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SCOPING REVIEW

Ai Chi for Balance, Pain, Functional Mobility, and Quality of Life in Adults

A Scoping Review

Dunlap, Emily PT; Lambeck, Johan PT; Ku, Pei-Hsin PT; Gobert, Denise PT, PhD

Author Information
The Journal of Aquatic Physical Therapy: January/April 2021 - Volume 29 - Issue 1 - p 14-28
doi: 10.1097/JAPT-D-20-00014
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Abstract

Ai Chi is a form of mindful aquatic exercise used for wellness and physical rehabilitation. Ai Chi combines breathing techniques with slow progressive active range of motion and balance movements based on elements of Qigong and Tai Chi. Qigong and Tai Chi are land-based martial arts with documented health benefits.1–6 Although recent evidence suggests that mindful movements such as Qigong or Tai Chi are effective in reducing pain and improving balance, functional mobility, and quality of life (QOL), limited studies have explored the therapeutic benefits of Ai Chi.

As a form of water-based exercise, it is reasonable to believe that Ai Chi may provide similar benefits as aquatic exercise therapeutic benefits. Well-documented evidence has demonstrated moderate positive effects of aquatic exercise on balance and functional mobility in older adults when compared with nonintervention control groups.7 Positive effects on pain and physical function are also observed with water-based exercise in adults with musculoskeletal conditions.8

Although Qigong, Tai Chi, and aquatic-based exercise have demonstrated known benefits separately, there is little evidence that explores the combination of these 3 exercises in the form of Ai Chi. The purpose of this project was to provide a scoping review and summarize the current evidence about the effects of Ai Chi for balance, pain, functional mobility, and QOL in adults.

METHODS

Data Sources and Searches

The methodological framework of the search was based on recommendations for a scoping review.9 An extensive literature search was performed using 5 databases (PubMed, CINAHL, Health Source Nursing, PsycINFO, and SPORTDiscus). After trialing various key words for each database, a final list of selected key words or a combination of key words was used to yield the most comprehensive output. In general, key words consisted of “Ai Chi” along with more general terms for aquatic exercise (eg, hydrotherapy) and terms for “pain,” “balance,” “falls,” “gait,” “function,” and “quality of life.” Reference lists in the included articles and relevant review studies were checked manually to identify any further articles not found in the systematic database search. The authors of this article, experts in aquatic fitness and physical therapy, checked their own libraries for additional literature that were not in the public databases. The review included publications appearing between 1993, the year Ai Chi was developed, and May 28, 2020. Comprehensive search strategy details can be found in the Texas Data Repository (https://doi.org/10.18738/T8/I5WX7U).

Study Selection

A literature search was conducted with inclusion criteria based on the following concept of clinical question development: Population, Intervention, Comparison, Outcome, and Study design (PICOS) system.10 The population criteria included adults 18 years or older, male or female, with any or no diagnosis. The intervention criteria included Ai Chi as at least 50% of the treatment compared with other activities. Studies were included with or without a comparison group, such as land-based exercise. At least one standardized outcome measure was required for balance, pain, functional mobility, or QOL. Both randomized and nonrandomized controlled study designs including single-system cohort designs were accepted. Exclusion criteria included single-subject case study design or nonintervention research. Selected publication years were from January 1993, the year Ai Chi was developed, to May 28, 2020. Selected languages included English, Spanish, and Portuguese.

After duplicates were removed, titles and abstracts were used to screen and remove obvious nonrelevant studies. Once relevant articles were identified, a full-article review was used in the final stage of study selection using titles and abstracts that fit the inclusion criteria. Two independent reviewers, both experts in aquatic physical therapy, selected articles based on a predetermined data selection form with inclusion and exclusion criteria. Discrepancies were resolved by a third independent member of the search team.

Data Extraction and Quality Assessment

Hard copies of all included articles were obtained and read in full by 2 independent reviewers who were fluent in the selected article language. To control for bias, the authors did not review their own studies. Consultants were used as needed for review of non-English articles.

