Marni was born and raised in Lexington, Kentucky, where her early years were shaped by competitive swimming, playing piano, and a growing passion for science. After four years as a collegiate swimmer (specializing in 100 fly, 200 breaststroke, 200 fly), she earned a Bachelor of Arts in Exercise Science with a minor in Psychology from Transylvania University in 2004. During her senior year, she joined the cross country team and discovered a love for off-road running.

In 2004, Marni moved to South Florida to attend graduate school at Florida Atlantic University, earning a Master of Science in Exercise Physiology in 2005. While balancing research, teaching, and graduate studies, she wanted a new athletic challenge and began training for her first marathon —coaching herself on a modest budget with a hybrid bike equipped with a kickstand. She qualified for the Boston Marathon in her debut marathon and quickly fell in love with endurance sports. A year later, within eight months, she completed the Boston Marathon, Disney Half Ironman, and Ironman Florida, qualifying for the Ironman World Championship after winning her age group (18-24) at her first Ironman.

In 2006, Marni met Karel on May 31st (her birthday). They were set up on a bike ride by mutual friends. A year later they got engaged (on Karel’s birthday, September 22) and in October 2008 they got married on the beach in Dunedin, Florida.

In 2011, after earning her Registered Dietitian credential, Marni worked as a Clinical Dietitian at Baptist Medical Center Beaches before launching Trimarni Coaching and Nutrition in 2012. In 2014, she and her husband Karel relocated to Greenville, South Carolina to grow the business full-time. Today, she is a licensed dietitian in South Carolina and holds a Board Certification in Sports Dietetics (CSSD).

Marni is the author of 3 books and has contributed to several publications such as Triathlete, Women’s Running, Bicycling, Outside and Men’s Health. While living in Jacksonville, Marni had several TV segments on nutrition at News4Jax. She was an ambassador for brands like Clif Bar and Oakley Women and is an accomplished public speaker.

Over the past two decades, Marni has completed 22 Ironman races, including six Ironman World Championship appearances and three XTRI events. Her accomplishments include a 5th place finish in the 40–44 age group at the 2021 Ironman World Championship in St. George and overall amateur female victories at Ironman 70.3 Louisville and Ironman Chattanooga in 2024. Along the way, she has coached athletes around the world and built a thriving coaching and nutrition practice grounded in science, experience, and support.

Marni’s journey has also included setbacks, injuries, and personal loss, including the passing of her father in 2014 (at the age of 67 years), who was her greatest supporter and the loss of her soul dog Campy, who passed away in 2023 at the age of 17 years. Those experiences continue to shape her perspective on health, resilience, and making the most of every day.

Through Trimarni Coaching and Nutrition, Marni remains passionate about helping endurance athletes fuel smarter, train stronger, and appreciate the incredible potential of the human body.

Karel grew up in the Czech Republic during the post-communist era, where opportunities were limited. Determined to build a better future, he moved to the United States in pursuit of the American dream. His early years in the U.S. were spent working multiple low-paying jobs—cleaning floors and working long hours just to make ends meet. For nearly five years, survival came first, and cycling was put on hold.

In 2005, everything changed. After reconnecting with cycling through the Gearlink cycling team, Karel returned to racing and quickly rose through the ranks of competitive cycling in Florida. Within two years, he advanced from Cat 5 to Cat 1, winning the Florida Points Series and Florida Cup Series along the way before competing at the national level against domestic professional riders. Rather than settling for local success, he constantly sought bigger challenges and stronger competition.

Karel met Marni in 2006 on a group ride—on her birthday—and the two have been building a life of endurance sport and adventure together ever since. After years working in the cycling industry and managing Trek Bicycle stores in Jacksonville, Florida, Karel joined Trimarni Coaching and Nutrition full-time in 2014. Shortly after, he and Marni relocated to Greenville, South Carolina, where they embraced a lifestyle centered around training, nature, and adventure.

In 2018, Karel officially became a U.S. citizen.

Over the past few years, Karel has discovered his passion for off-road racing, gravel cycling, and extreme triathlon events. Despite setbacks—including a serious hand injury in 2021 and two knee surgeries before completing Patagonman in 2025—he continues to pursue new challenges, including multi-day stage races and XTRI events around the world. In 2026, Marni and Karel completed Cape Epic - an iconic 8-stage mountain bike race in South Africa.

Karel believes deeply in self-improvement, resilience, and embracing discomfort. Rather than chasing times, he chases competition and personal growth. While cycling and triathlon are passions—not professions—he values the lifestyle they create: one built around health, movement, and adventure.

Today, Karel works closely with athletes through coaching, private camps, cycling skills instruction, and RETÜL bike fitting for age-group and professional athletes across the United States. He is passionate about helping athletes build confidence, improve performance, and discover what they are truly capable of achieving.

Karel loves coffee, croissants, chocolate, cats and ice cream.
Marni loves pizza, cinnamon rolls, all animals (and creatures) and carrot cake.