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Grinders Fitness

5 ★★★★★ 111 Google reviews · Kickboxing gym in Northglenn, Colorado

Kickboxing gym Free trial Beginners welcome Cardio kickboxing Competition team Affiliated

Affiliated gym — reviews and the gym's own info suggest it belongs to a known kickboxing or boxing-fitness franchise or network (think 9Round, iLoveKickboxing, CKO, TITLE Boxing Club or Jabz). Franchise gyms run a consistent class format and are often a friendly, familiar place to start. If a specific brand matters to you, confirm it on the gym's own site.

Boxing, kickboxing and jiu-jitsu gym, with a range of classes to suit all ages and skill levels.

Plan your first class

  • Free trial or intro class most gyms welcome new members with a free trial or intro class — check their site or give them a call to book your first session
  • 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
  • Sparring sparring and partner work for members who want it — always optional, eased in gradually, with the coach controlling the contact
  • 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 grindersfitnessgym.com — book classes and see the live schedule
  • Phone (720) 749-4779

Hours

Monday 11:30 AM–1:30 PM, 4:30–8:30 PM
Tuesday 8:30–10:30 AM, 11:30 AM–1:30 PM, 4:30–8:30 PM
Wednesday 11:30 AM–1:30 PM, 4:30–8:30 PM
Thursday 8:30–10:30 AM, 11:30 AM–1:30 PM, 4:30–8:30 PM
Friday 11:30 AM–1:30 PM, 4:30–7:30 PM
Saturday 8 AM–12 PM
Sunday 8–11 AM

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 Grinders Fitness, confirmed in members' own reviews and the gym's own info — not guessed from the sign out front.

🔥 Cardio Kickboxing 2 mentions

“If you looking for a new way to relieve stress and get a great workout get in here!”

All gyms that run cardio kickboxing →

🌱 Beginners 4 mentions

“The coaches at Grinders are patient and passionate in developing the skills in beginners.”

All gyms that run beginners →

🤜 Sparring 3 mentions

“Whether your focus is on strength training, technical sparring, weight loss, or competitive pursuits, they provide comprehensive support.”

All gyms that run sparring →

🏆 Competition Team

“It’s not your typical “boxing-inspired cardio” spot like Rumble, Title, et al - there are former pro and amateur fighters teaching that will help you level up.”

All gyms that run competition team →

🥊 Boxing 6 mentions

“It’s not your typical “boxing-inspired cardio” spot like Rumble, Title, et al - there are former pro and amateur fighters teaching that will help you level up.”

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 Grinders Fitness — mined from their reviews and the gym's own info.

🥊 Boxing 6 mentions

“It’s not your typical “boxing-inspired cardio” spot like Rumble, Title, et al - there are former pro and amateur fighters teaching that will help you level up.”

Other gyms that also teach boxing →

🏟️ MMA 2 mentions

“Whether you’re a newcomer to boxing or MMA veteran, you’ll love it!”

Other gyms that also teach mma →

🥋 Brazilian Jiu-Jitsu 2 mentions

Other gyms that also teach brazilian jiu-jitsu →

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 111 Google reviews — in their own words.

🧑‍🏫 expert, motivating coaching 3 mentions

“She is an incredible trainer; her encouragement and constant motivation pushes me to heights I never thought possible.”

🌱 welcoming to beginners 7 mentions

“Moreover, the community of members is among the most kind-hearted, welcoming, and FUN individuals I've had the privilege of training alongside.”

🎉 fun, high-energy classes 2 mentions

“If you looking for a new way to relieve stress and get a great workout get in here!”

💦 killer cardio workout 3 mentions

“If you looking for a new way to relieve stress and get a great workout get in here!”

⚖️ great for weight loss 3 mentions

“Whether your focus is on strength training, technical sparring, weight loss, or competitive pursuits, they provide comprehensive support.”

🧼 clean, well-equipped gym 3 mentions

“They always have energetic music playing, and the facility is clean and diverse in what equipment and room you can use.”

From the reviews

I can honestly say joining this amazing gym 3 year ago was one of the best decisions I ever made. I look forward to walking through the doors and always feel pumped up when I leave. Shannon has given me a sense of accomplishment by pushing me to do my best.

★★★★★ — Paula, Mar 2024

The 6-week challenge was tough, but exactly what I needed. It made me realize how important it is to build better habits around fitness, nutrition, and self-care. I’ve worked with Shannon since my days at Title Boxing, where I first fell in love with boxing — and she’s still just as motivating and supportive.

★★★★★ — Lindsey, Apr 2025

This place is awesome! All fitness levels are welcome. Modifications can be made for just about everything. The trainers are very knowledgeable and motivating. If you looking for a new way to relieve stress and get a great workout get in here!!!

★★★★★ — Reny, Dec 2017

I cannot say enough great things about this place! You want a workout to start your day, Jessica brings the energy and intensity to get you started right! You want a workout that makes it feel like it isn’t a workout? Beating up a bag is the best way to go! Shannon is one heck of a trainer!

★★★★★ — Tony, Aug 2024

Excerpts from public Google reviews. Read all 111 reviews →

New to kickboxing? Start at Grinders Fitness

Grinders Fitness comes up as a beginner-friendly gym — noted on their own site. 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 Grinders Fitness

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 Grinders Fitness

455 W 115th Ave #4, Northglenn, CO80234

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.