Renfitness team


RenFitness, LLC is a strength and conditioning team based in Seattle, established by Ren Caldwell. We’re passionate about creating programming, resources and providing education for the whole athlete. Our goals are to reduce injury risk for athletes, improve performance, and give players the tools and knowledge they need to pursue their passions and achieve their goals.

Contact Us


RenFitness Gym Ballard
1404 NW 49th Street
Seattle, WA 98107


Ren Caldwell, NSCA CSCS, FMS, Level 2 Kettlebell Instructor


Owner, CEO, CMO, Strength and Conditioning Coach

In the last few years, I’ve focused on providing high quality, sport-specific and innovative programming to the ultimate community. Now that we have this incredible space I'm excited to be extending my work into other field sports and people of all ages/ability levels - we're creating an awesome gym community! My work with individuals, coaches and teams focuses on helping improve movement patterns and safely load bodies for better performance and injury reduction. I'm especially dedicated to working with young female athletes, as they're under-resourced compared to their male counterparts, and helping people bridge the gap between rehab and returning to play/activity. My biggest thrill is the feedback I get when someone tells me they've added an inch to their vertical, made it through their season without injury for the first time, or can now move through daily tasks without pain. Results-oriented fitness and wellness is my passion!



CTO, Director of programs, Strength and Conditioning Coach

As a coach, I'm particularly invested in helping teams and individuals move their work in the gym and on the field from simply exercising to specific training that helps folks achieve their goals in life, sport, or whatever else they're chasing! My background is in secondary science, health, and outdoor & physical education, as well as coaching all levels and ages of ultimate players and other athletes.

I love working with athletes of all ages and skill levels, leveraging my understanding of the different ways people learn and develop to help reach their goals. I'm especially interested in experimenting with advanced training methods to help folks reach their athletic potential, including Olympic Weightlifting, triphasic training methods, and integrated speed and agility technique work. 

You can find my writing on exercise science on Ultiworld's Tuesday Tips column and my thoughts on equity in ultimate in my column for Upwind Ultimate, BertBrain. You can find me on the field with Seattle Mixtape!


Kira Morin, Basi Pilates Instructor

COO, CFO, Core & Stabilization Coach

As a core coach, I am focused on making sure athletes have a strong and stable foundation so they can train harder, safer and improve their performance. I have a background as a Pilates instructor, mental health specialist, and in Organizational Development. I like helping athletes be healthy and strong, and creating systems that help them be successful with their goals in life and sport from the physical to mental. 

I have been playing recreational ultimate for 10 years and more competitively in the last couple years. I have always loved the Spirit of the Game and the community it brings. When I got injured (hip labral tear and annular tear in my spine) I turned to RenFitness and Pilates to avoid surgery and to get stronger. It worked! When I heard that Ren wanted to open a gym, I jumped at the opportunity to help in any way I could.  With RenFitness I get to use my skills to advance the sport of ultimate and contribute to the community that I consider family. 


Gym Dogs

We love our dogs and hope you do too!!  They are usually with us when we are at the gym, so you will probably meet them when you enter. Each dog is unique so take a second to get to know them.

If you are uncomfortable with dogs, please let us know!

Please DO NOT bring other dogs into the gym without making prior arrangements with us. (Dogs need introductions on neutral territory so they can be welcoming to new friends.)



Speed & Agility Coach

I like to seize opportunities to escape and run (out an open door) & I like to use my sniffer to check you out before deciding to say hi. I love playing ball on the turf! Bert is my human.



doggo supreme

I am super chill - when I am laying down I do not like to be disturbed, but when I am up and about I love saying hi and getting butt scratches! Ren is my human.



Assistant Core Coach

I am very friendly! I will smile when excited (I am told it looks like a snarl). All I want is to smother you in kisses, cuddles, and love. I get really excited when people run or play with frisbees, too! Kira is my human.



Reactivity coach

I’m just a lil’ pup, so I’m learning my manners. I'm working on keeping all four paws on the ground when I greet folks and listening when people tell me "off". Kira is my human.