Jaaskelainen, 34, shows no signs of winding down as he still has three years to run on his contract and is in his testimonial season.
Barber told the Bolton News: "I think he can go on well into his 40s. Things have changed now in diets and fitness which mean players can last a lot longer.
"They are not just footballers, they are athletes now. Their food, weight and fitness is so carefully monitored, everything is done for them.
"But if you give them the tools they have to be able to use them, and that is why Jussi is at the top."