Zone 5: The Red Line Zone

If you’ve made it to the Red Line zone, with heart rates from 90% to 100% of your maximum heart rate, you have arrived at the top of the heap. Maybe we should say, if you’ve made it to the Z5 Red Line zone on purpose, you have arrived. Like the Threshold zone, this is another one of those places that most people end up visiting only unwittingly: chasing their escaped dog or cat down the street, or running to catch their train, plane, or boat. You already know Zone 5. This is the place where your heart feels like it’s going to burst and your legs soon feel like lead. While no one would ever want to live there, the vast majority of us wouldn’t even call the Red Line zone a nice place to visit.

If you’ve arrived at the Red Line zone on purpose, you’re one of a proud, perhaps crazy, minority. It’s a place I love. I love to eat lactates. I love to go hard. I love to see how long, how fast, how high I can go. It’s that place where we suffer excruciatingly from metabolic processes. It’s the place for masochistic athletes. Quite frankly, it’s wonderful – for me. You simply can’t hang out for long periods of time in the Red Line zone without dropping out of it for a breather. Your heart rate cannot hang out at or near maximum, because of its exceedingly high demand for fuels. Every second you are in the Red Line zone, your body’s oxygen and glycogen needs exceed your ability to deliver them. The heart muscle is a “work now, pay now” muscle, and it will not go into oxygen debt. Because skeletal muscles operate under the principle of “work now and pay later,” they have the ability to keep on going, past the balance point, and drive themselves into oxygen and glycogen debt. You might wonder what the price is for skeletal muscle deferment of metabolic payment.

The ability of those muscles to continue to contract without fuel is the extremely high production of lactates! Lactic acid junkies like me, love hanging out in the Red Line zone because we get faster while training at the same heart rate or intensity. Since the Z5 zone is the outermost zone in the heart zone chart, sitting just above Z4, all of your time spent in the Red Line zone is at a heart rate that is higher than your anaerobic threshold heart rate (if your anaerobic threshold heart rate is less than 90% of your maximum heart rate). After all, the best way to improve your anaerobic threshold is to train at-about-around your anaerobic threshold heart rate. This zone is also affectionately known as the “lactate tolerance zone” because this is the zone that conditions the body to buffer or withstand the high acidosis as well as to shuttle away the lactic acid to be resynthesized.

It is in the Red Line zone that you squarely, up front and with no way around it, meet your maximum heart rate. When you see your maximum heart rate, know that exhaustion – complete and total exhaustion – is no more than a minute away. Very soon, you will quite simply peter out. Z5 is a dangerous place, because if you don’t come visit often enough you can’t reach your peak, but if you overstay your visit your body won’t invite you to return.

The Red Line zone is feared by many and misunderstood by more. One of the most frequently asked questions about Heart Zones Training applies here: are the benefits cumulative?

In other words, if you hang out in Z5, are you going to get all of the benefits from the Healthy Heart, Temperate, Aerobic and Threshold zones. The answer is no. In each zone, a different process occurs that is specific to that process; if you want to receive that benefit, then you have to pay your dues in that zone.

RED LINE FUELS
For those wanting to burn off a high percentage of fat calories, the Red Line is one of those zones that won’t help you in the slightest. In the Red Line zone, since there isn’t any extra oxygen available, and since fat needs oxygen to metabolize, additional fat burning is all but turned off. The 5% of the total calories burned or so of the total energy burned in the Red Line zone that is from fats isn’t as helpful as in your lower zones.

For the calorie counters in the crowd, the Red Line is a great zone, because you are burning the highest number of calories per minute of any of the five zones – up to 20 calories per minute depending on your weight and muscle mass. But, unfortunately, there aren’t very many minutes involved in Red Line training, because you are in and out of the Red Line zone because you can’t sustain the intensity for long.

The Red Line zone is so hot that it demands the purest of fuels – the highest octane available to get the maximum combustion and thrust out of each muscle contraction. Our body’s preferred high-octane fuel is glycogen, or broken down carbohydrates. Even if your body could use the low grade fuels, fats or fatty acids, in the Red Line zone, it would be like putting diesel in your Ferrari – not recommended.

Our skeletal muscles love glucose or, as we like to think of it, “muscle sugar.” Glucose, when it is burned at high-intensity heart rates, is chemi-cally transformed into lactates which, as we know, are acids. It’s the build-up of these acids which leads to acidosis, that tell-tale feeling of overall fatigue, heavily wooden limbs, hard breathing, and burning muscle pain.

RED LINING AND OVERTRAINING
If you want to get fast, you have to train fast. It’s a standard rule that SSD (short slow distance) and LSD (long slow distance) workouts aren’t valuable as anything but recovery workouts for the individual training for high performance. However, the Red Line zone is so hot that an over-dose or miscalculation in training here can result in long-term damage and the need for long-term recovery.

There are some serious consequences of hanging out too long in this zone. First, with the high levels of acidosis from the presence of lactic acid, muscle cell enzymes are affected. That is, the enzymes that are responsible for aerobic metabolism are sabotaged, and one’s aerobic endurance capacity is hurt. Repeated days of high intensity red lining results in damage to these enzymes, and you simply can’t train aerobi-cally without problems.

What really happens is that the lactic acid damages the muscle cell after the race while only 2% of runners who trained for the same marathon but who didn’t actually run it became sick. It seems that a high dose in a single day of exercise weakens the immune system as well.

