As a personal trainer and running coach, I am often asked about high-intensity interval training (HIIT), as the benefits have been popularized in general fitness spheres for weight loss, boosting cardio fitness levels, and providing an efficient workout.
However, while HIIT gym workouts are in their more nascent stages in terms of popularity, distance runners have been doing interval running workouts for decades.
Much like any form of high-intensity interval training, interval running workouts involve bouts of running at a higher intensity, such as your race pace or VO2 max pace, and then taking a short recovery period before going hard again.
What I love about interval workouts is that there are tons of ways to vary them.
Variations are based on fitness level, target race distance, and physiological adaptations such as improving VO2 max, increasing anaerobic threshold, or helping runners get more comfortable at race pace efforts.
This guide breaks down what interval running is, why it benefits distance runners, and the best types of interval workouts to incorporate into your training.
What Is Interval Training?
Interval training is a method that involves alternating between running at a faster speed for a specific distance or amount of time followed by recovery periods.
For example, an interval workout for a half marathon runner might involve 6 x 1,000m at 5K pace.
While interval workouts are now commonplace in training programs, they have only been widespread since the 1950s, when runner Emil Zatopek implemented this revolutionary style of training.1Billat, L. V. (2001). Interval Training for Performance: A Scientific and Empirical Practice. Sports Medicine, 31(1), 13–31. https://doi.org/10.2165/00007256-200131010-00002
Emil Zatopek’s training style helped him break 18 world records and win five Olympic medals.
Is Interval Training the Same As HIIT?
High-intensity interval training, more commonly known as HIIT workouts, require you to reach at least 85% of your age-predicted maximum heart rate during the hard intervals.
Not all interval running workouts are necessarily high-intensity interval training, as half marathon and marathon runners can do longer anaerobic threshold workouts such as tempo runs that may be just below 85% of your maximum heart rate, depending on your fitness level.
Advanced runners have a higher anaerobic threshold, so they are typically able to run at a higher intensity for these types of longer intervals.
Beginners, on the other hand, who have not yet developed their aerobic and anaerobic fitness levels to the same extent would be at a lower intensity for this particular type of interval running workout.
That said, most interval running workouts fall under the umbrella of HIIT workouts.
What Are The Benefits Of Intervals?
- Add variety to your training plan which can decrease the risk of injury because you are varying the stresses and loads placed on your muscles, bones, joints, and connective tissues.
- Burn calories, and can accelerate fat loss for runners trying to lose weight.
- Are an efficient way to train because you can facilitate physiological adaptations such as improving VO2 max or aerobic capacity,2Scribbans, T. D., Vecsey, S., Hankinson, P. B., Foster, W. S., & Gurd, B. J. (2016). The Effect of Training Intensity on VO2max in Young Healthy Adults: A Meta-Regression and Meta-Analysis. International Journal of Exercise Science, 9(2), 230–247. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4836566/ running economy, and cardiovascular fitness level3Bacon, A. P., Carter, R. E., Ogle, E. A., & Joyner, M. J. (2013). VO2max Trainability and High Intensity Interval Training in Humans: A Meta-Analysis. PLoS ONE, 8(9), e73182. https://doi.org/10.1371/journal.pone.0073182 in a short amount of time for each interval training session relative to a steady-state run.
- Build mental toughness to help you push through discomfort on race day.
- Improve your running economy.4Barnes, K. R., & Kilding, A. E. (2014). Strategies to Improve Running Economy. Sports Medicine, 45(1), 37–56. https://doi.org/10.1007/s40279-014-0246-y
- Is easily scalable for all levels. Beginners can start with fewer, slower intervals and longer rest, while advanced runners can increase reps, intensity, and shorten recovery. As fitness improves, you can build volume, reduce rest time, switch to active recovery, and progress to more challenging workouts.
- An interval training program can be used with any training approach to long-distance running such as heart rate training, training by rate of perceived effort (RPE), or training by pace.
What Are the Best Interval Running Workouts?
#1: Hill Workouts
Hill sprints are one of the most versatile interval running workouts because they combine strength training with speed training and can be useful for runners of all fitness levels and all target race distances.
