Anemia (low healthy blood cells or hemoglobin) has an important role in exercise performance. However, the direct link between rapid changes of hemoglobin and exercise performance is still unknown. A study investigated 18 patients with a blood disorder (beta-thalassemia). Participants in the study performed an exercise test before and the day after receiving a blood transfusion. Data are given in the table.HB =

Hemoglobin

RER = Respiratory exchange ratio

ID Change in Obese RER > 1.1 HB -1.4 No No -1.5 No No -2 No Yes -2.1 No No -1.9 Yes Yes -1.6 Yes No -1.8 No Yes 8 -0.8 No Yes -1 No No 10 -1.2 No Yes 11 -0.8 No No 12 -1.5 Yes No 13 -1.4 No Yes 14 -2.6 No Yes 15 -1.7 No Yes 16 -2.6 No Yes 17 -2.7 Yes No 18 -1.5 Yes No