Reviewers independently extracted key findings using a predetermined data extraction spreadsheet to facilitate study comparisons. The data extraction sheet included language of study, study design, subject demographics, methods, experimental and control interventions, pool characteristics, and outcome results. Any unresolved discrepancies between reviewers were settled by a third reviewer.

Reviewers independently assessed the risk of bias for included studies based on the standardized Physiotherapy Evidence Database (PEDro) scale. The PEDro scale consists of 11 items and can detect potential bias with fair to good reliability for randomized controlled trials (RCTs).11 PEDro rating was also used for nonrandomized controlled trials (NRCTs) for consistency. Standardized PEDro ratings were used, with scores of 9 to 10 considered as “excellent” quality while scores of 6 to 8 were considered as “good” quality in terms of bias management and study design. Any scores between 4 and 5 were consider as “fair,” and any scores below 4 were considered “poor” quality.11

Any disagreements between review authors over PEDro criteria were resolved by discussion and involvement of a third review author as needed. In addition, results were compared with scoring guidelines on the PEDro website including consultations with the PEDro staff about any discrepancies for final clarification.

Data Synthesis and Analysis

First, a descriptive overview of study characteristics was organized by study population diagnosis. Then, all study outcomes were reported for the 4 primary outcome measures including balance, pain, functional mobility, and QOL. The outcome measure results were organized into 2 categories: showing either “no significant improvement after Ai Chi” (P > .05) or “significant improvement after Ai Chi” (P < .05). No other category was needed because no studies reported any negative or poorer result in the Ai Chi group for any category outcome. Information about P values was reported when provided in the study results. When sufficient data were available, the effect size of the Ai Chi intervention group also was calculated and reported using Cohen's d to provide a statistical indicator about within-group differences.12 Cohen's d effect sizes were categorized as follows: lower than 0.2 was considered very small; 0.2 to 0.49 was considered small; 0.5 to 0.79 was considered moderate; and 0.8 or higher was considered large.12

The last grouping included studies that compared Ai Chi with a comparison group and was further separated by 5 types of comparison groups: land, acupuncture, alternate aquatic intervention, spa thermal treatment, and usual care. The outcome measures for each study were placed into one of the 4 primary outcome categories: balance, pain, functional mobility, and QOL. The results were further organized into subcategories: Ai Chi better than the comparison group, Ai Chi and the comparison group similar, and the comparison group is better than Ai Chi. The reported outcome results are categorized on the basis of several criteria including the findings of significant difference and the magnitude of effect size. When sufficient data were available, the P value was reported and effect size dppc2 was calculated according to the method proposed by Morris13 using pre- and posttest measures of the Ai Chi and comparison groups. Effect sizes (dppc2) were categorized: lower than 0.2 was considered very small; 0.2 to 0.49 was considered small; 0.5 to 0.79 was considered moderate; and 0.8 or higher was considered large.

To optimize consistency or homogeneity within the qualitative analysis, we compared assessment outcome data taken immediately after the Ai Chi and comparison group intervention for all studies versus any long-term follow-up assessments.

RESULTS

Study Selection

The Figure shows a flow diagram of the literature search. Out of an initial search sample of 5949 records, only 54 full-text studies were assessed for eligibility for the purpose of this study. Twenty-two studies14–35 met the inclusion criteria and were selected for the qualitative synthesis analysis.

Fig
Fig:
Flow diagram of study screening process and search results.

