Should You Change How You Think About Tapers For Long Races?

This article originally appeared on Trail Runner

I love when athletes stir the pot on training theory by stepping up and doing something so damn different that it makes everyone take notice. It's easy to write off those training weirdos. "Cool cool," a critic might say, "But that's just an outlier. N=1, bitch!"

And I agree, N does equal 1 when looking at strange training oddities. But I think that when outlier N=1 athletes do something different and have great success at the top level of sport, we need to pay attention. Perhaps we are seeing an element of applied physiology that can't be duplicated in a lab. I get scandalously titillated when an athlete does something that seems dumb - only to have success.

Where empirical practice and science-driven wisdom diverge, that's when training theory gets really fun. So let's have fun together! Time to hop into a ball pit of curiosity and discuss some weird sh*t in the world of tapering of long races.

Taper Oddities

Earlier this month, the Ironman World Championship was held in Kona, Hawaii - October 6 for women, October 8 for men. For most people, training for an Ironman becomes a competition to see who can spend the least amount of time with their family. I know that someone is trained optimally when their kids haven't seen them in six weeks (unless riding a bike trainer). For pros, it's a competition to explore the limits of human physiology. Ride the dragon for 8 hours and try not to get burned.

Now it's time to play the game that every reader loves. GUESS. THIS. WORKOUT! You know how it works: I give you the context. You guess the workout. The winner gets a lifetime supply of Strava kudos. Here we go:

It's October 2, the Sunday before the Saturday men's Ironman race. What do you think race favorites Gustav Iden and Kristian Blummenfelt do as their daily workout? Swirl it around in your mind for a second. It's a fun game, even if you don't know much about triathlon.

Okay, time's up! The correct answer is that they completed a 100K bike ride. (That's what I would have answered.) The ride is great aerobic activation, and it's nothing that they won't recover from easily. Score one for me! Wait, why haven't I gotten the points yet? I won, everyone knows it. Don't make me rub poo-poo on the walls of the Capitol!

But, you see, I forgot to keep scrolling down on that Strava profile. Get this: that few-hour bike ride was just a warm-up. Gustav gathered all of his Big Brick Energy and followed that up with a 25-mile run in the heat, at 6 minute-per-mile pace. And 6 days later, he proceeded to light the world on fire to set the Kona course record.

RELATED: The Art of (Realistic) Tapering

When I saw that brick workout 6 days out from the Ironman, my jaw dropped so far that I could have swallowed a cantaloupe. What? Wouldn't that cause fatigue that reduces race-day performance? Maybe we could cast Gustav aside, citing his Norwegian training methods and mastery of recovery. But maybe we are just seeing the next example of a pattern.

Six days before setting a course record at UTMB, Kilian Jornet did 21.5 miles with 8,000 vertical feet of climbing, something we discussed with him in a podcast interview (he ran with Petter Engdahl, who would later go on to win CCC 6 days later). Ten days before her UTMB podium, Marianne Hogan did a 30k with 7000 feet of climbing. Six days before running the 50K world record, CJ Albertson did 13.5 miles at 5:11 minutes per mile pace (at an obscene 157 heart rate). Courtney Dauwalter also described a 9-day taper.

Go through Strava and training interviews and you'll find lots of examples like this. There is a ton of variance, with plenty of athletes doing big, full tapers like you might see in a study. And some athletes do such big training volumes that a 16+ mile run still classifies as a substantial volume reduction. But other elite athletes are sniffing conventional wisdom . . . and then taking a massive dump on it. We went into detail on the wild science of tapering in this week's podcast episode.

Taper Context

So what is that conventional wisdom? You have probably read about it before, with some nerd like me lecturing and serving you ads like the ones you see on the sidebar ("Apple Watch Ultra, the first performance watch to require a mortgage").

A 2007 meta analysis in the Medicine & Science in Sports & Exercise journal summarized 27 studies to come to the following conclusion: "The optimal strategy to optimize performance is a tapering intervention of 2-week duration, where the training volume is exponentially decreased by 41-60%, without any modification of either training intensity or frequency." A 2021 study in Frontiers of Sports and Active Living field-tested the lab results by gathering data from 158,000 athletes on Strava to confirm that longer, stricter tapers led to the most success in marathon runners. The formula is simple: two to three weeks, volume reduction, maintenance of intensity and frequency. It's called settled science, bro.

However, it's not that simple. Broh-no! A 2018 study in the Journal of Sports Sciences looked at how Olympic coaches structure tapers, finding a general overlap with the framework from studies, but with large deviations away from the textbook examples based on individual experiences. A 2022 study in Sports Medicine–Open examined the training of world-class runners and found that "most long-distance runners do not report a substantial decrease in training volume until the last 7-10 days prior to competition."

Those researchers specifically contrasted the actual practices of the best in the world with the study-driven conventional wisdom. Coach Avril Lavigne said it best: Why'd you have to go and make things so complicated?

The complications we are seeing with tapers are likely a microcosm of individual physiological variability. I have coached athletes who underperform in races if they taper for more than 7-10 days. I have also coached athletes who will implode if they spend any less than 21 days chillin'-out-maxin'. There are many possible explanations: training history, racing distance, sex differences, hormone levels, muscle fiber typology, metabolic properties, nervous system priming.

But here's the problem: we just don't know. A lot of training application is making individual guesses on top of general and specific physiological understandings, and that guessing-and-testing game can be especially disconcerting in taper windows.

Let's zoom into just one minor rationale of taper science.

As outlined by this 2007 study in Medicine & Science in Sports & Exercise, single-fiber studies look at individual muscle fibers under a microscope to evaluate muscle function responses to training interventions. So what happens to muscle fibers during a taper? Time to jump into the study pool!

