Q In almost every long run (over 25km) I get severe calf cramps; one or both of my calves just lock up. With the recent runs the temperatures have been great (10 to 15 degrees Celsius) and I have been well hydrated. What’s the cause of the cramping and how do I prevent it? – SEAN
A Cramping is one of the more common causes for a visit to the medical tent in most marathons.
There are a couple of schools of thought on cramping; one suggesting it is hydration and electrolyte based and another suggesting there is a neuromuscular cause involving fatigue. I tend toward the latter in the marathon setting. Bruce Jones did a lot of work on marathon medical problems with the Boston Marathon through the ’80s and ’90s. In a comparison of medical problems in a hot and cold marathon, he found most problems increased with hot conditions; however, muscle cramping stayed at the same high level in both groups. So, heat is probably not the culprit. If you’ve hydrated and supplemented well, with various combinations of electrolytes, vitamins and minerals in your training and on race day, fluid balance and electrolyte deficiencies are likely not the primary villain either.
My guess is that you are dealing with muscle fatigue resulting in severe and painful cramping, generally termed exercise-associated muscle cramping. The onsite treatment is to stretch the cramping muscle while simultaneously contracting the antagonist muscle, so for a quad spasm – stretch the quad while contracting the hamstring. This is easier said than done. We utilise a core of physical therapists in our tent at the Medtronic Twin Cities Marathon who utilise neuromuscular inhibition techniques to relieve the cramping and get runners up and moving again after the marathon. Sometimes this fails and we use other interventions. Most often the intractable cramps will respond to a litre of intravenous normal saline, which makes one wonder about hydration as a potential contributor. We always check serum sodium before administering the fluids to make sure the cramping is not caused by hyponatremia. If a normal saline fluid flush fails, we will occasionally give intravenous benzodiazepines to break the spasms, but that means the runner cannot drive for 24 hours and cannot leave the medical area alone.
Individual muscles are worked hard in a marathon. Few runners have run the marathon distance or greater in preparation for the race and it may be a simple volume overload causing localised fatigue and spasm. That last 10 kilometres; 10 more than the usual training 30s, may push the muscle over the brink. Maybe the excitement of the race and race day changes your pace just enough to cause problems. If you look in the literature on muscle cramping, you will find controversy regarding cause. Eventually we will figure this one out and likely there will be several contributing factors that lead to cramping in different individuals.
For the future, going into the race well trained; presenting to the start line rested, well fed and hydrated; and knowing your pace and heat limits will likely give you the best experience, and hopefully a cramp-free finish.