Do you want to tie your shoes at 80?? Try this.

The relation between limbering and your age.
As you age, especially reaching the age of 40, your muscles would become less pliable. In other words, you have to limber or stretch them longer. When you are under the age of 40, you can stretch your muscles and hold them for just 30 seconds. At the age of 40 and above though, it is best to hold your stretches at 60 seconds.