A 2006 study in the Journal of Applied Physiology looked at 7 runners during a 16-week marathon training cycle, providing one of my favorite tutorials on muscle fiber typology. For background, there are three types of muscle fibers: slow-twitch, intermediate, and fast-twitch.

Slow-twitch fibers power endurance performance, with tons of mitochondria and capillaries to use oxygen for a long time, with relatively low energy demands. Pure fast-twitch fibers generate a ton of power and use a ton of energy, suboptimal for endurance events. Intermediate fibers can behave like slow-twitch or fast-twitch fibers, and their behavior is heavily dependent on training status.

In the 13-week training window to start the study, strength in the slow-twitch and intermediate muscle fibers remained the same, peak power improved in both, and only slow-twitch fiber speed improved (by 28%). However, after the 3-week taper, intermediate fiber strength increased by 18%, with power increases as well, with no changes in slow-twitch fibers.

In other words, hard endurance training may make an athlete's muscle fibers behave more strongly slow-twitch, and a "taper period before the marathon further improved the functional profile of the muscle, which was targeted to the fast-twitch muscle fibers." A 2010 study on the myocellular basis of tapering (also in the Journal of Applied Physiology) provided a firmer understanding of the driving forces of these changes during a 3-week taper, finding no change in slow-twitch fibers but "[intermediate] fiber remodeling and an altered transcriptional response following the same exercise perturbation." A 2014 study in PLoS One backed that up with a finding of hypertrophy (muscle growth) in intermediate fibers post-taper.

RELATED: Eight Takeaways From Kilian Jornet's 2022 Training Data

So far, all I have shown is that I have access to Google Scholar and didn't go on dates in high school. WHAT DOES IT ALL MEAN?!

Well, it's complicated. On one hand, intermediate fiber strengthening is a likely justification for why athletes perform better after long tapers in studies, which usually measure shorter time trials or time-to-exhaustion tests, and it could translate to marathon and ultra breakthroughs too.

On the other hand, perhaps a big taper with less aerobic time could make an athlete rely less on their pure slow-twitch fibers, leading to less efficient output in very long events, higher rates of glycogen utilization, more cramping, etc. If tapers make a certain cohort of athletes have physiology that acts less slow-twitch, then it might be counterproductive for long distances, even if it might lead to better performances in a study protocol or 10K race. Contrast that with a 2020 study in the Journal of Applied Physiology that found athletes with a lower proportion of slow-twitch fibers needed more taper, with the caveat that it was based on an incremental treadmill test, rather than a long running race.

We just don't know the exact reason some athletes are choosing shorter tapers. Maybe it has to do with muscle fiber typology, and keeping those slow-twitch fibers at the forefront, though muscle fiber synergy is too complicated to measure effectively or summarize simply. That might explain why cyclists whose races are many hours don't taper down much from long efforts, whereas swimmers whose races are shorter rely on big tapers.

Or you can choose from this grab-bag of other possible explanations: metabolic efficiency and glycogen sparing (reductions in aerobic training levels could decrease fat oxidation rates relatively rapidly), endocrine system changes with rest (hormone profiles that go haywire with alterations in chemical stimuli), blood volume/cardiac output reductions, immune system activation in taper windows, psychological needs, innie versus outie - take your pick.

How To Think About Your Taper

There is no need to reinvent the wheel. The traditional taper is traditional for a reason–it works across hundreds of thousands of study participants. However, averaged study results do not apply to every individual athlete, especially professional athletes with extreme training contexts who recover rapidly. My guess is that the pros who use unique taper strategies have seen evidence in their own training when they perform best, and the exact physiological rationale will likely remain a mystery.

How can other athletes get clues into whether they should try something new? I think there are two general cohorts of athletes that can apply different thinking:

Cohort One: Peak races go well most of the time, without unexpected deviations from realistic forecasts across 2 or more races in a short window. If it ain't broke, don't break it by taking taper risks.

Cohort Two: There is some evidence of underperformance at peak races. Elements to look for:

• Training races outperform goal races

• Excessively high race-day heart rate unexplained by anxiety or excitement

• Muscle cramping that is not replicated in training

• Underperformance in events over 2 hours relative to training expectations, especially when accompanied by unexpected "bonking"

• Abnormal "flatness" that is a common problem in key races

If you fall into Cohort Two, it may be worth rethinking how you approach the two weeks before race day. Start with an easy long run the week before the event, something like 12 to 18 miles, with the high-end being reserved for very advanced athletes, and adding some moderate running for races a few hours or less. Consider dialing back workout intensity 2 weeks out, but maintain solid training volume to continue to stress the aerobic system. Still reduce training substantially in the 3 to 5 days before the event, which is a near-universal element even for athletes that have rethought their tapering.

Here is a sample of what that might look like for an athlete doing a trail marathon or ultra off 50-60 miles per week:

It might take you some time to find the perfect taper. But when you find it, PUT A RING ON IT. One of my biggest pieces of advice to new coaches is that when an athlete you coach absolutely nails a race, don't be shy about repeating a similar taper over and over (scaled up or down for changing training levels) until you have evidence that it's no longer working for them.

Applied physiology is wildly variable, in ways we are only beginning to understand. We'll probably never be able to isolate every element that makes each N=1 training experiment respond so differently during taper periods. But that doesn't mean we shouldn't chase answers and run with enthusiasm in the general direction of a new approach that maybe, just maybe, might work. When you catch that magic, even for just one race, you get a reminder of why training theory is the most fun field on the planet.

David Roche partners with runners of all abilities through his coaching service, Some Work, All Play. With Megan Roche, M.D., he hosts the Some Work, All Play podcast on running (and other things), and they answer training questions in a bonus podcast and newsletter on their Patreon page starting at $5 a month.

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