This US college football monster just nailed a five-foot seated box jump with a weights vest

American footballers are some of the most explosive athletes on the planet.

It's not like rugby where you have to be an all-round machine for 80 minutes - you just have to be supremely powerful over that first 10 yards in this game. Some of the hardcore training these guys get up to fascinates us. If you've not seen this highlights video of some of the insane gym work the Auburn Tigers got up to pre-season, then stop what you're doing right now and stick it on. But a new video has emerged of a young Texas college footballer showing just why these are some of the most powerful guys in sport. Texas Tech wide receiver Derrick Willies Jr has been working on his box jumps. It's a great plyometric technique (actually invented by Russian athletes in the 70s) that is brilliant for developing speed-strength. But Willies Jr has really taken it to another level. If you've ever tried even a 30-inch box jump at the gym, you'll know they're not easy. The 6ft 3in, 225lb athlete did double that with a 60-inch box. That's 5ft to you and me. If that wasn't enough he's stuck a 10lb weighted vest on, just to spice it up with a bit more resistance. https://twitter.com/derrickwjr/status/714160406399418368?ref_src=twsrc%5Etfw But just to make it that little bit more taxing, the young athlete has done it from a seated position. This might seem inconsequential. But it really does add another layer of difficultly to the movement. Why? Because it to takes the stretch-shortening cycle out of the movement (like when you do a box squat). This is so your leg muscles aren't loaded up like a spring in the down portion of the movement (eccentric) and you just have to explode upwards from a static position (the concentric portion of the move).   It's no wonder the Texas Tech star has freakish jumping abilities. His head coach Brad Smiley said Willies is a "red zone monster" and last season he tallied 1,115 receiving yards and 14 touchdowns for Trinity Valley Community College, according to 247sports.com .