled trial, 36 patients with radiographic grading (Kellgren–Lawrence 1–4) of knee osteoarthritis were selected for participating. patients were allocated in three groups aquatic exercises (n=12), Total Resistance eXercises (TRX) exercises (n=12) and control (n=12) by random. 8-week TRX and aquatic exercises were carried out by experimental groups. Pain severity was assessed by visual analog scale (VAS), Balance was also evaluated by Berg Balance Scale (BBS), quadriceps strength by dynamometer, and knee range of motion (ROM) by inclinometer, Western Ontario and McMaster Universities Osteoarthritis (WOMAC), self-reported KI were also measured before and after interventions.Results The results of One-way ANOVA showed that there was no significant difference between aquatic exercises and TRX (P>0.05) for KI, BBS, WOMAC, and pain. But there was significant difference between the aquatic exercises and the control for KI (P=0.0001), BBS (P=0.0001), WOMAC Stiffness (P=0.0001), and pain (P=0.006). Also, there was significant difference between the TRX and the control for KI (P=0.0001), BBS (P=0.0001), and pain (P=0.003) except WOMAC Stiffness (P=0.07).Conclusions TRX and aquatic interventions had a similar effect on the patients’ KI, pain, function, and also balance variables, but TRX exercises had more effect on the knee stiffness improvement.


One of the problems, which is common among the patients with knee osteoarthritis (KOA) is knee instability (KI) in their weight bearing or walking. KI is described as a sense of the knee buckling, shifting, or giving way during the weight bearing activities. High prevalence rate (65%) has been reported for KI amongst the patient with KOA [1]. In fact, the knee functional stability protects the joint by the use of the concurrent dynamic control of the stabilizer muscles while structural or mechanical stability was provided by the anatomical constraints like ligaments and bony prominences. Functional stability of the knee has benefit for activity daily living (ADL) improving, and also for preventing from the KOA progress. In earlier researches, KI has been associated with the pain increasing, ADL disrupting, gait pattern altering, and also fall number increasing [2, 3]. Additionally, investigations have reported that the factors involving in muscle neuromuscular deficiency like joint laxity, proprioception deficiency, and inappropriate muscle stiffness strategies can expose patients to this instability [3,4–6]. The most of the knee instability in the KOA patients occurs during walking. Accordingly, Schmitt and Rudolph (2007) have reported that knee instability can be considered as an important factor in motion predicting strategies for KOA patient during their walking [5]. Consequently, it is possible that people with knee instability have a kind of compensatory strategy in their walking pattern, which will affect the disease progression. The self-reported knee instability and the dynamic varus–valgus joint motion during the time of walking are associated to the worse knee confidence [7]. Therefore, it is probable that patient’s ADL, dynamic walking, and life quality will be changed, and this issue requires more investigations. In fact, the knee instability may result in increasing the knee movements in sagittal and frontal planes while walking and weight bearing, and altering the loading on the knee joint [8]. Walking sensitivity for quantifying the knee instability in Hobbelen and Wisse’s research confirms this phenomenon [9]. This problem can affect the patients’ life quality by reducing trust in the joint, and avoiding daily activities. Also, balance deficit has been reported in an individual with OA as the dynamic balance is more affected than static balance by KOA [10, 11], consequently, adding the joint instability to it can put these patients at fall risk, and lead to experience secondary problems, and also may change the walking pattern of the patients with KOA [12]. Evidence indicates improvement in pain and even joint deformation in patients with early osteoarthritis after their knee instability improving [13]. As attention to knee instability to accelerating the arthritis symptoms recovery, has also attracted the attention of specialists and researchers recently. Due to the importance of the problem and affecting aspects on the patient’s life, it is effective in preventing the disease. It is important to use strategies for treating the joint instability in patients with knee osteoarthritis. Some factors have influences on the neuromuscular control disorders like laxity, proprioception disorders, and inappropriate muscle stiffness strategies [2]. Recent researches have also reported that the self-reported instability may be an inadequate knee stability, and also reduced knee joint control symptom in these patients [1]. TRX exercises was announced as a training protocol, which uses from the body weight in order to strengthen the muscular system, and tend to have better muscle activation levels than current strength exercises, and would also improve the motor control [14]. As a result, it can be considered as an intervention for improving the self-reported instability feature, due to the fact that increased levels of the joint stabilizer muscles activation can reduce laxity and eliminate the need for a compensatory mechanism. Moreover, TRX exercises can play an important role in increasing the joint stabilizer muscles stiffness by utilizing the beneficial eccentric loads on the muscle-tendon unit in the safe Range of Motion (ROM), and as a result, it can be effective in muscle feed forward, and also feedback activation for the joint stability [14]. Evidences indicated the important role of hip extensors and plantar flexor muscles for stabilizing the patients unstable knee with ACL rupture, as concentration of some TRX exercises are on those muscle strength, so knee joint instability control can be expected. Another intervention that can be effective in improving proprioception and neuromuscular control, are recognized as therapeutic exercises in the water environment. The water environment, due to its special properties like hydrostatic pressure, is a suitable environment for stimulating the mechanical receptors, and enhancing the joint proprioception and also neuromuscular control [15]. The neuromuscular control development has involved the joint stabilization muscles significantly, and can be effective in controlling this instability.

