A recent study in the American Journal of Kidney Diseases has raised the question of whether running a marathon could cause more health harm than benefit. So what’s the truth?
Past studies have shown that in the first few days after running a marathon there can be an increased risk of the runner developing a cold. The theory is that the stress of the effort overwhelms the immune system. Equally possible is that hanging out with all the people in the crowd exposes them to more cold viruses.
Similarly, studies have shown changes in some marathon runners’ hearts and there are rare reports of runners suffering fatal heart attacks during or immediately after a marathon.
The present study looked at 22 runners in the 2015 Hartford, Conn. Marathon. The researchers discovered that about 80 per cent had evidence of damage to their kidneys in the first two days after the race. They theorized that running in the heat (the day of the race was sunny and the temp in the 60s F) exposed the marathoners to the double whammy of dehydration and increased core temperatures, both of which can damage the kidneys.
Furthermore, running that far for that long (they all ran for about four hours) can cause muscle damage. The substances that leak into the blood stream from the damaged muscles can also cause kidney damage. So there are logical reasons why running a marathon might cause immediate stress to the kidneys. The good news is that there was also evidence from this study that the kidneys were repairing themselves and even the authors admitted that there is no evidence of an increase in chronic kidney damage in previous scientific studies that have followed marathon runners over many years of competition.
So, is it safe to run a marathon? The simple answer is yes. None of these studies have shown long term health consequences that outweigh the fact that fit people live longer and better than those who are not fit.
Are there possible risks in running a marathon? Yes, but these can be mitigated by training properly, making certain you stay hydrated and not running too many marathons without giving the body a chance to repair itself between races. And, if you have risk factors for heart disease, being checked out by your doctor before you start to train.
The bottom line with running, as with any activity, is being sensible and taking the appropriate precautions if you want to reap the benefits and avoid the pain.
Dr. Mitch Shulman is an Assistant Professor, Dept. of Surgery, McGill Medical School and an Attending Physician, Emergency Department, McGill University Health Centre. He’s also the CJAD AM 800 Medical Consultant.