How Speedwork Improves Ultrarunning Performance

Written by:

Addison Smith

CTS Senior Ultrarunning Coach

Updated On

April 30, 2025

Ultrarunning isn’t typically considered a “speedy” sport, so incorporating speedwork into your ultramarathon training program may seem counterintuitive. After all, you’re unlikely to run at a maximal intensity much or at all during races that take 5 hours to 3+ days, except perhaps that sprint to the finish line or for the last oatmeal cookie in an aid station. However, speedwork benefits ultraendurance athletes by improving aerobic capacity (VO2 max), improving the body’s ability to utilize lactate as fuel, allowing the body to burn more fat at higher intensities (which makes you more efficient at fueling exercise for long durations), and helping runners learn to regulate efforts. Running fast in training gives you the tools to maintain your more moderate pace during races. Here’s how speedwork improves ultrarunning performance and how to do it.

What Is Speedwork in Ultrarunning? 

In some sports, speedwork refers to sprinting (10-15 second efforts) or very short interval workouts (30-45 second efforts), often repeated with very little recovery. In ultrarunning, the terminology is a little different and ‘speedwork’ is any sort of structured workout that intentionally increases intensity of running beyond a normal conversational/aerobic effort. In other words, interval workouts. For runners training for the marathon distance or below, this often includes efforts at a given pace (5k, 10k, mile, etc.) on flat ground that they will be either running on race day or faster, split into shorter distance repetitions with rest between them.

For ultrarunners, given the multifaceted nature of our races (undulating terrain in sometimes extreme environments over long distance), improving speed/pace for a specific shorter distance on flat terrain is a less valuable training target. Rather than focus on specific paces when doing different kinds of speedwork, it is more applicable for ultrarunners to focus on running at specific intensities. Within a training block, it is then important to accumulate enough time at those intensities to see performance benefits.

The Benefits of Speedwork for Ultrarunners

Speedwork improves fitness and performance beyond what you can accomplish with just steady aerobic exercise. Benefits include:

• Improved Aerobic Capacity:
  Although all aerobic exercise increases VO2max to some extent, incorporating harder efforts is necessary for reaching a higher percentage of your potential.
• Improved running economy:
  The metabolic adaptations you achieve through speedwork help you maintain a higher pace for a given oxygen consumption or allow you to maintain a more moderate pace at a lower oxygen consumption.
• Faster maximum sustainable pace:
  Speedwork increases fastest sustainable pace, or pace at lactate threshold, through adaptations that help you process and utilize lactate for fuel more quickly.
• Greater durability at moderate pace:
  The adaptations above allow you run longer and stronger because your easy to moderate pace now calls upon a lower percentage of your maximum capacity. A moderate pace takes less out of you.

The Best Speedwork Workouts for Ultrarunners

So, what are the recommended intensities for speedwork, how do you know you’re actually running at the appropriate intensity, and how do you organize these intensities into easy-to-follow workouts? You’ll notice in the workouts below that neither heart rate nor pace are provided for gauging your efforts. Because of the infinite variability trail and ultrarunners encounter during training runs (i.e., steep hills, loose rocks, soft earth, hard pack, pavement, varying weather and elevation, etc.), neither heart rate nor pace are very consistent or reliable for gauging intensity. Perceived exertion using a combination of a 1-10 RPE scale, respiration rate, and/or a talk test provides a more accurate and adaptable means of monitoring effort.

Here are 3 types of workouts that are essential to ultramarathon performance and overall endurance running performance:

RunningIntervals:

RunningIntervals improve VO2max (maximum oxygen uptake) or your “performance ceiling”. If you can raise your ceiling, you’re also raising your ability to run faster during conversational-effort runs. For reference, most ultramarathons are run at an average intensity of 60% of VO2max, which is a conversational pace. RunningIntervals are executed at a rate of perceived exertion of 9-10 on a 10-point scale. Your breathing should be short and rapid, and you should only be able to say a single word, which will most likely be a curse word.

TempoRun:

TempoRun improves the body’s ability to utilize lactate as fuel, which helps you sustain a moderately high intensity/pace for longer periods. At a rate of perceived exertion of 8-9, your breathing should be deep, labored, and fairly rapid, but not uncontrollable panting. In terms of talking, you should only be able to speak a 5–7-word sentence during the interval.