Unfortunately, despite of those studies that were done on the risk factors of the knee joint instability in patients with osteoarthritis, and its effects on their function and quality of life, but still no investigation has been conducted on its control strategies. Most of the therapists have just concentrated on the patients’ pain and function improvement, and knee joint instability in these patients has neglected. The main purpose of this study was comparing the aquatic exercises and TRX effects on the self-reported knee instability and its affected factors like balance, pain, and stiffness. It was hypothesized that 1). TRX and aquatic exercises caused improving in pain, balance, stiffness, and self-reported KI statistically, 2). the TRX would have more effectively reduced the self-reported KI than aquatic exercises intervention.


Trial design

This single blind, randomized, and controlled trial, which conducted at Razi University rehabilitation center in Iran, lasting eight weeks between February 2019 and May 2019. The evaluators who measured variables for patients were blinded about the group allocation. This study included three steps: 1. Pre-tests 2. 8-week aquatic exercises and TRX exercises for case groups, and the control group was done just the rheumatologist advise 3. Post-tests (Fig 1).


Subjects of this research (200 female) were recruited by regular referral from rheumatologist physicians, and those patients who waited for common physiotherapy in rehabilitation centers.

Participants were included if they had (1) the age of more than 40 years old, (2) American College of Rheumatology clinical criteria for knee OA, (3) Kellgren and Lawrence radiographic disease severity scale ≥ II, and (4) self-reported knee instability. Additionally, all participants were excluded if they (1) had strokes, (2) had uncontrolled hypertension, (3) were unable to walk without assistant instruments, (4) had received other treatment interventions in past three mounts, (5) had obesity (BMI>40kg/m2), (6) suffered from neuromuscular diseases like MS and Parkinson, (7) had lower extremity fracture, (8) concurrent hip osteoarthritis, (9) waited for arthroplasty, and (10) had cardiovascular diseases. The knee in which they reported symptom of instability was assessed for all patients in this study [16]. The G.Power 3.1 software was used to estimate the minimum sample size. According to the results of previous researches and based on the test power of 0.90, the effect size of 0.63 and the significance level of 0.05, the minimum sample size was determined to be 36 [17]. Finally, they were divided randomly into three groups including TRX (n = 12), aquatic exercises (n = 12), and control (n = 12) groups (Table 2).

Study interventions

TRX exercises

The TRX ® Rip Trainer ™ (model) was used for the exercises performance. TRX training was completed by TRX specialist, and also all exercises were done by two trainers. the safety points were checked by trainer to avoid injuries, before the exercises started in every session. The TRX straps hanging down from the anchor point, and Suspension AnchorTM was adjustable to execute various exercises. Exercises were designed based on the patients’ motion limitations like knee flexion and extension. Furthermore, TRX exercises were started at the easiest forms, and going to be hard progressively. Intensity of exercises were step by step increased by 1) Narrowing the base of support 2) Changing the angle of pull 3) The pendulum, in which the feet were placed in the suspension trainer and the hands were off the ground, was used for ground exercises. The gravity center in relationship with the perpendicular gravitational pull determined the exercise intensity. 4) Using a one handle can increase the exercises difficulty. 5–10 min introducing the sessions’ exercises and their correct techniques, 5–10 min warm-up, which was stretching exercises, and also 40–50 min TRX exercises were performed per session. Participants who had wrist pain through the planks’ tests, could put their forearm on the ground in order to prevent the wrist pain increasing. The TRX exercises protocol were done for eight weeks, three times a week, and during 60 minutes for each session. Most of the exercises were focused on the core muscles, hip abductors, and leg muscles strengthening. TRX exercises were executed in three sections: the first section included all exercises which were performed in Sundays, the second section included all exercises which were performed in Mondays, and the third section included all exercises which were performed in Wednesdays for one month (Table 1) [18].

