Understanding heart rate “zone training” can help you gauge your efforts and get the most out of your trail running training. Many trail runners may already be familiar with the concept of measuring heart rate during or after runs, but may not know the more complicated science behind what differentiates each heart rate “zone” and when you should train in each zone.
For this article, I speak with head running coach of Lifelong Endurance, Andrew Simmons, who shares his insights into how to properly incorporate zone training into your running and common pitfalls such as excessive “zone 3” efforts.
[TAYTE POLLMANN] Could you introduce us to the concept of running zones? How many are there and what differentiates each of them?
[ANDREW SIMMONS] There is a lot to consider when it comes to heart rate zones and it’s not always a simple thing to explain. Your heart rate indicates a number of physiological and metabolic changes as you increase your heart rate towards your max heart rate. Your heart rate is viewed on a spectrum starting with your resting heart rate on the lowest end of the spectrum and your max heart rate on the highest end of the spectrum. Everything in between is divided into zones based on a test that is either conducted as part of a workout or in a lab. Your zones indicate a few important metabolic and physiological changes that take place as your heart rate increases from rest.
The most important metabolic transition we’re looking for is when your body moves from utilizing free-fatty acid as its main fuel source (Zones 1 and Zone 2) and when you’re primarily using carbohydrates as its main fuel source (Zone 4/ Zone 5). The traditional 7 zone model accounts for the fact that our body also utilizes Adenosine Triphosphate and Creatine Phosphate as fuel as we sprint and approach our maximum heart rate. This is where Zone 5A, 5B, and 5C come into play. Most Endurance athletes spend very little time in Zone 5 outside of intense speed work or hill sessions. Optimizing these anaerobic systems provide minimal benefits for athletes who are trying to go further and longer.
There are numerous methods that break up your heart rate spectrum into as many as 10 zones. The method you choose is highly dependent on your view of zones and how you’re being coached. I personally believe that a little more granular detail is helpful and typically use the (Pace Zone Index) PZI-10 Model for zones with athletes.
[TAYTE] Many coaches prescribe to the old saying, “Keep your easy days easy and your hard days hard.” What’s your take on this principle and how it applies to zone training?
[ANDREW] You can add me to the list of coaches who preach this. I can’t stress enough that this comes back to understanding what you’re doing and where you’re going with your training. Putting a speed limit on yourself on your easy days isn’t simply about self-control, it’s about respecting where you are and not trying to finish every run feeling completely spent. I view this statement as a precursor to a bigger discussion on framing your easy days as a recovery effort and you should always finish your easy days feeling like you could have run faster and gone longer. By purposefully leaving a little on the table. Leaving something on the table allows you to have the energy (mentally and physically) to perform in your workout. Simply put, if you’re not getting what you want out of your workouts, you’re probably going too hard on your easy days.
[TAYTE] “Regular Zone 3 running is the illusion of progress.” What do you mean by this statement?
[ANDREW] I want to draw your attention to the word “regular” and even give it more depth to call it “chronic” Zone 3 running is the illusion of progress. I think this goes back to high achievers with big goals and athletes with a long-term development mindset – the clear difference here is that one of these athletes is willing to follow a methodology for a long-term pay off and the other athlete is looking for improvements after every session. It’s either a lack of patience or a need for instant gratification that leads people to treat every run as a hard run or finish every run feeling like they accomplished something. They fear that if they don’t get out of breath or bring themselves close to their goal pace – they will never hit that pace on race day. The illusion is that deeply entrenched fear that if it doesn’t hurt or feel hard, it won’t make you better – that’s simply wrong. As a society we’re really good at pushing ourselves because we fear that if we let off the gas, we’ll have the thing taken from us. Let me tell you that you can keep your foot on the floor, just change gears! The big problem with continuous Zone 3 running is that it’s sending a multitude of mixed messages to your body – at Zone 3 you’re burning a mixture of fat and carbohydrates and loading up your legs with a higher level of lactate than necessary, along with narrowing your training range. To that last point, when you’re cheating your easy days – you’re limiting what you can do on the top end because you constantly go in under recovered.
[TAYTE] Let’s talk about managing efforts with hills. How should trail runners approach hills on daily training runs? Do you have tips to remain in Zone 1 or 2 during hills on easy training days?
[ANDREW] Let me start by saying, it’s really hard to not blow up on hills and overdo it on hills. In combination with my last point on chronic Zone 3 running you don’t need to avoid zone 3 like the plague – you may drift into that zone occasionally during your run and that’s ok. If you find yourself shifting to more than 25 to 35% of your run in Zone 3 on extended climbs you may need to shift to walking. It’s really simply though, what’s the goal of your run that day? If it’s a recovery day, keep it easy and stay in Zone 2.
[TAYTE] Is there a time when we should prioritize Zone 3? Are there race distances/styles that may require more Zone 3 running than others?
[ANDREW] Absolutely, Zone 3 has it’s time and place in a training cycle – Zone 3 falls in what we call tempo and is good for times when you want to focus on hitting a specific pace. It’s important to note that Zone 3 heart rate is relatively broad and can comprise of your 10K, Half Marathon, and Marathon paces. It’s a good reminder that pace and heart rate are different constructs although both are often broken up into zones to aid in communication. Be conscious that heart rate can vary significantly due to environmental factors like heat and humidity as well as stress and caffeine intake. Training in Zone 3 for tempo workouts is totally fine and a great way to build your ability to run at a specific pace and get comfortable with a race day effort; it becomes an issue when you’re constantly encroaching on that effort day after day. Running just hard enough to feel like you’re doing something but not easy enough to recover – that’s a great place to run your marathon – not a great place to grow your ability.
