Why do people who participate in marathons tend to have smaller muscles? a. lifting weights provides no benefits for them. b. muscle endurance is more important for them than muscle strength. c. continuous running burns glucose and fat. d. they participate in a sport more suited to their body type.

Recovery heart rate is to determine how fast the heart recovers and should be measured five to ten minutes after vigorous activity. true or false

Which of the following is a nonspecific defense against pathogens? - b cells - antibodies - t-cells - inflammation

Check all that occur during ventricular systole. a. the av valves open to allow blood to enter the ventricles from the atria. b. the av valves open to allow blood to enter the ventricles from the atria. c. the semilunar valves remain closed throughout systole to prevent backflow of blood into the ventricles. d. the semilunar valves remain closed throughout systole to prevent backflow of blood into the ventricles. e. the semilunar valves open to allow blood to flow into the large arteries. f. the semilunar valves open to allow blood to flow into the large arteries. g. the av valves close to prevent backflow of blood into the atria.