Introducing the CrossFit Leiden team

Meet the fitness experts ready to help you achieve your fitness goals.

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CrossFit Leiden

Our team of fitness and nutrition professionals are invested in your health. We make every decision with our members’ well-being in mind. Achieve your goals with us!

The Team


Jeroen van Duijn & Kees Houwaart


Kees Houwaart: Born into Fitness Kees Houwaart was destined for the fitness world. Raised in a family that owned a top-tier gym in Katwijk, he was surrounded by barbells and dumbbells from a young age. After discovering the transformative power of CrossFit in 2012, Kees knew he had to share it. In 2014, he founded Gymbox Noordwijk, the first CrossFit-focused gym in the area. Kees, along with his wife Nathalie and their two sons Neal and Jake, reside in Katwijk aan Zee. Jeroen van Duijn: From Finance to Fitness Jeroen van Duijn’s love for sports was instilled early on by his athlete parents. From football to surfing, he was always active. Initially in Corporate Finance, Jeroen took a bold step in 2014 to follow his passion. His journey led him to Chile, where he trained people and taught nutrition. Returning to the Netherlands, transitioning to the fitness industry was a natural move. Jeroen, his wife Amanda, and their daughter Zoe live in Katwijk aan Zee and are expecting a new addition in February 2024. The Partnership That Built a Network Kees and Jeroen’s paths crossed in 2013, and they instantly connected over their love for fitness and community. In 2015, they teamed up with Coach Jeroen van der Most to co-found CrossFit Leiden. This trio laid the groundwork for what has now blossomed into the Creative Sports Company network of gyms. Though Jeroen van der Most took a different route in 2020, fate brought the original team back together in 2023. This is the story of how CrossFit Leiden came to be-a place where fitness legacies and entrepreneurial spirits unite to create a community of champions.

Rochelle coach at CrossFit Leiden



Say hello to Rochelle, the coach who’s won over the toughest critic-my daughter Zoe-thanks to her ‘Bring Your Kid’ sessions. Don’t let her friendly face fool you; she’s a gymnastics wizard who can teach anyone, from toddlers to centenarians, how to do a handstand or a cartwheel. When she’s not at CrossFit Leiden, she’s busy being a Dutch national gymnastics coach. Rochelle stumbled upon us during the Corona period, initially looking for a place to train her gymnastics squad. A few sessions in, and she was hooked-not just on gymnastics but also on weightlifting. Now, she’s a regular face, coaching at least two days a week at CrossFit Leiden, all while prepping her gymnastics team for world cups. Talk about a multitasker!

Stefania coach at CrossFit Leiden

Stefania Nalmpanti


Meet Stefania Nalmpanti, our Greek goddess of fitness who spices up CrossFit Leiden like a dash of oregano on a Greek salad. She joined us in 2017 and quickly went from member to coach, thanks to her professional water polo background. Yes, she’s played at the highest level, and now she’s scoring goals as a badass fit mom. Stefania is the coach who can teach you to lift like Hercules while also making sure you eat like a nutritionist. She’s so committed to your success that she won’t rest until you’re performing at your Olympian best. And let’s be real, if Stefania can juggle coaching, nutrition guidance, and motherhood, she can certainly help you juggle dumbbells and diet plans!

Jeffrey coach at CrossFit Leiden

Jeffrey Perez Stoof


Introducing Jeffrey Perez Stoof, the coach with a name as smooth as his coaching style-and yes, it hints at his Spanish flair. He joined us during the Corona era, but don’t let that fool you. This guy was a professional football player before he traded his cleats for CrossFit shoes (seriously, Google him!). Jeffrey knows what it takes to level up, both on the field and in the gym. He’s the coach who’ll push you to your limits while making sure you’re as comfortable as a cat on a warm windowsill. Depending on the group he’s coaching, he’s either ‘the butcher’-serving up intense workouts-or the ‘listening ear,’ offering a dose of empathy with your exercise. Like a chameleon, he adapts to what you need, ensuring each session is a win-win.

