Journal of Practical Studies of Biosciences in Sport

Journal of Practical Studies of Biosciences in Sport

The effect of aquatic training at different depths on lower limb muscle strength and balance in patients with chronic ischemic stroke

Document Type : Original Article

Authors
Hossein Babaeipour 1
Mansour Sahebozamani 2
Najmeh Parhizmeymandi 3
Alireza Vakilian 4
1 Assistant Professor, Department. of Sport injuries and corrective Exercises, Faculty of Sport SCiences,Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran.
2 Professor, Department. of Sport Injuries and Corrective Exercises, Faculty of Sport Sciences, Shahid Bahonar University of Kerman, Kerman, Iran.
3 Assistant Professor, Department of Sports Sciences, Faculty of Humanities and Social Sciences, Ardakan University, Ardakan, Iran.
4 Associate Professor, Department. of Neurology and Non Communicable Diseases Research Center, Faculty of Medicine, , Rafsanjan University of Medical Sciences, Rafsanjan, Iran.
10.22077/jpsbs.2025.9223.1965
Abstract
Extendrd Abstract
Background and Aim: Stroke is one of the most common causes of physical disability worldwide, resulting in lower limb muscle weakness, impaired balance, reduced mobility, and an increased risk of falling. These impairments, particularly in patients with chronic ischemic stroke, often lead to decreased quality of life and functional independence. Therefore, rehabilitation in such patients requires approaches that are both safe and highly effective. Aquatic exercises have been introduced as a promising method in the rehabilitation of neurological patients due to the unique characteristics of the aquatic environment, including reduced joint loading, enhanced, multidirectional resistance, and improved proprioceptive stimulation.
Despite the growing body of evidence supporting aquatic rehabilitation, limited attention has been paid to the influence of water depth on the effectiveness of aquatic exercise interventions. Previous studies suggest that water depth may affect muscle activation patterns, movement mechanics, energy expenditure, and ultimately the therapeutic outcomes of exercise programs. Accordingly, the aim of the present study was to examine and compare the effects of aquatic training at two different depths (shallow and deep water) on lower limb muscle strength and functional balance in male patients with chronic ischemic stroke.
Materials and Methods: This quasi-experimental study employed a pretest–posttest design with a control group. The study population consisted of men with chronic ischemic stroke in Rafsanjan, Iran. Thirty-six participants (60.70 ± 6.20 years) who met the inclusion criteria were recruited and randomly assigned, using stratified randomization based on age and Berg Balance Scale (BBS) scores, into three groups: shallow-water exercise, deep-water exercise, and control (n=12 per group). The inclusion criteria were as follows: a neurologist-confirmed diagnosis of first-ever ischemic stroke; a post-stroke duration of 6 months to 2 years; lower-extremity muscle strength ranging from 3.5 to 5.5 on the Medical Research Council (MRC) scale; a Mini-Mental State Examination (MMSE) score of ≥23; a BBS score between 21 and 44; the ability to stand independently for at least 5 minutes; and the ability to walk for at least 10 minutes with or without an assistive device. Participants were excluded if they had uncontrolled medical conditions, additional neurological or musculoskeletal disorders, unstable cardiovascular or respiratory diseases, a history of major central nervous system surgery, or missed more than three training sessions.
The intervention consisted of a 6-week aquatic exercise program conducted three times per week, with each session lasting 60 minutes. The exercises program included hip flexion, extension and abduction, multidirectional walking, hip rotation with knee flexion, scissors movements, and single-leg standing. Each session consisted of a 5-minute warm-up, 50 minutes of exercise training, and a 5-minute cool-down period. Training volume progressed gradually from two sets of three repetitions to three sets of ten repetitions throughout the intervention period. Exercises were performed at the level of the anterior superior iliac spine in the shallow-water group and at the level of the xiphoid process in the deep-water group. The control group did not receive any intervention during the study period.
