Changes in body composition and their association with erythrocyte mass in regular exercisers: A cross-sectional study

Most erythrocytosis cases are acquired and result from conditions that cause low oxygen levels, such as smoking; living at high altitudes; and certain heart, lung, or kidney diseases. Intense exercises aimed at changing body composition are being increasingly practiced. These exercises reduce body fat and increase the muscle mass. An increase in muscle mass is expected to increase the oxygen demand, which could lead to erythrocytosis. Therefore, this study aimed to investigate the effects of changes in body composition on erythrocyte mass. This study included 56 male volunteers who engaged in regular exercise to alter body composition and 51 male volunteers in the control group who did not engage in regular exercise. Height, weight, body fat, and muscle mass were measured, and laboratory studies were conducted. A total of 107 male participants with a median age of 24 (range 18-59), were included in the study. The body fat percentage was significantly lower in the athletes (18.8 ± 6.0 vs 24.9 ± 6.4, P < .001). Hemoglobin (Hb) and hematocrit (HCT) levels were significantly higher in the exercise group (Hb 15.9 ± 0.8 vs 15.3 ± 0.8; HCT 46.8 ± 2.6 vs 45.2 ± 2.4). The total testosterone levels were also higher in the exercise group (430 ± 174 vs 368 ± 138). Changes in body composition during exercise increased erythrocyte mass.