Aerobic training transforms your body on a cellular level, making you a more efficient running machine. It primarily improves the efficiency of your cardiovascular and muscular systems in using oxygen to produce energy. The magic lies in mitochondria—tiny powerhouses within your muscle cells. Aerobic training increases the size, number, and efficiency of these mitochondria, allowing your muscles to generate more energy (ATP) from oxygen.

Additionally, aerobic training enhances capillary density- these are the tiny blood vessels that deliver oxygen and nutrients to your muscles. This means your muscles get better "supply lines," ensuring a steady delivery of oxygen and removal of waste products like carbon dioxide and lactate. Over time, your body also becomes more adept at utilizing fat as fuel, sparing your limited glycogen stores, which is key for endurance.

Running at certain intensities is essential for maximizing these adaptations. Training within your aerobic zones, typically 50–80% of your maximum heart rate (depending on how trained you are), encourages steady oxygen delivery and APT production. At this intensity, your body primarily relies on aerobic energy pathways, stimulating mitochondrial growth and capillary development. There are also gains to be had by running a little faster as well. Tempo runs and interval training nudge your body toward its lactate threshold, enhancing your ability to sustain faster paces without fatigue.

Consistent aerobic training also lowers your resting heart rate and improves stroke volume (the amount of blood pumped per heartbeat), making your heart a more powerful and efficient pump. The result? You’ll run longer and recover faster while feeling like a superhero—at least until you hit the next hill.

Key Methods to Improve Aerobic Capacity:

1. Easy Long Runs: These are the bread-and-butter of endurance. By running at a conversational pace, your body adapts to longer durations, building stamina and mental resilience. Plus, it’s a great time to catch up on true crime podcasts (or daydream about post-run snacks).
2. Tempo Runs: Also known as "threshold training," these runs involve maintaining a "comfortably hard" pace for 20–40 minutes. It’s not quite sprinting, but it’s just enough effort to make you second-guess your life choices. The reward? A higher lactate threshold, which means running faster for longer with less energy spent.
3. Interval Training: Alternating between short, faster efforts and recovery jogs, intervals improve both aerobic and anaerobic systems. Think 4x800 meters at a hard pace with 2–3 minutes of recovery. It's like sprinting with breaks—because even your heart deserves a breather.
4. Fartlek Runs: Swedish for "speed play," fartleks mix up periods of fast and slow running in a single workout. They’re less structured and great for adding variety.
5. Cross-Training: Non-running aerobic activities like cycling, swimming, or rowing provide a way to maintain aerobic fitness while giving your musculoskeletal system a break. Plus, who doesn’t love a change of scenery?
6. Consistency and Volume: Progress comes with regularity. Gradually increasing weekly mileage strengthens your aerobic system over time. Just avoid the classic rookie mistake: doing too much, too soon, and ending up as a cautionary tale for your local running group.

Remember, aerobic training isn’t about pushing your limits every day—it’s about slow, steady improvement. The payoff? Running longer, faster, and stronger while still having energy to wave at fellow runners (or at least nod politely).

References:

Magness S. *The Science of Running: How to Find Your Limit and Train to Maximum Performance*. Origin Press; 2014.

Mujika, I. (Ed.). (2012). Endurance training: Science and practice. Vitoria-Gasteiz, Spain: Iñigo Mujika. ISBN 9788493997007.

Anaerobic Training for Runners

Anaerobic training focuses on improving the body’s ability to perform high-intensity efforts where oxygen demand exceeds supply. Unlike aerobic training, anaerobic efforts rely on energy systems that generate ATP (energy) through glycolysis and the breakdown of glucose without oxygen, producing lactate as a byproduct. This type of training is crucial for improving speed, power, and the ability to sustain high-intensity bursts, as well as improving running economy which will transfer to faster long run paces.

Types of Anaerobic Training

1. Interval Training:

• Short, intense efforts (e.g., 400-meter repeats at 90-95% effort) followed by rest or light jogging.
• Develops the lactate threshold and improves lactate buffering capacity.

2. Hill Sprints:

• Explosive sprints up steep gradients (3% or greater) for 20–30 seconds.
• Strengthens muscles and enhances power output.

