Why You Need Steady State Cardio and HIIT

Steady state cardio and high intensity interval training (HIIT) have both received their fair share of criticism and praise for their benefits and alleged downfalls. From the days of heavy low-intensity endurance work of marathoners in the 70s, to the refurbishment of HIIT through modalities like Crossfit, the view of the endurance component in the mainstream fitness industry has polarized itself into those advocating for one type of cardiovascular activity completely over the other. However, the elite distance running community has been rejecting this dogma of over polarization for decades, and brings to light training principles rooted in science that are more than applicable to the recreational athlete.

A study conducted in 2009 by Stephen Seiler and Espen Tønnessen sought to understand the influences of volume and intensity on improving endurance performance, and found that of the total work volume one does of cardiovascular exercise, in this case running, was best split with 80% of their total volume of work being performed at an easy-moderate intensity, with roughly only 20% of their volume being performed at a high intensity (above lactate threshold)

Through training analysis of various athletes, they found that this split improved endurance performance the most, rather than a focus on one aspect or the other. This is because low intensity endurance work improved the overall work capacity and base aerobic conditioning, while the high intensity work provided the specific stimulus necessary to condition the athlete for the event they were training for. The researchers further went on to say that the motor/neurological adaptations derived from the low intensity endurance work were crucial for developing the efficiency to sustain and execute the high intensity efforts within that modality, whether it was running, cycling, rowing, or anything else.

What this study ends up emphasizing is that an all-or-nothing approach to aerobic conditioning does not yield optimal training results, and an approach involving the proper distribution of intensities within a given work volume is the way forward.