Abstract Background: As individuals age, people often experience walking disorders attributed to muscle weakness and central nervous system decline. Mitigating age-related gait issues necessitates a focus on physical activity. Objective: To assess the impact of a water exercise program on the function of selected lower limb muscles during gait in middle-aged women. Methodology: This semi-experimental study employed a pretest-posttest design. Twenty middle-aged women (40-45 years) were randomly divided into two groups of 10 (water exercise group and control group). Muscle function, measured using an electromyography device during the stance and swing phases of gait, along with maximum voluntary isometric contraction, was assessed at the beginning and end of a 12-week water training period. Descriptive statistics, including mean and standard deviation, were used. Data analysis utilized one-way analysis of variance and Duncan's test at a significance level of 0.05. Results: In the water exercise group, after 12 weeks of training, the mean normalized electromyography (EMG) during the stance and swing phases and maximum voluntary isometric contraction increased in all muscles (Gastrocnemius, Rectus femoris, Biceps femoris, Tibialis anterior, and Erector spinae (L3)). The increase was statistically significant only in the maximum voluntary isometric contraction stage for all muscles {Gastrocnemius (P=0.000), Rectus femoris (P=0.000), Biceps femoris (P=0.020), Tibialis anterior (P=0.001), and Erector spinae (P=0.011)} (P<0.05). The comparison of muscle function before and after 12 weeks of training between the water exercise and control groups revealed no significant difference in the stance and swing phases (P>0.05). However, the water exercise group demonstrated a significant difference in the maximum voluntary isometric contraction phase in Gastrocnemius (P=0.000), Rectus femoris (P=0.000), and Erector spinae (P=0.006) muscles compared to the control group (P<0.05). Conclusion: Weight-bearing exercises in water are recommended for middle-aged women based on the observed differences between the water exercise and control groups
