Loss of muscle strength as a result of normal aging is reported to impair functional ability in various communities. The purpose of this study was to examine the age at which loss of muscle velocity, balance, and agility in adult healthy Iranian females. A sample of 928 healthy Iranian females aged 20-60 years participated in this study. The subjects were divided into four age groups, each representing a decade. Tests we studied included velocity, balance, and agility that performed and timed by a digital stopwatch. The finding indicated that muscle velocity, balance, and agility remained unchanged in the 20 - and 30 – year - old age groups. But in the age of 40, began to gradually decline. By increasing age muscle velocity, balance, and agility began gradually increase One- way ANOVA test showed that muscle velocity, balance, and agility differed (P<0.01) among decades, except between the second and third decades (P<0.28). Age, muscle velocity, balance, agility and power displayed a significant relationship (P<0.001). Loss of muscle velocity, balance, and agility strength seem to begin in the fourth decade of life. The changes in muscle velocity, balance, and agility have a significant relationship with aging.
