Physical fitness including muscle strength and endurance capacity varies substantially among individuals. Physical activity level and exercise behavior also vary among individuals. Many family studies and studies on twins have reported that genetic factors are responsible for heterogeneity in fitness-related traits. However, there is much dispersion in heritability, as previously reported. A systematic review was performed to determine the extent of heritability in physical fitness. A literature search was conducted through PubMed using the following keywords: (heredity or heritability) and (“muscle strength” or “muscle contraction” or endurance or athlete* or fitness or exercise) and (twin* or family). Finally, 43 articles that included 137 phenotypes met the criteria. Only one article focused on the heritability of athletic status. With respect to muscle strength, 23 articles and 54 phenotypes were collected, and showed a range of heritability of 0%-98% (mean: 55±22%). This heterogeneity was partly explained by the ages of subjects. With respect to endurance capacity, 13 articles and 28 phenotypes showed heritability of 0%-93% (mean: 54±25%). The considerable degree of variability in heritability of fitness-related traits may depend on age, sex, race, and environmental factors. Therefore it is necessary to investigate the interaction between genetic factor and factors other than genetic factor. On the other hand, with respect to exercise behavior or physical activity level which is important for improving the physical fitness or health status, the heritability of 0%-85% has also been reported. That is, the genetic factor plays a role in not only physiological phenotypes but also behavioral phenotypes. Understanding of these genetic factors and their mechanisms will lead to improvement in physical fitness or encouragement of physical activity/exercise behavior.

From April 2009 to April 2017, we experienced on average 40 cases of spontaneous pneumothorax per year at our hospital, but we encountered only 2 cases of nontraumatic hemopneumothorax over the entire 8-year period. In one of these cases, we performed transcatheter artery embolization. Extravasation of contrast media was observed on CT near the apex of the lung, and angiography revealed the culprit vessel. We performed embolization and were able to achieve hemostasis and symptomatic improvement. However, hemopneumothorax recurred as a result of adhesion tear due to re-collapse of the lung and required surgical treatment. In this report, we describe our experience of this relatively rare condition and discuss the case with reference to the literature.