The dose-effect relationship of aquatic exercise in improving physical function in older adults

Global aging has increased the risk of falls and functional dependence among elderly people. Aquatic exercise, with its low-impact and multimuscle group activation characteristics, provides a unique physiological stimulation environment for improving the physical functions of the elderly population. However, previous studies have insufficiently integrated multidimensional functional indicators and dose-effect relationships. In this study, a meta-analysis was conducted to systematically evaluate the effects of aquatic exercise on the multidimensional physical functions of elderly people and to determine the differential effects of different intervention programs.

Databases in both Chinese and English were searched up to April 2025, and 23 RCTs (1179 healthy elderly individuals aged ≥ 60 years) were included. The Cochrane tool was used to assess the risk of bias, and data on intervention programs (type, duration, frequency) and functional indicators were extracted. RevMan 5.4 was used to combine effect sizes (MD and 95% CI), and subgroup analysis was conducted to explore the sources of heterogeneity (I² > 75%).

(1) Balance ability: Static balance improved (single-leg standing time: MD = 3.05 s, P = 0.007); dynamic balance improved (TUG time reduced by 0.59 s, P = 0.028), with resistance training having the greatest effect (MD = -1.80 s, P = 0.006); and a higher frequency intervention (> 2 times/week) was more effective. (2) Muscle strength: Lower limb strength increased (30-s chair stand test increased by 2.77 times, P < 0.001), with combined resistance and aerobic training having the greatest effect (MD = 3.98 times, P < 0.001); upper limb strength increased (arm curl test increased by 3.17 times, P < 0.001). (3) Cardiopulmonary function: The 2MST increased 7.56 times (P < 0.001). (4) Flexibility: Lower limb flexibility improved by 3.21 cm (P = 0.024), whereas upper limb flexibility did not significantly improve. (5) Subgroup analysis revealed that long-term (> 12 weeks) and high-frequency (> 2 times/week) interventions were more effective for improving dynamic balance (MD = -0.87 vs. -0.34 s) and increasing lower limb strength (MD = 5.65 vs. 1.45 times); combined resistance and aerobic training had significant overall benefits.

Aquatic exercise can comprehensively improve the physical function of elderly people. High-frequency (> 2 times/week) and long-term (> 12 weeks) combined resistance and aerobic training programs are recommended. Clinically, task-oriented interventions should be designed on the basis of individual deficits, and future research should standardize exercise parameters and explore its psychological and social benefits.