True or false: cardiovascular endurance is defined as the boy's ability to use oxygen to meet energy demands of muscles through anaerobic exercise.
a. true
b. false

Me d: which system contains the heart, blood, and blood vessels? a. muscular b. circulatory c. respiratory d. digestive which system contains the pituitary, adrenal, and thyroid glands? a. respiratory b. circulatory c. endocrine d. reproductive