The acute consumption of dietary nitrate has been shown to improve exercise capacity in athletes, healthy adults and subjects with peripheral vascular disease. Many COPD patients have reduced exercise capacity, The investigators hypothesized that acute nitrate consumption, in the form of beetroot juice, might increase incremental shuttle walk test (ISWT) distance in COPD subjects.

Acute consumption of dietary nitrate (as beetroot juice) has been shown to improve exercise capacity in athletes, healthy adults and subjects with peripheral vascular disease. Many COPD patients have reduced exercise capacity, The investigators hypothesized that acute nitrate consumption might increase incremental shuttle walk test (ISWT) distance in COPD subjects compared to a matched, low-nitrate drink.

This study is a randomized, double-blind placebo-controlled, crossover trial.

Resting blood pressure, phlebotomy and ISWT are performed. Following completion, each subject is randomized to consume beetroot juice or placebo. 3 hours later, the same assessments are repeated by the same people. After a 7d washout, the entire protocol is repeated with the crossover beverage.

Inclusion Criteria:

• Information consenting out-patients with a previous physician diagnosis of COPD
• Clinically stable
• Ambulatory

Exclusion Criteria:

• Subjects who required supplemental oxygen for exercise
• Subjects with pulmonary hypertension and angina
• Intolerant to beetroot
• Insulin dependent diabetes
• Thyroid disease