Table 1. insert here

Aquatic exercises

Aquatic exercises intervention was accomplished for eight weeks, three times a week, 24 sessions in total, and during 90 minutes for each session. The water temperature was approximately 32 ° C (89° F), and the water depth was considered as 1.3 meter. The water based exercises protocol included: 10 minutes’ warm-up along with walking (forward, backward, and sidewalk), and also stretching exercises for lower extremity muscles (quadriceps, hamstrings, triceps surae, abductors and adductors of hip, and gluteal muscles), 20-minute strength exercises with elastic band and sandbag (gluteus, adductors and abductors of hip, quadriceps, hamstrings, and triceps surae muscles); 20 minutes of aerobic exercises (stationary running or deep water-running); 20 minutes of step training and proprioceptive exercises; and 10 minutes of core exercises, and after that 10 minutes of cool down. we selected exercises based on studies for outcomes function, pain, balance [19, 20].

Randomization and Blinding

Participants were randomized by the use of Random Number Generator Software, and also were allocated to three groups using Sequentially Numbered Opaque Sealed Envelopes (SNOSE) concealed allocation method. A physiotherapist who did not involve in the data collection and evaluation of the outcomes has done random allocation sequence, enrolled participants and assigned participants to interventions. Participants were distributed to TRX (n = 12), aquatic exercises (n = 12), and also control groups (n = 12) by random (allocation ratio 1:1:1).

The assessors of this research were blinded about the exercises and interventions assigned to the groups, but there was no possible way for blinding the subjects to training as well as statistician towards the groups and their assigned exercises.

Study outcomes

We compared some variables such as (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), pain, gait pattern, Berg balance scale (BBS), function, and quality of life (SF36) between subjects with and without self-reported knee instability before this research. We found that KI could effect on just four items like knee pain, WOMAC stiffness subscale, BBS [21], so we designed this research based on our results. We assessed the 8-week aquatic exercises, and TRX exercises effect on the affected factors by KI.

Knee pain

Knee pain intensity was measured by using 10-cm visual analog scale (VAS) with the scoring range between 0–10cm. “0” indicated the pain absence, “1” minimal pain, and “10” is extreme or intolerable pain. The participants were asked “how much pain do you have during your daily activities?” the VAS was used to measuring the intensity of participants’ subjective pain before and after the interventions. A good reliability and validity was reported for the VAS (intraclass correlation 0.92) [22].

WOMAC stiffness

WOMAC stiffness subscale had two items that were rated by the Likert scale of 0 (no symptoms)- 4 (extreme symptoms), with a total range of 0–8, and higher scores displaying worse symptoms [23].

Berg Balance Scale (BBS)

BBS, which was used to assessing the balance consists of 14 different tasks, was assessing balance in sitting and standing position and in transfer. Each motor task was rated by the use of 5-point scale ranged from 0 to 4. The total score ranges from 0 to 56, where 56 represents normal balance [24].

Knee instability

Self-reported knee instability was evaluated according to giving way, and also shifting evidence, during the last month by Felson’s questionnaire [25]. KI intensity was graded based on the numerical scale (0 to 5) in response to the following question “To what degree of giving way, buckling, or shifting of the knee would affect your daily routine activity?” The ratings were as followings: 5 = “I have no symptom”, 4 = “I have symptom, but it does not affect my ADL”, 3 = “Symptoms affect my ADL slightly”, 2 = “symptoms affect my ADL moderately”, 1 = “symptoms affect my ADL strongly”, 0 = “symptoms prevent me to perform all of my everyday activities” [25]. The test-retest reliability of this self-report rating of KI was estimated by the use of an intra-class correlation coefficient (ICC = 0.72) [26].

