Interval training. Just the words alone can make us shudder. They aren’t your nice, steady state, zone 2 run. No. Instead, they’re sprints, shuttle runs, tempo efforts, hill climbs. None of it is nice. All of it will test your lungs and legs.
But if you can learn to find beauty in the suffering, there are tremendous benefits to incorporating interval sessions once a week. They’ll help your marathon endurance training, build strength throughout your body, supercharge your mental resilience, and, crucially, shave precious minutes off your PB. Here’s everything you need to know.
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The Benefits of Interval Training for Endurance Athletes
‘Need’ is a strong word, but intervals are pretty great for you. They’re regarded as one of the most efficient ways to improve performance, driving key physiological adaptations like:
- Improving VO₂ max (your body’s ability to use oxygen) is a major predictor of endurance performance
- Increasing mitochondrial density, improving energy production at the cellular level
- Enhancing your lactate threshold, allowing you to sustain faster paces for longer
- Developing neuromuscular efficiency, helping you run more economically
“Intervals introduce intensity distribution into your training, meaning you’re not always running at the same effort,” explains Lewis Moses, a former international ultrarunner and founder of Run Through Coach. This variation is vital for stimulating adaptation across both aerobic and anaerobic systems. In other words, running intervals gets you fitter.
Finally, intervals are a really time-efficient way to get your workout in. Research, including a 2021 study in the International Journal of Environmental Research and Public Health, shows that high-intensity interval training can produce similar or greater improvements in fitness compared to moderate continuous training. Essentially, operating right on the edge of your fitness drives faster adaptations.
“Shorter bouts of hard work, separated by rest, allow you to accumulate far more time at a high physiological strain than continuous running permits,” Dr Carl James, Assistant Professor at the Department of Sports and Health Sciences, at Hong Kong Baptist University.
Whether you’re sprinting for five to 15 seconds or taking it up to mile repeats, James says that all intervals create massive spikes in oxygen demand and in our neuromuscular systems, forcing your body to adapt in real time. Which, horrible as it sounds, is a good thing when your goal is to get faster and fitter.
Related: I'm a Former NFL Strength and Conditioning Coach. This Simple Interval Workout Boosts VO2 Max for Men Over 50 in Just Weeks
What Are the Different Types of Intervals?
Running intervals are typically structured as repeated bouts of higher-intensity running followed (blissfully) by recovery periods. Common types include:
Tempo / Threshold Intervals
These are sustained efforts just below your lactate threshold. They’re typically prescribed with a 3:1 work-to-rest ratio, meaning you might run for 90 seconds, then rest for 30, and repeat. The benefit here is as much psychological as it is physical; by holding a challenging pace for a given period of time, you’ll drill into your brain that yes, you can do it, and no, some suffering isn’t that bad.
VO₂ Max Intervals
As the name suggests, these are higher-intensity efforts designed to push your aerobic ceiling. They’ll usually follow a 1:1 format, e.g., three minutes of work, with three minutes of recovery, repeated as needed. The key thing here is not to skimp on recovery. You might feel fine after your first set, but skip that rest, and quality will slip by the time you get to round three.
Hill Intervals
Sorry in advance about this one. No one likes hill sprints, but if you’re training for a hilly course, like the NYC Marathon, they’re a must. Outside of that, they encourage leg and core strength, running economy, and power—three factors which are useful in any race. Typically, they can be lower impact or higher impact for a shorter period. For example, your plan might ask you to sprint uphill for 60 seconds with a 30-second rest at the top and a gentle jog back downhill.
Fartlek Training
This Swedish method focuses on less structured intervals and instead mixes intensities. It’s less about hitting specific paces and more about running on feeling. For example, you might run to the next street sign at 80 percent effort, then run to the end of the road at 60 percent effort. It’s a useful tool for developing your awareness of pace, for simulating race day conditions when you might be held up by a crowd, and for adding some variety into your training.
Interval Training Risks: How to Avoid Injury
Apart from tiring out your legs, lungs, and brain, are there any downsides to intervals? Dr. Nicolas Berger, senior lecturer and expert in exercise physiology at Teesside University, UK, says that the main downside is that intervals are overly hyped on social media, making them a showy but unnecessarily common part of our training. “You might not need to do them; the reality is that even elite athletes only do these sparingly,” he warns.
Overdo intervals, or don’t allow enough recovery between sessions, and your injury risk increases. Your tendons, particularly the Achilles and Patellar (knee), are especially at risk.
“Do too much too soon, and you can end up stuck in a cycle of always feeling tired, but not actually improving,” warns Berger. It’s better to take your foot off the gas, miss a session if needed, and come back stronger for the next one so that you can fully engage and gain the benefits you want.
“Start slow and introduce only one new training variable into your weekly routine at a time,” agrees Roxana Ehsani, a sports dietitian who ran the fastest time at the Washington DC Marine Corps Marathon in 2026. Most experts follow the 10 percent rule, meaning don’t increase weekly mileage or load by more than 10 percent per week.
How you fuel your sessions matters, too. “As a sports dietitian, I always want to make sure runners are consuming enough total calories to prevent injury and avoid stress fractures,” Ehsani adds. And no, gels don’t count. Load up on carbs and protein before and after your session to avoid fatigue and to help your legs recover.
Related: How to Start Running: An Expert's Guide for Beginners and Returning Runners
What’s a Good Beginner Sprint Session?
For beginners, one interval session a week is ideal. “It can be useful to think flexibly and include a mix of tempo runs and fartlek sessions,” says Moses. Looking to give it a go? Here’s Moses’ beginner hill sesh.
Warmup
- 10 to 15 minutes easy jogging
- Dynamic stretching
- Running drills (e.g., high knees, skips)
- A few short strides to “prime” the system
Main session
- 8×12 second hill sprints
- Gradient: 7 to 10 percent incline
- Recovery: ~3 minutes walk or very slow jog
- Focus: Maximal form, power, and drive into the ground
Cool Down
- Easy jog for 5 to 10 minutes
- Followed by some light static stretching
“This type of session is low volume but high quality, ideal for beginners to safely introduce speed and strength,” he says. Good luck.
from Men's Journal https://ift.tt/yaZPFTA
