4 Weeks to the San Francisco Half Marathon
Four weeks ago, I made a decision that probably wasn't very smart.
I signed up for my first half marathon.
The catch? I had essentially zero running experience.
I've spent the past 15 years coaching basketball players. My world has been strength, power, jumping, sprinting, and force production. Distance running has never been part of my coaching or my own training.
Now I have four weeks to prepare for 13.1 miles.
So over the next month, I'll be reading the best research I can find on endurance training, injury prevention, biomechanics, physiology, recovery, nutrition, and marathon preparation.
I'll summarize each paper into practical takeaways, apply what I learn in my own training, and document the process along the way. Follow along here.
Whether you're training for your first 5K, your next marathon, or simply want to become a better endurance athlete, I hope this growing library helps you train a little smarter.
The Running / Endurance Research Library
1. Why Every Runner Should Lift Isometrics
What You'll Learn
Most runners think mileage is the answer to staying healthy. This paper argues that tendon capacity is one of the biggest rate limiting factors for runners, and that isometric training is one of the simplest tools for improving tendon stiffness, force production, and pain management. It provides practical programming strategies that fit easily alongside running.
Key Takeaways
- Stronger tendons improve running economy.
- Isometrics can reduce tendon pain while maintaining strength.
- Just a few minutes each week may improve tissue capacity.
Why Runners Should Care
Your aerobic fitness only matters if your tissues can tolerate the training. Building tendon capacity before increasing mileage may help reduce injury risk while improving performance.
Read the Paper
Egerton T. (2026). Isometric Strength Training in Endurance Runners: A Theoretical Framework for Adaptations and Performance Outcomes. Strength and Conditioning Journal. Study Link
2. Why Plyometrics May Be the Missing Piece for Endurance Performance
What You'll Learn
Running is a series of thousands of stretch-shortening cycles. This review explains how plyometric training improves tendon stiffness, running economy, and force production, helping runners become faster without increasing aerobic fitness.
Key Takeaways
- Plyometrics consistently improve running economy.
- Improved tendon stiffness allows runners to recycle more elastic energy.
- Small doses produce meaningful performance improvements.
Why Runners Should Care
You don't become a better runner by only running. Improving how efficiently you produce and absorb force means every stride costs less energy.
Read the Paper
Wynne K. (2026). Understanding and Prescribing Plyometrics for Endurance Runners: A Review. Strength and Conditioning Journal. Study Link
3. The Norwegian 4×4 Protocol: The Study That Changed Endurance Training
What You'll Learn
The modern Norwegian 4×4 protocol traces back to the landmark 2007 study by Helgerud et al., which showed that four 4-minute intervals performed at 90 to 95% of maximal heart rate improved VO₂max more than traditional endurance training. That paper became one of the defining studies in high-intensity interval training and laid the foundation for the protocol's widespread adoption.
Key Takeaways
- Four 4-minute intervals outperformed moderate-intensity continuous training for improving VO₂max.
- Training intensity proved more important than simply accumulating more volume.
- Improvements in VO₂max translated into faster running speeds at lactate threshold.
Why Runners Should Care
Many runners assume more miles are always better. This study challenged that belief and demonstrated that strategically placed high-intensity intervals can produce larger aerobic adaptations while requiring less total training time.
Read the Study
Helgerud J, Høydal K, Wang E, et al. (2007). Aerobic High-Intensity Intervals Improve VO₂max More Than Moderate Training. Medicine & Science in Sports & Exercise. Study Link
4. The Next Evolution of Norwegian 4×4: Why HIIT Still Beats Sprint Intervals
What You'll Learn
After introducing the original Norwegian 4×4 protocol in their landmark 2007 study, Helgerud and colleagues continued refining high-intensity interval training. In this 2023 study, they compared the classic 4×4 protocol with two popular sprint interval training (SIT) protocols in well-trained women and found that the original aerobic 4×4 protocol remained the most effective method for improving VO₂max.
Key Takeaways
- The Norwegian 4×4 protocol increased VO₂max by 7.3%, outperforming both sprint interval protocols.
- Both sprint interval protocols improved sprint performance, but neither matched 4×4 for aerobic development.
- The 10 × 30-second sprint protocol resulted in a substantially higher injury rate, while no injuries occurred during 4×4 training.
Why Runners Should Care
If your goal is to maximize aerobic fitness, this study reinforces the original message from Helgerud's 2007 paper: train hard aerobically, not all-out anaerobically. Sprint intervals have their place, but the Norwegian 4×4 protocol remains one of the most effective and practical methods for building endurance.
Read the Study
Helgerud J, Hov H, Mehus H, et al. (2023). Aerobic High-Intensity Intervals Improve VO₂max More Than Supramaximal Sprint Intervals in Females, Similar to Males. Scandinavian Journal of Medicine & Science in Sports. Study Link
5. Zone 2 Training: Does It Really Deserve the Hype?
What You'll Learn
Zone 2 has become one of the hottest topics in endurance training. This review takes a critical look at the evidence and asks whether Zone 2 truly deserves its reputation as the "best" training intensity. The authors conclude that while Zone 2 has an important place in endurance training, higher intensities remain essential for maximizing aerobic fitness and mitochondrial adaptations.
