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by Robert Rossbach

September 14, 2020

High-intensity interval training can provide the same level of fitness in a fraction of the time

The workout is on the whiteboard at the end of the lane, probably in red marker because your coach knows it’s going to hurt. Twenty-five-yard sprints, a bunch of them, in IM order, so you know this involves butterfly, and there are long rest intervals, so there is no excuse for anything but an all-out effort.

But should you do this workout when your next competition is an open water swim, maybe a miler, a 5K, or a long triathlon? Does it really make sense to swim 15 or 20 seconds all out when you’ll be racing for 30 minutes or an hour at a moderate pace?

For better or worse, the answer is probably yes.

What coaches call lactate sets—sprints with long rests between swims—are a perfect example of high-intensity interval training, and researchers say it’s very effective.

Although HIIT has been a part of coaches’ workout plans for decades, scientists are still unravelling why it works. Martin J. Gibala, chair of the kinesiology department at McMaster University in Canada, says renewed scientific interest in HIIT is yielding hundreds of research papers every year on the topic. Although none have focused on long, open-water swim events, Gibala says there’s good reason to believe that what works for other events such as running and cycling may also apply to swimming.

“Swimming is unique given the technical complexity and ‘feel for the water,’” he says, “but the evidence is compelling that incorporating interval training enhances endurance performance.”

Gibala points to some pretty amazing examples of HIIT’s efficiency. His laboratory conducted a 12-week experiment with sedentary men on stationary bikes. Half of the men did three 10-minute workouts every week. Each workout included a short warm-up, three 20-second all-out bursts of speed with two minutes of slow pedaling recovery, and a short cool-down. The other half did three 50-minute workouts, mostly at a moderate pace.

At the end of 12 weeks, men in both groups had essentially the same improvements on a set of key fitness measures, including their ability to transport oxygen. In other words, sprint-interval training accomplished the same fitness improvement in one-fifth of the time as a traditional, continuous workout—30 minutes per week versus 2½ hours.

Think about the possibility for serious athletes. Getting the same fitness improvement from a 10-minute swim with three lengths of sprints as grinding out 2,500 yards or more of pace laps? That would free up plenty of time for binge TV viewing.

Before you pony up for an upgraded video streaming service, though, remember that those were improvements in a set of young, sedentary males on bicycles.

Still, Gibala points to research from other laboratories that shows incorporating short, hard sprints improves performance in highly trained athletes. He acknowledges it may be different when it comes to swimming, and a breakdown in form may compromise training quality.

There’s still good reason to consider combining HIIT with race-specific training though.

High-level athletes often devote 15 percent to 20 percent of their training to HIIT workouts, Gibala says. Because elite athletes spend a lot more time training every week, 20 percent could be a pretty significant amount of absolute time: six hours out of a 30-hour training week. Serious amateurs who spend less total time training might benefit from schedules with as much as half devoted to some form of interval training, Gibala says.

Other researchers have pointed to many key variables to consider in HIIT research, including varying sprint durations, intensities, recovery periods, numbers of repetitions, and so on. With just a few adjustments in each of those, an athlete can quickly get to many possible sets. And that doesn’t consider race-specific workouts, which are likely still important.

So which do you choose? Gibala says it’s like investing in stocks. You might pick one that takes off, but it could also result in a big loss.

“So you’re better off spreading out the risk, knowing the best return might come from investing in a basket of stocks or using different interval training approaches,” he says. 

That’s where good coaching comes in because, as another sports researcher says, the best coaches are always innovating with different combinations and approaches, and researchers are always trying to catch up to find out why. In other words, read the bad news on the whiteboard, even the sets in red, then push off and swim hard because the HIITS just keep on coming.

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