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Effect of FIO2 on Oxidative Stress during Interval Training at Moderate Altitude


Medicine & Science in Sports & Exercise: November 2004 - Volume 36 - Issue 11 - p 1888-1894
doi: 10.1249/01.MSS.0000145442.25016.DD
Basic Sciences: Original Investigations

Purpose: To evaluate the effect of different fractions of inspired oxygen (FIO2) on oxidative stress during a high-intensity interval workout in trained endurance athletes residing at altitude.

Methods: Subjects (N = 19) were trained male cyclists who were residents of moderate altitude (1800–1900 m). Testing was conducted at 1860 m (PB 610–612 torr, PIO2 ∼128 torr). Subjects performed three randomized, single-blind trials consisting of a standardized interval workout (6 × 100 kJ) while inspiring a medical-grade gas with FIO2 0.21 (PIO2 ∼128 torr), FIO2 0.26 (PIO2 ∼159 torr), and FIO2 0.60 (PIO2 ∼366 torr). Serum lipid hydroperoxides (LOOH) and whole-blood reduced glutathione (GSH) were measured 60 min preexercise and immediately postexercise, and analyzed using standard colorimetric assays. Urinary malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) were measured 24 h preexercise and 24 h postexercise, and analyzed via HPLC and ELISA, respectively.

Results: Compared with the control trial (FIO2 0.21), total time (min:s) for the 100-kJ work interval was faster (5% in FIO2 0.26; 8% in FIO2 0.60 (P < 0.05)) and power output (W) was higher (5% in FIO2 0.26, 8% in FIO2 0.60 (P < 0.05)) in the supplemental oxygen trials. There was a significant pre- versus postexercise main effect (P < 0.05) for LOOH and GSH; however, there were no significant differences in LOOH or GSH between the FIO2 trials. MDA and 8-OHdG were unaffected by either the interval training session or FIO2.

Conclusion: Supplemental oxygen used in conjunction with high-intensity interval training at altitude (“live high + train low via supplemental O2” (LH + TLO2)) results in a significant improvement in exercise performance without inducing additional free radical oxidative stress as reflected in hematological and urinary biomarkers.

1Athlete Performance Laboratory, United States Olympic Committee, Colorado Springs, CO; 2Department of Exercise Science, Health Promotion and Recreation, Colorado State University–Pueblo, Pueblo, CO; 3The Orthopedic Specialty Hospital, Salt Lake City, UT; 4Oxis Research, Portland, OR; and 5Sport Science Department, USA Cycling, Colorado Springs, CO

Address for correspondence: Randall L. Wilber, Ph.D., Athlete Performance Laboratory, Sport Science Division, United States Olympic Committee, One Olympic Plaza, Colorado Springs, CO, 80909; E-mail

Submitted for publication January 2004.

Accepted for publication July 2004.

The authors acknowledge the subjects for their enthusiastic participation in this investigation. We also thank Nalani Cook, B.S., Stephanie Fitzgerald, B.S., Jeff Dolgan, M.S., and Wade Frear for their technical assistance.

This study was supported by the United States Olympic Committee and Oxis Research (Portland, OR).

©2004The American College of Sports Medicine