Why does the heart automatically adjust the flow of blood to match activity levels?
a.
extreme activity damages blood cells and the body needs replacements.
b.
the heart requires more oxygen when exercising.
c.
it builds up a higher level of oxygen in the blood.
d.
organs and muscles require more blood under stress.

Describe specific ways your friend can use frequency, intensity, time, and type to safely apply the overload principles to his workout schedule. provide two ways per training principle. sunday30-minute bike ride monday20 push-ups, 10 squats, and 20-minute jog tuesday30-minute bike ride wednesdayrest thursday20 push-ups, 10 squats, 25 curl-ups, and 20-minute jog friday30-minute bike ride saturdayone-hour walk

What is the hormone in your brain that makes you feel happy?

How does social isolation affect teens?