ⅠIntroduction

Characterized by reductions in muscle and bone density (Evans, 1999; Wagner et al., 1994), osteoarthritis affects the entire body, causing functional as well as mental and financial problems (Fielding, 1985; Chen, 2007). More than 50% of older adults suffer from osteoarthritis, and related medical costs have escalated along with the rapid growth of the aging population (Murphy et al., 2008). More older women suffer from osteoarthritis than do older men owing to post-menopausal cartilage loss and degeneration (Zhang & ordan, 2010).

Osteoarthritis in the elderly is likely to become a public health problem in South Korea: the percentage of elderly people in this country is increasing (Cho et al., 2015), and South Koreans have a sedentary lifestyle that involves squatting and sitting, which can lead to osteoarthritis (Lee et al., 2011). Treatment of osteoarthritis in South Korea is mainly limited to corticosteroid and hyaluronic acid injections and total knee arthroplasty (Yoon et al., 2005; Lee et al., 2015; Chung et al., 2015); alternative methods are therefore needed. As a potential alternative, water-based exercise has been shown to reduce pain and improve physical function in older adults with osteoarthritis (Hale et al., 2012). A previous study examined the effects of water-based exercise on shoulder, lower back, and knee pain in older osteoarthritic individuluals (Barker et al., 2014). While some findings suggested that water-based activity improved physical function to a greater extent than did land-based exercise (Oh et al., 2015; Simmons & Hansen, 1996) others showed similar effects (Simmons & Hansen, 1996; Lund et al., 2008).

Water-based exercise exploits the characteristics of water to therapeutically benefit body function and serves as a foundation for daily activities. These characteristics include buoyancy, which decreases stress in the joints and spine; viscous resistance, which improves muscle strength and balance (Koury, 1996); and hydrostatic pressure, which reduces swelling in the limbs and improves respiratory muscle and cardiopulmonary function (Becker, 2009). Moreover, the body bears less weight when in water than on land, which decreases the pressure on the joints, and has a greater range of free movement (Hurley, 1994). Therefore, water provides a beneficial, low-risk exercise environment in which the likelihood of musculoskeletal injuries and the fear of falling is reduced (Hauer et al., 2002; Skelton & Dinan, 1999). Water-based exercise could also benefit individuals, such as those with osteoporosis, who are frail, experience pain, or have poor balance or an abnormal gait (Forwood & Larsen, 2000).

Although the number of studies examining water-based exercise has increased, only a few have systematically reviewed its effects on osteoarthritis, and most were conducted in countries other than South Korea (Batterham, Heywood, & Keating; Lu et al., 2015). There is no evidence-based standard guidelines for water-based exercise for osteoarthritis or information about medical insurance coverage for water-based exercise programs in South Korea. Therefore, a trend analysis of water-based exercise for osteoarthritis in South Korea is necessary. Toward this goal, we systematically reviewed and here summarize the literature pertaining to the effects of water-based exercise on pain and physical function in older, community-dwelling women with osteoarthritis in South Korea.

ⅡMethods

1Study criteria

Our recent trend analysis was based on the findings of original articles in academic journals published between January 1995 and December 2016. Studies were included if the participants were older than 60 years of age and had been diagnosed with osteoarthritis at least 3 months previously. Studies involving development programs or non-human research were excluded, as were reviews, dissertations, and surveys.

2Search strategy

Four physical therapists reviewed the literature using the same search strategy and study criteria. Following the initial survey, overlapping and confirmatory articles were excluded at group meetings. The databases searched were PubMed, SCOPUS, the Physiotherapy Evidence Database (PEDro), the Korea Science Korean Studies Service System, the National Assembly Library of Korea, and the Research Information Sharing Service. The following keyword combination was used to search all databases: water exercise AND women AND older AND osteoarthritis AND pain AND physical function AND South Korea. Titles, abstracts, and keywords in the articles were searched, and seven articles were ultimately included in our review (Table 1). All seven were evaluated by using the PEDro scale (Moseley et al., 2002), which consists of 11 eligibility criteria: random allocation, concealed allocation, baseline similarity, subject blinding, therapist binding, assessor blinding, a <15% dropout rate, intention-totreat analysis, between-group statistical comparisons, inclusion of point estimates, and inclusion of variability measurements. PEDro scores were categorized as follows: 9–10, excellent; 6–8, good; 4–5, fair; and <4, poor (Moseley et al., 2002; Fernández-Argüelles et al., 2015)

ⅢResults

1Study characteristics

Our literature search identified 803 potentially eligible studies, seven of which were ultimately included in our analysis. The procedure used to identify eligible studies is outlined in the PRISMA flow diagram in Figure 1.

