How to Ramp Up Ultramarathon Training Without Injury

Written by:

Darcie Murphy

CTS Pro Ultrarunning Coach

Updated On

March 26, 2025

Increasing ultramarathon training volume or intensity is often a contributing factor for injuries. Your body has adapted to a certain workload, and increasing that workload is necessary in order to improve fitness. However, if you ramp up training too quickly or too much you are at increased risk of injury. Finding the right balance can be tricky. So, how quickly can an ultra runner increase their training workload without risking injury?

Measuring Training Workload

First, let’s identify the metrics commonly used to measure training workload. Volume, the amount of training time per day, week, month or year, is one of the most commonly used measurements. Distance is another frequently used quantity to determine training load. While these are important and useful tools, they fail to directly account for the physiological stress created by an individual training session or series of workouts (training block).

Training Stress Score (TSS) is an insightful metric that combines duration and intensity relative to the athlete’s threshold heart rate or threshold pace. It was developed by TrainingPeaks, one of the software systems CTS Coaches use to evaluate and plan training. TSS estimates total workload a bit more effectively than volume or distance alone. As a result, we’ll refer to TSS as we discuss how quickly a runner can ramp up their training without risking injury or burnout.

Guidelines for Increasing Training Workload

A customary guideline for an ultra runner who already has an established level of fitness can safely increase ultramarathon training from one training block to the next by at least 10% and up to 30%, depending on the length and type of the training. After the first several weeks the increase in training load should taper off gradually.

What does that look like in terms of numbers?

Let’s first look at the ultra runner with an established level of aerobic training. Referring to the article How Much Time To Train for an Ultra Event…this would be about 6 hrs/week for at least 3 weeks for a runner preparing for a 50k or 50 miler. For athletes preparing for the 100k to 100 mile distance, it would be about 9 hrs/week for at least three weeks. Let’s assume a runner of this fitness level has accrued an average of 500 TSS points weekly over the course of about three weeks. Their next build could (and should) have an average weekly TSS of at least 550 and up to 650 TSS based on the 10-30% guideline.

Ramping Up After Injury

Rapid progression may not be appropriate for athletes returning to running after injury. An injured athlete’s return to unrestricted training should be based on the guidance of their physician and/or physical therapist, and is highly individual. Patience is the most important component to successfully returning to unrestricted training.

Scheduling Recovery

How often should ultrarunners take recovery weeks? This depends on the intensity level of the training, among other things, but let’s focus on intensity. Many runners make the mistake of making all of their training blocks have a stereotypical three weeks hard to one week easy, regardless of the training intensity. This is a big error, as not all intensities are created equal in the amount of time it takes for an adaptation or the amount of time necessary for recovery.

Generally speaking, the lower the intensity of a training block, the longer that training block can be and vice versa. For an ultra runner focused on improving aerobic fitness (Endurance and Steady State Runs), almost all of their training intensity will be relatively low, about 65-80% of their threshold pace or HR. In these instances a training block can be 3-5 weeks long before taking a recovery period (usually 4-7 days with the total training load for this recovery period about 30% lower than the average of the other weeks).

As the intensity of training increases, the duration of the training block should decrease. Athletes completing 2-4 Tempo runs weekly to develop lactate threshold pace may do 2- to 3-week training blocks. A runner integrating VO2 max intervals should keep that block shorter. For instance, a block of 10 days to 2.5 weeks long to optimize adaptations while minimizing the risk of injury. This guideline applies to all runners from the beginner to the elite.

Subjective Self Monitoring

While numbers and data are terrific tools, they often don’t reveal the entire story. Subjective data, or how an athlete feels, is equally important. It’s important for athletes to stay tuned in to the feedback their body sends. While some fatigue is a normal part of the training process, extreme levels of fatigue or symptoms of injury may necessitate a slower weekly build up or shorter training blocks. Communicating regularly with your coach allows your coach to adapt the training approach based on how your physiology responds to the training. Self-trained athletes should keep consistent notes for future reference and so a potential future coach can review them.

Either way, this subjective data can give insight into the level of fatigue and when an injury first becomes apparent. Usually, if addressed early, the training approach can be altered in a manner that allows the athlete to keep training while avoiding a situation that will worsen a potential injury or create a level of fatigue counter-productive to fitness improvements.

Takeaway

Ultimately, the guidelines above will typically lead to improved fitness while keeping the athlete injury-free and mentally buoyant. All the same, build flexibility into the formulas because there is no one-size-fits-all approach to increasing ultramarathon training. But science and experience has shown these approaches to be both effective and safe.