3. Tempo Runs:

• Sustained efforts at a "comfortably hard" pace near the lactate threshold.
• Teaches the body to clear/buffer lactate more efficiently.

4. Fartlek Training:

• Alternating periods of hard running and recovery in a single session.
• Encourages adaptation to variable race paces.

You may notice that there is some overlap between aerobic and anaerobic training runs.

Importance for Long-Distance Runners

While anaerobic energy systems are less prominent during long-distance events, anaerobic training is still vital for:

• Improving Finishing Kick: Allows runners to surge in the final stretch of a race.
• Handling Surges and Hills: Prepares runners for bursts of speed during competitive scenarios.
• Delaying Fatigue: Enhances lactate clearance and tolerance, helping maintain pace even as intensity rises.
• Building Speed: Faster anaerobic efforts improve neuromuscular coordination, translating to efficiency at slower, aerobic paces.

Physiological Adaptations

Anaerobic training leads to:

• Increased glycolytic enzyme activity, boosting ATP production without oxygen.
• Enhanced lactate tolerance, delaying the point of muscle fatigue.
• Improved fast-twitch muscle fiber recruitment for explosive efforts.

For long-distance runners, combining anaerobic workouts with aerobic base training creates a well-rounded program, optimizing endurance and speed.

References:

1. Daniels, J. (1998). Daniels' running formula. Champaign, IL, Human Kinetics
2. Joyner MJ, Coyle EF. Endurance exercise performance: the physiology of champions. J Physiol. 2008 Jan 1;586(1):35-44. doi: 10.1113/jphysiol.2007.143834. Epub 2007 Sep 27. PMID: 17901124; PMCID: C2375555
3. Powers, S. K., Howley, E. T., & Quindry, J. (2021). Exercise physiology : theory and application to fitness and performance (Eleventh edition). McGraw Hill LLC.

Finding your aerobic heart rate can help you keep your easy runs "easy" so you can then keep your harder days, or "hot sessions" harder. It's not that aerobic benefits do not occur while training in your threshold paces, but the easier paces of aerobic training reduce the amount of stress on your body, allowing for better recovery, and more consistent training.

The Maffetone Method is a simple and effective way to determine your optimal aerobic heart rate for training, ensuring you're building endurance without overtraining.

Here's how it works:

1. Calculate Your Maximum Aerobic Function (MAF) Heart Rate

• Subtract your age from 180 (e.g., 180 - 30 = 150). This number serves as the upper limit of your aerobic training zone.

2. Adjust for Fitness and Health Factors:

• Recovering from injury or illness, or new to training: Subtract an additional 5–10 beats to account for a reduced fitness level. For example, if you’re 30, your target may be 140–145 bpm.
• Consistently training or injury-free: Stick to the unmodified number (e.g., 150 bpm for a 30-year-old).
• Highly trained with no recent injuries: Add up to 5 bpm (e.g., up to 155 bpm for a 30-year-old).

Once calculated, aim to keep your heart rate below this number during runs or aerobic activities. This approach maximizes fat-burning efficiency and aerobic development while minimizing stress on the body.

For best results, be patient! Training below your MAF heart rate might feel slow initially, but over time, your speed and endurance will improve at this lower effort. If using a heart rate monitor, warm up first and avoid sudden spikes in heart rate during workouts.

References:

• Maffetone, P. (2010). The Big Book of Endurance Training and Racing. Skyhorse Publishing.

There are two lactate thresholds, typically referred to as LT1 and LT2. These physiological milestones signify two points at which lactate, one of the biproducts of cellular metabolism, hits two major inflection points.

See Image 1.

Lactate Threshold 1 (LT1) signifies the point at which lactate begins to accumulate at higher than baseline levels but can continue to be cleared efficiently. LT1 is also known as aerobic threshold, and typically occurs between 50-80% of max heart rate depending on how trained someone is. The more trained the person is, the higher the HR% is that LT1 occurs. Training at or near LT1 can help improve your aerobic base, and if effort stabilizes, lactate clearance will continue to match production.