Overall, the analysis included 256 older, community-dwelling women with osteoarthritis in South Korea. Of these, 168 were 60–65 years of age, and 91 were older than 65 years of age. There was one within-group study (Kim & Kim, 2015) and six between-group studies (Choi, Choi, & Kim, 2010; Choi, Kim, & Kim, 2009; Im et al., 2014; Lee, 2006; Lee & Han, 2010; Lee, Lee, & Song, 2005). All experimental groups performed water-based exercises, whereas the control groups engaged in tai chi, self-management education, self-help exercises, stretching exercises, or conservative treatments. Activities were performed 2 days per week in five studies and 3 days per week in two studies. The activities lasted 6, 8, and 12 weeks in two studies, respectively. Exercises were performed for 50 min in two studies and 60 min in five studies. Water-based exercises included warm-up, main, and cool-down exercises; the main exercises included flexibility exercises (gentle range of motion: back and knee flexion and extension; shoulder and hip flexion, extension, abduction, adduction, external rotation, and internal rotation; walking forwards and backwards), strength exercises (jumping and kicking: front, back, left, right), and endurance exercise (balancing: standing on one leg with one eye closed or both eyes open). Pain, range of motion, agility, fatigue, stiffness, balance, strength, endurance, flexibility, and quality of life were assessed.

2Pain

Similar and significant decreases in pain were observed in the groups performing water-based exercises in three studies. Choi et al. observed a significant reduction in pain after as compared with before intervention in the water-based exercise group (3.66 ± cm and 5.66 ± 2.42 cm, respectively), but not in the control group (5.93 ± 1.94 cm and 5.50 ± 2.42 cm, respectively). In contrast, one study (Choi et al, 2010) reported significant reductions in pain in both the water-based exercise (pre-intervention: 4.62 ± 2.6 cm, post-intervention: 2.92 ± 1.71 cm) and control (pre-intervention: 5.56 ± 2.25 cm, post-intervention: 3.75 ± 1.5 cm) groups, with no significant difference between the groups (p > 0.05).

3Physical function

In one study (Lee & Han, 2010), the range of motion in knee flexion increased significantly in the water-based exercise group (pre-intervention: 35.00 ± 3.33°, post-intervention: 41.50 ± 6.26°), but not in the control group (pre-intervention: 40.00 ± 5.27°, post-intervention: 40.56 ± 6.82°). On the other hand, agility did not differ significantly between the water-based exercise and control groups (p > 0.05) in the study (Im et al, 2014).

In the study by Kim and Kim,27 fatigue decreased significantly in the water-based exercise group (preintervention: 7.17 ± 3.30 points, post-intervention: 5.55 ± 3.06 points), and in the study (Lee, 2006) knee joint stiffness decreased significantly in the waterbased exercise group (pre-intervention: 3.47 ± 1.96 points, post-intervention: 3.27 ± 1.58 points), but not in the control group (pre-intervention: 3.44 ± 2.37 points, post-intervention: 4.62 ± 2.03 points). Balance improved significantly in the water-based exercise group in two studies (Im et al., 2014; Lee, 2006) (both p values < 0.05). Strength was separately assessed in the upper and lower extremities. Upper extremity strength improved significantly in two studies (Choi, Choi, & Kim, 2010; Choi, Kim, & Kim, 2009) (both p values < 0.05), but not in a third (Lee, Lee, & Song, 2005) (p > 0.05). Lower extremity strength improved significantly in four studies (Choi, Kim, & Kim, 2009; Im et al, 2014; Lee, 2006; Lee & Han, 2010) (both p values < 0.05), and a fifth study showed significant increases in lower extremity strength in terms of knee flexion (p < 0.05) but not knee extension (p > 0.05) (Lee, Lee, & Song, 2005). One study (Im et al, 2014) reported that endurance improved significantly in both the water-based exercise (pre-intervention: 25.9 ± 23.4 s post-intervention: 66.0 ± 54.2 s) and control (pre-intervention: 29.9 ± 20.9 s, post-intervention: 37.1 ± 29.0 s) groups.

