It was the 2019 Western States 100 Endurance Run, in a throwdown to land the final three spots of the coveted Men’s Top 10. Kyle Pietari, Patrick Reagan, and I ran the fastest three splits ever recorded on Strava from Foresthill to the finish — the final 37 miles. At age 48, I was able to continually surge and recover, hitting speeds of sub-7-minute/mile pace on rolling trails and sub-6-minute/mile pace in the final few blocks to the track. How? By performing speed sessions of various difficulty, thereby sharpening my fitness, and allowing me to go there when necessary. Strategic speed work improves performance and running economy if structured properly.

To keep things simple, there are three main types of speed work: steady state, tempo work at or just below your lactate threshold (LT), and training around your maximal aerobic capacity (VO2 max). Lactate threshold and aerobic pace are limited by your VO2 max (the maximum volume of oxygen the muscles can consume per minute).  

Here’s another way to look at it: 

In a long race like an ultra or marathon, most people will run at approximately 55-75 percent of their VO2 max (depending on the individual’s fitness and genetics). Although there’s a general understanding that your VO2 max is determined primarily by genetics, there is definitely room for improvement. The previous consensus was that an athlete could only improve VO2 max by 5-15 percent. However, more recent studies have found the rate to be 10-30 percent when ample time (multiple years) and focus have been placed on aerobic volume (lots of training at or below aerobic threshold). This is great news. 

As a coach and ultra-runner, I generally adhere to the 80/20 rule: Eighty percent of weekly volume is at or below aerobic threshold (AeT), and the other 20 percent is focused on strategic harder efforts of varying intensities. This focus on low-intensity, high-volume training can be a robust stimulus for solid changes in VO2 max. This primarily comes from the observed relationship between training volume and cardiac stroke volume (the amount of blood your heart pumps each time it beats). We also know that stroke volume reaches its maximum limit at relatively low intensities of training — approximately 40-60 percent of your VO2 max. 

Needless to say, this is not a recommendation to neglect harder work. However, it’s important to understand that aerobic volume is the proverbial bread and butter of endurance training. Speed work is simply the icing on the cake. When combined, the two systems can be synergistic and can equal a higher rate of improved performance. It’s paramount, therefore, to understand the relationship between strategic hard work and a large aerobic volume focus. 

With that foundational understanding established, let’s dig into a few workouts that focus on different systems. Refer to the Rate of Perceived Exertion (RPE) Chart for referencing the appropriate effort for each workout type. 

Aerobic Runs 

RPE 2-4. These runs are your bread-and-butter workouts. Eighty percent of weekly volume should be performed at this effort. These are easy workouts at conversational pace. You should be able to speak in full sentences and easily maintain the pace for many hours. 

TIP: Add in high cadence cycling or hiking workouts if you’re injury prone or newer to running. This will help add additional low-intensity aerobic volume with a lower risk of injury. Veteran and masters-age athletes can use this type of cross-training to stimulate additional aerobic volume. 

Example workouts: Long runs, short maintenance runs, recovery runs, and easy cross-training sessions.

Aerobic Threshold (AeT) and Steady State (SS) Runs 

RPE 5-6. I put these two runs in the same category, as it depends on intensity. Many times, you will hover between these two efforts during a workout. Start an AeT run easy, then ease into a smooth rhythm and finish at a strong, steady pace. AeT runs are strong efforts right around your aerobic ceiling that increase the number and size of mitochondria and further develop the capillary network surrounding working muscles. These workouts are not all out, but are quick enough to require focus without taking away from the next day's workout. If the intensity is slightly stronger, it becomes a Steady State run. A lower-end sub-threshold run, SS runs take concentration to stay on pace, but are hard enough to need a recovery run the next day to obtain the full rewards. You should still be able to talk in short sentences, but it requires focus to stay on pace. Steady state runs boost endurance and forestall fatigue. Requires a 15-20-minute warm-up at easy pace and a cooldown period after.

Example AeT workouts: (RPE 5) Mid-week longish runs, strong-finish runs with 10-40 minutes at AeT effort.

Example SS workouts: (RPE 6) Strong-finish runs with 30-60 minutes at SS effort, 4x10 minute intervals followed by 3 minutes at easy aerobic pace, or 3x12 minutes with 5 minutes at easy aerobic effort. Start with shorter intervals and work up to longer durations as you progress.

Tempo and Lactate Threshold (LT) Runs 

RPE 7-8. Tempo and threshold runs are often used interchangeably. However, there are subtle nuances depending on the length of the effort. These runs are characterized as “comfortably hard” or “moderate-hard.” Ability to talk in one-to-three-word sentences and you must concentrate on breathing. The nuance: Tempo is a general term for a threshold run. If the session is 20 minutes or less, the runner will have the ability to perform at true LT pace (RPE 8). However, if the tempo effort is longer, the effort will be more of a sub-threshold effort (RPE 7). The intent of these workouts is to improve lactate clearing capabilities, yet not overtax that capability. Requires a 15-20-minute warm-up at easy pace and a cooldown. These workouts can be taxing and should be followed by an easy day to two of recovery running.

Example Workouts: 20-40-minute strong-finish runs, 4x4-minute intervals with 2 minutes aerobic pace, or 3x8 minutes with 5 minutes easy aerobic running in between. Start with shorter intervals and increase duration as you adapt. 

VO2 Max Intervals 

RPE 9. Also known as interval training. These are shorter duration intervals performed above your Anaerobic Threshold (AT) for a short amount of time. Described as a “hard” effort, these can take a toll on you. For most runners, these are best designed into a periodization phase of training when you’re not actively building run volume. Requires a 15-20-minute warm-up at easy pace and a cooldown. These workouts can be particularly taxing and should be followed by one or two easy running recovery days.

Example Workouts: 15x1 minutes, 6x2 minutes, or 4x3 minutes, all with equal or more jog recovery in between. 

Ready up your performance? Use the above guidelines to build your aerobic base and then add in strategic speed work to improve your speed. Giddyup! 

About the Author

Jeff Browning is a veteran ultra-runner and ultra-endurance coach. At 50 years old, he still likes to rip it up. You can learn more about him, his adventures, and his coaching at GoBroncoBilly.com or Instagram: @GoBroncoBilly