NEW YORK (Reuters Health), Jun 14 - Amateur marathon runners who run less than 40 miles per week during training often show signs of cardiac dysfunction after the race and some of these abnormalities may persist for up to a month after they cross the finish line, a study shows.
"Running less than 40 miles per week prior to running a marathon leads to temporary heart muscle weakness and increased pressure in the lung arteries," Dr. Malissa J. Wood told Reuters Health. "Individuals who consistently ran greater than 45 miles per week showed no such signs of damage after completing the marathon."
The findings are based on a study of 20 amateur athletes who ran the 2003 Boston Marathon and underwent echocardiography (ultrasound imaging of the heart) prior to, immediately after, and about one month after running the 26-mile race.
The number of people participating in endurance sports has increased in the past decade, Wood, from Massachusetts General Hospital and Harvard Medical School, Boston and colleagues note in a their study, published in the European Heart Journal.
In the U.S. alone, nearly 480,000 runners completed a marathon in 2001. And while the benefits of moderate exercise on the heart are well established, the effects of more prolonged exertion are less clear. Some studies have suggested that cardiac dysfunction or "cardiac fatigue" occurs during prolonged exercise.
The series of echocardiographs obtained for the 20 amateur marathoners demonstrated "attenuation" of heart function after the race.
There was evidence of abnormalities in both systolic function (the heart's pumping ability) and diastolic function (the heart's ability to relax during beats).
All of the systolic abnormalities normalized fairly quickly, but the diastolic abnormalities persisted for up to one month after the race, indicating an inherent alteration in the heart's ability to relax, the authors note.
Wood and colleagues emphasize that their results do not pertain to elite athletes; "our group consisted of runners who ran on average less than 40 miles a week during training, a level that is most consistent with the 'average' marathon runner."
Their study also does not address whether this transient dysfunction damages the heart or if there are any long-term cardiac consequences.
By Megan Rauscher
Last Updated: 2006-06-14 11:30:29 -0400 (Reuters Health)
SOURCE: European Heart Journal, May 2006.
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Playing their hearts out: Do young athletes need cardiac screening? August 16, 2006
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![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnieeurope.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&fit=crop&h=100&q=70&w=100)
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnieeurope.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&dpr=2&fit=crop&h=167&q=70&w=250)
