Objectives: The loss of physiological and functional capacity is a risk factor for falls, disability, and injury or death in the elderly. Water base-exercise (WEX) is one of the proposed methods for improving the performance of the elderly. The aim of this research was to study the effect of water base-exercise frequency on the balance and functional indices of untrained elderly man.
Methods & Materials:  This was a semi-experimental study consisting of 36 elderly men within the age group of 64.36±2.15 years, height 165.05±4.32 cm, weight 62.89±3.73 kg, and BMI 23.12±1.72, who volunteered to participate in the study. Prior to the initial assessment, each participant gave their written personal consent. Then the subjects were randomly divided into three groups of 12 members each: 2 d·wk^-1, 3 d·wk^-1, and control group. The water training protocol was followed for six weeks. Functional and balance parameters including flexibility, and strength of the lower extremities were evaluated before and after the completion of the training protocol. The differences in pretest and posttest for each group were examined using the paired t-test and one-way ANOVA was used for comparison among the three groups. The value of P≥0.05 was considered significant. SPSS 17 software was used for carrying out all statistical operations. 
Results: The search indicated that the factor of static and dynamic balance and movement ability between the 2 d·wk^-1 and 3 d·wk^-1 WEX groups were not significantly different (P≥0.05). On the other hand, lower extremity strength and flexibility in the 3 d·wk^-1 WEX group was significantly different from the 2 d·wk^-1 (P≥0.05). Although the t-test results revealed significant differences (P≥0.05) between pretest and posttest scores of the experimental group, this difference was non-significant in the control group (P≥0.05). 
Conclusion: It was concluded that the balance and movement ability factors of elderly people are highly affected by the volume of practice to training frequency. However, the increase in training frequency could improve other physical factors such as muscle strength and flexibility in the elderly.