One of the most common phrases I hear as a running coach and strength and conditioning coach is “I only want to work in my fat-burning zone because that burns the highest amount of fat.” It’s true that working in the fat-burning zone burns the highest percentage of calories from fat. However, it does not burn the most calories overall. With that said, I am going to clear up what each exercise zone does to your body, how to know when you are in each zone, and the benefits they provide.
Like any other element of fitness, runner’s pace is influenced by numerous factors. Below are the main factors influencing a runner’s pace:
Muscle fiber type: Not everyone is born to be an elite distance runner. There are two major fiber types: slow twitch (type I) and fast twitch (type II). Everyone has a combination of both fiber types, but people who are primarily slow twitch dominant are better at running slower longer distances, and people with a higher percentage of fast twitch are better at running faster shorter distances. Characteristics of each muscle type can be altered by doing the corresponding training. Muscle fibers can also increase in size by giving them the proper stress stimulus, heavy with long rest to increase the contractile filaments, and moderate with short rest to increase the metabolic component (read “How Muscle Is Made”). However, whether fiber types can be transformed is still a matter of debate.
Running economy: Running economy is directly related to a runner’s weight and gait and is a primary indicator of running performance. The less weight runners carry, the moreenergy they can save, thus use for running farther and faster. A runner’s gait also affects running economy. The more efficient a runner’s form, the more direct his movements will be and the better his running economy. Even if you are self-coached, it is a good idea to have your gait analyzed by a biomechanics expert who specializes in runners.
Fuel utilization: During high-intensity aerobic activity (>70 percent VO2max), the majority of energy comes from carbohydrates. However, through training this can be switched toward a higher fat-utilizing ratio. Fat has more energy than carbohydrates; therefore, the switch allows athletes to run further and faster since there is more energy available. Four hundred and sixty molecules of ATP (energy) are produced for every molecule of fat, whereas only thirty-six molecules of ATP are made for every molecule of carbohydrate. This means fat is twelve times more efficient than carbohydrates. The switch to better fat utilization can be triggered by running longer distances and performing ventilatory threshold training or exercising on a low-carb diet. Although medical clearance should be sought prior to any sever dietary restrictions during exercise. It is because fat is so much more efficient than carbohydrates that athletes need to take time training in a slow steady state prior to engaging in HIIT.
Each Training zone is reflected by a target heart rate range and associated benefits. The following is a chart listing training zones with corresponding purposes and outcomes of training in that zone.
Training Zones by Percent Max Heart Rate
Warm-up: This zone is used for exactly what it’s called, warming-up. It is performed between 50–60 percent of your max heart rate (MHR, fastest your heart can beat) and should be systemic (whole body). The more systemic the routine is, the shorter your warm-up can be. Remember, a warm-up for some could be a complete workout for others. Make sure you keep your heart rate in the correct region. Toward the end of the warm-up, heart rate should gradually build its way up to the focus training zone of the training session.
Recovery Pace: When we work in this zone, we are working at 60–70 percent of our MHR. This zone is popular because it is known as the fat-burning zone. However, while it is burning a higher percentage of fat, it is doing so at a significantly slower rate, this means you burn fewer calories overall and lose less weight in the end. While exercising in the fat-burning zone, you are primarily burning fat as energy, but because you are working more efficiently, consuming less oxygen, and activating less muscle, the total energy you are using is less. As you increase your effort, a higher percentage of energy comes from carbohydrates rather than fat, but you are burning more calories overall because calories are energy, and you need more energy to work at the higher intensity. The fat-burning zone can be more properly used for your recovery pace during metabolic workouts. When performing intervals, drop down to this pace for your recovery phase before raising it up again, or for the day before an exceptionally hard work out or race.
Base Building: The most fundamental aspect of metabolic training is building your base, yet far too often I see people struggling through intervals without a proper base built up first to help them sustain the high intensity of interval training. Yes, it is true; intervals are how you get faster. However, trying to perform quality intervals without a base is going to get you nowhere fast, please refer to the PROformance Training Systems PROgression Model to see how building a base is a necessary perquisite to injury free HIIT training. Otherwise known as “moderate pace,” this zone runs between 70–80 percent of your MHR and is the pace you keep when you are going for a steady state easy or long run. You should be in this zone between faster-training sessions. This zone should encompass most your running volume (80–90 percent). Here are the three basics to building your base before you get out there and become a roaring roadster with no gas.
1. Long steady distance (LSD): LSD is where you build your aerobic base, which all distance races feed upon. When first incorporating these distances, they can be as low as 60 percent effort for your body to get use to spending long periods of time on your feet. But eventually you want to get them up to 80 percent effort (but no higher! 80 percent is roughly the aerobic threshold; if you start to work harder, you are no longer working aerobically, thus not focusing on the goal of the workout). At first perform one LSD run every two weeks, and then once your body becomes accustomed to them, you can step it up to once per week if it does not hinder your performance for the rest of your weekly training. The distance of your LSD should be 20–30 percent of your total weekly mileage. So, if you are running sixty miles per week, then your LSD day should be twelve to eighteen miles. Higher mileage and frequency runners stay toward the 20 percent end, and lower total mileage and frequency runners use the 30 percent value. But make sure to take your time building up to that distance, increasing your mileage no more than 10 percent per week. Remember building up too fast only increases your chance of injury, and you cannot get faster when you’re on the injured list.
