Crushing the Sit-Up


A Part of Fierce Play’s Grounded Gymnastics Series 

The sit-up is an exercise in which the athlete sits up from a horizontal position on the floor without leveraging the strength of his/her arms or legs. The sit-up is one of the most foundational exercises used to strengthen the abdominal, or core, muscles. It should be noted that while sit-ups can be performed without the use of an AbMat® or other type of support device, Fierce Play recommends the use of an AbMat® to assist with a better extension of the back and ab muscles, and to ultimately increase strength. Athletes will immediately feel abdominal muscles activated as they perform the movement, with practically all of the exercise focusing on the use and strengthening of those core muscles.

Watch the video clip below for a full explanation of technique, tips and tricks for performing the movement with efficiency, as well as precautions for staying safe.


  1. Grab an AbMat®: You’ll notice that the AbMat® has a thinner and fatter part to it. Place the fatter end of the mat up against your glutes. This is the optimal position of the mat to allow for maximum extension of your abs, giving you more bang for your buck as you work to strength your core muscles.
  2. Butterfly Position: Place the soles of your feet together so that you have your legs in a butterfly position. This ensures that your knees aren’t in your way and that you actually can have a full range of motion while completing the sit-up.
  3. Reach Far: As you extend back and lower yourself onto the AbMat®, reach your arms all the way behind your head and touch your fingertips to the floor. Then, as you sit up, reach all the way forward with your arms extended and touch in front of your toes. This little bit of an extra reach will go a long way in improving your abdominal strength.


  1. Grab Your Legs: If you’re struggling to sit all the way back up using your core muscles, you can scale the exercise by grabbing your legs to assist in coming fully upright. Once you are sitting upright, still reach in front of toes and touch the floor to get the most bang for your buck from the movement.
  2. Scale: If you’re unsure about completing the sit-up with proper form, talk with your coach about scaling in a different manner so that you can focus on perfecting the technique while gaining strength. It’s great to push yourself to the next level, so long as you stay safe and prevent injury!


QUESTIONS: Ready to get started, or curious to learn more about how Fierce Play can help you meet your health and wellness goals? Contact us for more information. Also feel free to check out more of our videos series to learn how to perform the basics with solid form and efficiency. 


Fierce Play’s Grounded Gymnastics Series focuses on proper technique, as well as tips & tricks, to master some of the foundational movements that will be integrated into many of the workouts you will perform. Start your next workout with the confidence and skills to do the movement safely and effectively.


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CrossFit Level 1 Certification



Mark Mancuso started his fitness journey while enlisted in the United States Marine Corps. Like most individuals, at first, he only focused on bodybuilding type workouts. Mark learned quickly that focusing just on the aesthetics of the body would get you only so far. In 2013, Mark found out about Crossfit and fell in love with everything that it stood for.

In June of 2015, Mark was Honorably Discharged from the Marine Corps and returned from his duty station in Okinawa, Japan to his home in Maple Grove, MN. Not having any formal coaching in Crossfit he was on a mission to find a Crossfit Box to call home. Fierce Play welcomed him with open arms, and he hasn’t looked back. Mark obtained his Level One Crossfit certification in November 2015 and plans to add additional certifications in the future. He also intends to compete in a variety of Crossfit competitions as opportunities arise.


CrossFit Level 1 Certification


Owner & Head Coach

Jeff Birthler has a contagious passion for fitness. He graduated and obtained a personal training certificate from the National Personal Training Institute in 2010. On his way, he discovered and fell in love with CrossFit. Jeff hasn’t stopped learning, and still seeks a well-rounded education within the health domain, going beyond physical facets. He has trained clients at several corporate gyms, including Fitness 19 and LA Fitness, as he established a plan for his own gym.

Fierce Play was established in 2012 in a 500 sq. ft. garage. After a few moves and upgrades, it now has a permanent, 4800 sq. ft. location in Maple Grove. Jeff calls it “home”.


NPTI (National Personal Training Institute) CPT Diploma January 5, 2012

CrossFit Level 1 Certificate

CrossFit Level 2 Certificate

CrossFit Olympic Lifting Certificate

CrossFit Power Lifting Certificate

CrossFit Mobility Certificate

CrossFit Gymnastics Certificate

USA Weightlifting Sports Performance Certification



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