Association of red blood cell size and physical fitness in a military male cohort: The CHIEF study

Shiue Wei Lai, Kun Zhe Tsai, Yen Po Lin, Pang Yen Liu, Yu Kai Lin, Ping Ying Chang, Ming Shen Dai, Tsu Yi Chao, Chih Lu Han, Gen Min Lin

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Anemia manifested as reduced red blood cell (RBC) amounts or hemoglobin levels has been associated with lower cardiorespiratory fitness. However, the relationship of smaller RBC with physical fitness was unknown. We included 2933 non-anemic military males (hemoglobin levels: 11.1-15.9 g/dL and mean corpuscular volume (MCV) <100 fL) in Taiwan during 2014. Aerobic fitness was assessed by time for a 3000-meter run, and anaerobic fitness was evaluated by numbers of sit-ups and push-ups, each performed within 2 minutes. Multiple linear and logistic regression models adjusting for age, service specialty, lipid profiles, and hemoglobin levels were used to determine the associations. Microcytosis and normocytosis were defined as MCV ≤ 70 fL (n = 190) and MCV > 70 fL (n = 2743), respectively. The linear regression shows that as compared with microcytosis, normocytosis was associated with more numbers of sit-ups performed within 2 minutes (β = 1.51, P-value = 0.02). The logistic regression also reveals that those males with microcytosis had higher probability as the worst 10% performers in the 2-minute push-up test (odds ratio: 1.91, 95% confidence intervals: 1.18-3.12). By contrast, there was no association of microcytosis with 3000-meter running time. Our study suggests that non-anemic microcytosis was associated with lower anaerobic fitness but not with aerobic fitness. Whether the causative factors for microcytosis such as iron deficiency status and thalassemia trait unavailable in the study might account for the relationship needs further investigations.

Original languageEnglish
Pages (from-to)295-302
Number of pages8
JournalScandinavian Journal of Medicine and Science in Sports
Issue number2
Publication statusPublished - Feb 2021


  • military males
  • physical fitness
  • red blood cell size

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation


Dive into the research topics of 'Association of red blood cell size and physical fitness in a military male cohort: The CHIEF study'. Together they form a unique fingerprint.

Cite this