You either love or hate them, but intervals are an integral part of any sports and conditioning program, and cycling is no exception. The spring and summer months are the time of year for most athletes to reap the fruits of their labor from base training and aim more specificity to their key events with intervals. However, when completing these hard, short efforts, it is easy to get lost and wonder how these workouts play into a full training cycle and what benefit they will have. So let’s review the basics of interval training and why they’re important.
What Are Intervals, and Why Do We Do Them?
Interval training targets two physiological systems: aerobic capacity (VO2 max) and anaerobic capacity (above lactate threshold).
Aerobic capacity intervals — which range from 105-120% of your functional threshold power — are intervals in which you can breathe hard for a short period of time and typically can be from four to seven minutes. The purpose of these intervals is to train the body to better process oxygen during exercise. The less aerobically fit you are, the shorter you’ll be able to sustain a hard effort.
Anaerobic intervals or lactate threshold intervals — which are >121% of your functional threshold power — usually last between 30 seconds and three minutes and create lactate buildup—”a burning sensation in the legs.” These intervals teach your body to clear lactate while increasing your ability to repeat intense efforts over time.
As athletes, we typically spend 80% of our week typical life stuff like work, home chores, and the like. The other 20% of our time (at best) is our free time — which, for us cyclists, includes riding our bikes. Therefore, you need intervals to generate adaptation to make the most of your training time.
Research shows that high-intensity training is vital for experienced athletes in helping to reduce the natural decline of aerobic capacity (i.e., VO2 max) with advancing age. Intervals also help prepare your body for your event’s specific demands, whether that’s climbing, sprints, or time trialing. As a coach, it is my job to ensure the intervals and recovery periods you experience replicate the demands of your events while also addressing limiters that are individual to you at the right time.
When to Do Cycling Intervals
Interval training is best done within eight to 12 weeks of your goal event, otherwise known as the “build phase” of your training cycle, and should get progressively harder over time. Often, my athletes will start at a higher number of shorter intervals and learn to pace themselves.
The goal is to increase time at the intensity of the interval that replicates the demands of your event(s). So, if two minutes is as long as you can maintain an effort at VO2 max, then two minutes is the time you should spend in intervals at your target intensity.
How to Do Intervals
It is important to find adequate terrain on which to execute your intervals properly. For example, I train on a 4% road climb that works great for five to seven-minute VO2 max efforts. However, if I try to make these same VO2 max efforts on the trail, I will run out of trail or end up riding in my anaerobic zone.
Executing intervals takes practice and trial and error. Over time you will become very good at knowing where to best achieve your breaks. When all else fails, the trainer is a perfect place to complete intervals — just make sure you are off erg mode!
Even if I have completed the same intervals hundreds of times before, I always review what intervals I’ll be doing before starting the workout. This allows my head to get in the right space and sets an expectation on how many intervals I have to complete. It is often more difficult to complete intervals when you don’t know how many you have to do.
It is also important to ensure your head unit’s view fields are set correctly when doing intervals. All head units are different, but Garmin is the head unit typically used in training for the vast majority of my athletes. My head unit provides two options to view my workouts. The first view is the TrainingPeaks view, which shows a bar graph of your power output in relation to the power required for each interval. The others I recommend are:
- Lap Time: Displays total time for each interval
- Lap Power: Displays average power for each interval
- 3-second Power: Displays power on a 3-second average
- 30-second Power: Displays power on a 30-second average
- Elapsed Time: Displays total training time on the bike for the current workout
- Heart Rate: Displays current HR
I monitor my lap power and 30-second power to the power requirements of the interval. I also check my HR in relation to my power to ensure I am close to the heart rate zone that correlates with the power zone. Over time, you will become more familiar with how you perceive your effort in relation to your power numbers, which is your relative perceived effort, or Rating of Perceived Exertion (RPE) in TrainingPeaks.
For most athletes, the third interval tends to be where your body and mind accept that you are training hard. It is also a place in time where you can determine if you can complete all intervals. For example, if your eighth interval is 10-12% lower in power than the third interval, consider stopping the workout. This drop in power is often a sign that you may be overly fatigued or that the intervals are too difficult for you. Remember: it makes no sense to push through if you cannot meet the power targets. Your coach will determine how to adjust your intervals accordingly.
Other Cycling Interval Training Tips
- Be sure to warm up at least 10 minutes before intervals. Not warming up appropriately can cause you to fatigue faster and may impact your ability to complete your set of intervals.
- Don’t go too hard at the beginning of an interval session. Instead, stay conservative and try to meet the power demands of all intervals.
- Many times, you may not feel like doing intervals. Warm up and do them anyway. I often find that once my athletes get started, they can have a great workout.
- Make sure you have adequate recovery between interval sessions. Day-to-day interval sessions can impact your overall training program, including the duration and frequency of other workouts.
- View each interval as a challenge to conquer. You will find that completing intervals becomes a game. Intervals are not sexy, but they are important in your training program. And remember, they are just one part of your overall program.
References
Friel, J. (2015). Fast After 50: How to Race Strong for the Rest of Your Life. VeloPress.
