How can training principles improve your fitness levels?

Wich technque is not recommended for use as a supporting detail

What should you not do when doing abdominal workouts? a. keep your chin off your chest b. keep your head aligned with the spine c. put pressure on your neck d. all of the above

Active immunity refers to: a. the defenses people are born with. b. temporary immunity granted from another source. c. immunity gained through immunization and exposure to diseases. d. natural immunities that protect humans from other animal diseases