From Special Ops to Endurance Sports: Performance Nutrition with Kelsey Bailey

Kelsey Bailey didn’t start her career in endurance sports. Before working with professional athletes, she spent eight years as a performance dietitian with U.S. Special Operations, supporting tactical athletes whose lives depended on fueling well. That experience shaped her approach to nutrition: practical, evidence-based, and laser-focused on performance.

Now based in Denver, Bailey splits her time between her role at Eternal, a performance health company, and her consulting work in both the tactical and endurance spaces. She also balances life as a mother of three boys, which, she jokes, is another form of endurance sport.

Lessons From the Tactical World

Working with military, fire, and police populations gave Bailey insight into how stress and nutrition interact. Tactical athletes face irregular schedules, sleep disruption, and environments that test the limits of the body.

She draws parallels to endurance athletes who also deal with high training loads and cumulative stress. Both require careful attention to energy availability, recovery, and fueling habits that can withstand pressure.

Transitioning Into Endurance Sports

Bailey now applies that expertise to the running world. She works with marathoners, trail runners, and ultrarunners, helping them navigate the fueling mistakes she sees over and over. One of the most common? Under-fueling during both training and racing.

She emphasizes the importance of consistency over perfection. Missing a single gel won’t derail a race, but weeks of inadequate fueling will. For Bailey, nutrition is a long game: repeated, consistent behaviors that support performance and health.

Nutrition Fundamentals

When asked what really matters, Bailey strips it down to essentials: eating enough, balancing macronutrients, and matching fueling to training demand.

She often reminds athletes that performance isn’t just about race day—it’s about what you do daily. Skipping meals, ignoring recovery nutrition, or cutting carbs might seem harmless short term, but the long-term effects include poor adaptation, fatigue, and increased injury risk.

Her message is simple: eat to support the stress you’re putting on your body.

Women’s Health and Energy Availability

A growing area of Bailey’s work is women’s health in endurance sports. She sees the consequences of low energy availability, menstrual dysfunction, and hormonal imbalances that stem from chronic under-fueling.

She encourages female athletes to track their cycles, pay attention to symptoms, and seek help early if something feels off. While the cultural narrative often pushes “lighter is faster,” Bailey stresses that long-term health and sustainable training should take priority.

Navigating Social Media Noise

Bailey is vocal about the downsides of social media nutrition advice. She knows athletes are bombarded with fads, extreme diets, and conflicting information.

Her antidote is context. What works for one person may not work for another, and advice without nuance can do more harm than good. She advises athletes to seek credible sources, understand their unique needs, and not get swept away by trends.

Eternal and Comprehensive Care

As the lead performance dietitian at Eternal, Bailey helps deliver two-hour performance physicals that include metabolic testing, mobility assessments, bloodwork, and movement analysis. The idea is to give athletes a complete picture of their health and performance potential, rather than piecemeal fixes.

She believes this integrated approach can prevent common problems before they derail training. For Bailey, performance health is proactive, not reactive.

What You’ll Learn in This Episode

• How Kelsey’s Special Ops background informs her work with athletes

• The most common fueling mistakes in endurance sports

• Why women’s health requires specific attention in training and nutrition

• How to navigate nutrition advice in the age of social media

• The value of proactive, integrated performance health testing

Download this one for your long run this weekend 👇

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Building Authentic Partnerships in the Running World with Sydney Tremaine

From Family Vacation Run to Ultra Trails

Sydney’s running journey began with a competitive streak on a family trip, when she pushed herself not to let her dad finish ahead of her. That spark carried into middle school cross country, through high school and college racing, and eventually into trail ultramarathons. She battled through challenges along the way, including a heart condition diagnosed when she was a teenager, but continued to train and race because she found joy and community in the sport. Over the years, running became not just a physical outlet but also a guiding thread through her education, career, and friendships.

From Product Support to Partnerships at Garmin

Her professional path started in Garmin’s product support department, where she spent hours troubleshooting watches and devices with customers. At first glance, it wasn’t glamorous work, but Sydney credits those years with teaching her how important it is to meet people where they are. Every call was a chance to connect with another runner or cyclist and to learn the product from the inside out.

From there, she moved into sales roles before joining the sponsorship team, where she now oversees athlete partnerships and grassroots activations. Garmin’s roster of athletes has grown significantly in recent years, and Sydney has been part of shaping those relationships. What began with a small group of sponsored runners has evolved into a diverse team of road, trail, and multisport athletes representing the brand around the world.

Brand Marketing vs. Performance Marketing

Sydney’s approach to sponsorship is rooted in brand building, not performance metrics. For her, it is not about counting social posts or enforcing rigid requirements but about creating authentic connections between Garmin and the communities it serves. She sees athletes as extensions of the marketing team rather than as transactional partners.

By encouraging organic storytelling and trusting athletes to represent the brand in ways that feel natural, Garmin builds deeper, longer-lasting relationships. Sydney believes this strategy pays off in brand equity and community trust, even if it looks less formulaic than some performance marketing campaigns.

Building Relationships with Athletes

The heart of Sydney’s role is building relationships with Garmin’s sponsored athletes. She emphasizes the importance of partnership being a two-way street. Athletes bring personality, authenticity, and stories that resonate with fans, while Garmin provides support, resources, and a platform.

She has worked with athletes across disciplines, from trail runners like Dylan Bowman to road stars like Kiera D’Amato and Sharon Lokedi. Each brings something unique to the brand, and Sydney’s role is to create space for them to showcase it. Garmin’s priority is not just podium results but aligning with people who are good representatives of the sport and community.

The Future of Sponsorship and the Sport

Trail and ultra running are evolving quickly, with faster times, larger events, and greater attention from big sponsors. Sydney acknowledges the concerns some runners have about maintaining the grassroots feel of the sport while welcoming growth and investment. She believes the industry is still learning how to balance those priorities, but there is a right way to do it—one that keeps the spirit of the community intact while also embracing opportunity.

Garmin has begun experimenting with new event models, including launching its own marathon series in cities like Toledo and Tucson. These events give Garmin more control while also creating opportunities to partner with other brands and race organizers. Sydney describes these races as a chance to craft an experience that feels fully Garmin while still being inclusive and collaborative.

Why Brand Partnerships Matter

For Sydney, the key to sponsorship is character. Performance matters, but not as much as the kind of person an athlete is. She has seen examples of highly successful athletes who were not good partners, and she believes the real value comes from working with individuals who embody Garmin’s values, support the community, and inspire others to get outside.

That philosophy guides how she evaluates new partnerships and how she believes sponsorship should evolve. Brands that focus only on results may miss the opportunity to connect more meaningfully with their audience.

Get a Clearer Picture of Your Health 📈

I’m thrilled to introduce our new partner, Eternal — a performance health company built for runners, endurance athletes, and anyone serious about their training. Their two-hour in-person performance physical goes way beyond a standard checkup with mobility assessments, metabolic testing, bloodwork, and a full movement analysis from real experts.

Whether you’re chasing PRs or just want a clearer picture of your health, Eternal helps you run harder and longer. Book your performance physical at eternal.co, use the code FTLR for 10% off, and keep doing what you love for years to come.

About Jon Levitt and For The Long Run

Jon is a runner, cyclist, and podcast host from Boston, MA, who now lives in Boulder, CO. For The Long Run is aimed at exploring the why behind what keeps runners running long, strong, and motivated.

Follow Jon on Instagram, LinkedIn, and Twitter.