Lactate Threshold 2 (LT2) is also known as maximum lactate steady state (MLSS). After this point, lactate production outpaces lactate clearance and a rapid build up of lactate begins to occur. This build up of lactate can eventually signal the body to slow down or stop. Regardless of which Training Zone System (3, 5, or 7) you are using, LT2 demarcates the point at which anaerobic metabolism becomes the primary method of energy production. At this point you typically see a significant increase in breathing rate as well. Lastly, LT2 usually occurs between 70-90% of someone’s max heart rate, with higher trained individuals reaching LT2 with higher HR%. Training around LT2 paces can help improve race pace endurance.

References:

1. Bourdon (2013) Physiological Tests for Elite Athletes

2. Brooks, G. A., & Fahey, T. D. (2020). Exercise Physiology: Human Bioenergetics and Its Applications. McGraw Hill.

3. Foster, C., & Cotter, H. M. (2006). Blood lactate: implications for training and sports performance. Sports Science Exchange, 19(3), 1–6.

4. Joyner, M. J., & Coyle, E. F. (2008). Endurance exercise performance: the physiology of champions. The Journal of Physiology, 586(1), 35–44.

5. Seiler, S., & Kjerland, G. O. (2006). Quantifying training intensity distribution in elite endurance athletes: is there evidence for an "optimal" distribution? Scandinavian Journal of Medicine & Science in Sports, 16(1), 49–56.

Overtraining occurs when a runner's training volume or intensity exceeds their body's ability to recover, leading to physical and mental fatigue. This is especially common after chasing ambitious goals, such as setting a personal best in a race, where runners may feel compelled to maintain or exceed their peak performance. However, failing to incorporate adequate recovery can result in overtraining syndrome (OTS), characterized by symptoms like:

⬆️ fatigue

⬇️ libido/menses/AM erections

⬇️ performance,

🤬mood swings

😴disrupted sleep

⬆️ resting heart rate

⬆️ illnesses or injuries

Ignoring these signs can lead to prolonged recovery times and even burnout. Research underscores the importance of balancing training stress with recovery, emphasizing strategies like monitoring training loads, prioritizing sleep, and using periodization to prevent overtraining. To continue thriving post-PR, runners might consider embracing relative rest and listen to their bodies, recognizing that recovery is as vital as the training itself.

References:

Mujika, I. (Ed.). (2012). Endurance training: Science and practice. Vitoria-Gasteiz, Spain: Iñigo Mujika. ISBN 9788493997007.

Periodization is a systematic approach to training that organizes a runner's program into distinct cycles, each with specific goals to maximize performance while minimizing the risk of overtraining. By structuring training in phases, runners can strategically build endurance, strength, and speed, leading to peak performance at key races.

Types of Periodization

Linear Periodization: Gradually increases volume and intensity over time. For example, starting with longer, slower runs and progressing to shorter, high-intensity sessions closer to race day.

Nonlinear (Undulating) Periodization: Alternates between various intensities and volumes within a week or training block, offering more variability and flexibility.

Reverse Periodization: Focuses on high-intensity work early in the training cycle and shifts to building endurance closer to the event.

Block Periodization: Features concentrated blocks focusing on one or two specific abilities (e.g., VO2 max, strength) before transitioning to another focus.

Periodization Cycles

Macrocycles: The largest training unit, typically lasting 6–12 months, aligning with a season or specific race goal. It encompasses all the phases: base building, intensity, taper, and recovery.

Mesocycles: Subsections of a macrocycle, lasting 4–6 weeks, focusing on specific goals like building aerobic capacity, speed, or strength. Each mesocycle contains planned variations in workload to prevent plateauing.

Microcycles: Short-term training blocks, usually 1 week long, dictating the specific workouts (e.g., long runs, intervals) and rest days. Microcycles balance stress and recovery on a small scale.

Why Periodization Works

Periodization enhances performance by allowing gradual adaptation to increasing stress. It also incorporates strategic recovery to prevent overtraining and injury. For runners, this approach ensures the appropriate mix of volume, intensity, and recovery is met for sustained improvement and peak race performance.