Improvements in flexibility were reported in three studies but were significant in only one29 (upper flexibility in the water-based exercise group: -12.85 ± 8.80 cm and -9.08 ± 10.15 cm; upper flexibility in the control group: -18.31 ± 13.87 cm and -18.43 ± 14.09 cm; lower flexibility in the water-based exercise group: 12.52 ± 5.22 cm and 16.38 ± 4.94 cm; lower flexibility in the control group: 13.68 ± 8.12 cm and 12.81 ± 7.61 cm, pre- and post-intervention, respectively). Quality of life improved in the water-based exercise group in two studies, albeit insignificantly (both p > 0.05) (Choi, Choi, & Kim, 2010; Choi, Kim, & Kim, 2009).

Based on the PEDro scale, four studies were graded “good” (six points in three studies: Choi, Choi, & Kim, 2010; Choi, Kim, & Kim, 2009; Lee & Han, 2010) and seven points in one study (Lee, 2006), and three studies were graded “fair” (five points in all three studies: Kim, & Kim, 2015; Im et al, 2014; Lee, Lee, & Song, 2005); Table 2).

ⅣDiscussion

This review sought to clarify the effects of water-based exercise on pain and physical function in older, community-dwelling South Korean women with osteoarthritis. In brief, the results presented indicate that water-based exercise helps alleviate osteoarthritis in this population.

Most studies reported that water-based exercise reduced pain; however, one study showed that it did so less effectively than did tai chi (Lee, 2006). This result should not be interpreted as a non-recommendation for water-based exercise, because therapists have to choose between recommending water- or land-based exercises according to the patient’s situation.

The range of motion in knee flexion improved significantly after water-based exercise, perhaps owing to the assistance and resistance provided by water buoyancy (Lee, & Han, 2010). Water-based exercise also reduced fatigue (Kim, & Kim, 2015). During water-based exercise, energy consumption by the skin increases, wrinkling the skin with little loss of heat (Wilder-Smith, & Chow, 2003). However, if performed appropriately and combined with rest and land-based exercise, water-based exercise could reduce fatigue. Water-based exercise also alleviated stiffness, perhaps by significantly inhibiting muscle spasms, and improved balance. Improvements in balance may reflect the effort required to maintain specific positions in turbulent water.

Water-based exercise significantly increased strength in both the upper and lower extremities (Choi, Kim, & Kim, 2009; Im et al., 2014) although one study reported significant improvements in knee flexion but not knee extension (Lee, Lee, & Song, 2005). It also significantly increased endurance, as evaluated via isometric testing, in the one study that examined endurance. The study results indicated that water-based exercise was suitable for patients who needed to boost their endurance and muscle strength.

Improvements in flexibility were reported in three studies but were significant in only one (Choi, Kim, & Kim, 2009). However, all three studies showed that water-based exercise better improved flexibility than did land-based exercise. The duration of water-based exercise interventions should be increased, and water-based exercise programs focusing on flexibility should be developed.

Quality of life improved somewhat in individuals performing water-based exercises, although not significantly so. In addition to their health benefits, water-based exercises are fun and exciting, and programs that include competition and socializing may aid in improving quality of life (Takata et al., 2010). From this perspective, water-based exercise programs should be developed according to the recommendations of the World Health Organization and the International Classification of Functioning, Disability, and Health system (Pollard, Johnston, & Dieppe, 2011).

Water-based exercise provides numerous benefits including safety and comfort, and reduces the weight load on the lower extremities. Therefore, it appears to be a more effective means of improving the health of older adults with osteoarthritis than is land-based exercise.

1Limitations

Some of the articles referenced in our study were written in Korean and are only listed in the Korea Science Korean Studies Service System, National Assembly Library of Korea, and Research Information Sharing Service databases.

ⅤConclusions

This review documents the positive effects of water-based exercise on osteoarthritis-related pain and physical function in older women in South Korea. We recommend water-based exercise programs for improving the flexibility, strength, and endurance in older women with osteoarthritis, and their clinical usefulness is emphasized.