Ethical Considerations

This research’s protocols were reviewed and approved by the research ethics committee of the Medical Sciences University of Kermanshah in Iran (Registration no.: IR.UMMS.REC.1397.718). The study’s protocol was also registered in the Iranian Registry of Clinical Trials (Registration no.: IRCT20181222042070N1). The subjects provided informed consent forms, and all of the tests and measurements were carried out at the Sport Rehabilitation Laboratory of Razi University in Iran. As well, all of the patients completed the informed consent forms.

Statistical analysis

We analyzed BBS, Pain, WOMAC (stiffness), and self-report knee instability variables before and after the 8-week aqua therapy and TRX exercises.

At First, we used Shapiro-wilks and Leven’s test for assessing the normal distribution of data, and also the variances homogeneity. When variances normality and homogeneity tests were confirmed, the data were considered to be parametric. Consequently, the dependent variables’ mean comparisons amongst the groups were made by the one-way analysis of variance (ANOVA), and also Tukey’s post hoc test was used for the pairwise comparisons. The effect size (ES) calculated by ES [Due to technical limitations, this equation is only available as a download in the supplemental files section.] sum of squares between groupssum of squares total. The guidelines for interpreting this value included small effect = 0.01, moderate effect = 0.06, and great effect = 0.14 [27]. The 5% was considered as significant level. All results were reported as the mean ± standard deviation. SPSS software was used to data analysis ‌ (SPSS Inc., Chicago, IL; version 22). In addition, statistical significant level was considered 0.05.

Fig 1. Insert here


A total of 200 knee osteoarthritis’ patients were studied for eligibility and 36 met the eligibility criteria. 12 patients were allocated to the aquatic exercise, 12 patients to TRX exercises, and 12 to the control group. 111 patients didn’t meet the eligibility criteria and 53 declined to participate. The results of Shapiro Wilks and Levene’s test indicated that both assumptions for data distribution normality and homogeneity of the variances were accepted (P>0.05). Furthermore, the obtained comparative results about demographic characteristics and Kellgren & Lawrence in the pre-test for interventions and control groups are displayed in Table 2. The results of one-way ANOVA indicated that no significant differences were found amongst the treatments and control groups in the baseline characteristics. (all P> 0.05).

Table 2 insert here

The results of one way-ANOVA are presented in Table 3. Finding indicated that there was significant difference amongst the groups for all of the dependent variables (PVAS = 0.023, PInstability = 0.0001, Pstiffness = 0.002, PBBS = 0.0001). For KI, Tukey’s post hoc test indicated that there was no significant difference between aquatic exercises and TRX (P = 0.84), but there was significant difference between the aquatic exercises and the control (P = 0.0001) as well, there was significant difference between TRX and control groups (P = 0.0001). Tukey’s post hoc test, also, showed that there was significant difference between aquatic exercises and control groups about knee stiffness (P = 0.02), similar to that there was significant difference between TRX and the control (P = 0.029), but there was still no significant difference between the aquatic exercises and TRX (P = 0.07). Additionally, about VAS, Tukey’s post hoc test indicated that there was no significant difference between the aquatic exercises and TRX (P = 0.95), but on the contrary, there was significant difference between the aquatic exercises and control groups (P = 0.006). Also, there was significant difference between the TRX and control (P = 0.003). Moreover, about BBS, Tukey’s post hoc test indicated that there was significant difference between the aquatic exercises and control groups (P = 0.0001). There was, also, significant difference between the TRX and control (P = 0.0001), but there was no significant difference between the aquatic exercises and TRX (P = 0.92).

Table 3 insert here

On the contrary, pairwise comparison presented that KI was significantly decreased after 8-week aquatic exercises and TRX training (P = 0.0001). VAS and BBS variables were also significantly improved after 8-week aquatic exercises and TRX training (P = 0.0001). Moreover, knee stiffness was significantly decreased for TRX group (P = 0.04), but no significant difference was observed for the aquatic exercises(P = 058) (Fig 2).