Balance and lower limb muscle strength were assessed using the Berg Balance Scale (BBS) and the Medical Research Council (MRC) scale, respectively, before and after the intervention. Data were analyzed using the Shapiro–Wilk test, Levene’s test, one-way analysis of variance (ANOVA), and mixed-design ANOVA. Bonferroni post hoc tests and partial eta squared (η²) values were used to examine pairwise differences and estimate effect sizes. Statistical analyses were performed using SPSS version 22, with the significance level set at p≤0.05
Findings: One-way ANOVA results showed no significant differences among the three groups at baseline with respect to balance (F(2,27)=0.71, p=0.50) and lower limb muscle strength (F(2,27)=0.17, p=0.84). The mixed ANOVA results indicated a significant time×group interaction effect for balance (F(2,27)=115.63, p=0.0001) and muscle strength (F(2,27)=47.88, p=0.0001). Bonferroni-adjusted pairwise comparisons showed that participants in both the shallow-water and deep-water exercise groups demonstrated significant improvements in balance and lower limb muscle strength from pretest to posttest (p<0.001 for both groups). In contrast, no significant changes were observed in the control group (p=0.99). Furthermore, posttest comparisons revealed that both aquatic exercise groups achieved significantly higher scores in balance and lower limb muscle strength than the control group (p<0.001). However, no significant differences were found between the shallow-water and deep-water exercise groups in either outcome measure (p=0.90) (Figure 1).
Conclusion: The findings of the present study demonstrated that six weeks of aquatic exercise performed in either shallow or deep water significantly improved lower-extremity muscle strength and balance in patients with chronic ischemic stroke.These results suggest that aquatic exercise provides a favorable environment for enhancing motor function in this population. The aquatic environment likely facilitates functional movement by reducing effective body weight and decreasing joint loading, thereby allowing movements to be performed more safely and confidently. In addition, the uniform resistance of water continuously challenges the lower-extremity muscles throughout exercise, contributing to improvements in muscular strength.
The observed improvements in balance may also be explained by the sensory and mechanical properties of the aquatic environment. Hydrostatic pressure and water turbulence increase stimulation of sensory receptors and enhance sensorimotor feedback, which may improve postural control and balance performance. Furthermore, repeated practice of movements in an environment that requires continuous postural adjustments to external perturbations may promote neuromuscular adaptations and improve motor coordination. Increased lower-extremity muscle strength itself is also an important determinant of balance, and part of the observed improvement in balance may have occurred through this mechanism.
A notable finding of the present study was the lack of significant differences between the shallow-water and deep-water exercise groups. This finding suggests that the therapeutic benefits of aquatic exercise in patients with chronic ischemic stroke may depend more on regular participation in aquatic-based training than on the depth of water immersion. Immersion at hip level appears sufficient to reduce mechanical loading and facilitate functional movement, whereas increasing immersion depth to chest level does not seem to provide additional benefits for improving muscle strength or balance. Therefore, both immersion depths may be equally effective for promoting functional adaptations in this population.
Several limitations should be acknowledged when interpreting these findings. First, the sample consisted exclusively of patients with chronic ischemic stroke who met specific inclusion criteria, which may limit the generalizability of the results to other stroke populations. Second, no follow-up assessment was conducted to evaluate the long-term retention of the training effects. Finally, only two levels of water immersion were examined. Future studies are encouraged to investigate a wider range of immersion depths, include long-term follow-up assessments, and evaluate the effectiveness of aquatic exercise in more diverse stroke populations.
Ethical Considerations: This study was approved by the Ethics Committee of Rafsanjan University of Medical Sciences under the code IR.RUMS.REC.1396.207. All participants were informed about the study procedures and provided written informed consent.
Compliance with Ethical Guidelines: The study was conducted in accordance with the ethical principles of the Declaration of Helsinki and the approved institutional guidelines. Participation was entirely voluntary, and the confidentiality of participants’ information was maintained throughout all stages of the research.
Funding: This study did not receive any financial support from internal or external sources.
Conflicts of Interest: The authors declare that there are no scientific or financial conflicts of interest related to the conduct or publication of this research.
