Founded in 2018 by Greg Marshall, Treeline Endurance specializes in individualized coaching for trail runners, ultrarunners, road runners, and endurance athletes pursuing meaningful goals, from first finish lines to podium performances. Our work is grounded in exercise science, informed by years of coaching experience, and refined through close, ongoing collaboration with each athlete.

We believe strong training is not generic. Every athlete brings a unique physiology, schedule, training history, and motivation to the process. Coaching at Treeline Endurance emphasizes customized planning, adaptable scheduling, and clear communication to ensure training integrates seamlessly into real life, not the other way around.

Our approach blends structured endurance development with strength training, recovery practices, fueling strategy, and race-specific preparation. Athletes receive support not only for workouts, but also for decisions around gear, nutrition, terrain demands, and long-term progression. The goal is not just performance on race day, but durability, confidence, and consistency across seasons.

In addition to 1-on-1 coaching, Treeline Endurance offers both static and custom training plans designed for athletes who want structured, high-quality guidance with greater flexibility. These plans are built using the same evidence-based principles that guide our coaching work, with clear weekly objectives, purposeful workouts, and progression tailored to specific race demands. Custom plans provide an added layer of personalization, accounting for an athlete’s background, schedule, and goals, while static plans offer a proven framework for athletes who prefer a self-directed approach without sacrificing rigor or intention.

Treeline Endurance also partners with select races and organizations to improve the athlete experience through education, training resources, and transparent coaching support.

Treeline Endurance LLC

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