Study Characteristics

Table 1 presents a summary of study characteristics. Twenty-two studies in the review included 11 RCTs,14–24 5 NRCTs,25–29 and 6 cohort trials.30–35 Seven studies investigated participants with Parkinson disease: 4 of those compared Ai Chi with land-based exercise,14–17 one compared Ai Chi with usual care,25 and 2 were cohort studies with no comparison group.30,31 Three studies investigated participants with fibromyalgia: one compared Ai Chi with aquatic stretches,18 another compared Ai Chi with usual care,19 and one was a cohort study with no comparison group.32 Three studies investigated adults with balance deficits or fall risk: one compared Ai Chi plus spa thermal treatment with a spa thermal treatment alone,20 another compared Ai Chi with an alternative form of aquatic exercise,26 and one was a cohort study with no comparison group.33 Two studies investigated participants with multiple sclerosis: both compared Ai Chi with land-based exercises.21,27 Two studies investigated participants with chronic low back pain: one compared Ai Chi with acupuncture and a control group of usual care,22 and the other with an alternative aquatic exercise program.28 Two studies included healthy adults: one investigated healthy young adults and compared Ai Chi with land-based exercise,29 and the other study had a healthy elderly population as a cohort with no comparison group.35 The 3 remaining studies with different populations comprised the following: patients with chronic stroke, which compared Ai Chi with alternative aquatic exercise23; older adults with intellectual disability, which compared Ai Chi with Qigong/Tai Chi exercise24; and patients with knee osteoarthritis (OA), which used a cohort study design with no comparison group.34 Each study sample size (Table 1) varied from 9 to 81, with 710 participants in the total review. The age of participants ranged from 20 to 75 years. Ai Chi intervention treatment dosage varied from 20 to 60 minutes, 1 to 12 times per week, for 1 to 20 weeks.

TABLE 1
TABLE 1:
Overview of All Studies in Qualitative Analysis

Ai Chi Within-Group Outcomes by Study Population

Table 2 organizes studies by the subject population and provides a summary of all outcome results following the Ai Chi intervention for balance, pain, functional mobility, and QOL.

TABLE 2
TABLE 2:
Ai Chi Within-Group Outcomea

Adults With Parkinson Disease

Four of the 7 studies on people with Parkinson disease (Table 2) investigated effects of Ai Chi on balance using a variety of balance outcome measures including the Berg Balance Scale (BBS),14,15 Biodex-Overall Balance Index (OBI),14 single-leg stance (SLS),16 and the Tinetti Gait and Balance Assessment Tool.15 All reported significant improvement with small effect sizes in these balance measures following the Ai Chi intervention. Another 4 of the 7 studies in this group investigated effects of Ai Chi on pain using the visual analog scale (VAS) and reported significant improvement with large effect sizes following the Ai Chi program.15–17,30 An additional 4 studies in the grouping looked at the effects on functional mobility using the Timed Up and Go (TUG) test, and all found significant improvement, with most having moderate or large effect size.14–16,30 Two studies used the Five Time Sit to Stand Test (FTSST) as a different measure of functional mobility, and both found significant improvement with a small effect size following the Ai Chi intervention.15,16 Five of the 7 studies investigated effects of Ai Chi on QOL using various outcome measures including the Parkinson's Disease Questionnaire-39 (PDQ-39),12,14 Unified Parkinson's Disease Rating Scale (UPDRS),12,13 Geriatric Depression Scale (GDS),17 or 36-item Short-Form Health Survey (SF-36).31 Two studies showed significant improvement with moderate or large effect size for UPDRS scores,14,25 and one study showed significant improvement with SF-36.31 The rest of the results for functional mobility outcomes were mixed, with some studies showing significant improvement (PDQ-3914; GDS17) while 2 other studies did not show significant improvement (PDQ-3916,25; GDS31).

