Quality and interval sessions need to be hard or very hard to be effective and easy/endurance days need to be easy! A mistake we often see as running coaches is when runners do all their runs at a medium or hard-ish effort. It's not slow enough to be restorative or boost aerobic capacity and yet it's not fast enough to produce meaningful physiological change. You just get good at running at that medium pace, and don’ get any faster.
The first part of the equation is to run your easy days at a low effort. The second part is to run your quality and interval sessions FAST! It is very difficult to achieve the high levels of intensity required if a lot of your running is at a medium effort because you simply feel to fatigued form this type of work. The very hard interval work should be very challenging but doable and meet the target set by your plan for the length of session or interval required.
Many runners are afraid to run to easy as they feel they are missing a fastest time on a local loop or trying to keep up with others on social training apps like Strava, or simply they are not getting any level of conditioning from this intensity level, this could really be limiting your improvements and progression, holding you back from making big improvements with the high intensity training.
High Intensity training is challenging physically and mentally and requires full commitment to the session, ensuring you are fresh and well fuelled for these runs is a must, as well as performing a good warm up in the form of drills and some steadier running to reduce injury risk. Its often the case that runners are worried they won’t meet the pace or intensity level set and will start their intervals above the target intensity to get ahead of the split pace, which essentially means you work anaerobically for a short time and then get slower as the time progresses, pacing is key and confidence in your ability to achieve the intensity set by your coach.
To make the huge physiological gains from your hard intervals and benefit from the restorative and aerobic capacity conditioning of your easy runs make sure you are keeping your easy training easy and hard training hard.
How hard are your hard days? How easy are your easy runs? Do you fall into the trap of the medium intensity running?