114 Bicycling Australia May • June 2011

AT, LT, AeT, MaxHR, RestingHR…just the sheer number of terms you can encounter when discussing

cycling heart rate can overwhelm you. If that isn’t bad enough, then you have to calculate your own value for each one if you want to follow even the simplest train-ing program. If you’ve ever given it away as too hard, or just plain wondered what these terms mean, then you are in luck. In this article I will hold your hand and walk you through the fi eld of thresholds so that you too will know.

Heart RatesResting HR

Your heart is simply a pump. Your blood is the stuff being pumped, which carries oxygen everywhere in your body. Each heart beat pushes a volume of blood out into your body, through the lungs, the legs and the brain along with everywhere else from scalp to toe.

In the middle of the night when you are deeply asleep in bed your heart beats very slowly. When asleep much of your body is working at a very low level so the require-ments for oxygen are low. It is the demand for oxygen that is the primary driver of heart rate. You are also fl at on a bed. The pressure differential between your feet and head when standing forces your heart to work a bit harder, to pump a bit faster. Resting heart rate is a measured value, taken fi rst thing in the morning on waking

What Thresholds?while still prone in bed. This establishes the lower limit of your heart’s range. When I woke up this morning I did what I do every morning prior to getting out of bed, I took my heart rate. It was 44 beats per minute.

Max HRAt the end of a bike race when you are

pushing on your pedals for all you are worth your heart will beat as fast as it can (or nearly so). It is trying to supply enough oxygen to your leg muscles to keep them turning those cranks at top speed. Maxi-mum heart rate is another measured value. The value you see at the end of a particu-larly hard race is likely within a couple of beats of your true maximum. Any estimate based on your age is potentially off by such a great amount as to be worthless for train-ing purposes. Just as an example, I have worked with two good cyclists aged 40 years old. Cyclist A has a maximum heart rate of 200 while cyclist B has a maximum heart rate of 156. Both very different from the often espoused formula of 220 minus your age which suggests for these riders a maximum of 180bpm.

In the last two races I have entered my maximum on the heart rate monitor (near, but not at, the end of the race) was 189 both occasions, so I happen to be reasonably close to agreeing with 220 minusage formula.

Maximum heart rate is an essential detail to many training programs. I think this is

poor planning because most people do not know with any accuracy what their maxi-mum is. There are a few protocols to reach your maximum, but they are extremely taxing on the body and no one should try this without talking to their physician beforehand!

The one that I suggest is to pick a me-dium gradient hill – around fi ve per cent slope. Ride up the hill in a moderately large gear, perhaps a 53x16 if you race regularly and a lower gear if you do not race regularly. Going from bottom to top should take at least fi ve minutes but not more than 15. Ride quickly, about 80% effort. At the summit, turn around and ride down. Repeat the climb, this time trying to go harder, about 90% effort. Repeat a third and fi nal time. On this last go, start out at the same effort as the prior run, but each minute pick up the pace slightly. After 3-6 minutes you will have reached your limita-tions, at which time you should get out of the saddle and sprint a maximal effort as if you were fl eeing for your life. After 10-30 seconds of that you will have to back off your effort, but just before your heart rate starts to drop you will see your maximum value – maybe!

Like a car with a tachometer, you now have a range for the performance of your human engine. Idle speed is your resting heart rate and redline is your maximum heart rate. Everything you do on the bike happens somewhere in between.

Article by Michael Hanslip Photography by Simon Hayes

Thresholds?

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What Thresholds?

Training ZonesMany training programs have a method

that cuts this range into the different train-ing zones. The number and size of zones varies from program to program. Usually it is a matter of multiplying maximum by a proportion to estimate the various boundaries. I am not even going to discuss these here because I never use maximum in my own practice – I believe there is a better way.

LT (Lactate Threshold)Probably the most critical threshold in

cycling or indeed in most sports, is referred to as either Lactate Threshold (LT) or Anaerobic Threshold (AT). Yes, these two mean the same thing to 95% of coaches. There is a clinical defi nition which makes this threshold a measured limit as well. When you exercise hard your muscles may not get enough oxygen to power the contractions. Muscular work done in the absence (or insuffi ciency) of oxygen is called anaerobic work. A by-product of anaerobic work is lactic acid, also called lactate. When blood lactate reaches a level of 4.0 (mil-liMolar – but the units aren’t important) you are at your lactate threshold. Working harder than this sees lactate levels zoom up quickly. Working less than this level you can usually sustain this as long as your fi tness permits. This implies that everyone from couch potato to world champion cyclist cannot sustain work much over their lactate threshold for very long.