Adults With Fibromyalgia

None of the 3 studies on people with fibromyalgia (Table 2) investigated effects of Ai Chi on balance or functional mobility. However, all 3 of these studies looked at the effects of Ai Chi on pain using the VAS. One study reported no significant difference in pain,19 whereas 2 studies reported significant reduction in pain with moderate and large effect sizes following the Ai Chi intervention.18,32 In addition, all 3 studies investigated effects of Ai Chi on QOL and used a mixture of outcome measures including the Fibromyalgia Impact Questionnaire (FIQ), Pittsburgh Sleep Quality Index (PSQI), 12-item Short-Form Health Survey (SF-12), State-Trait Anxiety Inventory (STAI), Beck's Depression Inventory (BDI), and SF-36. Mixed results were found with these QOL measures. Some studies showed no significant improvement (BDI18; SF-1218; STAI18; FIQ,19), and some found a significant difference with moderate effect sizes in QOL post–Ai Chi intervention (FIQ18: PSQI18; SF-3632).

Adults With Balance Deficits

One of the 3 studies in this group (Table 2) investigated balance outcomes for older adults with the BBS and the Activity-specific Balance Confidence (ABC) scale. This study found significant improvement with a small effect size for the BBS score after the Ai Chi intervention; however, it did not find significant improvement in the ABC scale score.26 This same study investigated pain outcomes with the Numeric Pain Rating Scale (NPRS) and did not find a significant difference following the Ai Chi intervention.26 All 3 studies in this group studied Ai Chi effects on functional mobility using a variety of outcome measures including the TUG test, Ten-Meter Walk Test (10MWT), Functional Reach (FR) measure, Four Square Step Test (FSST), and Unilateral Step Test. All of these functional mobility measures significantly improved with small and moderate effect sizes following the Ai Chi intervention.20,26,33 None of the studies investigated effects of Ai Chi on QOL measures.

Adults With Multiple Sclerosis

This group includes 2 studies involving adults with multiple sclerosis (Table 2). One study investigated effects of Ai Chi on balance using the SLS test and found significant improvements.27 Another study looked at the effects on pain using the VAS and the McGill Pain Questionnaire-Present Pain Intensity (MPQ-PPI), with reported significant improvement in these pain measures following the Ai Chi exercise intervention with noticeably large effect sizes.21 Both studies also investigated effects on functional mobility using a variety of measures including the Roland Morris Disability Questionnaire (RMDQ), Multiple Sclerosis Impact Scale-29-Physical (MSIS-29-Ph), Modified Fatigue Impact Scale-Physical (MFIS-Ph), Barthel Index (BI), TUG test, and the Six-Minute Walk Text (6MWT). All but one functional mobility outcome measures found significant improvements in functional mobility following Ai Chi and many with moderate or large effect sizes.21,27 The one exception being the 6MWT,27 which did not show significant improvement following Ai Chi. Only one study in this group investigated effects on QOL using a variety of outcome measures including the McGill Pain Questionnaire-Present Rating Index (MPQ-PRI), Fatigue Severity Scale (FSS), BDI, Multiple Sclerosis Impact Scale-29-Psychological (MSIS-29-Ps), Modified Fatigue Impact Scale-Cognitive and Psychosocial (MFIS-Co, MFIS-Ps), and BDI.21 Significant improvements following the Ai Chi intervention were noted in all of these QOL measures and most with large effect sizes.21

Adults with Chronic Low Back Pain

One of the 2 studies about people with chronic low back pain (Table 2) reported on balance with the SLS test and found improvement with a small effect size after Ai Chi intervention.28 Both studies investigated pain using the VAS; one reported no improvement28 with the VAS, while the other reported a significant improvement in VAS with a large effect size following Ai Chi.22 One study measured functional mobility using the RMDQ and reported improvement with a small effect size after the Ai Chi intervention.28 Finally, one study measured QOL using the Oswestry Disability Index (ODI) and found improvement with a moderate effect size following Ai Chi intervention.22

Healthy Adults

The 2 studies included in this group (Table 2) consist of an article investigating healthy young adults29 and another looking at the effects of Ai Chi on healthy elderly persons.35 Both studies assessed the effect of Ai Chi on balance outcomes; one study used the Stork Balance Test29 and the other the BBS.35 Both studies found significant improvement in balance following Ai Chi intervention. These studies also looked at functional mobility outcomes using the Functional Independence Measure (FIM)35 and the TUG test.29 No significant improvement was found with the FIM test35; however, significant improvement with a large effect size was reported in functional mobility with the TUG test.29 Only one study in this group evaluated the effects of Ai Chi on QOL using the SF-36 outcome measure and did not find a significant difference following Ai Chi intervention.35