High zone training can downgrade the immune system because it results in a physiological response of the body which produces an increase in stress hormones (such as cortisol and catecholamines). Stress hormones decrease the activity of certain immune cells (T cells and NK cells) which are responsible for directly killing infected cells and invading microorganisms. Your defense or your resistance against infec-tious agents is compromised by high zone training.

Just as you may know about the “stress-makes-you-sick” problem, psychological stress can make you stupid, too. Exercise coupled with psychological stress further impairs immune function. Stress from competition, your coach, family expectations, sponsors, and spectators added to the stress of lack of sleep, travel to events, and absence from home can increase the risk of infection and may lead to sub-par perfor-mances.

Overtraining caused by high-volume and/or high intensity training with inadequate recovery results in the loss of performance. It’s not reserved for competitive athletes. First timers and recreational exercisers who crank up their Heart Zones Training points too high and too fast are subject to the overtraining syndrome. It’s usually too late when the symptoms appear, and they can literally appear “out of the blue” with little or no advance warning signs.

There is a way to reduce the risk if you have sophisticated and effective ways to monitor immune cell concentrations and blood sampling, but this is expensive and not available to most. Even with an optimal fortified nutritional program, with regular recovery and rest periods, it’s difficult to avoid the immune-suppressing stress hormones associated with high zone training.

RED LINE INTERVALS
Ultimately, the Red Line zone is the place where you can exercise yourself into exhaustion and optimum athletic training. This high level of fatigue has always fascinated exercise scientists. In my graduate years at UC Berkeley, I began my research by attempting to answer the fatigue question. In my athletic years, I have trained and raced in some of the longest and hardest races in the world in a continuing attempt to understand what makes us exhausted and what we can do about it.

The personal reason I want to find the source of fatigue is to combat it – to override it so we can go further and faster. It’s altruism that love-hate relationships are the most dangerous. You thirst for the love and suffer from the hate, and together the ambivalence can drive you crazy. For me and others, the Red Line zone is exactly that same relationship. You thirst for the benefits (enhanced performance) and suffer from the experience (pain), and together they can drive you to stardom or failure.

Still, because it is difficult, if not downright dangerous, to hang out for any length of time in the Red Line zone, it is time that needs to be carefully planned. We stay there for a short time, then recover and hop back into it. Then it’s out to rest again. This is called interval training, and there are actually two types of intervals: the exercise interval and the rest interval. The exercise or training interval is the amount of time that we spend at a certain heart rate or workload. The rest interval is the time that we spend recovering from the exercise interval. For example, let’s say you want to do lower Red Line zone intervals (90–95% maximum heart rate). You could do short, or “sprint” intervals (rather than middle or long intervals) of one minute at that heart rate, with a one-minute active recovery interval. That’s called a 1:1 ratio of effort to rest, because you are spending equal amounts of time (a minute each, in this case) exercising and resting.

If your maximum heart rate were 200 bpm, then to do this lower Red Line workout you would exercise in a narrow zone of 180-190 bpm for one minute. Then you’d slow considerably and rest, still moving (this is an active rest), letting your heart rate drop for one minute. Each group of one minute in Z5 and one minute out of Red Line is the “interval set.” You may choose to do 6-10 of these sets for your workout.

This Red Line workout can be done on a track, on a bike, Nordic skiing, running, or swimming. In your monitor, set the upper zone to 95% of your true maximum heart rate. In the case of someone whose maximum heart rate is 200, they would set the monitor to 190 beats per minute. Next set the monitor’s alarm to sound at every one minute. Use an active recovery of 30-60 seconds by walking, gliding or slow pedalling before you begin the next interval. Break the workout into two sets of five different 1:1 interval repeats, with a 3-5 minute rest between each set.

The reason you want active recovery between the exercise interval is to sustain high levels of lactates in your blood.

That’s one of the main purposes of the workout – lactate tolerance training. You are trying to build up your lactate concentrations during the session. When there is too much recovery, your lactates drop. If you can’t finish 5 repeats the first couple of tries, that’s fine. Start with 2-4 and build your way up.

There is a slight delay between your real heart rate and the monitor reading. That’s because your heart rate is higher than the monitor because it is updating the data each 5 seconds, so it is always delayed – on both the active and the recovery times.

This lagging of your monitor behind your true heart rate is one of the drawbacks to the technology as it exists today. In the near future there will be real-time heart rate monitors. But for now be satisfied that the data is so close (far better than you could derive from taking your pulse) and remember that we are only listening for the alarm as we accelerate our heart rate into the Red Line zone.

For runners who like track workouts, two of my favorites are called “ladders” and “dropping 1 second per quarter.”

Both add new dimensions to an already overtaxing experience. With ladders, change the heart rate ceiling by 2 beats (or 1%) per lap. In our example, the first lap is 190 bpm, second is 192, third is 194 until the fifth lap and then go back down the ladder. The second variation is to use time as the stimulus.

Drop one second in time for each quarter for the last five quarters. This is truly a delayed gratification workout. Tomorrow you will be tired and sore and wonder why – you’re thinking just a few laps around the track in the Red Line zone shouldn’t fatigue you to this extent. But it does! All Red Line training sessions will cheerily work you to the max. Only if you allow yourself recovery time can you arise as a stronger and faster athlete.