Keywords
Aquatic exercise
Motor rehabilitation
Stroke patients
Water depth
1. Zhou Y, Ren H, Hou X, Dong X, Zhang S, Lv Y, et al. The effect of exercise on balance function in stroke patients: a systematic review and meta-analysis of randomized controlled trials. Journal of Neurology. 2024:1-18. https://doi.org/10.1007/s00415-024-12467-1 
2. Takada H, Yamashita K, Osawa L, Komiyama Y, Muraoka M, Suzuki Y, et al. Assessment of lower limb muscle strength can predict fall risk in patients with chronic liver disease. Scientific Reports. 2024;14(1):64. https://doi.org/10.1038/s41598-023-50574-7 
3. Tan H, Gong Z, Xing S, Cao L, Liu H, Xu L. Effects of balance training in addition to auxiliary activity on balance function of patients with stroke at high risk for falls. Frontiers in Neurology. 2023;13:937305. https://doi.org/10.3389/fneur.2022.937305 
4. Azzollini V, Dalise S, Chisari C. How does stroke affect skeletal muscle? State of the art and rehabilitation perspective. Frontiers in Neurology. 2021;12:797559.  https://doi.org/10.3389/fneur.2021.797559 
5. Gobezie M, Kassa T, Suliman J, Eriku GA, Takele MD, Bitew DA, et al. Balance impairment and associated factors among stroke survivors in public hospitals of Amhara regional state: a multicenter cross-sectional study. BMC Neurology. 2024;24(1):387. https://doi.org/10.1186/s12883-024-03885-9 
6. Qi H, Tian D, Luan F, Yang R, Zeng N. Pathophysiological changes of muscle after ischemic stroke: a secondary consequence of stroke injury. Neural Regeneration Research. 2024;19(4):737-46. https://doi.org/10.4103/1673-5374.382221 
7. Rubenstein L, Josephson K. Interventions to reduce the multifactorial risks for falling. Revista Espanola de Geriatria y Gerontologia. 2005;40:45. https://doi.org/10.1016/s0211-139x(05)75085-x 
8. Veldema J, Jansen P. Aquatic therapy in stroke rehabilitation: systematic review and meta‐analysis. Acta Neurologica Scandinavica. 2021;143(3):221-41. https://doi.org/10.1111/ane.13371 
9. Faíl LB, Marinho DA, Marques EA, Costa MJ, Santos CC, Marques MC, et al. Benefits of aquatic exercise in adults with and without chronic disease—A systematic review with meta‐analysis. Scandinavian Journal of Medicine & Science in Sports. 2022;32(3):465-86. https://doi.org/10.1111/sms.14112 
10. Melo RS, Cardeira CSF, Rezende DSA, Guimarães-do-Carmo VJ, Lemos A, de Moura-Filho AG. Effectiveness of the aquatic physical therapy exercises to improve balance, gait, quality of life and reduce fall-related outcomes in healthy community-dwelling older adults: A systematic review and meta-analysis. PLoS One. 2023;18(9):e0291193. https://doi.org/10.1371/journal.pone.0291193 
11. Zhang Y, Wang Y-Z, Huang L-P, Bai B, Zhou S, Yin M-M, et al. Aquatic therapy improves outcomes for subacute stroke patients by enhancing muscular strength of paretic lower limbs without increasing spasticity: a randomized controlled trial. American Journal of Physical Medicine & Rehabilitation. 2016;95(11):840-9. https://doi.org/10.1097/phm.0000000000000512 
12. Gyu-sun M. The Impact of Water Depth and Speed on Lower Muscles Activation During Exercise in Different Aquatic Environments. International Journal of Internet, Broadcasting and Communication. 2024;16(2):169-78. https://doi.org/10.7236/IJIBC.2024.16.2.169
