• According to a recent study published in the Scandinavian Journal of Medicine & Science in Sports, short, 30-second, high-intensity efforts with 15 seconds of recovery deliver significantly greater performance gains than longer intervals.
• Repeated, short, high-intensity efforts helped the riders improve their abilities to buffer lactate so they could ride at higher lactate levels and boosted their power output.

By now, you probably already know that if your goal is to get fast, you need to train your body to go fast. That means intervals.

There are all sorts of ways to do interval training: steady tempo, hill repeats, efforts at the comfortably hard “sweet spot,” just to name a few. But if you really want to sharpen your performance, a growing body of research shows you should definitely make room for some leg-searing, super-short, high-intensity intervals that are sometimes overlooked by everyone but sprinters, crit racers, and cyclocross racers.

The latest among those studies is a paper published in the Scandinavian Journal of Medicine & Science in Sports comparing the effects of longer versus shorter interval training on highly-trained cyclists.

In the study, the researchers recruited 18 elite male cyclists who were fresh off their base-training period that included mostly lower-intensity riding (with a smattering of interval training) for 16 to 17 hours a week; tested their fitness levels, and had them perform specific interval workouts three times a week for three weeks.

Half the group performed 4 x 5-minute intervals with 2:30 minutes of recovery. The other half performed three sets of 13 x 30-second efforts with 15 seconds of recovery and 3:00 minutes between sets. The total interval time was similar (20 minutes for the long intervals and 19.5 minutes for the short intervals) for all the riders, and both groups were instructed to perform the intervals at their maximal sustainable intensity, aiming to crank out the highest possible average power during each interval session.

After three weeks, the riders doing the 30-second efforts were the clear winners. The short interval group improved their mean power on a 20-minute cycling test by 4.7 percent, compared with no significant improvement among the long interval riders. The short interval cyclists also saw significant boosts in their peak aerobic power and power output at lactate threshold, while their peers doing the longer intervals actually saw declines.

What made the short intervals so much more effective? For one, it appears these efforts increased the riders’ ability to tolerate lactate. By flooding their legs with lactate during the study period, the short interval riders forced their muscles to adapt to the stress and get better at buffering the acidic environment that comes with burning high-octane fuel.

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Those adaptations were obvious during their final 20-minute cycling test. The short sprint riders generated considerably more lactate in their post-test than their pre test, showing they had improved their ability to perform with higher lactate levels. In the long interval group, there was no increase in lactate levels between the pre- and post-tests among the riders.

The short interval group also generated more power overall during their interval work. On average, they hammered away at 94 percent of their max power during the short efforts. The longer interval riders’ average power was only 79 percent of their maximum wattage during work bouts, so it’s not surprising that the 30-second interval group saw bigger improvements in their power output.

While this study was small and conducted on elite cyclists, it is a follow-up to another study in which the same researchers worked with less trained (but still fit) cyclists that also showed short intervals provide better results. Both studies add to the large body of work that shows really short, intense interval training can raise your fitness fast, no matter who you are or how fit you are.

Pro tip: Sometimes the hardest part of doing an interval workout like the one in this study is keeping track of the intervals. It gets extra difficult to remember what number you’re on or how many you have left when you’re seven or eight sprints in, so set your lap timer for the time of the entire set (9:30 minutes). When the time is up, recover for 3:00 minutes and go again. When you’ve had enough of those, you can change it up with other micro intervals like 40 seconds on/20 seconds off. Warm up for a solid 15 minutes before starting and cool down as needed when you’re done.