Youth Running Training: The Scientific Basis for Growth Plate Protection and Weekly Mileage Limits

Introduction

Road running is becoming increasingly popular in Taiwan, and many parents are encouraging their children to develop running habits from a young age. However, the skeletal system of adolescents differs fundamentally from that of adults: the epiphyseal plates (growth plates) have not yet closed, and excessive impact and training volume during this period may lead to permanent bone damage. Based on research in sports medicine and child and adolescent athletic development, this article provides the most practical training guidelines for young Taiwanese runners and their coaches.

What Are Growth Plates and Why Do They Matter?

Growth plates (epiphyseal plates) are cartilage tissue located at both ends of long bones, responsible for longitudinal bone growth. Before the epiphyses are fully ossified (closed), this area is the most fragile part of the bone—even weaker than the surrounding ligaments and tendons.

Growth Plate Closure Timing by Region

This shows that before age 18, nearly all growth plates most relevant to running have not yet fully closed, meaning the window of risk for excessive impact training is quite long.

Scientific Basis: Weekly Mileage Limits for Adolescents

The American College of Sports Medicine (ACSM) and multiple studies on child and adolescent athletic development recommend the following reference upper limits for weekly training volume by age group:

Key principle: Weekly mileage should not increase by more than 10% from the previous week (known as the “10% rule”).

Practical Guidelines for Growth Plate Protection

Choosing the Right Running Shoes Is Critical

• Cushioning: Choose running shoes with adequate heel cushioning to reduce the impact force of each footstrike (impact force per step in adults is approximately 1.5–3 times body weight)
• Arch support: If the child has significant flat feet, it is recommended to seek evaluation at a sports medicine clinic and consider custom insoles
• Replacement cycle: Running shoes should be replaced every 600–800 km; since adolescents grow quickly, shoes should also be checked regularly to ensure they still fit properly
• Avoid hard-soled training shoes: Basketball shoes and canvas shoes are not designed for long-distance running and should not be used as training footwear

Choosing Training Surfaces

• Prioritize rubber tracks, grass, and asphalt roads, and avoid running on concrete surfaces long-term
• Concrete has the worst shock absorption; long-term use causes significantly greater cumulative bone damage compared to rubber tracks
• Trail running, due to its varied terrain, actually disperses impact points and is friendlier to joints, but attention should be paid to the risk of ankle sprains

Warning Signs: When to Stop Training

If any of the following symptoms appear, training should be stopped immediately and medical evaluation sought:

• Persistent pain at the front or back of the knee (may be Osgood–Schlatter disease, i.e., tibial tubercle apophysitis)
• Tenderness at the back of the heel (may be Sever’s disease, calcaneal apophysitis)
• Swelling or a burning sensation in any joint
• Pain that persists more than 24 hours after running

Intensity Control: The Importance of Easy Running Is Severely Underestimated

Many young runners (and parents) share a common misconception: that every training session should be run “all out.” In fact, sports science tells us that aerobic base building (the easy running zone, approximately 65–75% of maximum heart rate) should account for 70–80% of training volume and is the foundation for building long-term running capacity.

Excessive high-intensity training not only increases stress on the growth plates but also raises the risk of overtraining syndrome (OTS), which manifests as persistent fatigue, plateauing performance, or even regression.

How to Determine “Easy Run” Pace?

The simplest method is the “talk test”: if you can easily speak full sentences without gasping for air while running, that is easy intensity. If you cannot complete a full sentence, the intensity has exceeded the easy running range.

Practical Recommendations

1. Keep a training log: Record daily mileage, pace, and how the body feels to help detect overtraining early
2. Cross-training: Non-impact activities such as swimming and cycling can maintain aerobic fitness without adding joint stress
3. Schedule a recovery week every 8–10 weeks: Reduce weekly mileage by 30–40% to allow the body to fully adapt to the preceding training block
4. Balance academics and training: Academic pressure is high in Taiwanese junior high and high schools; training intensity should be proactively reduced around exam periods
5. Seek coaches qualified in youth training: Not all adult training methods apply to adolescents; please confirm that the coach has the relevant knowledge

Conclusion

Running is an excellent health activity for adolescents, but “more running is not necessarily better” is especially true at this age. Growth plate protection, sensible weekly mileage limits, and proper running shoe selection—these three core principles allow young runners to enjoy the health and competitive benefits of running without compromising their growth. The role of coaches and parents is to be guardians, not pushers.

Related Reading

• Bone Development and Running Volume Limits in Adolescents: How to Avoid Growth Plate Injuries
• Youth Running Safety: Training Volume, Intensity, and Long-Term Development During Growth
• Running Mileage Recommendations for Adolescents: Safe Weekly Mileage Limits for Middle School Students
• Training Volume During Growth for Adolescent Swimmers: Principles of Epiphyseal Plate Protection