Still Work to be Done

Although many types of periodization have successfully been performed over the years, this actually brings into questions the effectiveness of periodization itself. If so many different types of periodization work, or people have different responses to the same program, the effectiveness of periodization must be questioned. As always, there is still more research to be done in this area.

References:

Bompa, T., & Haff, G. (2009). Periodization: Theory and Methodology of Training. Human Kinetics.

Issurin, V. B. (2008). Block periodization versus traditional training theory: A review. The Journal of Sports Medicine and Physical Fitness, 48(1), 65–75.

Kiely, J . Periodization Theory: Confronting an Inconvenient Truth. Sports Med. 2018; 48(4): 753–764. Published online 2017 Nov 30. doi: 10.1007/s40279-017-0823-y

Seiler, S. (2010). What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance, 5(3), 276–291.

The role of static stretching in running has been extensively studied in recent history, with research challenging many traditional assumptions about its benefits. Current evidence presents a nuanced view of its effects on performance and injury prevention.

Regarding performance, static stretching has been shown to have a dose-dependent negative effect on running performance, meaning the more you do (above 60 seconds), the worse your performnace typical will be. According to Behm et al., static stretching lasting more than 60 seconds results in significant performance reductions (approximately 4.5% decrease), while stretching for less than 60 seconds shows insignificant changes in performance [1]. These performance decrements appear to be related to reduced muscle activation following static stretching protocols.

The relationship between static stretching and range of motion (ROM) is complex. While static stretching can improve passive range of motion, research by Mettler et al. demonstrates that these improvements don't necessarily transfer to active range of motion during running [2]. Their 3-week study showed that despite significant increases in passive hip extension following a stretching program, there were no improvements in active hip extension during running.

Concerning injury prevention, the evidence is mixed. Behm's meta-analysis of stretching-related studies found that only two out of five studies showed benefits of stretching for injury prevention in runners. Static stretching appears to be more beneficial for preventing acute muscle injuries (showing up to a 54% reduction) but shows limited effectiveness in preventing chronic or overuse injuries, which are more common among runners. The research suggests that static stretching may be more beneficial for sports with sprint components rather than endurance running activities [1].

Recent literature has begun to shift focus from static stretching to dynamic warm-up activities. Dynamic stretching has shown a modest positive effect on performance (approximately 1.3% improvement), though this benefit is relatively small for recreational runners. However, when static stretching is followed by dynamic activities as part of a comprehensive warm-up, the negative performance effects appear to be negated [3].

An interesting development in the literature is the emergence of resistance training as an alternative to static stretching for improving range of motion. Recent research indicates that resistance training may be equally or more effective at improving ROM compared to stretching protocols, while providing additional performance benefits [4]

References

1. Behm DG, Blazevich AJ, Kay AD, McHugh M. Acute effects of muscle stretching on physical performance, range of motion, and injury incidence in healthy active individuals: a systematic review. Appl Physiol Nutr Metab. 2016;41(1):1-11.
2. Mettler JH, Shapiro R, Pohl M. Effects of a Hip Flexor Stretching Program on Running Kinematics in Individuals With Limited Passive Hip Extension. J Strength Cond Res. 2019;33(12):3338-3344.
3. Behm DG, Alizadeh S, Daneshjoo A, Konrad A. Potential Effects of Dynamic Stretching on Injury Incidence of Athletes: A Narrative Review of Risk Factors. Sports Med. 2023 Jul;53(7):1359-1373. doi: 10.1007/s40279-023-01847-8. Epub 2023 May 10. PMID: 37162736; PMCID: PMC10289929.
4. Alizadeh S, Daneshjoo A, Zahiri A, Anvar SH, Goudini R, Hicks JP, Konrad A, Behm DG. Resistance Training Induces Improvements in Range of Motion: A Systematic Review and Meta-Analysis. Sports Med. 2023 Mar;53(3):707-722. doi: 10.1007/s40279-022-01804-x. Epub 2023 Jan 9. PMID: 36622555; PMCID: PMC9935664.

