Remember, Lemieux suffered serious back problems before his retirement 3 years ago. The back problems were a factor in his hanging up his skates. Many knowledgeable hockey people were excited when they heard that Lemieux was ending his retirement in hopes of leading the Pittsburgh Penguins to another Stanley Cup. But they were also aware that Lemieux had performed heroically on many occasions simply by taking the ice. His back problems were that severe.
Hockey is very rough on the back.
NHL teams, their doctors, trainers and conditioning coaches are well aware of this and have adopted many fitness techniques to alleviate the back and groin strains caused by playing hockey. But a perusal of the League's injury lists show that these preventive measures are only partly successful. There is only so much they can do to avoid, alleviate or reverse the back problems caused by playing hockey. Forwards, particularly centers like Lemieux, are also vulnerable to the shoving and two-hand stickwork that defensemen subject them to in front of the net. It's a fact of hockey that if you are going to score, you are going to pay the price.