Damaged kidneys, bleeding, muscle breakdown, injuries – what are the threats of excessive amount of running?

Running may be a safe physical activity, available for healthy people. But one word should be highlighted here: moderate. Against the current trends of organising street runs and promoting this form of activity – the distance of half-marathon and marathon may be dangerous for health – even for well-trained people. It was stated that longer distances, volume and intensity of the running training contribute to occurring many health problems. Like in case of long-lasting physical activity in adverse conditions, it's very easy to get dehydrated or overheated. Besides, it's thought that the reason of death of the first marathon runner, Filippides, was heatstroke.

First of all: long-distance runners are endangered with kidney damage

For example, in the experiment from Turkey, there were 45 competitors at the age of 16-59 (the average age was about 29.7), weight ranged from 54 to 76 kg, no kidney diseases. All of the volunteers completed a form concerning their current running training and they all finished the race at the distance of 21.1 km (half-marathon). 2 hours before the beginning of the run and right after the run, the urine samples were gathered from the competitors. The following markers were checked: the amount of glucose, bilirubin, ketons, proteins, blood, leukocytes, urobilinogen, nitrogen – to check the disorder in kidneys functioning. Before the run, there was nothing worrying in the samples. During their training, the volunteers ran 20 – 220 km a week on average, and they had run in half-marathons averagely 14 times before. They had averagely run for 7 years before. As you can see, they were mostly experienced competitors.

Right after the run the scientists found:

  • in 53.3% of competitors there was blood in urine (norm = 0!),

  • in 73.3% of competitors there was protein in blood (norm = 0!),

  • bilirubin – it was found in 8.9% of the runners (norm = 0!),

  • leukocytes were found in 13.3% of the runners (norm = 0!),

  • ketones were found in 6.7% of the runners (norm = 0!),

Despite the fact that the volunteers finished the distance in extremely various times – from 66 to 125 minutes – the disorders were not connected with it. The scientists didn't combine the symptoms with ageing. They suggest that the people who run frequently in marathons and half-marathons are prone to some serious kidney damage (e.g. nephrons, hypoxia).

Further studies – similar results; 98 runners took part in them. The samples of urine were gathered right before the half-marathon (~21 km) and marathon (~42 km). Proteinuria occurred in 35% of the half-marathon runners and in 69% of the marathon runners. Blood was found in 21% of the contestants of half-marathon and in 22% of marathon contestants.


  • Do blood and urine tests regularly,

  • pay special attention to the following markers: protein in urine, erythrocytes in blood and leukocytes.

Second of all: muscle breakdown (rhabdomyolysis) and heart damage

Sports people may have symptoms similar to those of car accident vitims or post-surgical muscle damage. In medicine such syndrome is called Crash Syndrome – CS. This expression was used for the first time during the second world war. Rhabdomyolysis characterises with intensive muscle pain (do not mix it with DOMS) and dark colour of urine.

Dagna M. Bobilewicz: “Rhabdomyolysis […] is the process of muscle tissue breakdown, as a result of which the components from inside muscle cells are transferred to blood and cause significant increase of their concentration (it concerns potassium and myoglobin) and activity (it concerns the intracellular enzymes, including mainly AST, CK and LDH). Apart from the outer mechanical or thermal damage (extensive thermal burn) there are many other reasons of rhabdomyolysis with various strength, such as: extreme physical effort, acute ischaemia of large muscle groups [...]”.

Practical example: the results of a patient after marathon run

After admitting the patient to the hospital ward (majority of markers 6 hours after admittance):

  • creatine kinase (CK): 1221 U/l (the norm is maximally 200 units; averagely 30-170), over six times higher than the norm! It proves muscle breakdown,

  • CK-MB (the activity of creatine kinase): 16.5 ng/ml (the norm is: 0 – 3.6 ng / ml); over five times higher than the norm! It proves muscle breakdown,

  • troponin: 0.32 ng /ml (the norm is less than o.1!) it means over three times higher than the norm! (it is the protein building heart muscle); the increase of this marker proves heart damage, necrosis, cardiomyopathy, rhabdomyolysis or it may be the marker of tens of other ailments,

  • creatine: 1.39 mg / dl (the norm ranges from 0.5 to 1.1 mg / dl),

  • right after admittance, also leukocythosis and high level of potassium.

The source: “the Review of Lab Medicine”. Author: Dagna M. Bobilewicz

“Among other reasons of occurring the crash syndrome, there are: long-lasting pressure on muscles (during e.g. coma), alcohol abuse, overdose of some stimulants (cocaine), hyperthermia and electrolytes disorder. During the crash syndrome, myoglobin is released from the damaged muscle fibres (rhabdomyolysis).

[Anesthesiology Intensive Care]

The marker of rhabdomyolysis is the level of CPK, i.e. enzyme (creatine kinase CK or CPK), which mainly occurs in muscles, heart or brain. Increased level of CPK proves muscle damage. The normal upper referrence value is around 200 (namely: two hundred units). The measurement of CK doesn't give 100% of certainty – because it may also turn out during heart attack or stroke. However, according to the specalists, in rhabdomyolysis the level of CPK may even reach few tens of thousands of units (much more than in other diseases). In 25 contestants of iron man half-triathlone (iron man triathlone: 1.92 km of swimming + 90 km of cycling + 21 km of running) there was the increased level of myoglobin – which proves it was the primal stage of rhabdomyolysis!

Third of all: bleeding from digestive tract

Bleeding occurs in 8 to 30% of long-distance runners. What's interesting, in case of marathon runners, the medicine blocking the excretion of gastric acid (cimetidine) turned out to be inefficient. Many sports people use non-steroidical anti-inflammatory drugs, such as aspirin or ibuprofen, carelessly.

“In the USA the population studies, achieved thanks to ARAMIS, assessed that about 100,000 of hospitalizations and 16,500 of deaths a year are caused by various comlications of using NSAIDs. In Poland, on the basis of that data, about 3,000 of deaths are estimated to be the result of using NSAIDs.”

[Chronic use of NSAID – threats, potential complications”]

Unfortunately, using NSAIDs is especially dangerous for runners. German scientists analysed the information from over 4,000 of runners (the contestants in the Bonn marathon in 2010). Over half of them took painkillers (including OTC) before their start. The scientists checked how the supply of painkillers (ibuprofen, aspirin) correlates with side effects, which occurred during and after the race in sports people. […] Those runners who used painkillers had to resign from the race much more often because of the digestive tract disorders. It was also claimed that the group using NSAIDs sufferred from muscle cramps more often (that made them resign from the marathon). It was proven that painkillers increased the risk of having side effects in runners five times.

This issue was developed in this article:

Non-steroidical anti-inflammatory drugs VS sports


  • don't use aspirin or any other products from the NSAID group before running, this way you increase the risk of cramps and the digestive tract disorders five times,

  • long-lasting use of NSAIDs may cause many serious diseases.