To physically measure lactate threshold requires a tiny blood sample and a portable blood lactate meter. State institutes of sport have these on hand, but what are the rest of us to do to determine our LT? Nearly all cyclists can estimate their LT within one or two beats by completing a ‘fi eld test’, recording an average heart rate and then dividing the result by 1.04 (see sidebar). As an example, I went out for my fi eld test and saw an average HR of 172 indicating my LT is 165. Physically measured a few weeks later my LT was actually 166.

AeT (Anaerobic Threshold)Another important threshold for cycling

is aerobic threshold (AeT). This one can also be directly measured, just like LT. Sleeping in bed or sitting at a desk your blood lactate level will be less than 1.0. When it hits 1.0 we would say that you have begun to get a workout. Below this level you are not train-ing. So AeT is critical for recovery. Go for a ride and keep your heart rate below AeT and it is a recovery ride. Push yourself above this level and rather than recovering, you are now adding to your fatigue levels.

In that same fi eld test used to determine LT, you can also estimate AeT quite accurately. Take the average HR from the effort and multiply by 0.7 to determine AeT. In my example above that yields an aerobic threshold of 120. I have never had this one directly measured but there are two pieces of evidence that strongly support this being my actual threshold.

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contractions. Muscular work done in the absence (or insuffi ciency) of oxygen is called anaerobic work. A by-product of anaerobic work is lactic acid, also called lactate. When blood lactate reaches a level of 4.0 (mil-liMolar – but the units aren’t important) you are at your lactate threshold. Working harder than this sees lactate levels zoom up quickly. Working less than this level you can usually sustain this as long as your fi tness permits. This implies that everyone from couch potato to world champion cyclist cannot sustain work much over their lactate threshold for very long.

ing. So AeT is critical for recovery. Go for a ride and keep your heart rate below AeT and it is a recovery ride. Push yourself above this level and rather than recovering, you are now adding to your fatigue levels.

In that same fi eld test used to determine LT, you can also estimate AeT quite accurately. Take the average HR from the effort and multiply by 0.7 to determine AeT. In my example above that yields an aerobic threshold of 120. I have never had this one directly measured but there are two pieces of evidence that strongly support this being my actual threshold.

Doing Your Own Field Test

Every cyclist I coach gets to do one hard ride each recovery week. This is the fi eld test. If you are

going to give this a try you need to identify the location before the fi rst attempt, trying to ride fi ve km against the odometer on your bike does not work for our purposes. It is more im-portant to have a repeatable distance than an accurate distance. My choice is a fi ve km odometer check section on a nearby highway although any two permanent landmarks approximately fi ve km apart will do. The fi rst task is to properly warm up. You cannot complete a time trial effort without at least 30 minutes of warming up fi rst. Most people take more time than even this. Once you feel like you are suffi ciently warmed up, you can proceed to the actual fi eld test effort. Unless you bring a starter with you, I suggest a slow rolling start with both feet clipped into the pedals instead of a standing start. The objective is to maintain a consistent effort that gets you along your course as fast as you are capable. Riders who aren’t used to time trial efforts go out too hard (or too easy) and end up with surging efforts as they pick it up and then are forced to back off. The fastest way is the smoothest. One of the benefi ts of doing this monthly is learning how to ride a consistent effort. Lucky for us, even if you are only moderately con-sistent your average heart rate for the trip doesn’t change very much.

You will need some sort of heart rate monitor that gives an average value for only the timed portion. To really see how you are going, repeat the timed run a second time. Once you cross your fi nish line, make your way back to the start line and have another run. This trip back should take between 15 and 20 minutes maximum. Use the higher average you obtain from the two runs to determine your ATand AeT.