Key Takeaways
- Zone 2 works, but it is probably not the only zone that matters.
- Higher intensity training often produces larger improvements in VO₂max and mitochondrial adaptations.
- The best endurance programs combine easy running with strategically placed harder efforts.
Why Runners Should Care
It's easy to get caught up in the Zone 2 conversation online. This review provides important context and reminds us that successful endurance athletes don't just train easy. They train across multiple intensities.
Read the Paper
Storoschuk KL, Moran-MacDonald A, Gibala MJ, Gurd BJ. (2025). Much Ado About Zone 2: A Narrative Review Assessing the Efficacy of Zone 2 Training for Improving Mitochondrial Capacity and Cardiorespiratory Fitness in the General Population. Sports Medicine. Study Link
6. The Science Behind Building Aerobic Capacity
What You'll Learn
Building endurance isn't just about running farther. This review explains that aerobic performance is driven by three key factors: VO₂max, lactate threshold, and running economy. It also outlines how different training methods specifically target each of these components.
Key Takeaways
- Aerobic performance depends on VO₂max, lactate threshold, and running economy.
- High-intensity intervals primarily improve VO₂max and lactate threshold.
- Strength and plyometric training improve running economy.
Why Runners Should Care
Instead of viewing endurance training as simply logging miles, this framework helps you understand what each workout is actually trying to improve. Better programming starts with knowing which physiological quality you're targeting.
Read the Study
Turner AN. (2011). Training the Aerobic Capacity of Distance Runners: A Break From Tradition. Strength and Conditioning Journal. Study Link
7. Can Cycling Replace Running?
What You'll Learn
Many runners use cycling during injury, recovery, or to reduce impact. This systematic review examined whether cycling can maintain running performance and aerobic fitness when replacing portions of running training. Across seven randomized trials, cycling performed remarkably well as a substitute for maintaining fitness over short training periods.
Key Takeaways
- Replacing some running with cycling did not significantly reduce VO₂max.
- Running performance was generally maintained during short-term cross-training.
- Cycling offers a practical way to reduce impact while preserving aerobic fitness.
Why Runners Should Care
Every mile carries mechanical stress. During periods of injury, heavy training, or recovery, cycling may help maintain your aerobic engine while giving your joints and connective tissues a break.
Read the Study
Menges T, Dindorf C, Dully J, Fröhlich M. (2026). Cross-Training Between Running and Cycling: Effects on VO₂max and Running Performance. A Systematic Review and Meta-analysis. Frontiers in Sports and Active Living. Study Link
8. Sprint Interval Training: Can Sprinting Make You a Better Distance Runner?
What You'll Learn
This randomized controlled trial compared sprint interval training with traditional endurance training in well-trained distance runners. After six weeks, the sprint interval group produced greater improvements in performance, particularly over 3,000 meters.
Key Takeaways
- Sprint interval training significantly improved 100 m, 400 m, and 3,000 m performance.
- Sprint training produced greater improvements in time to exhaustion than traditional endurance training.
- Just two sprint interval sessions per week for six weeks outperformed traditional high-intensity endurance sessions for 3,000 m performance.
Why Runners Should Care
You don't have to run more to run faster. A small dose of sprint interval training may improve endurance performance while reducing total training time.
Read the Study
Jin K, Cai M, Zhang Y, Wu B, Yang Y. (2025). Effects of 6-Week Sprint Interval Training Compared to Traditional Training on the Running Performance of Distance Runners: A Randomized Controlled Trial. Frontiers in Physiology. Study Link
9. Norwegian 4×4 Still Comes Out on Top
What You'll Learn
Following their landmark 2007 study introducing the Norwegian 4×4 protocol, Helgerud and colleagues continued testing whether newer sprint interval methods could produce even greater aerobic adaptations. In this study of well-trained men, the classic 4×4 protocol again produced the largest improvements in VO₂max and 3,000 m performance.
Key Takeaways
- The Norwegian 4×4 protocol increased VO₂max by 6.5%, outperforming both sprint interval protocols.
- The 8 × 20-second sprint protocol improved anaerobic capacity but produced only about half the VO₂max improvement of 4×4.
- The 10 × 30-second sprint protocol failed to significantly improve VO₂max in these well-trained runners.
- Improvements in 3,000 m performance were greatest following the 4×4 protocol.
Why Runners Should Care
If your goal is to maximize endurance performance, this study reinforces one of the biggest themes in the literature: spending more time at a high aerobic intensity is more effective than simply sprinting harder. For improving VO₂max, the original Norwegian 4×4 protocol continues to set the benchmark.
Read the Study
Hov H, Wang E, Lim YR, Trane G, Hemmingsen M, Hoff J, Helgerud J. (2023). Aerobic High-Intensity Intervals Are Superior to Improve VO₂max Compared with Sprint Intervals in Well-Trained Men. Scandinavian Journal of Medicine & Science in Sports. Study Link
I hope this helps,
Ramsey "your new running resource" Nijem
P.S. This guide will be updated with new studies over the next few weeks and beyond so be sure to check back regularly.
P.S.S. I am having fun sharing my new running journey and recruiting for the Pretend Runners Club.
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