Jane Fonda will probably always have her own page in history books for building an entire fitness empire from scratch. She was the first major star to promote the retro-fitness frenzy that would soon take over the world and sweep millions of workout aficionados with it, but it eventually came at a rather steep price, as experts point out for the Daily Mail.

Just the other day, the actress and exercise guru, who continues to work out just as lively and be in as best shape as ever even now at 71, went into surgery for knee replacement. As it turned out, she needed emergency intervention on the area after years of intense working out that took their toll on the cartilage and left bone rubbing on bone. A few years before that, she also had hip replacement surgery and had been suffering from back pains.

All these are nothing but the direct consequence of years of heavy pounding on these body parts with an exercise routine that stressed the importance of “feeling the burn,” specialists believe. New York physiotherapist Jane O’Connor, for one, tells the Mail that the problem was with Fonda not varying her workout to protect certain body parts. “Many healthcare professionals warned years ago that you can’t keep pounding your joints the way Jane did. Now here’s the evidence. By all means exercise, but mix in some low-impact work.” O’Connor recommends.

Another aspect that should be duly considered on a more general scale is the fact that an ever increasing number of gym fanatics are taking the same approach to working out, often putting their health at risk, experts point out. Just like with everything else in life, moderation is key here as well, as also is knowing how to swap routines to avoid injuries that can leave us marked for life, they say.

“We’re seeing many younger patients who may have exercised themselves into an early appointment in the orthopedic clinic – all that Jane Fonda ‘feeling the burn’ step-aerobics and road running has taken its toll.” consultant surgeon Roger Gundle of the Nuffield Orthopaedic Centre in Oxford explains for the Daily Mail.