Why Cyclists Need Anaerobic Exercise, Too

Quick anaerobic intensity workouts can improve your speed and endurance: here's how and why, and how it differs from aerobic exercise.

By Laura Williams Butos MD |

Anaerobic exercise runs the risk of being ignored as we fixate on polarised training and the worship of Zone 2 training. And it’s easy to skip it, cycling. On practically every “types of aerobic exercise” list, cycling is one of the primary examples. And for good reason: Cycling is, in fact, an aerobic workout that uses oxygen to provide energy for movement.

But even though cycling is primarily an aerobic workout, cyclists should still get familiar with anaerobic exercise or how to use anaerobic cycling workouts to improve performance and overall fitness. That’s because taking advantage of this higher intensity form of physical activity can make you a better cyclist—and even improve your aerobic fitness on the bike. Here’s how.

Anaerobic Exercise vs Aerobic Exercise

Just like your car needs gasoline (or diesel or electricity) to start up and go, your body needs energy in order to move. Your body generates this energy from the food you eat and the fat and glucose, or glycogen that you store in your muscles, blood, and liver.

The two overarching metabolic (energy-making) pathways your body uses are aerobic and anaerobic. While it’s possible for these pathways to work semi-independently, that’s fairly rare. Rather, you can think of them like a sliding scale, working together, where if you’re always creating 100 percent of the energy you need to move, you’re using a percentage of both aerobic and anaerobic energy systems to support the movement.

For example, if you’re taking a casual walk, almost all of the energy you need to move will be generated from your aerobic system, but there will still be some energy coming from the anaerobic system. As you pick up your pace and transition from a walk to a jog to a run to a sprint, a progressively greater percentage of the energy you generate will come from your anaerobic system, and less from your aerobic system. These two systems are constantly making adjustments to ensure you’re generating the energy you need.

The aerobic energy system is the one you typically use the most. Whether you’re lying down, walking around your house, or going out for a jog, aerobic exercise uses oxygen to keep you fueled and moving. If you can breathe comfortably (even if you’re breathing hard) in a way that you feel you’re able to maintain for a period of time, you can rest assured that your aerobic system is doing the heavy lifting, so to speak. For this reason, when you’re taking your bike out for a spin, it’s typically considered an aerobic form of exercise.

Anaerobic exercise, on the other hand, doesn’t need oxygen to create energy. It’s the system that kicks in to supplement or take over when your energy demands exceed the amount of energy your body is able to generate with oxygen. Essentially the anaerobic system is the one you’re using most when you start huffing and puffing to climb a tough hill, or you pick up your pace at the end of a race.

When your breathing becomes labored and uncomfortable, your legs start to burn, and you get to a point where you know you won’t be able to keep going unless you slow down or take a break? That’s when you know your anaerobic system is doing the most work.

Both the anaerobic and aerobic systems are important for all forms of exercise, and they each have specific roles, benefits, and drawbacks. For example, the anaerobic system can produce energy quickly, but it can’t produce very much of it, so it’s hard to maintain high levels of exertion for very long when relying on the anaerobic system. On the flip side, the aerobic system can produce a vast amount of energy for a long period of time, but it produces energy relatively slowly, so when you need that last-minute sprint? The aerobic system isn’t equipped to provide the extra energy, fast.

One surprising way to help boost your aerobic fitness? Include anaerobic workouts in your regular routine.

How Anaerobic Exercise Improves Fitness

“Combining anaerobic training with aerobic training is vital for any athlete, as it helps to build a well-rounded fitness base,” says Rory McAllister, UESCA-certified cycling coach based in the U.K.. “While aerobic exercise builds endurance and cardiovascular fitness, anaerobic exercise targets different energy systems and helps develop speed, power, and strength. By incorporating both types of training, you improve your overall fitness and are prepared to perform better across a wider range of racing scenarios.”

