What is base fitness?

Wondering what is meant by your base fitness level and why it is so important for endurance athletes? Dermott Hayes explains all

We explain why base fitness is so important

An athlete’s ‘base’ fitness is what provides the foundations for them to develop the ability to become stronger, faster and endure greater levels of tolerance to discomfort. Imagine building a house and the very first job is to dig down deep and lay foundations. This type of work can be dull and long, but it means that the house is solid and will stand for years. Your body is that house, and your base training is like laying the foundations. If you revisit the base training each year, you’re more likely to be stronger and resilient to injury.


The majority, in the region of 70-80%, of base training focuses on longer hours of moderate-intensity work that will improve an athlete’s ability to utilise fat as an energy source and develop the aerobic system – long steady bike rides and trail runs are perfect for this. At this stage, high-intensity efforts should be kept to a minimum and include sufficient rest  between them. An added benefit of base training is that you’re less likely to get injured due to the intensity being lower. Cut short the base phase at your peril!

Free 6 month Ironman base training plan