Other Population Categories

The last 3 studies listed in Table 2 have different subject populations including those with chronic stroke,23 older adults with intellectual disability,24 and those with knee OA.34

The study involving people living with chronic stroke investigated multiple outcome measures for balance showing improvement with large effect size for the BBS and the Limit of Stability (LOS) tests in the anteroposterior axis while no improvement for the LOS tests in the lateral direction.23 The same study also looked at gait parameters, with mixed results finding improvements with gait speed and stride length; however, there was no change with gait cadence, stride time (ST), stride length or time variability (STV, SLV), or spatial (SAR) and temporal asymmetry ratio (TAR). This study also looked at functional mobility via the Fugl-Meyer Assessment (FMA) and found significant improvement with a large effect size following Ai Chi.23

The study on the effects of Ai Chi in older adults with intellectual disability looked at balance and functional mobility outcomes with the Tinetti test.24 A significant difference with a small effect size was found with the overall Tinetti test as well as the gait portion of the Tinetti test; however, the study did not find significance with the balance portion of the Tinetti test.24

The last study in Table 2 investigated the effects of Ai Chi on people with knee OA and used a variety of outcome measures including the NPRS for pain; Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the 6MWT to assess functional mobility; and SF-12 as a measure of QOL.34 The study did not find a significant improvement in QOL or the functional mobility measure of gait speed.34 However, it did find significant reduction in pain and improvement in functional mobility using WOMAC-Physical measurement tool.34

Ai Chi Versus Comparison Group by Outcome Types

Tables 3 and 4 summarize 16 studies that compared Ai Chi exercise with a comparison group. These studies are grouped by 5 comparison intervention types: land-based exercise,14–17,21,24,27,29 acupuncture,22 alternative aquatic intervention,18,23,26,28 spa thermal treatment,20 and usual care.19,22,25 Outcomes are categorized into 4 groups: balance, pain, functional mobility, and QOL.

TABLE 3
TABLE 3:
Ai Chi Between-Group Comparison (Land and Acupuncture)a
TABLE 4
TABLE 4:
Ai Chi Between-Group Comparison (Alternate Aquatic, Spa, Usual Care)a

Results for Balance

Six studies investigated effects of Ai Chi versus land-based exercise on balance (Table 3) using a variety of outcome measures including the BBS, Biodex, Tinetti, SLS, and Standing Stork Test. All 6 studies found Ai Chi exercise to provide greater improvement than land-based exercise for these balance measures, with effect sizes ranging from very small to large.14–16,24,27,29

Three studies compared Ai Chi with an alternative aquatic exercise (Table 4) using a variety of outcome measures including the ABC scale, BBS, SLS, and LOS tests.23,26,28 The majority of the results indicated a similar balance outcome with the Ai Chi and alternative aquatic exercise groups (Table 4). However, a few notable exceptions comes from one of these 3 studies, which reported superior improvement with a moderate effect size for balance with the Ai Chi group using the BBS and superior improvement with a large effect size in the Ai Chi group for the end point excursion/anteriorposterior LOS test.23

Results for Pain

Four studies investigated effects of Ai Chi versus land-based exercise on subjective pain (Table 3). All studies used the VAS, while one study also used the MPQ-PPI to measure pain outcome.13,14,24 Results from the vast majority of the pain outcomes indicated the group that received Ai Chi exercise demonstrated greater reduction in pain than the land-based exercise group and all with moderate or large effect sizes.