One big way that training anaerobically can help you is that it builds tolerance for lactate buildup and also helps train your body to buffer this lactate more efficiently. Think about how your muscles start to burn as you try to climb a steep hill.

When your body produces energy without oxygen, it also creates lactate as the waste product. Lactate can be buffered away from your muscles, relieving the burn, but oxygen is required to do so. As long as you’re exercising anaerobically (without oxygen), the lactate continues to build. When you stop, you give your body a break and your oxygen consumption is able to start catching up with your oxygen demand, which allows for the lactate to clear.

“By pushing the limits of anaerobic capacity through intense intervals or short, intense efforts, athletes can train their bodies to better handle and clear lactic acid. This can delay the onset of fatigue and improve overall performance during high-intensity efforts,” explains McAllister.

The concept isn’t all that different from any other type of exercise training—your body is designed to become more efficient with practice, whether that’s with riding long distances, lifting weights, or climbing mountains.

The more often your body is faced with a particular challenge, it will undergo adaptations to make that challenge easier with time. For example, one 2016 study in PLOS ONE found that both sprint interval training (anaerobic) and high-intensity aerobic training led to improvements in lactate threshold and the onset of blood lactate accumulation in a group of mountain bikers.

“For cyclists specifically, anaerobic training is particularly important. It helps cyclists enhance their sprinting ability and power output. Sprints and short bursts of power are crucial in bike races, either during race finishes, when attempting breakaways, or in responding to attacks,” McAllister says. “Anaerobic exercises also help develop muscle strength and power. Stronger muscles allow cyclists to generate more force with each pedal stroke, resulting in greater speed and efficiency on the bike.”

Types of Anaerobic Workouts

There are different types of anaerobic workouts you can do to improve your cycling performance. Choosing one or two workouts to incorporate into your weekly training routine can help you achieve your long-term goals. McAllister points to the following types of anaerobic training methods:

High-Intensity Interval Training (HIIT)

You may have heard of HIIT workouts. This type of training involves alternating between a short burst of intense effort followed by a period of active recovery. Intervals are typically timed and have a pre-determined intensity-to-rest ratio that could be 1:1, 1:2, 1:3, or even 2:1 or 3:1. For instance, you might work at a 1:1 ratio of 30 seconds of intense cycling followed by 30 seconds of slow cycling (or even complete rest), repeated multiple times.

Hill Repeats

Hill repeats could be considered a type of HIIT training, but it depends on how they’re used and incorporated. The main difference, of course, is that hill repeats involve climbing hills. “Find a hilly route or segment and perform repeated efforts of climbing at a high intensity. Hill repeats are an effective way to build leg strength, power, and anaerobic fitness,” McAllister says.

Fartlek Training

“Fartlek, a Swedish term meaning ‘speed play,’ involves incorporating random bursts of high-intensity efforts during a regular ride,” says McAllister. The key difference here is that the sprints are random, rather than specific and timed. “It can be done by spontaneously accelerating and sprinting for short distances or between landmarks like trees, lamp posts, or road signs. Fartlek training adds variety and intensity to a workout, simulating real-life race situations,” he adds.

Strength Training or Circuit Work

Not all of your anaerobic workouts need to take place on the bike. In fact, strength training, which is inherently anaerobic, particularly when lifting heavier weights, is an excellent way to improve your overall fitness. “By including resistance exercises, such as squats, lunges, kettlebell swings, and plyometric movements, you can target specific muscle groups and improve muscular strength for more powerful pedaling,” McAllister says.

Guide to Nailing Your Anaerobic Workouts

The thing about anaerobic workouts is that they’re intense, so it’s important to be intentional about your approach to incorporating them into your routine.

1. Monitor Intensity Level

“There are two main ways to monitor anaerobic intensity: power zones and heart rate zones,” says McAllister. In either case, you’ll need to have access to equipment that can accurately measure and monitor your intensity.

“Power meters are devices that measure the actual power output in watts while cycling. They provide precise and reliable data on your effort level. To determine your anaerobic intensity, you can establish power zones based on your functional threshold power (FTP). FTP is the maximum power you can sustain for about one hour,” he explains.

