Issue #19: The Science of Tapering

✍️ Author’s Note

Welcome back to The Threshold Lab, where each week we dissect a training topic, dig into the research and translate it into practical strategies. I’m Stephen Pelkofer, an aspiring HYROX Elite 15 athlete and research/data nerd. This week’s edition is focused on the science of the taper.

👨‍💻 Introduction

Topic: The Science of Tapering

I’m in the middle of a mini taper right now for HYROX Boston, and I know many of you are in the same boat with big fall marathons or other races around the corner. The taper is tricky: you can’t gain fitness in the last couple weeks, but you can absolutely lose performance if you get it wrong. Too little rest and you stay fatigued. Too much rest and you feel flat. The science points us toward some clear principles, and they line up with what the best runners and coaches have been doing for decades.

Today we’ll look at some key studies over the years and a special collection of my kindle highlights from years of being a training research nerd 🤓 

🔬 Deep Dive on a few studies

Longer Disciplined Tapers Improve Marathon Performance for Recreational Runners – Smyth & Lawlor (2021)

Analyzed taper duration and discipline in real-world training data of ~158,000 recreational runner.

• Strict 3-week tapers (meaning a steady and consistent reduction in weekly mileage, not sporadic cutbacks) gave the best results (~2.6% faster marathons, ~5–6 min saved).

• Longer, structured tapers (2–3 weeks, meaning a gradual step-down in volume week by week with consistent training rhythm maintained) consistently outperformed short or inconsistent tapers.

• "Relaxed" or sloppy tapers (meaning inconsistent reductions in volume, cutting back only occasionally, or failing to follow a clear taper plan) were far less effective.

Effects of Tapering on Performance - A Meta Analysis of 27 studies – Bosquet et al. (2007)

The purpose of this was to assess the effects of taper components on performance in competitive athletes, through a meta-analysis.

• ~2-week exponential taper (meaning volume is reduced progressively in a curve-like fashion, trimming a little more each session/week rather than one sudden cut) with ~50% volume reduction showed the best results.

• Keep intensity and frequency the same –> only reduce volume.

• Short (<1 week) tapers didn’t work; long (>3 weeks) risked detraining.

Single Muscle Fiber Gene Expression with Run Taper – Murach et al. (2014)

Runners tapered for 3 weeks after heavy training while researchers measured muscle changes.

• Fast-twitch fibers grew ~15% larger and ~9% stronger during taper.

• Slow-twitch fibers changed little, showing fiber-specific adaptations.

• Tapering “unlocks” hidden power/speed from fast-twitch fibers without losing aerobic fitness.

• Implication: taper duration should be individualized by fiber type — fast-twitch = longer, slow-twitch = shorter.

Time for some lab notes ⬇️

🧪 Lab Notes

The lab notes are going to look a little different this week. These are some of my favorite kindle highlights from training/running books that I've read over the last few years. The highlights are very consistent with the papers cited above and point to some clear themes. And they give you some insight into what I do with my free time 😁 

• Highlights from: Developing Endurance, NSCA

  • When reducing endurance training loads before a competition (during a taper), the best approach is to decrease the volume and intensity of individual training sessions rather than decrease the frequency of training. Using this practice during a taper results in significantly higher performance levels.
    

• Highlights from: Advanced Marathoning, by Pete Pfitzinger

  • Put simply, tapering corrects the accumulated wear and tear of training. More specifically, it appears that tapering leads to improvements in running economy (how much oxygen you need to run at a given pace) and muscle strength and power.

  • When you consider that any one workout will give you less than a 1 percent improvement in fitness but that a well-designed taper can provide an improvement in race performance of several percent, it’s wise to err on the side of tapering too much rather than not enough. For the marathon, a well-designed 3-week taper will leave you optimally prepared and recovered for the race.

  • Both scientific and anecdotal evidence indicate that the key to effective tapering is to substantially reduce your mileage while maintaining the intensity of your training.

  • The more effective approach to tapering is to intersperse harder efforts within an overall trend of recovery.
    

• Highlights from: Periodization of Strength Training for Sport, by Tudor O. Bompa, Carlo Buzzichelli

  • The taper macrocycle has a maximum duration of three weeks in order to avoid detraining of physiological systems that are key to performance.

  • The highest reduction percentage should be reached only in the last days of the taper. In addition, recent computer simulations suggest that the most reduced level of intensity reduction should be reached four days before the event and that intensity should be increased again by using medium and medium-high intensities during the last three days in order to stimulate further adaptations without affecting the elimination of fatigue (Thomas, Mujika, and Busso 2009).

That’s it for this edition of the Threshold Lab. If you are racing in HYROX Boston, come say hi! I’ll be in the 7:10pm Men’s Pro heat on Sunday night.

References

• Smyth, B., & Lawlor, A. (2021). Discipline and duration of tapering in marathon running: Influence on performance. Frontiers in Sports and Active Living, 3, 648994.

• Bosquet, L., Montpetit, J., Arvisais, D., & Mujika, I. (2007). Effects of tapering on performance: A meta-analysis. Medicine & Science in Sports & Exercise, 39(8), 1358–1365.

• Murach K, Raue U, Wilkerson B, Minchev K, Jemiolo B, et al. (2014) Single Muscle Fiber Gene Expression with Run Taper. PLOS ONE 9(9): e108547.

• Lievens, E., Klass, M., Bex, T., Derave, W., & Bishop, D. J. (2020). Muscle fiber typology substantially influences time to recover after fatigue. Journal of Applied Physiology, 128(3), 648–659.