One study compared Ai Chi exercise with acupuncture (Table 3) and found greater improvements in VAS scores in the acupuncture group with a large effect size.22

Three studies compared Ai Chi exercise with a different form of aquatic exercise (Table 4), and all found no significant difference in pain between the Ai Chi and alternate aquatic exercise groups.18,26,28

Two studies compared Ai Chi with a control group of usual care (Table 4). One study found no significant reduction in pain,19 while the other found significant reduction in pain with a large effect size.22

Results for Functional Mobility

Seven studies investigated effects of Ai Chi versus land-based exercise on functional mobility (Table 3) using a variety of outcome measures, most commonly the TUG test.14–16,21,24,27,29 A few functional mobility outcomes did not differ significantly from the aquatic and land-based groups. However, the results from the majority of the functional measures indicated that Ai Chi treatment resulted in greater functional improvement than land-based exercise, with effect sizes ranging from small to large.

Three studies compared Ai Chi with an alternative form of aquatic exercise (Table 4) and used a variety of tools to report functional mobility outcomes.23,26,28 The majority found similar improvements in functional mobility in both the Ai Chi and alternative aquatic exercise groups. The one exception reported superior improvements with a large effect size in the FMA functional mobility outcome measure for the Ai Chi group compared with alternative aquatic exercise.23

One study compared Ai Chi + spa thermal therapy with the spa therapy alone (Table 4) and found superior functional mobility performance with the group that had Ai Chi in addition to the spa thermal therapy.20

Results for QOL

Four studies investigated effects of Ai Chi versus land-based exercise (Table 3) on QOL using a variety of outcome measures.14,16,17,21 There was a mixture of results, with some finding the Ai Chi and land-based groups to have similar QOL outcomes. While others reported superior improvements in QOL in the Ai Chi group compared with the land-based group.

One study compared Ai Chi with acupuncture (Table 3) and found that acupuncture showed greater improvements with a moderate effect size in QOL measures than the Ai Chi intervention based on the ODI.26

One study compared Ai Chi with aquatic stretches (Table 4) using a variety of QOL measures. This study found similar results for QOL outcomes for both the Ai Chi and aquatic stretching groups.18

Three studies compared Ai Chi with a control group of usual care (Table 4) and used a variety of QOL outcome measures. These studies had mixed results, with some reporting QOL outcome measures similar for both groups. Still others found superior improvement with large effect sizes in QOL outcomes in the Ai Chi group.

Risk of Bias Within Studies

Table 5 provides a summary of methodological quality risk of bias, which was evaluated using PEDro criteria. Six of the 22 studies (27.3%) scored 6 out of 10 or higher, with the PEDro rating scale consistent with moderate to high quality.14–17,21,23 All the included studies lacked blinding of subjects and therapists, which is a common finding for studies involving an aquatic intervention.14–35 Only 3 studies (13.6%) involved concealed allocation.14,21,23 Less than half of the studies (27.3%) met criteria for blind assessor.15,20,23,24,27,28 Exactly half of the studies had random allocation of a control group14–24 and intent-to-treat analysis.14–18,23,25,28,30,33,34 More than half met criteria for adequate follow-up (59.1%),* between-group comparisons (63.6%),14–26 and baseline compatibility between groups (63.6%).14–26 A large majority included point estimate and variability measures (86.4%)14–18,20–30,32–34 and adequate eligibility criteria (90.1%).15–28,30–35

TABLE 5
TABLE 5:
Risk of Bias for All Included Studies Using PEDro Rating Categories

DISCUSSION

Strengths and Limitations

This review scopes the available literature on the effects of Ai Chi on balance, pain, functional mobility, and QOL. Multiple study designs are presented including randomized controlled, nonrandomized controlled, and cohort studies. The inclusion of varied study designs can be considered a strength because all current evidence is included that guides further research. However, allowing lower-level evidence into the review limits the ability to draw conclusions on the consistency of treatment effects of Ai Chi across all studies. Because of the broad inclusion criteria, the resulting final sample lacks homogeneity within these 22 studies. The studies include a wide variety of subjects, comparison groups, Ai Chi dosage, and outcome measures. This limitation is addressed by separating the data into smaller more homogeneous groups, which, in turn, yielded a smaller sample size for each grouping.