Strength training has gained recognition as a valuable component of training regimens for runners, complementing traditional endurance workouts. Research highlights several benefits of incorporating strength training into a runner's routine, as well as certain limitations to consider.

Benefits of Strength Training for Runners

1. Improved Running Economy (RE): Running economy refers to the energy demand for a given running velocity. Enhanced RE allows runners to use less energy at the same pace, thereby improving performance. Studies indicate that strength training, particularly high-load and plyometric exercises performed two to three times per week for 8–12 weeks, can significantly improve RE in middle- and long-distance runners. [1]
2. Enhanced Performance Metrics: Incorporating strength training has been shown to improve maximal and reactive strength qualities, which are crucial for endurance performance. A 40-week strength training program led to significant improvements in these strength qualities, RE, and velocity at VO₂ max (vVO₂ max) in distance runners. [2]
3. Possible Injury Reduction: Strength training may play a role in reducing injury risk among runners. To date, the research is inconclusive, but tends to suggest resistance training is at worst, neutral and at best positive. [3]
4. Concurrent Training Benefits: Combining strength and endurance training, known as concurrent training, has been found effective in enhancing both strength and endurance adaptations without significant interference effects. A 12-week concurrent training program improved body composition and performance variables in recreational runners aged 30 to 40. [4]

Limitations and Considerations

1. Potential for Increased Muscle Mass: While strength training can enhance performance, there is a concern that significant increases in muscle mass might impair RE due to added weight. However, studies have shown that strength training can increase muscular strength without a corresponding increase in muscle mass, mitigating this concern. [5]
2. Training Specificity: The effectiveness of strength training can depend on the methods employed. High-load and plyometric training have been shown to improve RE, whereas submaximal load and isometric strength training appear less effective for this purpose. [6]
3. Time and Recovery Demands: Incorporating strength training into a runner's regimen requires additional time and can increase overall training load. It's essential to balance strength sessions with running workouts to prevent overtraining and ensure adequate recovery.
4. Individual Variability: Responses to strength training can vary among individuals. Factors such as training history, running experience, and individual biomechanics can influence the degree of benefit gained from strength training.

In conclusion, integrating strength training into a runner's training program offers several benefits, including improved running economy, enhanced performance metrics, and potential injury prevention. However, it's crucial to consider the type of strength training, monitor training loads, and tailor programs to individual needs to maximize benefits and minimize potential drawbacks.

References:

1. Balsalobre-Fernández C, Santos-Concejero J, Grivas GV. The effects of strength training on running economy in highly trained runners: a systematic review with meta-analysis of controlled trials. J Strength Cond Res.2016;30(8):2361-2368. doi:10.1519/JSC.0000000000001316.
2. Blagrove RC, Howatson G, Hayes PR. The effect of strength training on performance indicators in distance runners. J Strength Cond Res. 2017;31(1):1-20. doi:10.1519/JSC.0000000000001464.
3. Desai P, Jungmalm J, Börjesson M, Karlsson J, Grau S. Effectiveness of an 18-week general strength and foam-rolling intervention on running-related injuries in recreational runners. Scand J Med Sci Sports. 2023;33(5):766-775. doi:10.1111/sms.14313
4. Prieto-González P, Sedlacek J. Effects of running-specific strength training, endurance training, and concurrent training on recreational endurance athletes’ performance and selected anthropometric parameters. Int J Environ Res Public Health. 2024;21(10):1234. doi:10.3390/ijerph21101234.
5. Karp JR. The effects of strength training on distance running performance and running injury prevention. J Phys Educ Sport. 2024;24(10):259. doi:10.7752/jpes.2024.10259.
6. Llanos-Lagos C, Ramirez-Campillo R, Moran J, Sáez de Villarreal E. Effect of strength training programs in middle- and long-distance runners’ economy at different running speeds: a systematic review with meta-analysis. Sports Med Open. 2024;10(5):109. doi:10.1007/s40279-024-01087-5.

Training Zones in Endurance Training

Endurance training zones are structured ranges of effort based on heart rate, pace, or perceived exertion that guide training intensity. These zones help athletes target specific physiological adaptations, such as aerobic capacity, lactate threshold, or anaerobic power. Training zones vary across systems, with the most common being the 3-zone system, 5-zone system, and 7-zone system.

