Echinacea purpurea supplementation does not enhance V̇O₂max in distance runners

Oral supplementation of Echinacea purpurea (ECH) has been reported to increase levels of serum erythropoietin and as a result improve endurance performance in untrained subjects. The purpose of this study was to determine if ECH supplementation alters maximal oxygen uptake (V̇ O₂max) in trained endurance runners. Using a double-blind design, 16 trained endurance runners (9 ECH and 7 placebo [PLA]) supplemented with either 8,000 mg d ^-1 of ECH or wheat flour (PLA) for 6 weeks. Maximal aerobic treadmill tests and blood samples were measured before and after supplementation to determine V̇ O₂max, hematocrit (Hct), and hemoglobin (Hb). V̇ O₂max, Hct, and Hb did not differ between the ECH and PLA groups before or after supplementation. Furthermore, supplementation of ECH failed to improve V̇ O₂max (67.37 ± 4.62 vs. 67.23 ± 5.82 ml kg^-1 min^-1), Hct (43.57 ± 2.38 vs. 42.85 ± 1.46%), or Hb (14.93 ± 1.27 vs. 15.55 ± 0.80 g dL^-1) from baseline measurements. Echinacea purpurea supplementation of 8,000 mg d^-1 for 6 weeks failed to increase V̇ O₂max, Hct, or Hb in trained endurance runners and thus does not seem to influence physiological variables that affect distance running performance.