Jacob Arnstein is a teen originally from Guatemala who now lives in Massachusetts with an adopted family. He also previously competed on the third season of American Ninja Warrior Junior before competing on the main show.
American Ninja Warrior 14[]
Jacob competed in the second episode of qualifying. There he was the first competitor shown that episode who got past the fifth obstacle, Piston Plunge, and later the first clear in his rookie debut. He placed 8th overall. Jacob later competed in the fourth and last semifinals episode. His run there was digested, but he failed on the ninth obstacle, Flipped Around. He placed 12th overall, advancing him to the national finals. At the national finals, he was the first competitor shown to have failed the new fifth obstacle, Tetherball after a bad dismount, ending his rookie season.
American Ninja Warrior 16[]
Jacob was selected for American Ninja Warrior 16, and competed in the fourth Qualifying round. In his run, he managed to clear the course, placing 6th on the men's leaderboard and earning a trip to the Semifinals. During the Semifinals, he raced Noah Buschur. His run was digested, but it was shown that he cleared the course while Noah failed Sideways, earning another trip to the National Finals. At the national finals he run was digested, but he hit his face as he made the transition from the first barrel to the second barrel on Barrel Roll but still cleared the obstacle. He ended up falling two obstacles later on the Jumping Spider, ending his second season.
Results[]
| ANW | # | Result | Notes |
|---|---|---|---|
| 14 | Failed Tetherball (Stage One) | ||
| 16 | Failed Jumping Spider (Stage One) | Digest. |