14 DAY TRIAL // German researchers used a mobile MRI unit to follow runners over a two-month period and a 4,500 kilometers course, in order to study the way that their bodies answered to the high-stress conditions of such a long distance.
The TransEurope-FootRace 2009 took place from April 19 to June 21, 2009, beginning in southern Italy and ending nearly 4,488 kilometers later, in North Cape in Norway.
44 runners took part at the study, and the researchers gathered blood and urine samples daily, alongside biometric data.
During the two months of the race, the runners also passed other exams (they were assigned randomly) like electrocardiograms.
Every three or four days during the race, 22 of the runners in the study underwent whole-body MRI examinations, which equals a total of 15 to 17 exams in 64 days.
At the end of the race, the scientists assessed all data: whole-body volume, body fat, visceral fat SCAT (abdominal subcutaneous adipose tissue), skeletal muscle and fat of the lower extremities.
Among the points of interest there were the stress-induced changes in the feet and legs from running, and the complex MRI techniques – a MAGNETOM Avanto magnetic resonance imaging (MRI) system, allowed the quantification of muscle tissue, cartilage and fat changes.
Uwe Schütz, MD, a specialist in orthopedics and trauma surgery in the Department of Diagnostic and Interventional Radiology at the University Hospital of Ulm in Germany, said that MRI is the best way of assessing the musculoskeletal system of a runner.
After all data was processed, the researchers concluded that runners lost, on average, 5.4% of body volume during the race, and most of this loss happened during the first 2,000 kilometers.
At the middle of the race, they had lost 40% of their body fat, and an additional 10% over the rest of the course.
“One of the surprising things we found is that despite the daily running, the leg muscles of the athletes actually degenerated because of the immense energy consumption,” Dr. Schütz said, after the analysis showed that the runners lost an average of 7% muscle volume in the leg.
What is really interesting though, is that fat tissue was the first tissue affected by running, and more importantly, visceral fat loss (70% on average) happened much earlier in the running process, than the researchers would have thought.
Visceral fat is the most dangerous fat inside the body, and is associated with insulin resistance, glucose intolerance, dyslipidemia, hypertension and coronary artery disease.
Also, the analysis showed that most overall fat loss occurred early in the process.
Dr. Schütz said that “when you just begin running, the effects of fat reduction are more pronounced than in athletes who have been running their whole life, but you should do this sport constantly over the years.
“If you stop running for a long time, you need to reduce your caloric input or opt for other aerobic exercises to avoid experiencing weight gain.”
It is known that most people never reach such running extremes, but this study is actually important even for the marathon runner or the recreational runner, Dr. Schütz claims.
“Due to the exceptional setting of this study, we could acquire huge amounts of unique data regarding how endurance running affects the body's muscle and body fat,” he said.
“Much of what we have learned so far can also be applied to the average runner.”
For example, there are some leg injuries that are not as bad as we would think: if a runner has intermuscular inflammation in the upper or lower legs, he/she can usually continue running without risk of further tissue damage.
There are other overuse injuries – like joint inflammation, that have a higher risk of progression, but not always with persistent damage.
“The rule that 'if there is pain, you should stop running' is not always correct,” the doctor said.
The study was presented at the annual meeting of the Radiological Society of North America (RSNA).