Functional Interval Training: HIIT Circuit Training for Core Stability

Functional Interval Training: HIIT Circuit Training for Core Stability
Presented by Spartan Training®

This week of functional interval training kicks off with some core-burning HIIT circuit training to give you Spartan abs.

When running gnarly trails with screaming inclines and fierce turns, your core is what keeps you safe, solid, and moving forward. We hope you enjoy these workouts after our Week 1 kickoff, where we introduced the seven kinds of motion and worked on our lateral movements.

Functional interval training, the focus of this month, is what allows you to do exercises like these in smartly chosen intervals of time that will maximize your results.

Week 2: HIIT Circuit Training

Day 1 - Strength

Circuit 1 - 3 Rounds

  • 15kcal Assault Bike
  • 10 Shoulder Taps
  • 5 MB Slams

Circuit 2 - 6 Rounds

  • 10 DB Thrusters
  • :30 Pull-Up ISO Holds
  • 12 Curtsy Lunges
  • 10 Core Extensions

Related: Functional Foundations: 6 Workouts

Key Points:

  • Always keep a stable core while doing shoulder taps. Make sure there is no shifting of the pelvis. During hard HIIT circuit training, it is easy to lose form. 
  • For core extensions, grab a light-to-moderate weight. Start by laying flat on your back, bringing your arms above your chest and keeping a 90-degree bend in your knee. From there, extend your upper and lower body straight out, making sure your lower back does not leave the floor.

Day 2 - Conditioning

Core Warmer - 3 Rounds

  • 10 Hanging Knees to Elbows
  • 10 Plank Up-Downs
  • 10 Suitcases


  • 400m Run
  • 25 Burpees
  • 400m Run
  • 20 Burpees
  • 400m Run
  • 15 Burpees
  • 400m Run
  • 10 Burpees

Key points:

  • Hanging knees to elbows is a progression of toes to bars until you gain the strength to complete the full movement. Starting from a dead hang position with your toes pointed out, draw your knees up into your chest, activating your core with the goal of making contact between your knees and elbows.
  • Plank up-downs will be similar to shoulder taps because we want to keep a stable and controlled core, with little movement in our hips and pelvis. Make sure you’re alternating which arm presses up so you don’t get fatigued too quickly.

Day 3 - Active Recovery

5 Rounds:

  • 8 Single-Leg Glute Bridges
  • 10 Bird Dogs
  • 5 Kettlebell Single-Arm Windmills
  • 8 Yoga Push-Ups
  • 10 Squats to Overhead Reach for Mobility

Key points:

  • When doing your single-leg bridges, focus on driving that planted heel down into the ground as the other leg remains extended, keeping both knees aligned. It’s important to squeeze the glutes and not overextend your lower back.

Day 4 - Strength

Circuit 1 - 3 Rounds

  • 10 Standing Scapular Punches
  • 10 Jumping Pull-Ups

Circuit 2 - 5 Rounds

  • 20 Weighted Step-Ups
  • 10 Ring Rows
  • 10 Alternating Lateral Lunges
  • :30 Hollow Rocks

Related: Use This Secret to Inspire Your Kids to Exercise

Key points:

  • Try not to overthink the scapular punches. Imagine walking into your kitchen and opening your fridge door. Hold your arm straight in front of your shoulder with your palms facing each other. We're looking for that slight retraction of the shoulder blade, forward and back. 
  • During your hollow rocks, make sure the lower back and floor maintain contact, your toes are pointed, and your hands are extended directly over your head.
  • Each time you go through a sequence of HIIT circuit training like this, be sure to reset and focus on form each round.

Day 5 - HIIT Circuit Training 

6 Rounds, :20 each

  • Jump Rope
  • Push Press
  • Alternating Leg Lowering
  • Lateral Hops
  • Hand Release Push-Ups

Day 6 - Strength 

Time to lace ‘em up, because we’ve got a two-mile run on deck followed by three rounds of today’s strength circuit. This circuit will have:

2-Mile Run Followed by 3 Rounds of:

  • 50ft Single Arm Farmer’s Carry
  • 10 Extended Plate Squat
  • 10 Dead Bugs
  • 10 Lateral Step-Ups
  • 10 Hanging Shoulder Taps

Key points:

  • We’re going to focus on the single arm farmer’s carry. Grab a moderately heavy kettlebell, keep your shoulders square and level, push your chest out, and begin to walk at a slow and controlled pace. Once you’ve hit 50 feet, turn around, switch hands, and head back. Circuit training with moves like this allow you to work on mobility, but keep you near a strength training station. 

Day 7 - Rest 


About This Week’s Program Designer: Danielle Bitts, SGX

Danielle Bitts is the Senior Content Manager for Spartan. As a writer, editor, and certified personal trainer living in New York City, she can usually be found working out in the gym or creating content in one.

About This Week’s Performers:

Christina LaGrega:

Christina LaGrega is a certified group fitness instructor, SGX coach, and Spartan Strong educator from Long Island, NY. She has been a staple in the industry for over nine years, traveling the country as a Master Trainer and National Presenter. Christina uses her platform to create positive impact and influence in every community she encounters. She believes that we all acquire the ability to be empowered and be in control of our destination and journey in life. Her spicy, yet authentic personality makes her workouts and training sessions challenging, yet fun. She may be tough, but her beliefs that “growth comes from discomfort” will help guide you through every moment of doubt and right through that finish line.

Walter Derrig:

Originally from New Jersey, Walter grew up with a love of sports. Running fast was his natural talent, so track and field is what he gravitated towards. Excelling with hurdles, 110High and 400 intermediate, he’s no stranger to running over obstacles. After leaving the nightlife to start a career in fitness, he spent time as a head coach at Tone House NYC. He now spends his time focusing on a new gym — Project Sculpt in Hoboken, New Jersey — and racing, chasing his podium dreams on the weekends. His approach to training is simple: If it doesn’t challenge you, it won’t change you. Walter proudly holds his NASM CPT.

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