The premise of the 10% rule
This principle has been widely promoted in running communities and training programs as a preventive measure. The 10% rule is rooted in the idea that gradual training progression allows the body to adapt to new stresses, thereby reducing the likelihood of musculoskeletal injuries. It has gained traction for its simplicity and ease of application, but it fails to address the multifaceted nature of running-related injuries (RRIs).
Research results revealed no difference in injury rates
The study conducted put the 10% rule to the test. This study involved 532 novice runners who were randomized into two groups: one followed the 10% rule based program over 13 weeks, and the other followed a standard 8-weekprogram. The results revealed no difference in injury rates between the two groups, with injury incidences of 20.8% and 20.3%, respectively. This suggests that the 10% rule does not significantly reduce injury risk.
Here are the key findings:
1. No Difference in injury rates
Both groups showed nearly identical injury incidences — 20.8% in the 10% rule-based group and 20.3% in the standard training group. This indicates that the 10% rule did not reduce the rate of running-related injuries (RRIs).
2. No impact on injury severity or distribution
The study also found no significant difference in the type or severity of injuries sustained by runners in both groups. Injuries primarily affected the lower leg and knee, consistent with other running studies.
3. Fails to account for personal differences
Despite being well-intentioned, the rule may not account for individual differences, such as baseline fitness, biomechanics, and load tolerance levels (influenced by exposure to high-impact activities, running experience and many other individual factors).
Why the 10% rule falls short
Several factors could explain the lack of effectiveness:
1. Oversimplification of mechanical load
The 10% rule focuses solely on distance or duration, ignoring other critical factors that contribute to the actual load on a runner’s body. These include:
- Speed: Faster running increases impact forces and load on the body.
- Running style: Biomechanical differences, such as stride length or footstrike pattern, affect load distribution.
- Surface: Hard or uneven surfaces can amplify load on joints and muscles, depending on the individual running style & footwear.
- Footwear: The choice of running shoes significantly alters shock absorption and load impact.
By failing to account for these variables, the 10% rule overlooks the true cumulative load on the body with each step that cause running-related injuries.
For example: 5km versus 5.5km is a 10% progression, but for instance, increasing the speed by just 1km/h, this can easily result in an additional +20 to +40% load.
2. Generic and static approach
The 10% rule applies a one-size-fits-all guideline, ignoring individual differences in:
- Load tolerance: How much load your body can handle is not static; it varies based on individual factors like prior injuries, training & impact history, age, body weight, muscle & tendon strength. Fatigue and stress can temporarily further lower load tolerance.
- Recovery and adaptation rates: Some individuals may require longer recovery periods or be capable of faster progression.
- Baseline fitness levels: Beginners, experienced runners, and those returning from injury all have vastly different tolerance levels based on their impact history.
Understanding the dynamic interaction between load and load capacity
The relationship between cumulative load and load tolerance is central to understanding injury risk according to the study of Bertelsen & colleagues.
Cumulative load refers to the total stress placed on musculoskeletal structures during a running session, while load tolerance is the capacity of these structures to withstand the applied stress without injury. Balancing cumulative load and load tolerance requires recognizing individual variability in load patterns and modifiable risk factors. Effective injury prevention strategies therefore should consider personalized training loads and recovery protocols to prevent exceeding load capacity.
Injuries happen when the total load on your body (called "cumulative load") goes beyond what your body can handle ("load tolerance"). This can happen if you run too much, too fast, or with poor recovery time between runs.
A call for individualized training approaches
The findings from the study trial emphasize the need for more nuanced training strategies. Instead of adhering rigidly to the 10% rule, runners should adopt a personalized approach that considers:
- Look at gradual progression by measuring actual cumulative load on the body
- Gradual progression tailored to individual capabilities
- Regular assessments of recovery and injury risk
Takeaways for injury prevention
While the 10% rule offers a simple guideline for training progression, evidence suggests it fails to address the complexity of running-related injuries. By focusing narrowly on distance or duration and ignoring critical factors like speed, biomechanics, and individual load tolerance, the rule often oversimplifies injury prevention. Instead, a more individualized may be more effective for reducing injury risks.
For runners, coaches, and healthcare professionals this study serves as a reminder to critically assess the efficacy of widely accepted training principles and adapt them to the needs of each individual. OnTracx empowers them to move beyond one-size-fits-all rules like the 10% guideline and make informed decisions tailored to individual needs to minimize injury risk by monitoring key metrics such as actual load & load progression, effect of speed & other critical factors on load, while also considering factors that influence individual load tolerance.
