Date of Award

Fall 12-2011

Degree Type


Degree Name

Doctor of Philosophy (PhD)


Human Performance and Recreation

Committee Chair

Michael J. Webster

Committee Chair Department

Human Performance and Recreation

Committee Member 2

Timothy P. Scheett

Committee Member 2 Department

Human Performance and Recreation

Committee Member 3

Geoffrey M. Hudson

Committee Member 3 Department

Human Performance and Recreation

Committee Member 4

Gregor Kay

Committee Member 4 Department

Human Performance and Recreation


The purpose of the present study was to investigate the effect of six weeks of oral Echinacea supplementation on serum erythropoietin (EPO) and erythropoietic status, plasma nitric oxide [NO], submaximal endurance exercise performance, and maximal oxygen uptake (V˙O2max). Twenty-four males (mean ± SE): age = 25.2 ± 1.4 yr, height = 178.1 ± 1.4 cm, mass = 78.1 ± 1.6 kg, percent body fat = 12.7 ± 0.9 %, V˙Omax = 52.9 ± 0.9 mL·kg-1·min-1 were randomly grouped using a matched-pair, double-blind design and self-administered 8,000 mg·d-1(5 × 400 mg × 4 times·d-1) of either Echinacea purpurea (ECH) (n=12) or placebo (PLA) (n=12) for 42 consecutive days. Blood samples were collected and analyzed for EPO, red blood cells (RBCs), hemoglobin (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), nitrite, and total nitrite (nitrite/nitrate) concentrations. Graded exercise tests were performed on a treadmill to assess submaximal exercise performance and maximal oxygen uptake (V˙O2max). Separate 2 × 4 (Group × Time) factorial ANOVA with repeated measures were used to determine statistical differences with significance set at p ≤ .05. There were no statistically significant (p > .05) interaction, group or time effects observed for EPO, erythropoietic status markers, nitrite, nitrate, nitrite/nitrate, submaximal V˙O2, submaximal heart rate (HR), or V˙O2max. The present study indicates that six weeks of oral ECH supplementation in apparently healthy, recreationally active, males with above average fitness status (V˙O2max = 52.9 ± 0.9 mL˙kg-1˙min-1 ), does not enhance EPO, erythropoietic status, [NO], or endurance exercise performance. These findings are in contrast with previous reports of Echinacea supplementation and any explanation for these differences, including the role that training and/or physical fitness level of participants, is unclear and speculative.