Methodological and Reporting Concerns

In addition to the PEDro criteria items in Table 5 that were not met in some studies, several reporting concerns deserve discussion.

Three studies from the same author15–17 included similar populations and outcome data, which indicate the possibility that the same cohort of subjects was used in multiple studies. Since the attempt to contact the author for clarification was unsuccessful, the VAS15–17 and TUG15,16 measures from these studies are possibly recorded in duplicate in Tables 2–4.

Multiple studies17,19,20,22,25,27–29,31 had inconsistent or no reporting of basic participant characteristics of age and/or sex. Several studies did not report pool water temperature or depth, which is an important factor with any type of aquatic exercise. In addition, while Ai Chi was often reported in enough detail to replicate the intervention, comparative exercise groups frequently lacked sufficient detail.

Finally, a few studies had inconsistent or unclear reporting and the numerical data provided in the article did not match the written explanation. Measures were taken to contact authors when unable to confidently interpret results. In one study, the author confirmed the numerical data were inadvertently reversed on a specific outcome measure; therefore, a correction to this specific outcome data was made for this review (TUG29: Tables 2–4). Two other studies had similar inconsistencies with the numerical data and the written text.15,17 Since no confirmation was received from the author, these specific outcome measures were not reported in this review (UPDRS15; SF-3617)

Indication of Underpowered Studies

The statistical power of a study indicates the ability to detect a difference in outcomes if a difference really exists. The minimum power typically recommended for clinical trials is 80%.12,36 The vast majority of articles in this review have no report of the study's power, and signs exist that some studies may be underpowered. For instance, the RCT on people with Parkinson disease25 had a sample size of 15 and did not detect a statistical difference in the PDQ-39 following the Ai Chi intervention. However, the study found improvement in the PDQ-39 score with a moderate effect size (PDQ-39: P > .05, ES [effect size] = 0.65). This could indicate a type II error (false-negative) with an underpowered study due to a low sample size. Another similar example is the RCT investigating people with chronic stroke,23 which did not detect a statistical difference with multiple outcome measures yet found improvement in these outcome measures with moderate effect sizes following the Ai Chi intervention (LOS-DC-AP23: P > .05, ES = 0.66; STV23: P > .05, ES = 0.48; SAR23: P > .05, ES = 0.50). Again, this points to a potential type II error and low power due to a low sample size. Underpowered studies reduce the chance of detecting a true effect, thus increasing the type II error rate.37 In addition, low power in studies can overestimate effect size, making it difficult to be confident in the findings if small studies are the sole source of that evidence.37

Ai Chi for Balance

Half of the studies in this review investigated balance outcomes. The most commonly reported balance outcome was the BBS. The core findings show improved balance following Ai Chi intervention for people with Parkinson disease, multiple sclerosis, chronic stroke, and chronic low back pain, healthy adults, or adults with balance deficits.

Ai Chi for Pain

Just over half of the research in this review assessed the effects of Ai Chi on pain using the VAS. The vast majority reported reduction in pain with a large effect size following Ai Chi intervention for people with Parkinson disease, fibromyalgia, chronic low back pain, and knee OA.

Ai Chi for Functional Mobility

Well over half of the studies in this review evaluated the effects of Ai Chi on functional mobility. The most commonly reported outcome measure was the TUG test. A majority of the functional outcome results showed improvement following Ai Chi for adults with Parkinson disease, balance deficits, multiple sclerosis, chronic low back pain, intellectual deficits, and knee OA.