While power zones vary from person to person, McAllister says that anaerobic workouts typically fall between a zone of 5 or 6, which indicates very high to maximal outputs. While power zones are very accurate in helping gauge intensity levels, there’s just one problem: “Power meters are prohibitively expensive for many cyclists, making it more difficult to monitor power zones,” he says.

Your other option to monitor intensity is your heart rate zone. Heart rate monitors are widely available and can be as simple as a watch or arm band, or may include a chest strap. “Heart rate monitors can estimate the intensity of your exercise based on your heart rate response. However, heart rate can lag behind changes in effort level, and it can be influenced by factors such as fatigue, heat, and hydration,” says McAllister, explaining that it might not be quite as accurate for anaerobic exercise as a power meter. That said, it’s an affordable option that can be useful in providing a gauge for your intensity level.

If you have neither a power meter or a heart rate monitor, you can also use your rate of perceived exertion (RPE) or the talk test to help to make sure you’re working at a high intensity. Anaerobic efforts should hit at least an 8 out of 10, working up to a 9 or 10, on the RPE scale, and you shouldn’t be able to talk while working through them.

2. Warmup and Cool Down

Making time to warm up and cool down for every workout is important, but it’s particularly important when you’re doing high-intensity workouts. A proper warmup helps prepare your muscles for the work they’re about to do, and a cooldown gives your body the time to gradually return to baseline following a tough workout, rather than going from 100 to 0 in a second.

3. Allow Time for Recovery

Tough workouts place significant stress on your muscles, tendons, and joints. This stress is actually damage that your body needs to repair postworkout to be stronger and more prepared for your next tough routine.

It’s incredibly important to allow for adequate rest following an anaerobic workout. Give yourself at least a 24 to 48 hours of downtime before your next intense routine. That said, active recovery—taking a walk or low-intensity bike ride, doing yoga, or going swimming—can help support your recovery.

4. Increase Intensity Gradually Over Time

“It’s crucial to gradually increase the intensity and duration of anaerobic exercise over time,” says McAllister. “Start with shorter intervals or fewer repetitions and gradually progress as your fitness level improves. Pushing too hard or progressing too quickly can increase the risk of overuse injuries or burnout.”

It’s a good idea to work with a coach or to follow a pre-set routine when you’re new to anaerobic workouts. This will help ensure that you’re not taking on more than your body is prepared to manage. “Everyone responds differently to anaerobic training, so it’s important to personalize your workouts based on your goals, fitness level, and ability,” McAllister says.

5. Balance Aerobic and Anaerobic Workouts

The last tip McAllister offers for any cyclist who wants to incorporate anaerobic exercise is simple: Don’t ditch your aerobic workouts completely. “It’s essential to maintain a balance between anaerobic and aerobic training. Aerobic endurance forms the foundation for performance and overall fitness. Your training program should include both types of workouts to maximize your cycling potential,” he says.

Your Anaerobic Cycling Workout

If you don’t feel comfortable creating your own workout the first time you train anaerobically, don’t sweat it—McAllister has you covered. Try the following example workout to amp up your training routine.

Warmup and Cooldown

Regardless of which workout you choose, start by warming up with 10 to 15 minutes of easy pedaling at a gradually-increasing pace to raise your heart rate and get your muscles firing.

Likewise, finish your workout with a similar 10 to 15 minutes of easy pedalling. When your heart rate and breath rate have slowed to near-normal, add light stretches to help facilitate recovery.

1:2 Sprint Intervals Workout

Working on a flat stretch of road or on a stationary bike, perform 8-10 sprints of 20 seconds of all-out work followed by 40 seconds of active recovery (slow cycling).

“During the sprints, aim to reach your maximum effort level and maintain a high cadence,” McAllister advises. “Focus on generating power and explosiveness with each pedal stroke.”

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