When I was a runner in high school, training zones were not quite as common as they are today. We absolutely varied our intensities through fartleks, 800- and 1600-meter threshold runs (just below max effort), 200-meter sprints, hill repeats, and LSD runs (long, slow, distance). As a high school athlete, I may not have known the intricacies of why we did what we did, but it worked. While many things remain the same, so much has changed in the last 25 years.

INTRODUCTION TO TRAINING ZONES

The utilization of training zones in endurance sports became popularized in the late 20th century, particularly in the 1980s and 1990s. 

The concept gained traction as coaches, scientists, and athletes sought more structured and scientific approaches to training. This period saw advancements in sports science, including the understanding of physiological adaptations to different intensities of exercise.  Gone are the days of training all-out all the time.

Moreover, the introduction of technologies like heart rate monitors, power meters (for cycling), and GPS devices provided athletes with tools to monitor their training intensity more accurately, making it easier to implement training zone-based programs.

Since then, the utilization of training zones has become standard practice in endurance sports training, with athletes across various disciplines relying on them to optimize performance and training adaptations.  Between advancements in technology and science, we are breaking barriers that were likely unimaginable just a few decades back.  It’s an exciting time to be an athlete!

What are training zones?

Training zones in endurance sports are specific intensity ranges used to prescribe and monitor training. They are typically divided based on percentages of maximum heart rate, lactate threshold, pace from field tests, or functional threshold power. 

These zones help athletes train more effectively by targeting different physiological systems, such as aerobic endurance, lactate threshold, and anaerobic capacity. By training within these zones, athletes can optimize their training adaptations and improve performance while minimizing the risk of overtraining or injury.

Depending on what training principle you follow, you will find anywhere from three training zones up to six or more zones.  Zones are established by different types of tests, depending on the training modality.  For example, as a triathlete, you will establish zones through different tests for your swim, bike, and run training.  While I prefer to use pace and power for training zone targets, my goal is to break this down to something easily digestible, and then we will dig into the specifics. 

Rate of Perceived Exertion (RPE) is a subjective measure used to gauge the intensity of exercise based on how hard you feel you’re working. It’s often rated on a scale from 1 to 10, with 1 being very light exertion (minimal effort) and 10 being maximum effort (complete exhaustion). If you were to use six zones for training, here’s a breakdown of how it might look as a scale of RPE:

Zone 1 (Recovery): RPE 1-2

• Description: Very light exercise, feels like you’re barely exerting yourself.
• Example: Walking at a leisurely pace, gentle stretching.

Zone 2 (Endurance/Aerobic): RPE 3-4

• Description: Moderate intensity, feels like you’re working, but you could maintain the effort for a long time.
• Example: Easy jogging, conversational-paced cycling, comfortable swim pace.

Zone 3 (Tempo): RPE 5-6

• Description: Moderate to high intensity, feels challenging but sustainable for shorter periods.
• Example: Running at a pace where conversation is possible but slightly difficult, brisk cycling, swimming at a pace that’s starting to feel challenging.

Zone 4 (Threshold): RPE 7-8

• Description: High intensity, feels difficult, and you’re pushing close to your maximum sustainable effort.
• Example: Running at a pace where conversation is difficult, fast-paced cycling with heavy breathing, swimming at an effort that you can sustain for 5-10 minutes (note that swimming is a little harder to quantify as skill/technique varies greatly but has a large impact on time/efficiency in the water).

Zone 5 (Maximal): RPE 9-10

• Description: Maximum effort, feels extremely hard, and you’re pushing yourself to your limit.
• Example: Sprinting as fast as you can, high-intensity interval training, swim sprints.

Zone 6 (Anaerobic Capacity): RPE 9-10+

• Description: Maximum effort beyond sustainable levels, feels extremely intense, and can only be sustained for very short bursts.  Long recovery between sets is needed.
• Example: All-out sprinting for a very short distance, extreme exertion in high-intensity interval training, swim sprints.

Remember that individual perceptions of effort can vary, so it’s important to listen to your body and adjust intensity accordingly. Additionally, using a combination of RPE and other objective measures (such as heart rate or power output) can provide a more comprehensive understanding of exercise intensity. We will discuss this further below.

