Every week, a new STACK Challenge gives you an opportunity to test your athletic ability and win a STACK T-shirt. Take the challenge and enter to win a T-shirt by tweeting your results with #STACKChallenge.

This week’s STACK Challenge tests two of the most underrated athletic attributes—grip strength and mental toughness. With improved grip strength, you’ll be able to catch more passes, tackle better and hit harder. Build your mental toughness so you can keep fighting hard in the fourth quarter when your opponent has lost a step.

For this test, you grip a Chin-Up bar with the palms of your hands facing you. Bring your feet off the ground and keep your arms straight. Keep your body under control and don’t sway.

The Challenge

Hold on for as long as you can. Time starts when your feet leave the ground.

How Do You STACK Up?

Rookie: Under 60 seconds
Pro: 1:00-1:45
All-Star: 1:45+

How to Win a STACK T-Shirt

1. Complete the challenge by Feb. 16
2. Follow STACK on Twitter (@stackmedia)
3. Tweet your results and include #STACKChallenge

We’ll announce the winner in next week’s STACK Challenge.

Get Better

Not an All-Star yet? Get better by incorporating the following exercises into your training:

• Farmer’s Walk
• Towel Curl
• Chin-Ups followed by Straight-Arm Hang