[TAYTE] How do you make sure you’re in the proper zone when training?
[ANDREW] This is where many coaches start to define their methodologies more succinctly. Training with a metric like heart rate is best because it takes into account all of the factors that can impact performance. Your heart rate will reflect the impacts oof increased stress, heat, and altitude. This ultimately allows us to key in and see progress by using tracking tools over time by showing an increase in pace at the same heart rate over time. We can objectively say that moving from holding 7:10 pace for 30 minutes at 163 bpm and 3 months later holding 6:45 for 30 minutes at 163 is a large improvement in fitness.
When it comes to using pace only, we normally want to use a secondary qualifier like heart rate or power to evaluate the performance. Pace alone without heart rate is still a great way to coach and allows you to run the same course over time to evaluate for performance improvements. When we dive into the subjective side of perceived effort, we start to lose out on objective variables that are accounted for with heart rate. Perceived effort is wildly variable on a given day, the temperature outside, how stressful your day was, and your mood going into a run can have a massive impact on a given performance.
I like to coach by moving from objective to subjective feedback from my athletes. I want to see their heart rate, how fast they ran, and how they felt about the performance. It’s most important to know your why – why are you doing this workout? Is it supposed to be a hard day or easy? Did you sleep poorly? There is a lot that goes into finding the right groove and constraints, more on that shortly.
[TAYTE] What zones would you advise runners prioritize in their training? Does this depend on their specific event/race distance?
[ANDREW] For the majority of runners that race conventional road and trail races – the name of the game is building general aerobic fitness. By most measures, this is considered zone 2. Aerobic fitness alone builds your capacity, running towards your aerobic threshold and over is widely considered “speed work”. As a beginner running 20 miles a week can manage 2 to 3 miles of speed work in a 7 to 10 day period. As athletes increase mileage and aerobic capacity the amount of speed work they can handle to build and maintain fitness also grows higher. As a general rule 20 to 35% of your time training should be comprised of work outside of Zone 2. This work can come in many different forms from hills, intervals, extensive climbs, or tempo runs; the options are endless.
Different events require different types of training. The longer the event, the greater the aerobic capacity an athlete needs. That doesn’t always necessitate an increase in mileage, it just necessitates an increased amount of aerobic fitness. Training for a fast 5K will demand an increased amount of speed work where a trail 100K doesn’t demand your body to maintain high aerobic fitness and high turnover so time is best spent building the ability to run longer at a pace that demands as little energy as possible.
[TAYTE] Does zone training differ between younger athletes (middle/high school) and masters/aging runners?
[ANDREW] Yes. Middle Schoolers and High Schoolers can recover from hard workouts significantly faster than masters athletes. Youth athletes can build fitness quickly due to the increased recovery whereas masters athletes need to utilize a longer build up. This is where periodization (how training load is cycled) becomes essential to understand. A masters runner will likely build up for 2 weeks before taking a lighter week where youth athletes can build their training load for 3 or 4 continuous weeks before we “deload” and rest the athlete so they can absorb the fitness.
[TAYTE] Could you share any personal/coaching stories that demonstrate how properly managing your Zone 3 efforts leads to fitness gains?
[ANDREW] I coached a girl this last season that would run about 7:15 pace almost every single run throughout her cross country season – easy day, hard days, she would average about 7:15 and had a hard time breaking through her times that season. We had to have a sit down and formally discuss why having a large disparity in your training is important. For track we focused on keeping our easy days closer to 8:15 and making sure our hard days are very hard. This allowed us to break into new territory for her mile, 2 mile, and 800m races. This built a significant trust and buy-in with her as an athlete. I’m really excited to see what she can do by focusing on her aerobic fitness for her cross country season.
[TAYTE] From your experience working with very competitive high school athletes, do you see more of a tendency to run too fast on easy days? Why is keeping your daily training runs easy an important principle for even the most competitive of runners to understand?
[ANDREW] Without a doubt it’s the number one problem I have to overcome with my athletes. There is a thought in their brain that if it’s not “hard” they aren’t improving or getting better. So then everyday turns into a race or hard effort. This leads to under recovered athletes and a quick plateau because they can’t push or run faster because they built specific fitness in the middle of their fitness range. Slowing down allows for recovery and builds capacity, this leads to a greater capacity and allows the athlete to run more reps or hold their desired race pace for longer.
[TAYTE] From my experience running on a college team, I can say that sometimes I felt I was simply pulled along by the group and sometimes ran too fast on my easy training days. How do you find your own “easy pace” as opposed to just running the group’s pace?
[ANDREW] It’s always hard to be the lone wolf. As you become more comfortable with what an aerobic conversational pace is, you’ll see the benefits show up in workouts. If you’re lucky, you’ll stick to your guns long enough to outrun these guys pulling you along on workouts and leave them breathless on the easy days asking “is this pace too hard guys?”. Jokes aside, know the objective of every run before you head out. If you’re cruising at a pace that doesn’t line you up for tomorrow’s run then you need to slow down and stick to your principles. Having tough conversations with friends and teammates is never easy and knowing when to let the group go on without you is a tough lesson in maturity but I promise it pays off in the long run!