A jumping jack (US), stride jump (Canada) or star jump (UK and other Commonwealth nations), also called side-straddle hop in the US military, is a physical jumping exercise performed by jumping to a position with the legs spread wide and the hands touching overhead and then returning to a position with the feet together and the arms at the sides. The jumping jack name comes from the traditional toy of the same name, while "star jump" refers to the person's appearance with legs and arms spread.
More intensive versions of this jump include bending down (over) and touching the floor in between each jump.
A similar jump exercise is called half-jacks, which were created to prevent rotator cuff injuries, which have been linked to the repetitive movements of the exercise. They are just like regular jumping jacks, but the arms go halfway above the head instead of all the way above the head. The arms also hit the sides to help tighten the jump.
Although he played no part in inventing the exercise, the late fitness expert Jack LaLanne was given credit for popularizing the exercise in the United States. LaLanne utilized the jumping exercise during routines he promoted in decades of television fitness programming.[1]
According to the Guinness World Records, the world record for most Jumping Jacks (Star-Jumps) in one minute is 108, and belongs to American Lawrence Bond.[2]
Ashrita Furman set the Guiness World Record for consecutive jumping jacks in 1979 at 27,000.[3]