Wouter coach at CrossFit Leiden

Wouter Laurens


Introducing Wouter Laurens, the man who turned from flipping in the air to flipping kettlebells at CrossFit Leiden. He joined us in 2017 and immediately stood out, thanks to his acro gymnastics background. Seriously, the guy could do handstands before he could walk! After a nearly two-year island retreat in Saba, Wouter returned to us in December 2019, and we couldn’t be happier. He’s the coach who can teach you high-level moves while also breaking down the ABCs of basic movement. As the ‘Welcome Wagon’ of CrossFit Leiden, Wouter is in charge of onboarding new members, ensuring everyone starts off on the right foot-or handstand. He’s a social butterfly at our community events, and if you’re looking to share a beer with him, make sure to pencil in one of our Flex Friday (bring a friend) sessions. Cheers!


Jari Jansen


Meet Jari Jansen, the guy who was so eager to join CrossFit Leiden, he showed up during our opening week in 2016-before he even cracked open a textbook at CIOS. Talk about being ahead of the game! With roots in sunny Curacao, Jari brings a tropical flair to our Dutch climate. Over the years, he’s evolved from an eager intern to a coach who’s basically a Swiss Army knife of skills. Need to fix an injury? Jari’s your guy. Want to train future coaches? He’s on it. You’ll catch him leading a few classes, but he’s mostly the ‘Yoda’ of workshops, seminars, and educational programs. And get this: he’s so fit, he can grow muscles just by looking at a kettlebell. No, really!

Sem coach at CrossFit Leiden

Sem Li


Meet Sem Li, the coach whose smile is as permanent as a tattoo. He’s the guy who’ll lift your spirits, no matter what kind of day you’re having. And while he’s at it, don’t be surprised if he tries to sell you something from his Panda Power brand-talk about multitasking! Sem is a big fan of Olympic weightlifting, and you’re more likely to spot a panda running than see him jog. He’s the kind of coach who makes a point to connect with everyone in his classes, offering a unique blend of energy and friendliness. And get this: he’s so committed to CrossFit that he’s up training at 5 a.m., just so he can coach you in the 6 a.m. class. Now that’s dedication!




Meet Saskia, our General Manager and Client Success Manager, who’s so good at her job, she might as well wear a superhero cape. A few years ago, she joined CrossFit Leiden to kick her back pain to the curb, and let’s just say, she’s never looked back—literally! Saskia enjoyed the gym so much that she traded her scrubs in the emergency room for workout gear, shifting from saving lives in the ER to helping people avoid it altogether. Talk about a career pivot! She’s the wizard behind the curtain, managing the day-to-day operations and making sure all our members are on the fast track to success. With Saskia at the helm, you’re not just joining a gym; you’re joining a success story in the making.

Kasper coach at CrossFit Leiden



Introducing Kasper, the newest star in our CrossFit Leiden galaxy. By day, he’s molding young minds as a history teacher—think Indiana Jones but with lesson plans. By night and on his days off, he swaps his chalk for chalk powder, helping you move better and live healthier. Kasper isn’t new to the coaching game; he’s been at it for years and even founded his own CrossFit gym. That’s right, he’s a fitness entrepreneur! Always up for a challenge, Kasper sets new goals and adventures for himself faster than you can say ‘burpee.’ He’s a living, lifting testament to what it means to be an inspiration, or as we like to call him, a ‘real-life action hero.




Max has worked as a coach for several years, including the last four as a personal trainer and CrossFit coach in a PT studio.
He is passionate about hiking and wild camping, activities he loves to enjoy with his family, and is always ready for a new adventure.
As a coach, Max loves creating a fun and positive atmosphere. His favorite WOD is ‘Cindy’ because it’s perfectly balanced – not too long, not too short, and suitable for everyone to join in.
Having already led a few classes as a guest coach and trained with us for several weeks. Max felt immediately welcome in our community and is looking forward to meeting everyone. If you see him in the box don’t hesitate to introduce yourself and have a chat with him.




Say hello to Maaike, the welcoming committee, gatekeeper, and all-around first impression of CrossFit Leiden. If you’re thinking about joining us, chances are you’ll chat with Maaike first—and you’ll be glad you did! She’s been a member for years and is basically the Yoda of living a better life. Whether it’s teaching you to breathe like you’re meditating on a mountaintop or helping you discover your life’s mission, Maaike’s got you covered. Her role here is to chat with potential new members, and she’s so good at it, you’ll feel like you’re catching up with an old friend. Together, you’ll figure out if CrossFit Leiden is the right fit for you—and spoiler alert: it probably is!

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