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Why Doing a Marathon in the Same Year as Your Ironman Can Be a Big Mistake
On paper, it sounds logical. If you can run a marathon, surely you’ll be better prepared to run a marathon off the bike in an Ironman. More toughness. More confidence. More fitness. In reality, for most athletes, doing a standalone marathon in the same year as an Ironman often hurts Ironman performance more than it helps. Here’s why.... Scenario 1: Racing a Marathon 3–6 Months Before Your Ironman This is one of the most common setups I see. The thought process usually goes so
Mark Cullen
Feb 42 min read


How to do properly do Threshold Run Training
Threshold running is one of the most commonly used workouts in endurance training, and also one of the most misunderstood. When done well, it is one of the highest return on investment sessions you can include in a training plan. When done poorly, it becomes a fast track to excessive fatigue and stalled progress. This post breaks down what threshold training actually is, why it works, how hard it should feel, and how to use it effectively without overcooking yourself. What Is
Mark Cullen
Feb 43 min read


How Elite Crossfit Athletes are seeing massive benefits from endurance training
I have worked with many competitive athletes across Triathlon, Running and CrossFit. I truly believe Crossfit athletes are some of the fittest people on the planet. Strong, Technical, Fast and mentally tough. But time and time again, I see one limiter quietly cap performance once workouts get longer, competitions stack events, or fatigue starts to accumulate. That limiter is endurance. I think most are not investing enough time in structured endurance training that supports C
Mark Cullen
Feb 42 min read


The 4 Best Marathon Prep Long Run Workouts
When marathon training goes well, it is rarely about adding more mileage or smashing every long run. The athletes who run their best marathons are the ones who use their long runs with intention, patience, and purpose. In the final 6–8 weeks before race day, long runs shift from general aerobic work to marathon-specific execution. This is where pacing, fueling, rhythm, and confidence are built. Below are four long run styles I rely on heavily with my athletes. Each one serves
Mark Cullen
Feb 43 min read


Why Heart Rate Training Is Often Overrated (And How I Coach Instead)
Heart rate training has been part of endurance sports for decades. For a lot of athletes, it’s the first metric they ever use to structure their training. And while heart rate can be useful, I think it’s often overrated as a primary tool for both training and racing. The biggest issue is that heart rate is reactive , not proactive. It tells you how your body is responding to the work you’ve already done, not what you’re doing in the moment. Pace and power, on the other hand,
Mark Cullen
Feb 42 min read
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