Fig 2. Insert here


One of the most common characteristics of the patients with KOA is self-reported KI, which was greatly associated with the limitations in physical function. Esch et al (2016), reported KI as a highly prevalent (61 %) characteristic in their patients with knee KOA cohort study [26]. Though, there wasn’t any clear reason for the sense of KI, consequently we investigated two interventions effect on the self-reported KI, balance, pain, and knee stiffness. This study results were in agreement with the first hypothesis that there was no significant statistical difference in all of the research outcomes between intervention groups. In fact, Water’s natural viscosity or resistance is very effective for muscle strengthening and increasing the rehabilitation progressions, on the other hand Hydrostatic pressure also supports and stabilizes the patients, allowing people with balance deficits to perform exercises without a fear of falling, decreasing pain, and improving their cardiovascular return. Accordingly, these water characteristic probably affect the studies variables. Some of the researchers who were studied about the aquatic interventions like Alcalde et al., Taglietti et al., and Lu et al. reported the same results, and also inconsistent with our results [20–28–29]. They reported that aquatic exercises could improve pain, function, and balance in patients with KOA. On the other side, body weight and TRX sling also provide an appropriate resistance to strengthen the core and extremities muscular in KOA patients. Both intervention protocols had strengthening exercises in order to strengthen the core muscle, the thigh and the legs muscles, but the outcomes indicated that quadriceps muscle strength increased more in TRX group than the aquatic exercises. this different strength progression between groups maybe due to muscle relaxation caused by water characteristic. Significant increases in pain, balance, and knee instability in these patients may have been due to the core and legs muscles strengthening. Foroughi and colleagues have also stated that, adding isolated core postural control training to physiotherapy exercises was associated with significantly greater improvements in pain, function, and CoP trajectories than physiotherapy exercises alone while we have used TRX exercises to strengthen core and hip muscles [30].This is, also, inconsistent with our results. Arazi et al., and León et al. have published the matching results. They stated that extremities function was influenced by lumbo-pelvic-hip muscular strengthening in TRX exercises [31,32].

Besides, second hypothesis was confirmed so that there were significant statistical differences in all research outcomes between pretest to posttest for intervention groups except the stiffness subgroup of WOMAC, which supports our research hypothesis.

TRX is the new sling training for an intense full-body workout, which would mobility effectively improve coordination, stability, and. The earlier researches results have indicated that TRX exercises activated the stabilizing muscles of the various joints of the body, especially the core muscles that would improve the lower extremity function [33]. Other benefits of this exercise are including the variety of exercise and attractiveness, simplicity, ease to use, and little space occupying [34]. Former researches about KOA recommends that individuals with unstable knees often used the strategies like knee flexion excursion reduction and increased muscular co-activation in order to maintain the knee stability. They also recommended that knee-stiffening is the strategy for improving the knee stability during gait in individuals with knee KOA [7,8, and 26]. This study results established it, because TRX exercises indicating better effect than water-based exercise protocol on the knee stabilizer muscle system strength. since joint stiffness in the TRX group has significantly improved in comparison with the water-based exercise group. Also, it seems that TRX exercises could strengthen the hip and core muscles, so the patients can put the foot within the base of support area and provide confidence to the patients. Shakoor et al., investigated that quadriceps muscle strength as an important the incidence and worsening predictor of the knee instability [35]. Reduction in the dynamic KI could decrease pain and knee stiffness, and also improve balance in KOA patient. This research had some limitations, First, the analyses were based on the self-reports of instability symptoms instead of instability objective measurements. Second, the sex of subjects (as only women participated in the study), a small sample size and inability to use more groups, failure to control the diet, the subjects’ life style, insufficient time to measure the electromyography (EMG) activity associated to the involved muscles. And subjects’ motivation for doing exercises, whose control could provide better results. In future studies, it may be worthwhile to examine the mixed model of TRX-aquatic exercises, and compare it with the TRX and aquatic exercises. Additionally, it may be worthy to examine the Pilates and TRX intervention effect on other variables like quadriceps strength and muscle EMG.


Based on this study results, we concluded that TRX and water-based interventions had a similar effect on the self-reported KI, pain, function, and also its balance variables, but TRX exercises had more effect on knee stiffness, statistically, in comparison with the water-based exercises. As a result, TRX intervention could be recommended to physical therapist as an appropriate protocol for the KOA patients rehabilitation.

