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Mixed Martial Arts Underground

4.7 ★★★★★ 31 Google reviews · Kickboxing gym in Crystal Lake, Illinois

Beginners welcome Kids & teens Cardio kickboxing Competition team

Plan your first class

  • Beginner-friendly all fitness levels welcome, including total beginners — no experience needed, and you get in shape by training, not before
  • 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
  • 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 mmaunderground.info — book classes and see the live schedule
  • Phone +1 847-219-5920

Hours

Monday 9–10 am, 5–8:30 pm
Tuesday 9–10 am, 4:30–8:30 pm
Wednesday 9–10 am, 5–8:30 pm
Thursday 9–10 am, 4:30–8:30 pm
Friday 9–10 am, 5–7 pm
Saturday 10 am–12 pm
Sunday Closed

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 Mixed Martial Arts Underground, confirmed in members' own reviews and the gym's own info — not guessed from the sign out front.

🔥 Cardio Kickboxing 3 mentions

“Whether you are just looking for a great cardio burn and strengthening to various forms of fighting, you will find it here.”

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🧒 Kids Kickboxing 2 mentions

“There is even a kids class for young ones to learn mixed martial arts, I have a 7 year old daughter and she absolutely loves it just as much as I do.”

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💪 Women's Kickboxing

“As a woman, I have not only physically strengthened, but mentally strengthened.”

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🌱 Beginners 4 mentions

“MMA Underground is a highly respectable gym carrying a variety of workouts for all levels with a supportive environment to push everyone in a direction of total wellness.”

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🏆 Competition Team

“Whether you want to compete, become a professional fighter, tone up, or just pick up a new hobby Oscar and the team at MMA Underground can help you achieve your fitness goals.”

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🥊 Boxing 4 mentions

“I have never had better results from any other workout before-- the 30 minute strength training (Kettlebells, circuits, kick boxing, etc) is always a challenge.”

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Kickboxing Bootcamp

“I have trained in countless gyms across the country, that includes Weight Lifting gyms, Boxing Gyms, Mixed Martial Arts, boot camp training and Aerobics.”

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Other martial arts here

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

🥊 Boxing 4 mentions

“I have never had better results from any other workout before-- the 30 minute strength training (Kettlebells, circuits, kick boxing, etc) is always a challenge.”

Other gyms that also teach boxing →

🏟️ MMA 20 mentions

“MMA Underground is a highly respectable gym carrying a variety of workouts for all levels with a supportive environment to push everyone in a direction of total wellness.”

Other gyms that also teach mma →

🛡️ Self-Defense

“In training, fighters are mixed among weight classes as there is also an emphasis on real-world fighting and self-defense.”

Other gyms that also teach self-defense →

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 31 Google reviews — in their own words.

🧑‍🏫 expert, motivating coaching 2 mentions

“Great trainers that will teach and motivate you.”

🌱 welcoming to beginners 5 mentions

“MMA Underground is a highly respectable gym carrying a variety of workouts for all levels with a supportive environment to push everyone in a direction of total wellness.”

🎉 fun, high-energy classes 3 mentions

“If you are just looking for a great workout he has that everyday also.”

💦 killer cardio workout 6 mentions

“The workouts (before the MMA classes) are fantastic and put me in the best shape of my life and can be suited for any person with any level of endurance.”

⚖️ great for weight loss 5 mentions

“I have never had better results from any other workout before-- the 30 minute strength training (Kettlebells, circuits, kick boxing, etc) is always a challenge.”

🏆 active competition / fight team 2 mentions

“Whether you want to compete, become a professional fighter, tone up, or just pick up a new hobby Oscar and the team at MMA Underground can help you achieve your fitness goals.”

From the reviews

I've tried several gyms and could never find a place that I felt like I could fit in or be comfortable or get motivated to achieve what I wanted. MMA Underground is hands down the best experience I've ever had in a gym. Oscar is a wonderful instructor with an extensive martial arts background.

★★★★★ — Liz, Mar 2015

MMA Underground has changed my life for the better. The trainers and students are absolutely amazing. Anyone is willing to help you out and help improve your weaknesses. If you want to become a great fighter quickly this is the place to train at.

★★★★★ — Piotr, Mar 2015

VERY NEWCOMER FRIENDLY! I trained here for about a year and a half. Unlike larger gyms, training was very personal and the sensei was constantly reviewing techniques and movements during drills.

★★★★★ — Joshua, Mar 2015

I am so GRATEFUL to have found this dojo. Sensei Oscar is a amazing teacher.He also is a wonderful example of a man who incorporates not only his teachings but his thoughts of who a truly good person is. I have personally seen awesome transformations of the MMA fighters who train there.

★★★★★ — Maria, Mar 2015

Excerpts from public Google reviews. Read all 31 reviews →

New to kickboxing? Start at Mixed Martial Arts Underground

Mixed Martial Arts Underground comes up as a beginner-friendly gym, going by their listing and members’ reviews. If you've never thrown a punch or a kick, that's exactly who a good beginners class is for. A few things worth knowing before your first week. First, you don't need to be fit or coordinated to start — you get in shape by training, not before it, and coaches scale every drill to you. Second, you won't be thrown into hard sparring — reputable gyms build the basics (stance, footwork, and punches and kicks on pads and bags) first, and any contact eases in gradually under a coach's control. Third, all fitness levels really are welcome — ask about a dedicated beginners or fundamentals class time so your first session is alongside others who are also starting out. Most gyms are happy to let you watch or try a class first, so reach out before you commit.

Check beginner classes on their site

Your first kickboxing class at Mixed Martial Arts Underground

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 Mixed Martial Arts Underground

835 S Virginia Rd #C, Crystal Lake, IL60014

Get directions

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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.