“What intensity should I be doing for the majority of my training?” As a coach for many different athletes, I get this question a lot.

There is no “one size fits all” answer as so many factors come into play such as training hours, status of athlete (beginner or advance), current training volume, injuries and more. But to narrow it down, there is a specific intensity in which you should be doing most of your training.

For most endurance athletes the intensity during workouts should be moderate to high. This “high intensity” is zones 4-5, with more zone 5 when you start your in-season phase. The reason is that by going through the endurance, base-building phase, you are adding more volume (miles, hours, meters) which results in a majority of the workouts being aerobic.

This is fine if you are working at building your endurance base, but it will not get you faster for races. Research has shown that working at an intensity at or above lactate threshold will improve running economy, lactic threshold, resistance to fatigue and more. Doing aerobic training will also improve this, but it will take longer, which is not an efficient use of training hours.

Instead of running six days a week, run four days, but make two of those tempo days, one an easy run and the last a long day. By working at a higher intensity, not only you will you increase your performance and be ready for your race but there is less chance for injuries. Most injuries come from increases in volume. Of course, you cannot run hard all the time, so it’s about balancing your tempo/speed days with recovery, nutrition and listening to your body.

If you are just starting out with endurance training (less than one year racing), things can get tricky. While higher intensities will improve your performance faster, you still need to build an aerobic base. Taking the time to build this base will help your confidence in completing the distance of your race, improve your running economy, and aerobic fitness, so later on you can concentrate on speed. Beginners should include at least one day of higher intensity work to add some speed into their program. The base phase will range in length depending on race distance, training history and goals.

For athletes who have been training and competing for a number of years, you’ve most likely already built up your endurance and should focus on speed throughout training. When starting to increase your intensity, make sure to gradually build up the miles and keep the rest times at the appropriate lengths. As with anything, it is a balancing act to find what works for yourself in regards to intensity, volume, duration and frequency. Once you find out what works, the opportunities are endless.

Overall, once athletes have already established an endurance base, most should be working out at zones 4-5 and focusing on increasing speed. Not only will this increase performance, but you will be doing less volume and getting better results compared to high volumes of low intensity. Having a coach who understands your sport, and who can design a program which will take you from where you are in winter to where you want to be for your races, will make this journey even more attainable. In this game, it’s about being optimal with our training.