Monitoring Training Load for Runners: How to Reduce Injury and Improve Performance
Running has always been a popular form of exercise due to its accessibility and minimal equipment requirements. During the pandemic—when gyms closed and social distancing increased—the number of new runners grew significantly. Whether training for a 5K or an ultramarathon, runners are continually pushing themselves to the next level. However, with increasing training demands comes an increased risk of injury.
So how can recreational runners measure and monitor training load to improve performance and reduce injury risk?
Why Monitoring Training Load Matters
Weekly mileage has traditionally been the primary way runners assess training load. Although it provides an objective number, it does not capture the complete picture. A 2020 article in the Journal of Orthopaedic & Sports Physical Therapy recommends evaluating both extrinsic factors and intrinsic factors to better understand the stress placed on the body.
Extrinsic Factors
These represent the physical work performed, such as:
Distance
Pace
Total time spent running
Intrinsic Factors
These reflect physiological and psychological responses, including:
Heart rate
Rate of Perceived Exertion (RPE)
Fatigue, stress, and overall well-being
Rate of Perceived Exertion (RPE): A Key Tool for Runners
RPE is a valuable metric because it considers how a runner feels on a given day—an important variable influenced by sleep, stress, nutrition, and recovery.
The RPE scale ranges from 1 (minimal effort) to 10 (maximal effort).
How to Calculate Training Load Using RPE
Sports scientist Tim Gabbett proposed a simple formula:
Training Time (minutes) × Average RPE = Training Load (Arbitrary Units or “Exertion Minutes”)
Example:
100 minutes × RPE 5 = 500 Exertion Minutes
This calculation helps capture the true training stress on the body—even when mileage alone doesn’t.
Acute vs. Chronic Training Load
Tracking the balance between short-term and long-term training stress helps identify risky spikes that may lead to injury.
Acute to Chronic Load Ratio (ACWR)
ACWR = Current Week’s Training Load ÷ Average Load of the Previous 4 Weeks
Gabbett’s research suggests:
0.8 – 1.3 = Optimal “sweet spot” with lower injury risk
Above 1.3 = Increased risk of injury
Below 0.8 = Potential detraining or loss of fitness
Monitoring this ratio helps runners progress safely while minimizing injury risk.
How Training Load Affects Injury Risk
Injury occurs when tissues are pushed beyond their capacity. Sudden increases in intensity or volume significantly raise this risk.
General guidelines include:
Avoid increasing weekly training load by more than 10%, although this varies between individuals.
Novice runners should progress even more gradually, as they have a higher risk of injury.
High weekly mileage is correlated with increased injury risk.
If you begin to feel discomfort or early signs of injury, reduce:
Weekly mileage
Intensity
Duration per run
This allows tissues time to recover.
Don’t Forget Sleep and Mental Health
A 2021 study in the Journal of Sports Science and Medicine reported that 54% of recreational runners experienced a running-related injury (RRI) within six months. Poor sleep quality and mental health were significant contributing factors.
Training load isn’t just physical—your recovery and emotional stress matter too.
Using RPE and Exertion Minutes to Prevent Injury
Tracking exertion minutes (RPE × duration) helps ensure:
Gradual progression
Fewer sudden spikes
Better understanding of your personal limits
Combining this with the acute-to-chronic ratio gives you a comprehensive view of your training stress.
Why Does the Same Run Feel Harder on Some Days?
If your RPE is higher than usual for the same distance or pace, consider factors such as:
Poor sleep
High stress
Inadequate nutrition
Accumulated fatigue
A harder-feeling run is often a sign to temporarily reduce intensity. Running through fatigue may lead to inefficient mechanics, increased tissue stress, and higher injury risk.
The Bottom Line
Running injuries have many contributing factors, but monitoring training load—using duration, mileage, and RPE—can significantly reduce your risk. Gradually progressing your training, addressing sleep and mental health, and modifying workouts when needed all help you stay healthy and consistent.
Not only can this keep you injury-free, but it can also improve performance—a topic we’ll cover in an upcoming blog!
And remember: addressing pain early leads to faster recovery. If you’re experiencing discomfort while running, a physical therapist can help you identify the cause and get you back on track.
