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Inner Strength Martial Arts

4.9 ★★★★★ 153 Google reviews · Kickboxing gym in Duluth, Minnesota

Kids & teens Cardio kickboxing Private lessons Competition team

Plan your first class

  • Cardio kickboxing classes high-energy cardio kickboxing on the bags and pads — a fun, sweaty workout built for fitness and weight loss, at your own pace
  • Kids & teen classes kids and teen kickboxing classes — built around confidence, focus, and fun
  • Private lessons one-on-one coaching available — a focused way to start or to work around a busy schedule; ask about availability and rates
  • Competition team a competition team for members who want to test themselves in the ring — amateur kickboxing, muay thai, or K-1
  • Today see hours ·
  • Website & schedule ismaacademy.com — book classes and see the live schedule
  • Phone +1 920-475-7022

Hours

Monday 4:30–8 pm
Tuesday 4:30–8 pm
Wednesday 4:30–8 pm
Thursday 4:30–8 pm
Friday 4:30–8 pm
Saturday 12–1:30 pm
Sunday 12–2 pm

Hours shift for holidays and class-schedule changes — worth a quick check before a special trip.

The classes they run

Kickboxing classes on the schedule at Inner Strength Martial Arts, confirmed in members' own reviews and the gym's own info — not guessed from the sign out front.

🧒 Kids Kickboxing 16 mentions

“My son is very active and this place has brought him discipline and a great workout that will give him skills to protect himself and his family for the rest of his life ❤️🙏🙌💪”

All gyms that run kids kickboxing →

🏆 Competition Team

“What stood out most to me is their dedication to training young female athletes and giving them real opportunities to compete.”

All gyms that run competition team →

🥊 Boxing

“My son chose karate and jiu jitsu while his brother chose boxing, which occurs at the same time downstairs.”

All gyms that run boxing →

Other martial arts here

Kickboxing gyms are usually multi-discipline. Here's what else members mention training under the same roof at Inner Strength Martial Arts — mined from their reviews and the gym's own info.

🥊 Boxing

“My son chose karate and jiu jitsu while his brother chose boxing, which occurs at the same time downstairs.”

Other gyms that also teach boxing →

🥋 Brazilian Jiu-Jitsu 3 mentions

“started training kickboxing and jiu jitsu at inner strength in august of 2024 and have loved it ever since then.”

Other gyms that also teach brazilian jiu-jitsu →

🥋 Karate 5 mentions

“My child has been doing karate for years, has learned a lot and enjoys it.”

Other gyms that also teach karate →

Disciplines are mined from reviews and the gym's own info — they show what members have trained, not a formal class guarantee. If you specifically want muay thai, boxing, or MMA alongside your kickboxing, confirm the current schedule with the gym.

What members say

The things reviewers bring up again and again across 153 Google reviews — in their own words.

🌱 welcoming to beginners 5 mentions

“Robert is so welcoming and you can tell everyone shares a respect for the art of martial arts.”

🎉 fun, high-energy classes 2 mentions

“My son is very active and this place has brought him discipline and a great workout that will give him skills to protect himself and his family for the rest of his life ❤️🙏🙌💪”

🧒 strong kids program 3 mentions

“Our kids love it, and we even got my niece and nephew to join too!”

💵 good value / fair pricing 2 mentions

“Classes are reasonably priced with flexible scheduling, making it easy to fit into our budget and our schedule.”

💗 welcoming to women 2 mentions

“What stood out most to me is their dedication to training young female athletes and giving them real opportunities to compete.”

🤝 friendly, family gym 10 mentions

“My son is very active and this place has brought him discipline and a great workout that will give him skills to protect himself and his family for the rest of his life ❤️🙏🙌💪”

From the reviews

Inner Strength Martial Arts is both a family friendly place for kids to learn and train as well as a place for adults to come together and learn skills in Jiu Jitsu and Karate under the capable care of Professor Mrotek.

★★★★★ — Joshua, Feb 2021

I definitely have to give this place 5 stars! We were looking for a place for our kids to attend, as there is not a lot to do in our small town. We found this place, and they love it! Robert is very patient with his younger class and takes time to work with them, even when they are a bit shy or embarrassed.

★★★★★ — Ashley, Oct 2025

great place to train. started training kickboxing and jiu jitsu at inner strength in august of 2024 and have loved it ever since then. everyone is very welcoming and kind. the coaches are amazing and teach great techniques everyday. they are also just great people and good examples of what to look up to.

★★★★★ — Clara, Apr 2025

worth the money - flat rate with incremental fees depending on how many classes you want to take, no additional fees to sign up and includes access to equipment outside of class schedules.

★★★★★ — Kari, Jun 2026

Excerpts from public Google reviews. Read all 153 reviews →

Your first kickboxing class at Inner Strength Martial Arts

Nervous about walking into a kickboxing gym for the first time? Almost everyone is, and good coaches expect beginners to come through the door. Here's what to know. What to expect: a typical first class is a warm-up, then drilling the basics — stance, footwork, and punches and kicks on pads or a heavy bag — not hard sparring. Go at your own pace and rest whenever you need to; no one will bat an eye. What to wear: comfortable athletic clothes you can move and sweat in, and supportive trainers. What to bring: water, and hand wraps and gloves if you have them — many gyms lend loaner gloves for a first class, so it's worth asking when you call. As you keep training you'll add your own gloves and wraps (and shin guards once you start sparring). Sparring is optional and eases in gradually, once your basics are solid. Arrive 10–15 minutes early to sign a waiver and meet the coach. It gets easier fast — most people feel far more at home by their third class.

Kickboxing is a contact sport. Warm up, pace yourself, listen to your coaches, and if you have any injuries or health concerns, mention them before class and check with a doctor if you're unsure.

Where to find Inner Strength Martial Arts

2908 W 3rd St, Duluth, MN55806

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Listing verified July 2026 from public business records and member reviews. Something out of date? Report a correction. Own this gym? Claim your listing — it's free.