The 5 running zones and why varying your running pace helps with overall fitness

Many people take up running and choose a single distance and run it hard every time they train, trying to set a new personal best each time. Other people try to increase their distance but never change their pace, "one-pace-wonders" so to speak.

Training in this way will result in temporary improvements to fitness, some instant gratification, and comfort, but will eventually lead to fitness plateaus and stale, boring workouts. Over the years the fitness community has developed a much better and effective way of training, one which targets different body systems by running different paces.

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Tuning Your Gearbox

We can compare running to a long-distance car race. Each car has a variety of properties, like power-to-weight ratio and drive-train efficiency that influences how fast the car can go. The car must also have the fuel economy to go the race distance. A V10 super car may be fast and responsive, but it isn’t terribly fuel-efficient and will run out of gas.

A factor that could easily be overlooked, however, is the tuning of the gearbox. You may have a car with decent fuel economy and a strong engine, but if the transmission gets stuck in second gear, you’re going to guzzle fuel and struggle to accelerate past a certain point without redlining. All the gears need to be tuned to work together.

Running at different speeds and doing different workouts used to them is akin to tuning the transmission of a car. Every workout has a purpose and exists in the context of a plan, and as always, I’d recommend that you find a thoughtful, descriptive training plan tailored to your fitness level and race goals.

In this article, I will go over 6 basic running speeds and efforts you’ll utilize in your training, starting with zone 2 to stick with the common zone naming conventions.

The body has certain metabolic thresholds that make it react quite differently to different paces, efforts, and workouts. Sometimes a small change in pace and effort can cause large changes to the way the body adapts to and accomplishes the pace. For example increasing your pace by just 10 seconds per mile, if its crosses over the lactate threshold (the rate at which your body processes lactate as fast as it creates it) will dramatically reduce the distance you can run at that pace. For these reasons, it is helpful and common practice to break down the benefits we receive from and body stress we acquire from each effort.

I created the chart below with a combination of research and my running experience. You’ll find it is unique but closely correlates with other formulations.

Key Terms

RPE (Rated Perceived effort): A common scale from 1 to 10 where an individual rates their effort, with 1 being the easiest and 10 being the hardest.

Percent Heart Rate Reserve: This Incorporates resting heart rate (HR) and maximum heart rate. On this scale 0% would be your resting heart rate and 100% is your maximum. It can be calculated on a website that I’ll leave in the references or, for math nerds, by the formula:

Lactate Threshold: Maximum pace and effort that can be held for an hour

VO2 Max: The maximal aerobic capacity of the body; the fastest it can intake and use oxygen. This occurs at about the fastest pace an individual can hold for 10 minutes. At this point the body must supplement aerobic respiration by burning glycogen in anaerobic metabolism.

Running Zone Chart:

Chart is easiest to see on desktop computer and is downloadable in a large format

Zone 2: Endurance

This is the most common zone for training and encompasses your recovery runs and long runs (which won’t feel as easy by the end). These runs maintain your fitness and gradually build long-term strength, develop capillaries and blood flow, and increase mitochondrial density. The benefits of these runs take the longest to see but they are also the longest-lasting, setting the foundation for your fitness goals. Keep these runs at a conversational pace and, in the case of the recovery run, allow yourself to recover so you can hit your next difficult workout and race better.

When training for a race distance 10k or greater (and often the 5k) do at least one long run a week. For shorter distances less than 5k, speed work is often more important.

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Zone 3: Steady/Stamina

This zone encompasses the fastest marathon pace a fit runner might have. Running in this zone feels good. You’re working hard enough to feel you’re accomplishing something, but not so hard that you’re in pain or laboring. You’re going fast and with some effort you can probably still talk. Be careful with this zone though, if you run in zone 3 when you should be running in zone 2 then, day after day, you’ll compromise your recovery and see less improvement. If you are training for a marathon, this zone is good for pace work. It also is decent for muscular endurance.

Use this zone sparingly: for many runners, it’s not as effective as lactate threshold training or zone 2 mileage, but on the high end of the zone it’s a nice pace to work on to supplement your tempo runs and is a good pace to do a few fartleks (temporary accelerations in a zone 2 run).

Zone 4a: Tempo/Lactate Threshold

This zone is key in most distance races. While lab scientists have different definitions for lactate threshold, most coaches figure it as the fastest pace a fit individual can hold for 1 hour. This zone encompasses paces between half-marathon and 10k race pace. A good runner may be able to hold in this zone, slightly lower than their lactate threshold, for a half-marathon, which is why I put the max duration at about 90 minutes. For many a 10k will be a bit faster than their lactate threshold and start approaching their anaerobic threshold.