13. Lim H, Azurdia D, Jeng B, Jung T. Influence of water depth on energy expenditure during aquatic walking in people post stroke. Physiotherapy Research International. 2018;23(3):e1717. https://doi.org/10.1002/pri.1717 
14. Hunter GR, McCarthy JP, Bamman MM. Effects of resistance training on older adults. Sports Medicine. 2004;34:329-48.  https://doi.org/10.2165/00007256-200434050-00005 
15. Persch LN, Ugrinowitsch C, Pereira G, Rodacki AL. Strength training improves fall-related gait kinematics in the elderly: a randomized controlled trial. Clinical Biomechanics. 2009;24(10):819-25. https://doi.org/10.1016/j.clinbiomech.2009.07.012 
16. Roberts R, Callow N, Hardy L, Markland D, Bringer J. Movement imagery ability: development and assessment of a revised version of the vividness of movement imagery questionnaire. Journal of Sport and Exercise Psychology. 2008;30(2):200-21.  https://doi.org/10.1123/jsep.30.2.200 
17. Wilson JL, Hareendran A, Grant M, Baird T, Schulz UG, Muir KW, et al. Improving the assessment of outcomes in stroke: use of a structured interview to assign grades on the modified Rankin Scale. Stroke. 2002;33(9):2243-6. https://doi.org/10.1161/01.str.0000027437.22450.bd 
18. Zhu Z, Cui L, Yin M, Yu Y, Zhou X, Wang H, et al. Hydrotherapy vs. conventional land-based exercise for improving walking and balance after stroke: a randomized controlled trial. Clinical Rehabilitation. 2016;30(6):587-93. https://doi.org/10.1177/0269215515593392 
19. Berg K, Wood-Dauphine S, Williams J, Gayton D. Measuring balance in the elderly: preliminary development of an instrument. Physiotherapy Canada. 1989;41(6):304-11. https://doi.org/10.3138/ptc.41.6.304 
20. Hiengkaew V, Jitaree K, Chaiyawat P. Minimal detectable changes of the Berg Balance Scale, Fugl-Meyer Assessment Scale, Timed “Up & Go” Test, gait speeds, and 2-minute walk test in individuals with chronic stroke with different degrees of ankle plantarflexor tone. Archives of Physical Medicine and Rehabilitation. 2012;93(7):1201-8. https://doi.org/10.1016/j.apmr.2012.01.014 
21. Mao H-F, Hsueh I-P, Tang P-F, Sheu C-F, Hsieh C-L. Analysis and comparison of the psychometric properties of three balance measures for stroke patients. Stroke. 2002;33(4):1022-7. https://doi.org/10.1161/01.str.0000012516.63191.c5 
22. Flansbjer U-B, Blom J, Brogårdh C. The reproducibility of Berg Balance Scale and the Single-leg Stance in chronic stroke and the relationship between the two tests. PM&R. 2012;4(3):165-70. https://doi.org/10.1016/j.pmrj.2011.11.004 
23. Dibble LE, Lange M. Predicting falls in individuals with Parkinson disease: a reconsideration of clinical balance measures. Journal of Neurologic Physical Therapy. 2006;30(2):60-7. https://doi.org/10.1097/01.npt.0000282569.70920.dc 
24. Prado AK, Reichert T, Conceição MO, Delevatti RS, Kanitz AC, Kruel LF. Effects of aquatic exercise on muscle strength in young and elderly adults: a systematic review and meta-analysis of randomized trials. The Journal of Strength & Conditioning Research. 2022;36(5):1468-83. https://doi.org/10.1519/jsc.0000000000001595 
25. Zhou W-S, Mao S-J, Zhang S-K, Xu H, Li W-L. Effects of aquatic exercises on physical fitness and quality of life in postmenopausal women: an updated systematic review and meta-analysis. Frontiers in Public Health. 2023;11:1126126. https://doi.org/10.3389/fpubh.2023.1126126 