2. Hills for strength: I know I said do not throw in intervals without a proper base first. However, hills offer you something speed intervals do not, strength. For your muscles to get stronger, they need to fight against a resistance (in this case gravity via going up a hill), not increase speed (two hundred meters on a track). It is resistance not speed that builds muscle, and for this reason, hills should be done during the middle to later stage of the base-building phase to increase strength sowe are stronger once it is time to introduce speed workouts in order to blast through faster track intervals with a lower risk of injury. [CE1] When starting hill repeats, begin with six to ten short and intense repeats lasting eight to ten seconds, adding one more repetition every week. After you reach fifteen repetitions, move up to four to eight repetitions of twenty- to thirty-second hills, at a calmer yet still fast pace. Build up to twelve repetitions, and then perform four to six repetitions of sixty- to ninety-second hill repeats at race pace, building up to eight to ten repetitions. The key points to remember with hills are the shorter the duration of the hill repeat, the steeper the hill and longer the rest.
The hill training chart below will give you an idea of how hills can be performed depending on your goal. This chart is not to be taken as one size fits all advice, but as a guideline to build upon when devising your program. The shorter the hill, the faster you run the repeat and the longer the hill, the slower you run. Regardless of hill length, rest is relatively equal since the lack of speed on longer hills is made up by the time-under-tension running up a longer grade.
3. Rest to rejuvenate and rebuild: Although the final section of this book is titled “Rest and Recovery,” I need to mention here that it is while we rest that our body becomes stronger. Resting gives our body and mind a chance to rejuvenate and replenish our energy stores while rebuilding broken down muscle tissues. Our mind also needs a break, mental fatigue and burnout occurs when we keep intensity elevated for too long without a rest day or longer recovery period. Research has shown our mind needs to recover in the same manner as our body. So remember to wait forty-eight hours between all hard efforts (recovery and easy efforts are a part of training). It is the easiest part of getting faster; don’t skip out on it.
Building a base is essential to endurance sports because that is the foundation of their strength. With that said, ball sports also benefit from base building prior to HIIT because it raises the anaerobic threshold, meaning athletes can compete longer before working aerobically and second, the low intensity repetitive stress is a good primer for the mechanical demands of HIIT. Yet, as important as base building is for endurance athletes, and the majority of their training should be spent in the aerobic zone, the majority of high-intensity sports training must focus on HIIT after establishing a base to become competitive.
Race-Pace: Lactic threshold training has been used by runners for years. It is perhaps the most important form of training for getting yourself in race shape. With that said, we have learned through research that there are different forms of lactic threshold training depending on your goal’s race distance and relative intensity. We must train differently to hit each goal. However, to see the best results, we should incorporate a mix of all three types of lactic threshold training into our routines.
During a race as the intensity increases, the amount of lactate accumulating in your muscles increases as well until it reaches the point where your muscles cannot clear out the lactate as fast it is building up, and you start to slow down, as discussed earlier. What we have come to learn is the rate at which lactate builds up in your muscles varies depending on the length and relative intensity of the race. The higher the intensity, the quicker lactate builds up. For that reason, it only makes sense to train your lactate threshold using different techniques depending on the nature of the lactate accumulation rate. It has also been decided by some in the field including myself to refer to lactic threshold training as race-pace training when referring to endurance sports, because as we move away from the typical “twenty minutes at threshold pace” and start to develop more individualized training programs for varying distances, we believe that the term “race-pace training” is better suited.
For our purposes let’s break races distances and intensities into three different categories:
1. Low-speed/high-volume:These include races lasting between two and three hours.
2. Moderate-speed/volume:For races lasting between one and two hours.
3. High-speed/low-volume:For races lasting less than one hour (generally thirty to forty-five minutes).
Low-speed/high-volume: Races in this zone range from half marathons to marathons. The workout should last between forty and ninety minutes, increasing the time spent at race pace as you become more accustomed to it at shorter durations. Training at race pace is important especially for distances of such length because your body should become an efficiency monster at race pace if it is expected to hold it for such a long time.
Moderate-speed/volume: These races range from 10 miles to 20k. These workouts last between twenty and forty minutes at race pace.
