Marija Kostić – Technical Trail Specialist with a Passion for Downhill Precision & Strength
Professional Trail & Sky Running Coach | Downhill Technique Specialist | Strength & Mobility for Trail Runners | Arduua Coach
Hi, I’m Marija Kostić — a trail and sky running coach from Serbia, driven by a deep love for mountains, movement, and human potential.
I help runners build confidence, efficiency, and control on technical terrain, with a coaching style that blends science, intuition, and real mountain experience.
My path into coaching started on the trails of the Balkans — where I discovered the kind of freedom only steep ascents and wild descents can give.
Curious by nature, I studied biomechanics, running technique, and strength training to understand how the body moves — and how to help others move better.
At Arduua, I coach athletes of all levels — from beginners taking their first steps off-road to advanced mountain runners preparing for demanding sky and ultra races.
Whether your challenge is downhill speed, confidence, mobility, or just staying consistent with training, I’m here to guide you every step of the way.
What I specialize in
- Technical downhill running & terrain adaptation
- Strength & mobility for trail runners
- Running mechanics & movement analysis
- Beginner-to-trail transitions & confidence building
- TrainingPeaks structured plans & data analysis
- Supporting runners with busy daily lives
Qualifications & Certifications
- EREPS Level 4 Certified Personal Trainer (Studio One Fitness School)
- Certified in Running Mechanics & Gait Analysis (Human Kinetics)
- Experto en Descensos – TTrail Academy Madrid
Advanced downhill biomechanics, control & technique - TrainingPeaks Essentials & Advanced Essentials
- Fluent in English & Serbian (beginner Spanish)
Competition Background
- Represented Serbia at European & World Skyrunning Championships (2021–2023)
- Ranked among Top 5 female skyrunners in Serbia
- Experienced in vertical kilometers, sky marathons & technical alpine terrain
My coaching philosophy
Trail running is not just numbers. It’s movement — rhythm — feeling the ground beneath your feet.
I coach the whole athlete — body, mind, habits, confidence.
We train with structure, but also with curiosity.
We build strength not only to run faster — but to enjoy the mountain more.
If you want to run with more power, more flow, and more joy in the mountains — I would love to guide your journey.
Train with me
Explore my coaching approach at Arduua Coaching Plans
or reach out directly if you want to start your training journey together.
E-mail: marija.kostic@arduua.com