Common Findings for Balance, Pain, and Functional Mobility

The bulk of findings from the balance, pain, and functional mobility outcomes followed a similar pattern: superior improvement following Ai Chi compared with land-based exercise and similar improvement following AI Chi or an alternative aquatic exercise program. This suggests the aquatic environment contributes to enhanced outcomes. Literature on other forms of aquatic exercise also found improved balance, pain, and/or functional mobility outcomes following the aquatic intervention.38–48 However, studies in this review additionally suggest Ai Chi has superior results compared with land-based exercise. There is less clarity in the literature on the superiority of all forms of aquatic exercise than for land-based exercise. Some studies indicate that various forms of aquatic intervention yield superior results when compared with land-based exercise.42,43 Still others report similar improvements on balance with both land-based and aquatic interventions.38,41,49,50 In any case, it is well documented that various forms of exercise therapy are effective to improve balance, pain, and/or functional outcomes.51–55 Aquatic exercise provides the added benefits of buoyancy and hydrostatic pressure that lead to greater ease of movement, increase time to use balance strategies, and reduce fear of falling while in the aquatic environment. The typical pool temperature ranged between 30°C and 36°C for the studies in this review. Warm water immersion has been shown to have local peripheral antihyperalgesic effects mediated, at least in part, through peripheral opioid, adenosine, and cannabinoid receptors in an animal model of persistent inflammatory pain.56 The warm water's analgesic effects along with unloading of weight-bearing joints from buoyancy could be an important factor for people with chronic pain.

Another potential rationale for the superior outcomes seen with Ai Chi in comparison with land-based exercise in this review includes the effects of mindful movement. The mindful movement of Ai Chi could provide added benefit in addition to the aquatic environment. There is evidence to support that mindful movement such as Qigong and Tai Chi will improve balance, pain, and function mobility in people with chronic conditions.57–64 It is plausible that the mindful movement of Ai Chi along with benefits of the aquatic environment contributes to the superior outcome effects reported in this review. This is a potential area for future research.

Ai Chi for QOL

More than half of the studies in this review assess QOL measures using a wide variety of outcome tools, with the most common QOL measures included the PDQ-39, UPDRS, and SF-36. Results were mixed, with some studies showing improvements in QOL following Ai Chi intervention while others did not. The mixed results continued when comparing Ai Chi intervention with a comparison group. One study found acupuncture to provide superior results for improved QOL compared with Ai Chi. Others found Ai Chi to be similar to land-based exercise or an alternative aquatic exercise intervention in regard to QOL measures. Still some studies showed superior improvement in QOL for those who participated in Ai Chi intervention compared with land-based intervention. There is an obvious need for future research in this area.

CONCLUSION

This review summarizes current evidence on the effects of Ai Chi on balance, pain, functional mobility, and QOL for adults. Significant heterogeneity was found among all study designs in population, comparison intervention, and outcomes. This diversity precludes any conclusive findings of results. However, the qualitative analysis of the current evidence does reveal a number of favorable results, with benefits from Ai Chi intervention on balance, pain, functional mobility, and QOL. The bulk of the findings found Ai Chi intervention to have superior results for balance, pain, and functional mobility compared with land-based intervention and similar results compared with an alternative aquatic intervention. A variety of populations saw improvements, including persons with neurological disorders (Parkinson disease, multiple sclerosis, chronic stroke, and balance deficits) and those with chronic pain disorders (fibromyalgia, knee OA, and low back pain). More research is required to better understand the therapeutic effects of Ai Chi in adults. These results can guide researchers to develop higher-quality research to further investigate the benefits of Ai Chi.

ACKNOWLEDGMENTS

The authors of this review thank Silvana García from Medellín, Colombia, Maria Eugenia Hernández Ruiz of Mexican Association of Aquatic Therapy, Mexico; Rosane Barroso Caetano of Instituto Vita, Sao Paulo, Brazil; and Maria Graça of Health School of University of Aveiro, Aveiro, Portugal, for their assistance with review of non-English study data collection.

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*References 14-17, 19, 21, 23, 25, 28, 30, 32-34.
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Keywords:

Ai Chi; aquatic exercise; mindful movement

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