About RenFitness

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 ultimate frisbee players locally and around the world. Our goals are to reduce injury risk for field athletes, improve on-field performance, and give players the tools and knowledge they need to pursue their sport at whatever level they desire.

Contact Us



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

About our team

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 sport-specific training. 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. 

You can find my writing on exercise science in our blog, and my thoughts on equity in ultimate in my column for Upwind Ultimate, BertBrain. You can find me on the field with Seattle Mixtape and the Seattle Cascades, and on the sideline of Ghost Train's practices as a coach.


Kira Morin, Basi Pilates Instructor

COO, CFO, Core & Stabilization Coach

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. I have a background as a Pilates Instructor and in Organizational Development. I like helping people be healthy and strong, and creating systems that help people and organizations be successful. With RenFitness I get to do all of that and get to work in a place that cultivates the ultimate community!