A jumping jack (Canada & US) 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, sometimes in a clap, and then returning to a position with the feet together and the arms at the sides.
The name origin for the jumping jack exercise has sometimes erroneously been identified as World War I U.S. General John J. "Black Jack" Pershing, who is said to have developed the exercise, but in fact the name comes from the jumping jack children's toy, which makes similar arm swing and leg splay motions when the strings are tugged.
"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.
Power Jacks are similar to jumping jacks, except a person squats lower and jumps as high as possible during each repetition.
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 like regular jumping jacks but the arms go halfway above the head instead of all the way above it. 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 it in the United States. LaLanne used the jumping exercise during routines he promoted in decades of television fitness programming.
The most jumping jacks in one minute is 97 and was achieved by Brandon Gatto (USA) at the Old Forge High Veterans Memorial Stadium in Old Forge, Pennsylvania, USA, on 1 August 2011. This was equalled by Mario Silvestri (Italy) in Venafro, Isernia, Italy, on 3 March 2018.
In 2010, National Geographic Kids organized an event in 1,050 locations as a part of Michelle Obama's "Let's Move!" exercise campaign in which 300,365 people were measured doing jumping jacks (for one minute) in a 24-hour period.
- "The Jumping Jack Is Named after Its Inventor, General "Black Jack" Pershing".
- "Bodyweight Exercises Periodic Table with How-To Videos". Strength Stack 52.
- Erik Hayden. "Remembering Fitness Legend Jack LaLanne". The Wire.
- Guinness World Records. "Most Jumping Jack's in One Minute". Guinness Book of World Records. Retrieved 2018-12-13.
- "Most people doing jumping jacks in 24 hours". Guinness World Records. Retrieved 29 August 2013.