Once you understand that there are multiple systems of zones, you may find clarity when reading or discussing them by first acknowledging which system is being referred to. The best example of this would be referencing Zone 2, which has become very popular recently.

Within the 3 zone system, zone 2 refers to lactate threshold intensity, while in the 5 and 7 zone systems, zone 2 will be referring to more purely aerobic endurance work.

Threshold is another term that becomes a little less clear unless the same system is being discussed. Once again threshold work is in reference to zone 2 in a 3 zone model, but zone 3 in a 5 zone model, and zones 3 AND 4 in a 7 zone model. The difference between the 5 and 7 zone models being that the 7 zone model distinguishes between work done near your first lactate threshold (zone 3) and your second lactate threshold (zone 4).

3-Zone System

The 3-zone system is simple and groups training intensities broadly:

Zone 1: Low-intensity, aerobic training (easy pace).

Zone 2: Moderate-intensity training (threshold work).

Zone 3: High-intensity, anaerobic work.

This system works well for beginners, recreational athletes, or any athlete who is looking for a simplistic approach to their training. However, the 3 zone system m lacks nuance in differentiating the critical aerobic and anaerobic adaptations in more advanced training.

5-Zone System

The 5-zone system provides more granularity, dividing training intensities into:

Zone 1: Recovery (very light intensity).

Zone 2: Aerobic endurance (moderate intensity).

Zone 3: Tempo/lactate threshold (comfortably hard).

Zone 4: VO2 max (hard, near-max effort).

Zone 5: Anaerobic/sprint effort (all-out).

This system balances simplicity and precision, making it the most widely used among runners, particularly for long-distance training. Each zone aligns with specific physiological markers such as fat oxidation, lactate accumulation, or maximal oxygen uptake.

7-Zone System

The 7-zone system, often used in cycling or elite endurance sports, divides efforts further:

Zones 1–2: Easy, recovery, and base endurance.

Zones 3–4: Threshold (upper/lower thresholds distinguished).

Zones 5–7: High-intensity efforts (VO2 max, anaerobic capacity, and sprint power).

The added complexity allows for precise targeting of specific adaptations but can be overwhelming or unnecessary for most runners.

Why Systems Differ

The primary difference lies in the level of detail required for training goals. Elite athletes or those in multidiscipline sports (e.g., triathlon) may benefit from 7 zones for pinpoint adaptation. Recreational runners often prefer the 3-zone system's simplicity or the 5-zone system's balance of usability and specificity.

Comparison Chart of Heart Rate Zones

System: Zone%, HR Max, Training Focus

3-Zone

• Zone 1: <75% Base endurance, recovery
• Zone 2:75–90%Tempo, threshold
• Zone 3:>90% Anaerobic capacity, sprint work

5-Zone

• Zone 1: (Recovery)<60% Active recovery
• Zone 2: (Endurance)60–70% Aerobic endurance, fat utilization
• Zone 3: (Threshold)70–80%Lactate threshold, aerobic efficiency
• Zone 4: (VO2 Max)80–90% High-intensity aerobic
• Zone 5: (Anaerobic)>90% Sprinting, explosive power

7-Zone

• Zones 1–2: (Recovery/End)<65% Recovery, aerobic base
• Zone 3: (Tempo)65–75% Lower lactate threshold work
• Zone 4: (Threshold)75–85% Upper lactate threshold
• Zones 5–6: (VO2 Max/Anaer)85–95% VO2 max intervals, anaerobic conditioning
• Zone 7: (Sprint)>95% Explosive efforts

References:

Brooks’, G. A., & Fahey, T. D. (2020). Exercise Physiology: Human Bioenergetics and Its Applications. McGraw Hill.

Edwards, A. M., & Clark, N. A. (2006). Running economy and performance. Sports Medicine, 36(12), 1063–1081.

Seiler, S. (2010). What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance, 5(3), 276–291.

Before reviewing this section please review the "Training Zones" section above.

