When it comes to workouts that utilize the Assault Bike, I’m often asked questions like, “How hard should I be going?” or “What pace do you think is best for this particular WOD?” These questions are often difficult to give a definitive answer if certain information about the athlete’s fitness level is unknown. In the world of CrossFit, much of the work we do involves high intensity efforts, so I often find myself answering these questions by saying something along the lines of “You should be going at an intensity of 8, 9, or 10 on a 0-10 scale, with 10 being max effort.”

While using the 0-10 scale [also known as the Ratings of Perceived Exertion (RPE) Scale] can be a decent way of gauging intensity, especially for a novice athlete, it is prone to error, especially at lower intensities, where active recovery sessions are done. I find that athletes generally underestimate their efforts at lower intensities and go harder than they should during these sessions. The same is often true at the other end of the spectrum. I often see athletes in the first half of their METCON go out way too hard on the bike and end up burning out in the second half with nothing left because their pacing strategy was inappropriate.

This brings me back to the opening point of this article. What bike pace do you think is best for any particular WOD? How hard should you be going? The answer to this question lies in uncovering some objective data about your current fitness level and not solely relying on how you “feel” (which is subjective). There is a time and place to use RPE, but using objective data will help guide your pacing strategy more effectively in any workout involving the Assault Bike.


So, what is this data, and how can we uncover it to make ourselves more effective on the bike?

It starts with something called your Lactate Threshold.

What is lactate threshold? Simply put, lactate threshold (also known as anaerobic threshold) is the point at which you start to accumulate lactic acid in the blood, which generally occurs at an intensity that corresponds to a level of 7-8 on the RPE Scale. Below this point, you are working aerobically, which means you have adequate oxygen supply to create the energy you need to keep you exercising. Once we get to the threshold, we begin to switch from aerobic effort to anaerobic effort, which means we have an insufficient amount of oxygen coming into the body to sustain that effort, and other means must be used to generate energy. Once you get above the threshold, that exercise intensity cannot be sustained for very long, which is why you will find yourself slowing down after a certain amount of time going really hard (generally 2-3 minutes or less, depending on fitness level, if you’re going at a near all-out intensity).

So, why is this important to you and how will it make you better on the bike? If you know what your Lactate Threshold Heart Rate (LTHR) or Functional Threshold Power (FTP) (I’ll explain this soon) are, then you can estimate intensity with far greater accuracy than just going by feel.

There is a test called the Lactate Threshold Test, which will help you identify your LTHR and/or FTP. When you are exercising at your lactate threshold, generally, this intensity can be sustained for about an hour, but it’s a very painful hour. This would be the most accurate way, besides getting a test done at a lab, of estimating your numbers, but this is very time-consuming and miserable. Lucky for you, there is a test that can be done in 20 minutes that will give you a reasonably accurate estimate, and the more you practice it, the more accurate it will become.

Taking a step back to FTP, this is your power output in watts (W) at your lactate threshold. What makes the Assault Bike so great is that it provides power output for you on the screen. The reason we want to use FTP is because we can refer to power output easily on the screen during a workout, whereas it’s a little less practical to bring a heart rate monitor and watch with you to the gym all the time, but you can certainly do it if you’re serious enough about it. Also, power output gives you feedback on your intensity level instantly whereas heart rate takes some time to increase or decrease (i.e. it’s a lagging indicator of intensity).

Now that we’ve covered that important background info, how do we do this test and what do we do with the data after we’re done?


Step 1: Come to the gym fresh

What I mean by this is: no muscle soreness, well-rested, with at least 1-2 days without high-intensity exercise. Otherwise, you will not get an accurate result.


Step 2: Do a warm-up

Hop on the bike for 10 minutes starting at a low intensity of 2-4 on the RPE Scale for the first 5 minutes, then bump it up to 5-7 for the next 3 minutes. Feel free to jump above threshold pace for a few short bursts of 10-20 seconds occasionally during these few minutes, but do not fatigue yourself. The purpose of this warm-up is to gradually build intensity to prepare your muscles and body for the test. Reduce your intensity back down to 2-3 for 2 minutes. Then stop the bike. If you haven’t seen what the screen’s data looks like after a set duration workout, at the end of your 10 minute warm-up take a look at the screen to see what your average power output was and where it’s located. Make sure you do this warm-up by setting the duration to 10 minutes so the bike stops automatically and provides you with the data.