This zone does a great job at building up speed-endurance and leg strength, is excellent pace work for most races, and trains the aerobic system to handle moderate loads.

Training this zone can be accomplished by intervals, often 2-3 x 5-10 minutes at a moderately hard effort, each interval being followed by about 3-5 minutes of easier running.

Zone 4b: Anaerobic Threshold

This zone includes your 5k race pace and effort. Training at this pace is often done in 3-5 minute repetitions. The popular Yasso 800’s are run close to this effort. Another popular workout is 5-7x1000m.

Workouts in this zone are hard but have major benefits to speed-endurance, muscle strength, upper aerobic capacity, and form. One of the keys to gaining the most endurance benefit from these workouts is to keep the rest between intervals low (2 minutes or less, not more than 3). You should attempt to run each rep (usually 6-10), at about the same pace and at the end of the workout you should feel like you could have done one more at that target pace.

When training for races 10k or under, these workouts are very fruitful. Try to do at least one zone 4 run a week, making sure you spend some time working on your goal race pace.

Zone 5a: VO2 Max/Speed

Like was mentioned above, VO2 max is the fastest pace your body can hold for about 10 minutes. This is likely going to be slightly slower than your fastest mile pace (and can be predicted by the McMillan Running website [3]).

This pace is crucial if you want to run a fast mile or need to improve your speed (the athlete who can last forever but lacks top-end speed). It will start recruiting more fast-twitch muscle, will force you to hold your form, and will test your maximal aerobic capacity.

Workouts in this zone are often include 8-12x200m (45-60 second rest), 6x400m (60-90 second rest), or 4x800m (90 second – 2 minute rest). Do these at an even pace, and, again, at the end of the set, make sure you feel like you could do one more. Moderate rest works well.

Zone 5b: Sprint

Sprint training can be tiring for endurance athletes, but when done occasionally (10 days), it tunes your form, improves your fast-twitch capabilities, improves your explosiveness, and enhances muscle recruitment. It should be performed every couple of days for sprinters, with supplemental weight training.

While sprinting, allow yourself plenty of rest (3+ minutes) to allow yourself to continue fully recruiting your fast-twitch muscles. Also keep your number of repetitions low. Common sets may include 3x200m followed by 3x50m, 4-6 x 150m with a running (flying) start, or 4-6x100m at 95% effort. Stay relaxed.

It’s common for high school athletes to do 8 or more 200m repetitions on lower rest but these will be at 85-90% effort. Wind-sprint 400’s are also common and but you shouldn’t do more than 3 or 4 at 90% effort. Any more repetitions and the intensity will need to be reduced.

While in theory this zone would max your heart rate, in practice, the intervals are too short and too anaerobic to achieve your true max heart rate. Sprints don't improve your long distance aerobic capacity much, but they do help with your form, muscle strength, and explosiveness.

Strides at the end of a workout can help your speed. These are typically 4-8 x 60-100m done at a relaxed but fast (and accelerating) pace. They are not all-out sprints and shouldn't be taxing.

Full disclosure

No zone is completely isolated from the benefits of another. For example a long run can slightly improve running economy and speed, but won’t do so nearly as much as a sprint. Elite sprinters don’t go on 15 mile slow runs in practice, because it doesn’t benefit their goals. In the same way, people training for marathons don’t focus on flying 150m sprints or their 40yd dash time.

Also each person also has slight variances in their zones, which is why elite athletes get tested to find their exact zones and paces.

Elite athletes can typically hold a heart rate closer to their max longer than the normal person.

Different exercise physiologists also have different formulations of key metrics (e.g. lactic threshold) and the zones. The differences are influenced by their study, focus, and what they can measure. The important thing is that the individual creating the chart can explain why they did and what principles they used.

My particular formulation is true to my experience and should apply well to most competitive recreational athletes. It is also closely related to the most commonly used 5 zone system. I explain the principles at play, and again it is true that while paces exist on a continuum, the body has different mechanisms to achieve different speeds and it’s useful to know how that affects the benefits and adaptations.

References:

This article discusses the different fitness adaptations and how long they take: http://runnersconnect.net/coach-corner/how-long-before-you-benefit-from-a-workout/

This site calculates your zones given your resting and max heart rate and describes each zone: http://www.runningforfitness.org/calc/heart-rate-calculators/hrzone

This site is the most common guide to pacing based on your current fitness and goals. This site is a must for determining how fast your workouts should be: https://www.mcmillanrunning.com/

Another formulation of the 5 training zones: http://i.stack.imgur.com/imel8.gif