What is heart-rate training?
Expectedly, heart-rate training is tailoring your workouts and performance based upon your heart rate. Believe it or not, even if you don’t own a heart-rate monitor, you’re already sort of doing this. When you run at what you consider an easy pace, what does that really mean? Among other things, it means that you run at a heart rate that you consider maintainable for a relatively long duration. Conversely, when you really pour on the juice, you’re performing a high-intensity speed workout, one that you can maintain for a shorter period.

In a nutshell, you want to train at varying levels of intensity to accomplish different things. You can gauge these intensity levels using your own feedback and experience (trainers use the term Perceived Level of Exertion), or gauge intensity by monitoring your heart rate, which gives you the advantage of precision and eliminates a lot of subjectivity.

How do you monitor your heart rate?
Ever see someone at the trailhead after a run with two fingers held up to the carotid artery taking their pulse? Well, that’s one way. I can churn my own butter too, but I’m not Amish so I’ll kick it up a notch technologically speaking.

To get started, purchase a heart-rate monitor. Several manufacturers offer them, including Polar, Timex, Suunto and Nike. Monitors have two pieces, a strap you wear around your chest to capture your heart rate and a receiver, typically a watch. You can get all kinds of bells and whistles, e.g. altimeter, calories burned, PC-synch capabilities, compass and barometric pressure, but all you need is one that displays your heart rate and the time.

Now, let’s splash some water on our faces and learn how to use this new toy. During HRT you will target various intensity training zones, sometimes keeping your heart rate within a certain zone to build aerobic capacity, other times seeking a more vigorous zone to build speed. These zones can be calculated using two main methods: maximum heart rate and lactate threshold.

Maximum heart rate
You may have heard that to find your maximum heart rate you subtract your age from 220. Actually, this method is a wild guess, like estimating your shoe size is the same distance from your elbow to your wrist. The equation was uncovered in the 1930s by finding the maximum heart rate of a variety of individuals, some smokers, some trained, some sick and so forth, and then a line was drawn down the middle to find an average of the general population. Purge that equation from your memory.

The most reliable way to determine your absolute maximum heart rate is to run till you have a heart attack, but since that ruins the weekend, we’re going to approximate it using a far more accurate method called lactate threshold (LT). Put a cool washcloth on your head, this gets more involved than the 220-minus-age estimate.

Lactate threshold
So what is lactate threshold? Well, it all has to do with something you may have heard of: lactic acid. During low-intensity exercise, your muscles produce lactate (commonly referred to as lactic acid, although chemically different, close enough for our discussions), and your body absorbs it back, keeping the overall concentration in the blood low. As your exercise intensity increases, your muscles produce more lactate than your body can absorb and the concentration in your blood goes up.

This point where the body can’t keep up with the lactate production is called the lactate threshold and is the highest exercise intensity that a person can maintain for about 30 minutes. The more time you train above this point, the greater the imbalance between what your body can absorb and what your muscles are producing, and eventually it will cause you to slow or stop.

Unfortunately there’s no way to measure your LT from the couch, which is why so many people don’t know theirs. You’ve got to go out and suck some wind. You could, of course, do what the pros do and have blood drawn during your exercise sessions to measure the lactate in your blood, but I’ll assume you’ll pass on that level of detail and expense. You also have a different LT for each activity. So you may have a different LT for trail running than you do cycling. This not only means you have to do the LT test for each sport, but that you’ll have different training zones for each sport. Luckily, the way you perform the test is identical for most endurance sports, or at least for running and cycling, which are far and away where HRT is used the most. It’s really not as complicated as it seems and the benefits of this type of training sure outweigh the minor challenge it is to determine all these zones.

To determine your LT for trail running, perform a 30-minute time trial on a relatively flat course. Here’s how:

Warm up for 15 minutes and during the last five minutes do a few 30-second sprints to get your heart rate up. For the test, your goal is to maintain the hardest pace possible for 30 minutes.

After 10 minutes, if your heart-rate monitor has a “lap” function, press that lap button to get an average heart rate over the remaining 20 minutes of the test. If you don’t have a lap function, take a reading every minute and do the average yourself. A treadmill and a training partner are helpful in this situation. Remember that you want to end the trial without a whole lot left in the tank. Really push yourself.

That’s it! Your LT is your average heart rate over the last 20 minutes.