UNDERSTANDING LACTATE THRESHOLD

Lactate threshold (LT) is the exercise intensity at which lactate begins to accumulate in the bloodstream faster than it can be cleared away. This accumulation is associated with an increase in hydrogen ions, leading to a decrease in pH and the sensation of muscle fatigue. The lactate threshold is a key physiological marker that influences athletic performance, especially in endurance sports.

In the context of training zones, understanding and training around the lactate threshold is crucial for improving athletic performance. For example, when training in zone 3 (Tempo) and zone 4 (Threshold), these training zones are typically set around or just above the lactate threshold. By training at these intensities, you can improve your body’s ability to clear lactate and buffer acidosis, which helps delay the onset of fatigue during high-intensity efforts.

Regular training at or slightly above the lactate threshold can lead to adaptations that improve LT. This includes increased mitochondrial density, improved lactate clearance, and enhanced muscle buffering capacity. As a result, you can sustain higher intensities for longer periods before reaching fatigue.

Additionally, training at or slightly above LT is beneficial for athletes preparing for races or events where sustaining a high intensity is necessary. If you have a Sprint or Olympic triathlon on the horizon, this pertains to you. By spending time in Zone 4, you can familiarize yourself with the discomfort associated with racing at or near your lactate threshold. This may help you mentally and physically prepare for competition.

Lastly, changes in lactate threshold can serve as an indicator of training progress and fitness level. As athletes become more fit, their lactate threshold typically increases, allowing them to sustain higher intensities before reaching fatigue. Monitoring lactate threshold through regular testing can help athletes and coaches adjust training plans and track improvements over time.

HOW TO ESTABLISH TRAINING ZONES

Training zones can be established through various methods.  You can use sites like the 80/20 zone calculator or TrainingPeaks to calculate each of them using different tests. 

Maximal Heart Rate (MHR) is determined by performing a maximal exercise test, where the highest heart rate achieved is considered the MHR. Zones are then calculated as percentages of this value.  A way that I have pulled my MHR in the past is from a 5K race.  I know that I push myself to my upper limit and trust this to be close to my MHR.

As discussed, Lactate Threshold (LT) is the point at which lactate accumulation in the blood increases significantly. Athletes can undergo lactate threshold testing in a lab or estimate LT using field tests. Zones are then set relative to LT. 

A lactate threshold field test is a practical way for athletes, particularly cyclists and runners, to estimate their lactate threshold intensity without the need for laboratory equipment. Here’s an example of a lactate threshold test specifically designed for runners:

1. Warm-Up: Begin with a thorough warm-up of approximately 15-20 minutes of easy jogging, gradually increasing the intensity to elevate your heart rate and prepare your muscles for the test. Include dynamic stretches and mobility exercises to further prime your body for the effort ahead.
2. Main Test Protocol: The main portion of the test involves sustained efforts at increasing intensity. Choose a flat or gently rolling course with minimal interruptions (traffic lights, intersections, etc.). Here’s a suggested protocol:
   a. Start with a baseline pace that feels comfortably challenging but sustainable for at least 10-15 minutes. This pace should be slightly below your anticipated lactate threshold intensity.
   b. After the warm-up, begin the first effort segment at a moderate intensity, aiming for an RPE (Rate of Perceived Exertion) of around 6-7 on a scale of 1-10. Maintain this effort level for 10-15 minutes.
   c. After completing the first effort segment, take a brief active recovery jog of 5-10 minutes at an easy pace to allow your body to clear accumulated lactate and prepare for the next effort.
   d. Repeat the effort segment followed by active recovery for a total of 2-3 times.
3. Monitoring and Recording Data: Throughout the test, monitor your heart rate (if available), pace, and perceived exertion. Note the average pace and heart rate for each effort segment.
4. Analysis: After completing the test, analyze your data to identify your lactate threshold intensity. The lactate threshold typically corresponds to the pace and heart rate that you can sustainably maintain for the duration of the effort segments.
5. Cool Down: Finish the test with a gradual cool down of at least 10-15 minutes of easy jogging to aid in recovery and facilitate lactate clearance.

As with any high-intensity exercise, it’s crucial to approach this test with proper preparation and caution. Listen to your body, stay hydrated, and stop the test if you experience any signs of distress or discomfort. Additionally, performing this test periodically can help track changes in your lactate threshold and fitness level over time.

When it comes to cycling zones, many will agree that the gold standard is Functional Threshold Power (FTP).  This is a relatively easy test to perform. FTP represents the highest average power output an athlete can sustain for one hour. FTP testing or estimation allows athletes to set power-based training zones.

Performing a 20-minute FTP (Functional Threshold Power) test is a common method for cyclists to estimate their FTP, which is the highest average power output they can sustain for one hour without fatiguing. You can do this outdoors, as well, but be mindful that terrain and traffic may impact your performance and the accuracy of your results. Here’s a guide on how to perform a 20-minute FTP test on a trainer:

1. Preparation:
   • Ensure your bike is properly set up and maintained. Check tire pressure, gears, and brakes.
   • Warm up for at least 15-20 minutes, gradually increasing intensity to elevate your heart rate and prepare your muscles for the test. Include some short, high-intensity efforts to activate your muscles and nervous system.
2. Test Protocol:
   • Begin the 20-minute test effort. Aim to ride at the highest sustainable intensity you can maintain for the entire duration. Pace yourself carefully to avoid starting too hard and fading towards the end.
   • Focus on maintaining a consistent effort throughout the 20 minutes. Monitor your power output, heart rate, and perceived exertion to gauge your intensity.
   • Avoid looking at your power meter or other metrics too frequently, as this can distract you from maintaining focus and effort.
   • Stay mentally strong and push through any discomfort or fatigue. Remember that it’s a relatively short effort, and the discomfort is temporary.
3. Cool Down:
   • After completing the 20-minute effort, gradually ease into a 10-15 minute cooldown at an easy pace. This helps facilitate lactate clearance and aids in recovery.
4. Analysis:
   • Once you’ve completed the test and cooled down, analyze your power data to determine your average power output for the 20-minute effort.
   • Your FTP estimate is typically calculated as 95% of your average power from the 20-minute test. This adjustment accounts for the fact that most people can sustain a higher power output for 20 minutes compared to one hour.
5. Training Zones:
   • Use your estimated FTP to establish training zones for your workouts. These zones will help guide the intensity of your training sessions and ensure you’re training at appropriate levels to achieve your goals.

Performing a 20-minute FTP test periodically (e.g., every 4-6 weeks) can help track changes in your fitness level and adjust your training accordingly.

Rating of Perceived Exertion (RPE) can be used to help athletes establish zones based on their perceived effort level on a scale of 1 to 10.  Zone ranges correspond to different RPE values.

Field Tests, such as time trials or interval sessions, can be used to gauge performance at different intensities and establish training zones based on those results.  When it comes to my running zones, I prefer to use a 5K as my time trial.  It is hard to push yourself as hard as you can when running solo.  But if you enter a 5K and use that as your baseline, you will likely have a more accurate target of what you are capable of. 

It’s important for athletes to periodically reassess their training zones as fitness levels change over time. Consulting with a coach or sports scientist can also provide valuable insights into establishing accurate training zones tailored to individual needs and goals.

ZONE 2 TRAINING – GO SLOW SO YOU CAN GO FAST

This was a hard concept for me to grasp when I first started racing in duathlon and triathlon. I wanted to go fast because I felt like I could. Rarely did I follow the recommended paces or heart rate when I was supposed to be running in zone two. Maybe there was a fear that I would just lose speed if I didn’t train fast enough often enough. But the reality is that when I learned to slow down when I was supposed to go slow, my body thanked me. My joints weren’t as cranky, my recovery improved, my mood proved, and not surprisingly, so did my performance.

While training around your LT is extremely important and valuable for increasing fitness and your ability to endure the discomfort on race day, zone two training just may have it beat as the King of your training zones.

Zone two training is crucial for endurance athletes for several reasons:

1. Developing Aerobic Capacity: Zone 2 training primarily targets the aerobic energy system, which is essential for sustaining activities over extended periods. By training in this zone, athletes can increase their aerobic capacity, allowing them to perform better during longer endurance events.
2. Building Endurance: Zone 2 training helps build endurance by improving the body’s ability to utilize oxygen efficiently. This leads to enhanced endurance performance, enabling athletes to maintain a higher intensity for longer durations without fatigue.
3. Fat Utilization: Training in Zone 2 encourages the body to use fat as a primary fuel source. This is beneficial for endurance athletes, as it helps conserve glycogen stores, which are crucial for higher intensity efforts. By relying more on fat for energy, athletes can sustain their performance over extended periods.
4. Reducing Risk of Overtraining and Injury: Zone 2 training is typically lower in intensity compared to higher zones. This allows athletes to accumulate training volume without overstressing their bodies, reducing the risk of overtraining and injury. It provides a balance between stress and recovery, promoting long-term athletic development.
5. Improving Recovery: Training in Zone 2 enhances blood flow and oxygen delivery to muscles, which aids in recovery from more intense workouts. By incorporating Zone 2 training into their regimen, athletes can expedite recovery and maintain consistency in their training without experiencing burnout or excessive fatigue.
6. Enhancing Cardiac Function: Zone 2 training promotes cardiac adaptations, such as increased stroke volume and improved cardiac output. These adaptations result in a more efficient cardiovascular system, allowing athletes to deliver oxygen-rich blood to working muscles more effectively, ultimately improving overall performance.
7. Building Mental Toughness: Endurance events often require mental fortitude to push through discomfort and fatigue. Zone 2 training provides athletes with opportunities to practice mental resilience during prolonged, lower-intensity efforts, helping them develop the mental toughness necessary to excel in endurance competitions.

Overall, Zone 2 training lays the foundation for endurance athletes. It’s a cornerstone of effective endurance training programs and is essential for optimizing long-term athletic performance. Go slow so you can go fast.

HOW OFTEN SHOULD YOU REASSESS YOUR ZONES?

As with all aspects of your training – you should approach your zones and reassessments based on where you are at as an athlete and your training cycle. If you are newer to endurance sports, you will likely see more frequent improvements in your capabilities. Another thing to consider is where you are at in your season. Do you have a few races under your belt this year? Or are you just approaching the start of your race season?

When it comes to reassessing your training zones, frequency is key to ensuring they remain accurate and effective. At the beginning of the season or if you’re just starting out, it’s advisable to reevaluate around every four weeks. During this period, your fitness levels are likely to improve rapidly, and regular reassessment helps keep your training tailored to your current abilities.

As the season progresses and your improvements become more gradual, you can extend the reassessment interval to every eight weeks. Again, this recommendation is general, and you need to take into account individual circumstances and preferences. This balanced approach ensures your training zones stay relevant, optimizing performance gains while avoiding overtraining.

HOW DO TRAINING ZONES TRANSLATE TO RACE DAY?

Training zones play a crucial role in preparing athletes for race day by informing their pacing strategies and optimizing performance. Here’s how training zones translate to race day:

Pacing Strategy: Athletes use their knowledge of training zones to develop a pacing strategy that aligns with the demands of the race. For example, they may start conservatively to stay within their aerobic zone and avoid early fatigue, gradually increasing intensity as the race progresses.

Efficiency and Economy: Training in specific zones helps athletes improve their biomechanical efficiency and economy, allowing them to maintain a steady pace with minimal energy expenditure. This translates to more efficient movement patterns during the race, conserving energy for later stages.

Nutrition and Hydration: Understanding training zones helps athletes plan their nutrition and hydration strategies accordingly. They can adjust intake based on the intensity of each zone to meet energy demands and maintain optimal performance.

Adaptability: Training across different zones prepares athletes for the variability of race conditions, such as changes in terrain, weather, or competition dynamics. They learn to adapt their effort level to navigate these challenges while staying within their optimal performance zones.

Race Execution: By practicing race-specific intensities during training, athletes develop the mental and physical resilience needed to execute their race plan effectively. They learn to push through discomfort while staying within their sustainable zones, optimizing performance without risking burnout.

Overall, training zones provide athletes with a structured framework to prepare for race day, allowing them to pace themselves strategically, conserve energy, and perform at their best when it matters most.

FINAL THOUGHTS

Training zones are an invaluable tool when preparing for endurance events. They support multiple adaptations while minimizing the risk of injury. We have so many tools at our fingertips and sometimes it can be overwhelming. I’m a believer in sticking to the basics – proper nutrition, strength training, mindset, and of course your endurance training sessions. It doesn’t have to be complicated, it just has to be consistent and tried and true. Zone training and following an 80/20 format (or close to it) has proven results. If you have questions on zone training or would like to learn more about my approach to working with athletes, send me a message to get started. I always love connecting with athletes!

It’s your journey, your pace, and all my support.