26. Duffy K. Aquatic therapy for a patient post-stroke: A case report: Florida Gulf Coast University; 2014.
27. Del Vecchio A, Casolo A, Negro F, Scorcelletti M, Bazzucchi I, Enoka R, et al. The increase in muscle force after 4 weeks of strength training is mediated by adaptations in motor unit recruitment and rate coding. The Journal of Physiology. 2019;597(7):1873-87. https://doi.org/10.1113/jp277250 
28. Weiss A, Suzuki T, Bean J, Fielding RA. High intensity strength training improves strength and functional performance after stroke. American Journal of Physical Medicine & Rehabilitation. 2000;79(4):369-76. https://doi.org/10.1097/00002060-200007000-00009 
29. Roth AE, Miller MG, Ricard M, Ritenour D, Chapman BL. Comparisons of static and dynamic balance following training in aquatic and land environments. Journal of Sport Rehabilitation. 2006;15(4):299-311. https://doi.org/10.1123/jsr.15.4.299 
30. Torres-Ronda L, i del Alcázar XS. The properties of water and their applications for training. Journal of Human Kinetics. 2014;44:237. https://doi.org/10.2478/hukin-2014-0129 
31. Mattos Fd, Leite N, Pitta A, Bento PCB. Effects of aquatic exercise on muscle strength and functional performance of individuals with osteoarthritis: a systematic review. Revista Brasileira de Reumatologia. 2016;56(6):530-42. https://doi.org/10.1016/j.rbre.2016.09.003 
32. Nayak P, Mahmood A, Natarajan M, Hombali A, Prashanth C, Solomon JM. Effect of aquatic therapy on balance and gait in stroke survivors: a systematic review and meta-analysis. Complementary Therapies in Clinical Practice. 2020;39:101110. https://doi.org/10.1016/j.ctcp.2020.101110 
33. Marinho-Buzelli AR, Bonnyman AM, Verrier MC. The effects of aquatic therapy on mobility of individuals with neurological diseases: a systematic review. Clinical Rehabilitation. 2015;29(8):741-51.  https://doi.org/10.1177/0269215514556297 
34. Bakker LB, Lamoth CJ, Vetrovsky T, Gruber M, Caljouw SR, Nieboer W, et al. Neural Correlates of Balance Skill Learning in Young and Older Individuals: A Systematic Review and Meta-analysis. Sports Medicine-Open. 2024;10(1):3. https://doi.org/10.1186/s40798-023-00668-3 
35. Taube W. Neurophysiological adaptations in response to balance training. German Journal of Sports Medicine/Deutsche Zeitschrift fur Sportmedizin. 2012;63(9). https://doi.org/10.5960/dzsm.2012.030 
36. Shao C, Wang Y, Gou H, Xiao H, Chen T. Strength training of the nonhemiplegic side promotes motor function recovery in patients with stroke: a randomized controlled trial. Archives of Physical Medicine and Rehabilitation. 2023;104(2):188-94. https://doi.org/10.1016/j.apmr.2022.09.012 
37. Feratywi A, Dewi AC. Correlation between Improved Balance and Decreased Limb Spasticity and Improved Muscle Strength in Post-Stroke Hemiparesis. Journal of Sports and Physical Education Studies. 2024;4(1):01-6. https://doi.org/10.32996/jspes.2024.4.1.1 
38. Lund H, Weile U, Christensen R, Rostock B, Downey A, Bartels EM, et al. A randomized controlled trial of aquatic and land-based exercise in patients with knee osteoarthritis. Journal of Rehabilitation Medicine. 2008;40(2):137-44. https://doi.org/10.2340/16501977-0134 
39. Kutzner I, Richter A, Gordt K, Dymke J, Damm P, Duda GN, et al. Does aquatic exercise reduce hip and knee joint loading? In vivo load measurements with instrumented implants. PloS One. 2017;12(3):e0171972. https://doi.org/10.1371/journal.pone.0171972 
40. Hosseinimehr SH, Anbarian M, Mohammadi Z. Effects of 12 weeks water training in shallow and deep part of pool on balance and lower limb muscles strength in elderly. Studies in Sport Medicine. 2022;14(33):97-114. [In Persian]. https://doi.org/10.1007/s11332-024-01183-y 
41. Zamanian F, Vesalinaseh M, Nourollahnajafabadi M, Asadysaravi S, Haghighi M, Najafabad I. Comparison of the effects of aquatic exercise in shallow and deep water on Postural Control in elderly women with chronic knee Osteoarthritis. Life Science Journal. 2012;9(4):5768-71. [In Persian]. http://dx.doi.org/10.32598/sija.2022.546.2
Journal of Practical Studies of Biosciences in Sport
Volume 14, Issue 39
Summer 2026
Pages 8-23