Why cant you smoke before a cardio-pulmonary exercise test?

Is brown discharge with pains in upper tummy normal at 5 weeks pregnant? What is needed to fight infection? The glands on both sides of my neck are swollen and it makes it really hard to swallow.What could this be a sign of? What are HBA1s? Can your body trick itself into thinking it is pregnant after you miss your period from stress? The process of recording a picture of blood vessels is called? Can people still smoke if their gums are cut on the bottom? A general term for any non disease causing agent is? Which function does calcium ions perform? What does a woman's fertile fluid look like? What is the stimulus for a platelet plug or blood clot to form? Is dryness and brown dry blood or discharge normal after 3 month of taking the Depo shot? Can a 4 year old get a urinary tract infection? Why is there an age limit on drinking alcohol? What color is Ashtons eyes? What is the color of the lobster? Normal whole blood contains g of hemoglobin per 100 mL? How will you know if its fungal or bacterial? Relating to blood cells what does MCV stand for? What do polio and aids have in common?