TrainersThose of you stuck on an indoor

trainer can still undertake the fi eld test. You will need a rear-wheel-driven odometer and the heart rate monitor to do this. In this case you will watch for fi ve km on the odometer, because there is no other way to determine dis-tance. Everything else is the same, ex-cept that because you are sitting inside and getting very hot, your actual heart rate will be low. How low depends on how hot. Even on a cool evening with a monstrous fan blowing on my back my indoor FT still comes out six to eight beats lower than outside. While the thresholds you calculate aren’t valid for outside riding, they are for computing your zones to work out on the same trainer. Which is to say, don’t try to use AeT or LT computed outside for work on the trainer as you will be going too hard – or vice versa. Finding a good grade of hill is important,

preferably on a quiet road where you cankeep a steady effort.

Michael Hanslip is a Level Two coach. He has

won four National Masters titles (two each in Individual Pursuit and Individual Time Trial) and has a PHD in Oceanic Archeaology. He has a day job as a govern-ment scientist in Can-berra but also works as a coach with one of his pupils winning a World Champion-ship title. His other interests include fast cars and hi-fi systems.www.michaelhanslip.com email: coach@michaelhanslip.com

Michael Hanslip

116 Bicycling Australia May • June 2011

First is what I call the singing test. Anyone who has ridden a bike with mates will know the feeling of cruising along chatting one minute and barely being able to squeeze out words as soon as you hit a hill without slowing down. The harder you are working, the harder it is to speak. If you can ride your bike and sing, you are below the aerobic threshold. As soon as it becomes diffi cult to sing you are exceeding that level. For me this happens when my heart rate hits 120.

The other indicator is looking at my average heart rate for a ride. If that average is 117 I feel very refreshed by the ride. If it increases to only 122 I feel about as tired as I did prior to the ride.

WattsEverything I have written also applies if

you are training with a power meter. The average power returned from the fi eld test divided by 1.04 is LT power. That fi eld test average power multiplied by 0.7 is AeT power. At resting heart rate power is zero watts. Wattage at maximum heart rate is unpredictable and not very useful to know.

The big difference between using heart rate and power to train is that power is more reliable. After a late night or a hard week at work your heart rates can be elevated. In this case you would think you are doing the appropriate effort, but actually going less hard. When ill or tired

your heart rate can also be depressed. Your heart rate in this circumstance would have you working too hard. Watts are always watts, however.

A lactate tolerance drill might require you to ride at a heart rate or power just above the LT. On a good day it doesn’t matter which measure you use. On a bad day, the power measure is still correct but the heart rate can be out (up or down) by as much as 10 percent. The same thing happens with a recovery ride. The singing test is always accurate. Staying below AeT power is also always accurate. Sometimes riding below AeT heart rate can still be over the line.

VO2MaxVO2 is an abbreviation for volume

of oxygen. This is not a threshold and not directly related to heart rates. It is measured by having the cyclist ride on a trainer whilst breathing into a machine that measures how much oxygen this cyclist has removed from the air they breathed. It is measured in millilitres of oxygen per kilogram of body weight per minute of time. The maximum level reached is called VO2max. There is a very strong genetic determination in VO2max. Changing body weight is the best way to change this number. If, like me, your VO2max is below 75 then it is incredibly diffi cult (but not actually

impossible) to one day become a world class cyclist. Knowing what yours is might be a good conversation starter at the coffee shop, but it doesn’t help your training very much at all. World class cyclists will often be in the 80s or even 90s of V02Max, though not always. Henk Vogels for example usually sat around 78.

SummaryI discussed four values in this article.

Resting heart rate establishes the lower limit of your heart and is a good tracking device for both fi tness (long-term changes) and recovery (daily changes) with lower generally being better for both fi tness and recovery. Aerobic threshold is the barrier that separates easy, recovery type exercise from harder, training type exercises. Keeping aware of this one is probably the single best reason for owning a heart rate monitor. Anaerobic threshold is the barrier between mostly aerobic exercise – the kind that you can keep up for a long time – and mostly anaerobic exercise. Too much time spent over this threshold will run you down in short order. Maximum heart rate is the upper limit for your heart. Remember if you see a number bigger than what you thought was your max, as long as you don’t have a heart problem then it means your old estimate wastoo low. then it means your old estimate was

SRM power meters are a great way to fi nd your power threshold.

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