Short steep hills help build all-out running speed and power and longer hills improve anaerobic and aerobic fitness.
Hill workouts can be scaled by increasing the number of reps and of course, increasing the speed or intensity level.
#2: VO2 Max Intervals
These interval workouts involve running different distances on the track at your VO2 max pace in order to stimulate physiological adaptations improving your VO2 max, running economy, and anaerobic capacity.
Improving aerobic capacity will help you have a more efficient cardiovascular system, so you use oxygen more efficiently at faster running speeds.
An example is five repetitions (reps) of 1000m, which is 2.5 laps of the track, at 95% of VO2 max pace.
According to Jack Daniels, one of the most renowned distance running coaches, well-trained runners who don’t know their exact VO₂ max can estimate it by using their 3K race pace or the fastest pace they can sustain for about eight minutes.
Interval sessions for improving VO2 max should have intervals that take between three and six minutes for each of the reps.
#3: Shorter Intervals
It can also be helpful to do track intervals with shorter reps at mile pace or faster to train your anaerobic system.
A classic speed training workout for distance runners is 10 to 12 reps of 400m at mile race pace or 5 to 10 seconds faster than 5K pace.
Long-distance runners can also benefit from all-out sprints like strides at the end of an easy run.
#4: Fartlek Runs
A fartlek run is a workout that involves interspersing short periods running at a faster pace built into a continuous endurance run.5Kumar, P. (2015). Effect of fartlek training for developing endurance ability among athletes. ~ 291 ~ International Journal of Physical Education, Sports and Health, 2(2), 291–293. https://www.kheljournal.com/archives/2015/vol2issue2/PartE/3-3-75-957.pdf
For example, after a 10-minute warmup of easy running, you might throw in 10 repetitions of 90 seconds at 5K race pace followed by 60 seconds at your normal steady-state running pace.
Fartlek workouts are essentially like speed workouts on the track but may also be less structured. Some runners, for instance, may choose to use landmarks such as stop lights or lampposts to denote when to switch running speeds.
#5: Tempo Runs and Lactate Threshold Intervals
Tempo runs or lactate threshold interval sessions on the roads are a great way to simulate race conditions with hilly courses.
The lactate threshold occurs around 83-88% of your VO2 max or roughly the pace you could hold at maximum effort for an hour of running.
For most runners, the lactate threshold pace is about 15-20 seconds per mile (9-12 seconds per kilometer) slower than their 10K race pace.
Therefore, if you run a 45 minute 10K race, your tempo runs and threshold interval workouts should be run around 7:30-7:35 minutes per mile or about 4:39-4:42 minutes per kilometer.
Tempo runs are a minimum of 20 minutes at your lactate threshold pace, but you can also do shorter intervals with recovery periods as you build up your endurance.
Tips for Adding Interval Running to Your Training Plan
As with your overall mileage, it is important to gradually build up the intensity and number of reps or distance for your workouts.
While there are many training, health, and running performance benefits of interval running, even short periods at an all-out effort, or running at a high RPE or heart rate is taxing on your cardiovascular, metabolic, and musculoskeletal system.
Therefore, it is very important to build in enough recovery after your interval training sessions.
Consider cross-training or taking an active recovery workout the next day, especially when you are first starting interval running workouts or are doing longer and higher intensity interval training sessions.
You should always do a warm up and cool down to bookend the intervals, even if you are doing longer intervals like a tempo run or lactate threshold intervals that aren’t at an all-out effort.
The warm up increases blood flow to your muscle groups and prepares your body for running faster.
The cool down after hard workouts serves as a form of active recovery to help begin flushing the metabolic byproducts out of your muscles and bringing oxygen and nutrients for muscle recovery.
Overall, almost all long-distance runners should incorporate some type of interval training into their plan.
The benefits of interval workouts span the gamut from decreasing the risk of injury from constantly running the same steady-state pace every day to helping you get fitter, faster, and stronger in a shorter period of time due to the intensity and efficiency of interval running.
For an inside look at the different types of running workouts, check out this next guide:
