The 28-year-old Russian, the younger sister of former men's number one Marat Safin, won 12 singles titles including Madrid and reached three grand slams finals but has not competed since losing in the second round in the Spanish capital in 2011.
"I took as much time as I could," Safina said in an interview on the WTA website (www.wtatennis.com).
"I am not this kind of person that I would say no, and then I would think and maybe come back," she added.
"I was having so much pain in my back, it was tough, everything was hurting me.
"Also when you don't compete your body is different, once you stop your body is in a big shock."
Asked how she had been filling her time the past three years, Safina said: "nothing that's so serious but a little bit of everything", including studying, working with her brother and a spot of commentating at the French Open.
- Sports & Recreation
- Marat Safin