Step 3: Set up for your test

Set up the bike to do a workout 20 minutes in duration.


Step 4: Complete your test

You will start at a high effort, but you should feel like you can go faster after the first 5 minutes. Start the test at around a 5-6 level of effort. After 5 minutes, bump up your effort to 7-8. Once you’re 10 minutes in, you can decide on whether or not you can go a little harder or stay at the intensity you’re in. Remember, you shouldn’t be slowing down. This effort should be maintained the rest of the time.

What should your effort at FTP feel like? This is a difficult test. You should be breathing fairly heavily and you should feel a pretty strong burning sensation in your muscles. You will feel like you want to slow down but you don’t have to.


Step 5: Gather the data (Cool Down after)

When you have completed your workout, the bike will give you your average power output for the 20-minute session. Write this number down (e.g. 200W). Subtract 5% from this number (e.g. 5% of 200W is 10W. So 200W – 10W = 190W). In this example, 190W is your FTP. This is your power output that will bring you to your lactate threshold. If you used heart rate as well, do the same thing for your average heart rate over the 20 minutes and subtract 5% from it to get your LTHR. LTHR is your heart rate at your lactate threshold.

So, now that you know where your lactate threshold is, you will need to re-test it periodically. Depending on how serious you are, you may test it once a month or once every other month. As your fitness on the bike improves, you can expect your LTHR and FTP to improve as well (i.e. increase, although FTP will probably change more than LTHR).

We’re almost at there…One final step is to create Heart Rate and/or Power Zones so that we can be more effective on the bike during any WOD.

By setting up heart rate and/or power zones based on your lactate/anaerobic threshold, you can more accurately gauge your exercise intensity and stay at the appropriate intensity based on the intended workout stimulus!

These zones are described as percentages of your anaerobic threshold and correspond to a desired training stimulus. I have adapted these zones from power zones that are normally used when riding a standard bike, but they are effective on the Assault Bike as well.


Power Zones (you will use these most often with the Assault Bike)

Zone 1: <55% (Warmup or Recovery)

Zone 2: 55 – 74% (Aerobic Endurance)

Zone 3: 75 – 89% (Intensive Endurance/Tempo)

Zone 4: 90 – 104% (Threshold Training)

Zone 5: 105 – 120% (Anaerobic Endurance)

Zone 6: >120% (Speed and Power Development)


Now, you can more accurately gauge where your effort should be. As CrossFitters, most of the time we will be at Zone 4, 5, or 6. Just remember, if you are above your threshold, you will not be able to sustain that pace for very long (depending on fitness level of course), so think about that when doing your next WOD that involves a bike.

Ask yourself: “What other movements are involved in the workout that will keep me from maintaining a higher intensity on the bike? Wall Balls and Deadlifts…Ok, so maybe I’ll stay sub-threshold in Zone 3 or lower Zone 4 for this WOD”, “Am I doing a METCON that only involves hard intervals on the bike? Ok, then I can push it hard into Zone 5 and maybe 6.”

Always consider the context of the workout and what you’re trying to achieve. Once you have your zones established, crunch a couple numbers before your workout and stay in your optimal zone. You’ll find that your performance on the bike will greatly improve over time. Finally, although you want to adhere to these zones, when all is said and done, these are guidelines and just another tool to help make your training more effective. If they don’t feel accurate, do another test and see if your numbers change. Also, don’t completely dismiss what your body is telling you and how you feel. Use a combination of tools to find the appropriate intensity for you that day.

In closing, even though most of you will not be using heart rate zones for the bike, some of you might, so here are the zones and their corresponding percentages as well.


Heart Rate Zones

Zone 1: <81% (Warmup or Recovery)

Zone 2: 81 – 89% (Aerobic Endurance)

Zone 3: 90 – 94% (Intensive Endurance/Tempo)

Zone 4: 95 – 102% (Threshold Training)

Zone 5a: 103 – 106% (Anaerobic Endurance)

Zone 5b: >106% (Speed and Power Development)