SteadyStateRun:

SteadyStateRun workouts develop a stronger aerobic engine and allow you to burn more fat at higher intensities, which makes you more efficient at burning calories to fuel exercise for long durations. At a rate of perceived exertion of 7-8, your breathing rate should be deep and labored but less rapid than during a TempoRun effort. You should be able to speak 2-3 sentences at a time during the interval.

How to Incorporate Speedwork into an Ultrarunning Training Plan

Within the Training Plan (12 months to a year)

 The keys to a successful training plan are identifying the physiological demands for the event, focusing on the most race-specific intensities closest to the race day, and focusing the least race-specific work farthest from the event. Consequently, if there is enough of a training runway leading up to an event, the highest intensity training (RunningIntervals) would be done at the beginning of the training plan because it is the least race-specific. Ideally, a moderate-intensity TempoRun block would fill in the middle portion of the plan, followed by a SteadyStateRun block or a high-volume block of low intensity training closest to the event.

Within a Training Block (3 weeks to ~6 weeks)

When CTS coaches use block periodization for our athletes we assign workouts of a given intensity for a period of multiple weeks. The goal is to maximize the adaptations from that particular workout-type before having athletes recover and move onto a different type of workout intensity.

Blocks of training differ in length depending on the time course of adaptation for a given workout intensity. For example, adaptations for VO2max intensity workouts like RunningIntervals happen relatively quickly. As a result, I typically only prescribe them in 3-5 week blocks. I typically schedule TempoRun blocks to last 3-6 weeks because the desired adaptations take longer to achieve. Similarly, I schedule SteadyStateRun blocks to last 4-6 weeks for the same reason.

Within a Week of Training

There are various ways to add speedwork to your weekly training. More experienced athletes can incorporate speedwork of varying intensities 3 times (sometimes but rarely 4 times) a week whereas beginner athletes should stick to 1-2 per week. Arranging speedwork within a weekly schedule depends on the goal of the block and its context within the greater training plan.

For example, if an experienced athlete is at the start of a training block and has a long runway to their ultramarathon event, I may give them 2 RunningInterval workouts on back-to-back days to start the week, followed by a recovery run day and then a shorter endurance run day. Then they’d get a third RunningInterval workout within an endurance run over the weekend. This pattern creates a robust high intensity stimulus over the course of 6 days while keeping the athlete’s running volume relatively low. We do this to maximize the VO2max-focused adaptations but also to make sure it is a sustainable training load that balances intensity and volume. We don’t want to increase both volume (hours or miles) and intensity simultaneously.

If this same runner had a shorter runway to his ultramarathon race (8-12 weeks for example), I likely wouldn’t include RunningIntervals into this particular training pattern, and focus instead on SteadyStateRun intervals. This would narrow focus to intensities that are more specific to the intensities the athlete would be running on race day and the adaptations that would be most beneficial in the short term.

Common Mistakes to Avoid When Adding Speedwork

Despite its benefits, there are some common pitfalls to avoid when implementing various types of speedwork into your plan:

1. Too Much, Too Soon:
   A little bit of speedwork can go a long way when you’re first introducing some into your training. Too much too soon leads to excessive fatigue and soreness, which hurts the quality of all your training. For athletes new to speedwork, starting with one workout per week to see how your body responds and adapts to the new stimulus is key to making it a sustainable addition to your training practice.
2. Ignoring Terrain Specificity:
   Many ultramarathon courses feature undulating or extreme terrain. Flat and fast workouts may look flashy, but you must make sure your body is biomechanically ready for the demands of uphill running. You also must learn to listen to RPE cues that change when you’re going uphill vs. downhill vs. running on flat ground.
3. Sacrificing Training Volume for Speedwork Too Close to Your Race:
   Speedwork is a key component to any ultramarathon training plan, BUT it can’t make up for a lack of fundamental aerobic endurance run time. There are aspects of aerobic development and durability, as well as the practical skills needed to for ultramarathon competitions (fueling, hydration, pacing practice, etc.) that come from slower and longer days out on the trails/roads. Remember that easy long runs are the most specific type of training to most ultramarathon race efforts you will face, and make sure to not neglect them in your training especially closer to race day.

Coach Insights

As a coach, I know the benefits of speedwork and incorporate it into training plans for virtually every athlete I work with, from marathoners to 100-milers. Some athletes are resistant or skeptical at first. The idea of running hard may seem antithetical to the “steady progress” ethos of ultrarunning, but that skepticism only lasts until athletes start seeing results. No one I’ve met has ever complained about a long run feeling easier after they put in some hard work to develop that fitness.