It’s no secret that sprinters will do anything to avoid endurance training and distance runners would rather go the extra mile or ten before working on speed drills. Such is the nature of humans and wanting to stay in our proverbial “comfort zones”. However, avoiding training in a variety of different energy zones is done at our own peril. Only through the adaptation of multiple stressors do we really become the best version of ourselves. The best way to understand this can be done with a simple formula: stress + rest = growth.
Endurance training is a very important stressor for all athletes. It accustoms athletes to the grind that is long distance running. For runners, cyclists, and the like—this means dedicated training time between 70%-90% of max heart rate zones. These sessions aren’t often seen as “sexy” like the speed interval days, but they definitely do a ton for our overall fitness. Since a range from 70-90% is quite vague let me break it down into more specific examples and explain everything you’ll need to know.
I always begin my training programs from the outer edges of the speed zones and then work my way into the specifics. This means short to medium range aerobic runs and, of course, the weekly long run. These training runs should extend somewhere between 70-79% of max heart rate or about 60 to 90 seconds per mile slower than your current marathon pace. The purpose is to build out more mitochondria (the power center in the cell), improve transfer of energy from the blood to the working muscles, and improve muscle and tendon stiffness. Since these runs aren’t as taxing as higher intensity work, they end up being the bulk of our mileage in a typical training week. These are also known as easy runs and are what we call “base work”. These miles build the foundation upon which all of the following endurance workouts come to rest upon. If you haven’t built out a sufficient base,then faster running becomes much harder to maintain.
As soon as we’ve mastered easy runs, we can start to move on to what I like to call “Aerobic Threshold” runs—also known as marathon pace. This training zone tends to be somewhere between 80 - 85% of max heart rate. This is where I begin all of my tempo run paces early in a training block and then I work to extend it out over longer distances. This is especially helpful when training for half marathon or marathon race distances. The purpose of this zone is to maximize an athlete's ability to utilize fats and carbohydrates as an energy source. If your pace is too fast, your body will switch over to only carbs. When this happens, hitting the wall becomes inevitable. However, if we stick to our prescribed effort level, over time our body will adapt and faster running will feel easier over the same distances. By developing this first system in the harder zones of training it creates another step on which to build upon for shorter race distances. A weekly tempo run at this effort early in the season is crucial for building fitness while avoiding over-training.
The final phase is referred to in different terms but the common phrase is threshold. You’ll hear people use words like ‘lactate threshold, anaerobic threshold, or functional threshold power. It’s all the same. Regardless of what you call it,this zone reaches from 85-89% of your max heart rate and is hands down the most important zone to build your fitness for any race distance from the 3k up to the marathon. In layman terms, this begins at your half marathon pace and picks up to 15k race pace (or whatever pace you can run for about 40 to 45 minutes). As far as workouts go, these sessions can be split between continuous efforts for a set amount of time or distance or they can be broken down into threshold pace intervals with short rest while trying to chase extra fitness. Either way, the training within this zone has great merit and should be a staple in any program. In our training programs, we recommend doing some variation of a threshold workout each week once you have achieved a foundation of fitness.
Incorporating endurance runs as well as tempo runs into your training is crucial for running a faster 5k. These workouts provide the backbone to handle the faster work and other speed interval sessions without sending you over the training edge. The best way to think about this training is as the support system that lives behind the scenes. These runs may not get all the praise that they deserve, but without them it is hard to think that holding your 5k pace from start to finish would ever be possible.