Iam preparing for an anaesthetist to sink a hypodermic needle into my back at a busy London hospital ahead of a scheduled surgery to replace my knee. Knowing this might be painful, I ask a fellow patient how he got his mind around the jab. “Two spliffs of good dope worked for me,” he confessed. I’m yet to try that, but this is my second left knee replacement in less than 15 years – an increasingly common story as our population ages and obesity levels cause growing strain on our joints. More than 2m hip and knee replacements have been performed in the UK since the early 2000s and waiting lists continue to grow. By 2060, demand for hip and knee joint replacement (based on data for England, Wales, Northern Ireland and the Isle of Man) is estimated to increase by almost 40%. But I think there is another reason for these soaring figures: I blame the fitness gurus. Joe Wicks and his ilk, with their fashionable shorts and bulging quads, all promise we can become leaner, sexier, more athletic versions of ourselves if we just follow their workout programmes. Park fun runs will improve your cardiovascular health, they promise. Pass on high-intensity exercise and risk diabetes, stroke or heart disease, says the doomy warning. But speaking from experience, pounding the road for decades on end hasn’t always been healthful. I was once a running junkie. Running is addictive. It induces a rush of endorphins that provoke the “runner’s high” – and just like drugs, you increasingly need the fix. A missed session can induce guilt, even anxiety, and a compulsion to train harder. This obsession began when I was a teenager. At 16, I was already a 400m county champion, London champion, south of England champion, the second-fastest in my age group in the country, and selected by the Amateur Athletic Association as a future Olympic athlete. To achieve this dream I was told by coaches I had to push my body to near-breakdown levels. Vomiting after hard winter track sessions was the norm. These sessions were often so gruelling I felt as if my eyes would pop out of my head. They were sometimes followed by blinding headaches. My mother, a state registered nurse, deeply concerned, advised me against such physically damaging endeavours; that there would be a price to pay in later life. But I loved to run, and in later life I continued to push myself to the limit of endurance. I was so conditioned to running as hard as I could, I just couldn’t shake it, even though I feared what it was doing to my body. This dependency has led me to the operating table for an achilles heel tear, countless hamstring and muscle rips, a damaged hernia caused by weight training, and a heart valve replacement. I have had a knee cartilage repair followed by two knee replacements. Now, when I see middle-aged men puffing their way around hard city streets, I want to show them my X-rays. Of course, it would be wrong to suggest “fun runs” in moderation will result in the kind of physical breakdowns I suffered. Indeed, much of the evidence on exercise and musculoskeletal health points to running having a beneficial impact on the joints in later life, not to mention the mental health benefits. But pushing yourself past the point of pain is not good. And the simple truth is that as the body ages, you can’t continue to do what you once did. The trouble is, once you’ve got the running bug, it’s hard to scale back, even when your body demands it. I have seen this obsession to run hard not only in champions but in ordinary park runners, who, once hooked on the chemical release that comes after a satisfying session, feel an overwhelming desire to keep hitting the road – running longer and longer distances in pursuit of even greater highs. A wise coach, having observed the damage done to marathon runners, once told me the distance was suitable only for “horses and fools”. My latest knee op was carried out in the orthopaedic department of Chelsea and Westminster hospital. My eight-day stay in men’s surgical as I recovered was instructive. The NHS may be under tremendous pressure (the overall hospital waiting list stands at nearly 8 million, up from about 4 million before the pandemic) but the kindness, attention and advanced surgical standards made a painful replacement knee op bearable. Concerned for my wellbeing, support staff even sent a guitarist to play soothingly at my bedside while I convalesced. I’m on the mend now, though forbidden to jog by my surgeon, the brilliant Luke Jones, himself a former rugby star who understands my passion for running. But sadly, I am just a diehard recidivist. I am so conditioned to run that, even though I know the damage it may cause, I fear I will soon be tempted on to the track again. The truth is, when I run I feel 16. It’s the only shortcut back to youth I know, desperate though that may sound. Another thing I have come to know (and pardon the pun) is that, in the long run, running really can be bad for your health. Rod Gilchrist is a freelance writer