Association between mild anemia and physical fitness in a military male cohort: The CHIEF study

Anemia defined as reduced hemoglobin levels of red blood cells may carry less oxygen to skeletal muscle and impair physical performance. Previous studies have shown that exercise intolerance was related to moderate or severe anemia, however, the relationship to mild anemia was unknown. We investigated the cross-sectional association of mild anemia defined as a hemoglobin level of 10.0–13.9 g/dL with physical fitness in 3,666 military young males in Taiwan in 2014. Aerobic fitness was evaluated by 3000-meter run test, and anaerobic fitness was evaluated by 2-minute sit-ups and 2-minute push-ups, respectively. Multiple logistic regressions for the best 10% and the worst 10% performers were used to determine the relationship. There were 343 mild anemic males in whom 47.8% were microcytic anemia and 3,323 non-anemic males for the analysis. The multiple logistic regression shows that as compared with non-anemic males, mild anemic males were more likely to be the worst 10% performers in the 3000-meter run test (odds ratios (OR) and 95% confidence intervals: 1.47, 1.01–2.14) after adjusting for age, service specialty, body mass index, waist size, mean blood pressure, unhealthy behaviors, lipid profiles, and exercise frequency. On the contrary, mild anemic males had higher possibility to be the best 10% performers in the 2-minute push-ups test (OR: 1.48, 1.08–2.04). However, there was no association between mild anemia and 2-minute sit-ups. Our findings suggest that unspecified mild anemia might be associated with lower cardiorespiratory fitness but not with anaerobic fitness in physically active military males.