List Of Abbreviations

KOA: Knee osteoarthritis; TRX: Total Resistance eXercises; KI: Knee Instability; SNOSE: Sequentially Numbered Opaque Sealed Envelopes; ADL: activity daily living; ROM: Range of Motion; BBS: Berg Balance Scale; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index; VAS: visual Analog Scale; ES: Effect Size; EMG: Electromyography; BMI: Body Mass Index; ANOVA: Analysis of variance.


Ethics approval and consent to participate

Patients have a right to privacy that should not be infringed without informed consent. And the patients give written informed consent for publication that approved by the research ethics committee of the Medical Sciences University of Kermanshah in Iran (Registration no.: IR.UMMS.REC.1397.718). This study was registered in the Iranian Clinical Trial Center with the number IRCT20181222042070N1,, registered 02 February 2019.

Consent for publication

Not applicable

Availability of data and materials

Not applicable

Competing interests

The authors declare that they have no competing interests.


No funding

Authors’ contributions

FG was responsible for the conception and design of the study. FG was involved in the analysis and/or interpretation of data. ShA, MM and FS were responsible for the first drafts which was revised by all authors.


I would like to express my very great appreciation to dr. Abbasi for his valuable and constructive suggestions during the planning and development of this research work. I would also like to thank the patients who participated in this study and performed all of the exercises interventions exactly.


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Table 1. TRX exercises protocol

First Month


Section 1

1)TRX row, 2) TRX biceps curl, 3) TRX scapular retraction,

4)TRX standing roll out, 5) toe touches, 6) TRX hip press, 7) TRX hamstring curl, 8) walking high kick, 9) TRX Sit Up

Plank exercises 3 set 10 second

Section 2

1)TRX mid row, 2) TRX calf raise, 3) TRX kick back,

4) TRX standing push up plus, 5) clamshell, 6) lying side leg lift/ lateral raise, 7) Hamstring runner TRX, 8) TRX bent raise (single leg), 9) TRX side plank.

Plank exercises 3 set 15 second

Section 3

1) TRX high row, 2) TRX single leg reaching Roman deadlift, 3) TRX split fly, 4) TRX chest press, 5) lying leg raise, 6) TRX Routain, 7) supine plank TRX, 8) TRX bent leg raise, 9) TRX hip abduction.

Plank exercises 3 set 20 second

                            At the week1 and 2, All exercises 3 set 10 repetition.

                            At the week 3 and 4, All exercises 3 set 15 repetition.

Second Month


Section 1

1) TRX T deltoid fly, 2) TRX standing hip drop, 3) TRX triceps press, 4) TRX standing calf raises 5) Flutter kicks 6) Side crunch leg raises 7) TRX supine plan/with pull through 8) TRX hip abduction, 9) TRX assisted sit up

Plank exercises 3 set 20 second

Section 2

1) TRX Y deltoid fly TRX hip press, 2) TRX torso rotation, 3) TRX overhead back extension, 4) TRX prone iron cross, 5) Side oblique crunch, 6) Swimmers, 7) supine TRX on elbow, 8) TRX saw 9) TRX oblique leg raises

Plank exercises 3 set 25 second

Section 3

1) TRX L deltoid fly, 2) TRX power pull 3) TRX bicep revers curl 4) TRX chest fly 5) Russian twist with medicine ball 6) Alternate heel touchers 7) TRX side plank/ top arm assisted pike 8) TRX pendulum, 9) TRX Pike

Plank exercises 3 set 30 second


                            At the week1 and 2, All exercises 3 set 10 repetition.

                            At the week 2 and 4, All exercises 3 set 15 repetition.




Table 2. demographic characteristics of study participants


TRX (n=12)


Aquatic exercises (n=12)


Control (n=12)



Age (year)





Weight (kg)





Height (cm)





BMI (kg/m2)










Kellgren & Lawrence





* No significant differences among groups for pretests. BMI: Body Mass Index.



Table 3. Summary of results for all tests performed


TRX (n=12)

Mean (SD)

Aqua therapy (n=12)

Mean (SD)

Control (n=12)

Mean (SD)



Knee Instability


Week 8












WOMAC Stiffness


Week 8














Week 8







0.8 (1.8)







Week 8












: Posttest – pretest; SD: standard deviation; ES: effect size; VAS: visual analogue scale; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index; cm: centimeter.

Significant difference among groups (P<0.05).