Zone 2 Aerobic Training: What It Is and Why It’s a Game-Changer for Runners

Zone 2 aerobic training is the not-so-secret weapon of many successful runners. It’s all about running at a pace where you can still hold a conversation—a.k.a., the "easy pace." This training zone is typically 60-70% of your maximum heart rate, and may be up to 80% in very trained individuals (Mujika, 2021). If you’re not using a heart rate monitor, think of it as the pace that feels comfortable, sustainable, and, dare I say, a little slow (Fitzgerald, 2014).

Here’s the deal: Zone 2 training builds your aerobic base, which is your body’s ability to efficiently use oxygen for energy. The better your aerobic base, the better your endurance. That means you can run farther, recover faster, and even crush those faster-paced runs (Runner's World, n.d.).

But why is this slow running so effective? When you run in Zone 2, your body primarily burns fat for fuel instead of carbohydrates. This metabolic efficiency improves your stamina and delays fatigue, especially during longer runs, as you have saved your Glycogen stores for faster paces (Holloszy & Coyle, 1984). You’re also strengthening your heart and increasing your ability to transport oxygen to working muscles, which is essential for endurance athletes (TrainingPeaks, n.d.).

Benefits of Zone 2 Training for Runners

1. Improved Endurance: Zone 2 training increases the number and size of your mitochondria (the "power plants" of your cells), making your muscles more efficient at producing energy (Holloszy & Coyle, 1984).
2. Faster Recovery: Running at an easy pace reduces muscle strain and promotes recovery between harder efforts (Fitzgerald, 2014).
3. Increased Fat Burning: It teaches your body to rely more on fat for energy, preserving glycogen stores for when you really need them—like during a race (House, Johnston, & Jornet, 2019).
4. Stronger Cardiovascular System: Running in this zone strengthens your heart, allowing it to pump more blood with each beat (Achten & Jeukendrup, 2003).
5. Injury Reduction: Zone 2 training is gentle on your joints and muscles, reducing your risk of overuse injuries (TrainingPeaks, n.d.).

The magic of Zone 2 isn’t in one or two runs—it’s in the consistency. Most runners should spend 70-80% of their weekly mileage in this easy zone (Fitzgerald, 2014). This might feel frustratingly slow at first, especially if you’re used to pushing hard, but trust the process. Over time, your Zone 2 pace will naturally get faster, and you’ll see the payoff on race day when your legs feel fresher and stronger for longer (Polar, n.d.; Garmin, n.d.).

So, if you want to run farther, and feel stronger, embrace the power of Zone 2. Slow and steady really does win the race (or at least helps you train for it)!

Resources

• Achten, J., & Jeukendrup, A. E. (2003). Heart rate monitoring: Applications and limitations. Sports Medicine, 33(7), 517-538. https://doi.org/10.2165/00007256-200333070-00004
• Fitzgerald, M. (2014). 80/20 Running: Run stronger and race faster by training slower. Penguin Random House.
• Garmin. (n.d.). Understanding heart rate zones. Retrieved from https://www.garmin.com
• Holloszy, J. O., & Coyle, E. F. (1984). Adaptations of skeletal muscle to endurance exercise and their metabolic consequences. Journal of Applied Physiology, 56(4), 831-838. https://doi.org/10.1152/jappl.1984.56.4.831
• House, S., Johnston, S., & Jornet, K. (2019). Training for the uphill athlete: A manual for mountain runners and ski mountaineers. Patagonia.
• Mujika, I. (2021). Endurance training: Science and practice (2nd ed.). Human Kinetics.
• Polar. (n.d.). What is heart rate training? Retrieved from https://www.polar.com
• Runner's World. (n.d.). The science of running easy. Runner's World. Retrieved from https://www.runnersworld.com
• That Triathlon Show. (n.d.). Heart rate zones and optimizing intensity. Retrieved from https://scientifictriathlon.com
• The Science of Ultra. (n.d.). Zone 2 training and its importance. Retrieved from https://scienceofultra.com
• TrainingPeaks. (n.d.). The importance of Zone 2 training. TrainingPeaks. Retrieved from https://www.trainingpeaks.com