Endurance training is quintessential “base training” where you focus on building mileage — or workout duration. Endurance events by definition require the ability to move for long periods of time, necessitating a well-developed aerobic system to supply energy for the duration of your activity.
Endurance training targets both extensive endurance and intensive endurance as you increase the duration of your long runs or workout sessions.
The key workout during this phase is the standard base-training endurance workout in the “conversational” zone — that is, at or below your aerobic threshold (AeT) — to develop your aerobic system. These “conversational” zone endurance workouts involve a continuous effort with durations of 20 minutes up to several hours. The training effect targeted is your body’s ability to better metabolize fat and spare glycogen (stored carbohydrate) as a long duration energy source.
During a “conversational” effort, you should be able to breathe through your nose and hold a back-and-forth conversation with someone running next to you (taking turns to speak). Breathing is moderate and not labored. Once you’ve moved beyond this effort level, you’ve moved beyond your aerobic threshold (AeT).
During endurance training blocks, you will gradually increase the duration of one or more weekly endurance workouts. The duration you work up to will depend on the duration of the event you’re training for. Whereas a 90-minute long run may be sufficient for runners racing half marathons or shorter, marathoners may target long runs of 2-3 hours, and ultrarunners may do long runs that last 6+ hours.
Another key workout during this training phase is the “comfortably hard” tempo workout — also known as, “steady state” or “marathon simulation.” These workouts, which are used to build intensive aerobic endurance and improve lactate tolerance (and to simulate marathon-distance race pace), involve sustained tempo intervals of 20-60 minutes with a 5:1 up to 8:1 work to recovery ratio. Total time at intensity during these workouts can range from 30 minutes to 2 hours. For example, after you’re warmed up, you might do 30 minutes at a “comfortably hard” effort followed by some additional time at a “conversational” effort before warming down, or your workout might involve 2 x 20-minute “comfortably hard” intervals with a 4-minute recovery interval between them.
During a “comfortably hard” effort for these tempo workouts, you should still be able to breathe through your nose, but your ability to talk will be limited to 2-3 sentences at a time. Breathing is deep and labored.
Endurance training might span 8-12+ weeks in your training plan.