What are the training zones?
Now that you know your LT, you can now figure out your training zones. Then you’ll know exactly what heart rate (HR) you should be training at for a variety of goals. Following are the training zones based on your LT:
Zone 1: Recovery Zone-65 to 85 percent
Zone 2: Extensive Endurance-85 to 90 percent
Zone 3: Intensive Endurance-90 to 95 percent
Zone 4 -5a: Lactate Threshold-95 to 102 percent
Zone 5b/5c: Power Training-102 to 110 percent
For example, if your LT was 160, your Zone 2 HR would be 136 to144 (160 multiplied by .85 and .90).

Now, you can tailor your workouts to your goals. To build your aerobic capacity and train yourself for endurance over speed, keep your HR in zones 1 or 2.

Zone 3 isn’t low intensity enough to build your aerobic base and not really high intensity enough to effectively build speed or increase your LT. If you find yourself in this zone, either speed up or slow down, depending on your goal, to get to zone 2 or 4.

Zone 4 is the sweet spot to increase your LT and gain speed over mid-distance events.

To build pure speed in the form of sprints, get to zone 5.

A common question is whether you can move between zones during your run. The answer depends on your goals. If you’re looking to raise your overall LT, then you can employ interval training during which your heart rate will fluctuate significantly. However, if your goal is to stay in a lower zone and build an aerobic base, you want to be a lot more cognizant of staying in your zone. If you charge up a steep trail, you’re going to build up your blood lactate levels and will have a very difficult time getting rid of it quickly enough to maintain the workout you intended.

Putting it all together
If you’re serious about making performance gains as efficiently as possible, determining your lactate threshold and using the guidelines above is essential. Your buddies may cite the fact that many great athletes don’t use this method and perform incredibly using only their own senses as feedback. Sure, some other gifted athletes have genetics that allow them to train much more haphazardly and still outpace the competition, but perhaps they could have gotten to the same place in far less time using more precise heart-rate-training techniques.

A great resource for a detailed explanation of the topic is the Triathlete’s Training Bible, by Joe Friel. Also view resources on the subject at  HYPERLINK “http://www.MadisonTrainer.com” www.MadisonTrainer.com, including the recent university research discounting the antiquated maximum-hear-rate equation, as well as a training-zone calculator

Remember that your LT will change as you become more conditioned so you will need to repeat the test periodically to update your training zones. Don’t fear: by following the above recommendations you’ll be pleased at how quickly you start to burn through the trails and will start to look forward to the LT tests.

Go Fast
Sample workouts for specific goals
To gain endurance for a marathon or other long distance event
10-minute warm up in Zone 1
1-hour or more in Zones 1-2
10-minute cool down in Zone 1

There isn’t much variety in this workout since our goal is building aerobic capacity and not necessarily speed. Since your HR will stay relatively low throughout the session, you also don’t need much of a warm up.

To gain moderate endurance and speed over mid distance, such as 10K
10-minute warm up in Zones 1-2
30 minutes in Zone 4
10-minute cool down in Zones 1-2

In this workout you can warm up a little bit faster and then move right into our Zone 4 sweet spot to increase you LT and get some speed improvements over this distance.

To gain speed and burn fat most efficiently.
10-minute warm up in Zones 1-2
1 minute in Zone 5
1 minute in Zone 2
(repeat 5-10 times)
5-minute cool down in zone 1-2

To really crank up your speed, warm up, and then move right into 1-minute sprints, alternating with 1-minute low-intensity intervals. This technique is called many things, including intervals, HIIT or fartleks. Do as many intervals as you can, but if you’re doing more than 10, you’re probably not going fast enough.

My favorite workout
10-minute warm up in Zones 1-2
1-minute in Zone 5
1 minute in Zone 2
(repeat 5 times)
20 minutes in Zone 4
1 minute in Zone 5
1 minute in Zone 2
(repeat 5 times)
5-minute cool down in Zones 1-2

Here’s the prescription for all around athleticism, and my personal favorite workout. Warm up, get in your sprint intervals to build speed and torch your body fat, then do 20 minutes in Zone 4 to increase your LT and get some mid-distance endurance, and then grit your teeth through another set of intervals that I guarantee will hurt. Close it out with your cool down, and go down lie down in the shade-you’ve earned it.

Rich Butkevic is an ISSA Certified Fitness Trainer, triathlete and author from Madison, Wisconsin. He trains clients at www.madisontrainer.com and can be reached at rich@trimuscle.com.

This article appeared in Trail Runner magazine, issue #54 (OCTOBER 2008). Order your back issue now!