Inclusion Criteria:  Between ages of 18-50 No medical history of cardiovascular, respiratory, nervous system, or metabolic disease Females must be pre-menopausal  Exclusion Criteria:  Any known cardiovascular, respiratory, nervous system, or metabolic disease (however, participants with controlled arterial hypertension will not be excluded) Having travelled above 2,000m within 1 month of testing at low and high altitude Females who are pregnant, confirmed by a pregnancy test Females who are post-menopausal Participants that are classified as obese (body mass index > 30kg⋅m²) Have a history of smoking regularly in the last 6 months (but nicotine substitutes (patch, gum) not an exclusion criteria) Those with a known allergy to sulfites Participants taking monoamine oxidase (MAO) inhibitors or tricyclic antidepressants