High-speed/low-volume: These are your repeats for races 5–10k. While doing these, it is important to remember that they are not anaerobic repeats. They are still race-pace repeats for endurance races, and the pace should be equivalent to race pace, no faster. A good way to keep pace in check is to keep the work to rest ratio low such as 5:1 (work:rest). This will force runners to hold back, so they can make it through their entire workout. A good trick that will get your pace roughly in the correct training is to add five seconds per mile for every ten minutes over twenty minutes your workout plans on being. So, if you are running six-minute miles for a standard twenty-minute tempo run, then you would be running 6:10 miles for forty minutes (RunnersWorld.com). Note: This pace starts after a proper warm-up.
There are many benefits to training at race pace. It prepares our body to run at certain lactate levels, teaching us that racing in the discomfort zone is acceptable. The important thing to remember is volume not speed yields the best results during these workouts. We are not trying to enhance “launch time” (that is for a different workout), but we are trying to enhance efficiency at race pace. Don’t bother training for your sprint to the finish if you have not trained at race pace first, so you can get there.
VO2max (Maximum effort/VO2max threshold pace): Working in this zone is not for the faint of heart. It involves getting up to 98 percent of your MHR for brief amounts of time (note: the whole interval is not at 98 percent MHR). These intervals are done for no longer than five minutes without a break. The point of VO2max training is to increase your ability to get oxygen to the working muscles. To give you an example of how hard the pace is, the effort is one that you cannot maintain running for more than two miles. The pace is 85–95 percent VO2max (92–98 percent MHR) or ten to thirty seconds faster per mile than your 5k-race pace.
Repetition Pace (sprint repetition): This zone is short and brutal. It is performed faster/harder than your VO2max pace; although it does increase VO2max, it does not develop it as effectively as performing VO2max intervals. Repetitions improve your races by developing your running economy and enhancing your speed. Each repetition should be performed at 95–100 percent MHR, in other words, all out for short periods. Running sprints are generally shorter than two hundred meters.
Metabolic Training for Runners’ Volume Breakdown
As runners, we have all become so amped up in the weeks leading up to a race that we decide to take our training up a notch and push ourselves a little harder than we should. We become so focused on hitting our goal time or beating a buddy in an upcoming race that we start running faster every time we head out the door for a training run only to get to race day and finish with a less than stellar performance. After the race, you’ll begin to ask yourself questions like, “Why did this happen? I trained harder than I ever trained before, where did I go wrong?” Then you may realize the answer is obvious. In retrospect, you see that you had been training too fast.
There is a difference between training too fast and training too hard. By training faster, we must pick up the pace, but to train harder, you can also increase your volume, add more hills, decrease your rest interval, or up your frequency. These are the variables that a runner should focus on when deciding to up his intensity.
Distance running is an aerobic sport, relying mainly on fat as fuel. Although the other energy systems contribute to energy production during a run, our fat stores provide more energy than we would need for most endurance activities (even for an elite marathoner). This is because evolution made us “fat efficient.”
The problem with increasing training pace is that you will likely enter the anaerobic zone (without oxygen). Your anaerobic gateway begins at 80 percent max heart rate (MHR). Once you are here, you are no longer primarily focusing on enhancing your body’s ability to use fat as fuel. Consequently, come race day your body is less efficient at using its primary endurance fuel source (fat) than it was prior to your increased training intensity because it has become accustomed to burning a higher percentage of carbohydrates as fuel, whereas a distance race relies predominantly on fat as fuel. We can slightly raise our max heart rate with training; however, our main benefit for fat utilization is elevating the anaerobic threshold, so we can run at higher intensities aerobically with fat as our main fuel source. We are in essence raising the bar.
Working on your base, under 80 percent max heart rate, increases your VO2max up to 20 percent and endurance up to 10,000 percent! But when we get into race-pace training, we should only expect an increase of up to 3 percent (Finke and Finke 2004). [CE2] Think of race-pace training as sharpening the blade. Sharpening the blade is useless if you did not take the time to fortify the metal making it strong enough to withstand the stress of the initial strike.
Most of an Endurance Athlete’s Progress Occurs Below the Ventilatory Threshold
A useful tip for while you’re out on a run to ensure you are working in the aerobic zone is reciting the pledge of allegiance. If you can say it without gasping for air, then you are working aerobically.
Notice how large the portion dedicated to aerobic training is in the chart below. Athletes need to spend more time training aerobically prior to engaging in anaerobic metabolic conditioning. This does two things, first it enhances our ability to use fat as fuel, and second it raises the bar at which we enter anaerobic metabolism (it holds off heavy breathing).
Ideal Distance Runner Training Volume Distribution
I know it can be difficult to distinguish between the shades in this pie chart, but Metabolic Training for Distance Runners’ Volume Breakdownis the corresponding table. The big take away here is how aerobic training consumes the majority of the chart for distance runners.
Muscle Fiber Activation Thresholds by Heart Rate
This chart shows you the threshold range during which muscle fibers enter a new training stimulus. Once heart rate hits the athlete’s individual threshold within a given range, low-end or high-end, they are focusing on training the focus listed above (aerobic, ventilatory threshold, VO2max intervals, repetitions sprints).