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What explains performance in athletes? The more scientists learn about genetics, the more they see that the complexity may be related to non-linear associations across different parts of the genome. As they measure protein expression or muscle-fiber characteristics or hematological variability, they find that the only rule is that there are few universal rules. It’s a chaotic stew of disparate ingredients that add up in tough-to-predict ways. Now you can see why I got fired from my job as copywriter for Campbell’s Chunky Soup.
Those are a sampling of zoomed-in physiological mechanisms, but take a step back, and there is still a Crock Pot of uncertainty bubbling away. I often write about study protocols that lead to beneficial outcomes. However, the physiological mechanisms underlying study outcomes work on different time scales, and progression in a shorter-term study protocol may be fully unhinged from a longer-term trajectory.
Give an athlete almost any unique training intervention, and you may get some significant results at first. For example, you have probably heard of “Tabatas,” intense 20-second intervals with short recovery that lead to fitness gains in most study protocols. But zoom out a bit more, and most training theory would indicate that doing too many intense sessions like Tabatas could lead to aerobic inefficiency or injury. The same complications apply to almost any style of workout, from strength work to even my beloved strides. Sometimes, it can seem almost impossible to discern the line between significant results and significant BS.
My wife/co-coach, Megan, is a doctor and researcher and coach, and she has suggested this concept on our podcast. The best evidence is often taking what we know about physiology and study outcomes and cross-referencing them with what people actually do in the real world for successful long-term results.
Every athlete is an N=1 experiment.
We are all human, but beyond that baseline humanity, the individual variability can be staggering. Each N=1 athlete experiment is implicitly taking in thousands of variables to apply them over time and spit out outcomes. Coaching is the process of trying to explain and facilitate those future outcomes. But it’s an inexact science.
All that brings me to today’s subject: an amazing 2019 study in the Journal of Strength and Conditioning Research that looked at 85 elite athletes over their first seven years of serious training to draw conclusions about the type of runs associated with top performance. It’s one of my all-time favorite studies, adding together 85 x N=1 experiments, almost like a review article on individual training practices.
The very descriptive study title gives away the big conclusion: “World-Class Long-Distance Running Performances Are Best Predicted by Volume of Easy Runs and Deliberate Practice of Short-Interval and Tempo Runs.” To be similarly descriptive, I think the movie Titanic should be renamed: “A Fully Sinkable Ship and A Door That Could Definitely Fit Two People.”
Before getting into the details, a few caveats.
First, the study was on male athletes. With physiology, small differences can have large downstream impacts on what works and what doesn’t. And sex differences are not small differences in the scheme of human physiology. As the incredible Dr. Stacey Sims says, “Women are not small men.”
Second, the population was confined to elite athletes. That may strengthen the findings since the margins of performance variability are narrow (i.e. 10 seconds can make a big difference in a track 10K), but there could be different physiological mechanisms that are more important for non-professional athletes. And within that study population, all the normal issues apply: perhaps some athletes excel with totally different protocols, the error bars are big, the results may apply differently for longer or shorter events, etc.
Third, training data was not gathered quantitatively in many instances, and the long-term data was extrapolated from shorter blocks before races, so accuracy or precision may be off. It’s possible that annual, quantitative data would lead to different results.
The study broke down training into five categories: short intervals between 200 meters and 1,000 meters and 95 to 100% of max heart rate; long intervals between 1,000 meters and 2,000 meters and 92 to 95% of max heart rate; tempo running between 82 and 92% of max heart rate; races; easy running; and races. Based on that breakdown, the easy running category likely also includes steady running above aerobic threshold but not a formal workout. Each athlete was graded on international performance charts for their events at three-, five- and seven-year intervals. The study authors do a wonderful job summarizing findings and limitations, so check out the full paper if you’re interested in more detail without my personal interpretation mixed in.
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There were five findings that I think are most important for how you think about your own training.
ONE: Volume of easy runs had the highest correlation with performance, from 0.72 at 3 years to 0.68 at seven years. Easy running is non-specific to the intense events measured, but it formed the base for all intense performance. That makes sense if you read about training theory. Easy running is extremely important, even if it should not stand alone in a well-rounded training plan (even during a base phase).
Easy running may enhance recovery and adaptation, while also increasing the density of capillaries around muscle fibers, increasing the recruitment of slow-twitch Type 1 muscle fibers, improving oxygen processing and improving metabolic efficiency. There is no substitute for consistent training over time. (These findings were backed up by a 2020 study in the European Journal of Sports Science.)
TWO: Tempo runs became more important as an athlete developed, from 0.50 correlation at three years to 0.58 correlation at seven years. The authors theorize the findings are “highlighting the importance of progressive specialization from the most fundamental training sessions (easy runs) to those most specific to long distance racing (tempo runs).” Up-tempo but not excessively hard runs provide a sweet-spot for development, with lower breakdown and hormonal impacts, and a big aerobic bang-for-the-buck due to how the body processes energy at these effort levels.
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Trail runners can add semi-structured tempo on uphills, particularly in long runs, or as standalone workouts and cruise intervals with easy recovery. Perhaps for trail runners, similarly specific efforts would be on variable terrain (or for ultrarunners, done at lower effort levels).
THREE: Long intervals had the lowest correlation with performance, at 0.22 after seven years. This finding is fascinating, and likely due at least partially to it being the reverse-Goldilocks workout: a lot of stress but without the efficiency/speed of shorter intervals or aerobic base benefits of tempos or easy running. During long intervals, athletes may be tempted to make each individual effort like a little race, which may lead to fewer beneficial long-term adaptations.
FOUR: Short intervals had moderate correlation of 0.56 after seven years. Most likely, short intervals develop running economy by reinforcing musculoskeletal, biomechanical and neuromuscular adaptations needed to actually go fast. As intervals progress to longer distances, many athletes may reduce output substantially at the same perceived effort level (or race the workout), which could lead to more inefficiency. Smooth and fast intervals (and strides) may allow for optimized output at lower overall stress levels.
FIVE: The grind is real. The study was framed through the sub-field looking at “deliberate practice” (DP), a concept with lots of literature related to music and other areas involving highly-focused skills development. But the authors made a different conclusion. “[The result] means that although DP is considered very relevant by subjects to improve performance, the most fundamental practice required to succeed in long-distance running is not DP.” Deliberate practice of hard efforts plays a big role, but the most important dividing line in the study was related to aerobic volume over time mixed with enough intensity to turn that base development into high performance.
As athletes, we like to focus on the hardest workouts. I think this wonderfully designed study highlights a truth that incorporates physiology and applied studies and training theory into a helpful takeaway:
The sexy workouts may get the headlines, but the long-term grind makes the champions.
From: Trail Runner