First off, congratulations on doing an Anaerobic Threshold Heart Rate (AT HR), test, or for having your Coach make you do it! This is the first step in improving your overall fitness and training, but why do you need to know your AT HR?

Your AT HR is the maximum average heart rate that you can maintain for one hour and basically defines the crossover point in our body’s ability to train aerobically, “with oxygen”, versus anaerobically, “without oxygen.” Of course we are never really without oxygen while running, so what it really means is without enough oxygen to continue at the same pace. You can only run anaerobically for so long as your heart and lungs can meet the demands of your muscles at an anaerobic pace. Ultimately your HR will increase to your maximum HR if you let it, the byproducts of your hard pace will collect in your muscles as your body can no longer flush them out fast enough, and eventually you will have to slow down or stop. Knowing your AT HR allows you to control your pace over time based on the distance of your training run or the race you’re in, i.e., how far can I run this fast.

My opinion is that most age group athletes that do not use HR in their training, that don’t have a periodized training program to follow, train to between 80-90% of their capacity, if that. Knowing your AT HR allows you to create a HR Zone training chart that you can follow in your training plan to more accurately define the level of effort of each of your workouts, as compared to just going by feel or Perceived Exertion, PE. With this knowledge you can begin to chip away at that last 10-20% of your training capacity.

One thing to note is that your AT HR for the run is probably not the same as your AT HR for the bike, so a separate test needs to be performed to determine your bike AT HR, to further improve your level of triathlon training.

There are multiple ways to determine your AT HR on the run and so now that you’ve already done this what should you be doing? Let me try and make it simple:

1. Perform a test  to determine your AT heart rate, see some options below
2. Plug your AT HR into a HR Zone chart (see below), to define your HR training zones
3. Perform a performance baseline test (see below)
4. Using the HR training zones in your HR Zone chart, train for 4-8 weeks using these zones in your weekly training runs
5. Repeat Step #3 to see if you are making improvements to your baseline performance, and then continue your training as in Step #4
6. At some point after repeating the baseline test, step #3, you will have run significantly farther than the first time you ran to establish your baseline, so now it’s time to start again at Step #1, your AT test

So, not really that complicated when you break it down into simple steps. Since you’ve already taken the first step, you’re well on your way to completing all of them. Actually, once you’ve done an AT test once and understand why, it becomes easier to do after you’ve been training for a while. And then the actual training, now that you’re training in the correct HR zones for the kind of workout you’re doing that day, that becomes more focused and in some ways easier. Without knowing it, on your easy days you were probably running too fast, so now you’ll be running more slowly, albeit probably a little longer on time. And on your fast days, guess what, you weren’t running fast enough and probably too long, so now running a little faster allows you to run a shorter distance. Sounds like a win-win to me!

See the descriptions that follow on how to determine your AT, plug your AT HR into the HR Training Zone chart, do a baseline fitness level test, and then start training “smarter”, not necessarily “harder”.

I’ve given you the information, now you just have to provide the determination and perspiration!

Anaerobic Threshold HR Determination Tests

• Option 1 – Run 4 miles as follows, recording your maximum HR for each separate mile:

1. Mile 1 around your half marathon pace, rest 2 minutes
2. Mile 2 at your 10k pace, rest 3 minutes
3. Mile 3 at your 10 mile pace, rest 2 minutes
4. Mile 4 at your 5k pace
5. Take your average HR for miles 2 and 4, average them together, this is a good approximation of your AT HR
6. This is by far the easiest of the three options I have used, while #3 might be the most accurate.

• Option 2 – Perform a 30 minute run at a very hard level of effort, at or just below your 5k pace, depending on how fast your run; faster runners will need to back it off a bit.

1. Start your watch at the beginning of the run and at 10 minutes into the run hit the lap button then complete the rest of the 30 minute run
2. Your average HR for the second lap, the 20 minute lap, should be around your AT HR

• Option 3 – On the track perform the following, which is kind of hard to describe, let me see what I can do.

1. After an easy warm up, run 1 lap around 3 minutes slower than your 5k run pace, hit the lap button at the end of the lap
2. From this point on run, at every half lap (200m), you will run slightly faster, about 2.5 seconds/200m for every 200m until you can no longer maintain the pace for the full 200m, hitting the lap button every 200m. If you can remember, pay attention to your breathing and notice what lap you were on when you started to pant.
3. Eg., If you run 7:00/mile for a 5k, start at 10:00/mile or 2:30/lap, 1:15/200m. After 200m descend your time to 1:12.5, then again at the next 200m to 1:10, then 1:07.5, etc. This will seem very slow to start, but eventually you will be running all out, trust me!
4. When you’re done, download your HR/lap and see if there’s a plateau and then a large jump in the rise of your HR between two laps, that’s likely where you went anaerobic, and if you remember, when you started to pant. Take the average of the max HR of those two laps, that will be your AT HR

HR Zone Chart, Running

Run AT	160	HR % of AT		Calculated HR
	Run Zones	Low	High	Low	High
1	Active Recovery	70	84	112	135
2	Extensive Endurance	85	89	136	143
3	Intensive Endurance	90	94	144	151
4	Threshold Training	95	99	152	159
5a	Threshold Training	100	102	160	164
5b	VO2 Max Intervals	103	106	165	170
5c	Anaerobic Repetitions	107	110	171	176

Use the HR % of AT values in this chart to plug into an Excel spreadsheet (or something like that), to generate the Calculated HR. I used an AT HR of 160, replace that value with your AT HR. The Run Zones as defined here by percentage and name are straight out of Joe Friel’s Triathlon Training Bible. This has become an industry standard and if you use these HR zones everyone will know what you’re talking about.

AT Baseline Test

To establish your current level of fitness, right after establishing your AT HR, you need to set a benchmark that you will compare your results against after you’ve gone out and trained for some extended period of time.

1. Either on the track where you can monitor how far you’ve run, or if you have a GPS enabled HRM, do a 30 minute run at your AT HR. Do a good but easy warm up, rest for a few minutes, and then start the 30 minute run.
2. Get your HR up to your AT HR quickly, but don’t sprint to get there. At 30 minutes mark the distance you have traveled.
3. When you repeat this test after training for a while, see if at the same AT HR you have run further, indicating an increase in your level of fitness. And if not, then see what kind of training you’ve done to determine how you can improve it to get the fitness gains you desire.