What is the Build Phase?
The Build Phase follows the Base Phase and aims to specifically increase your endurance level and enable longer running segments.
It builds directly on the Sweet Spot intervals of the Base C Phase, with the goal of continuing to develop your endurance at a high pace.
HIT sessions remain part of your training, but the focus now shifts. In addition to high-intensity intervals, threshold workis introduced. You’ll now train more at your anaerobic threshold – the point where your body still works efficiently just before fatigue sets in.
These sessions improve your ability to maintain a fast pace for longer, increase your lactate tolerance, and boost your performance in competition.
What changes now?
Easy runs get a bit longer
Walk breaks become shorter or less frequent
Your body is challenged purposefully but not overwhelmed
Training intensity distribution shifts
What is the focus?
Longer continuous running segments
Developing pace stability (pacing)
Threshold intervals challenge your body in a new way – “steady state” is the motto. You aim to find a sustainable but demanding pace you can hold for extended periods.
Mental endurance: stay focused, even when it gets unfamiliar
What should you keep in mind?
Fatigue is normal – but watch for signs of overtraining
Stay hydrated and eat enough to replenish your energy stores
Prioritize good sleep – recovery is especially important now
Tip:
You’ll be doing fewer high-intensity bursts and spending more time in the threshold zone – right on the edge where your body learns to run fast and efficiently at the same time. It feels tough but manageable. If you stick with it, you’ll notice your pace becoming more stable, your stamina increasing, and your confidence growing.
Fun Fact:
In this phase, your body becomes better at using fat as a fuel source – you become more “economical” when running. This means your heart rate will gradually decrease compared to the start of the plan.