Most sports science studies the averages. But what about the people who aren't average, the ones at the very top of their sport?

A typical study recruits a group, splits them into different treatment groups, and reports what happened on average. Group studies cancel out the noise that could otherwise come from one athlete's great week, another's cold, or a third's bad night of sleep.

This is the kind of research Blonyx leans on. Before a product makes it into your hands, we want to know it's safe and effective across a large group of athletes, not that it happened to work well for one individual.

But what if you want to know what's possible at the extreme edges of human performance? Tracking a single athlete's training won't tell you whether a new recovery protocol improves FTP for a recreational cyclist, but it can tell us where the upper edges of human capability actually sit.

Here are 5 studies that followed individuals across triathlons, marathons, and professional cycling, and what each taught us about what's actually possible.

 

1. Breaking the "Metabolic Ceiling"

The metabolic ceiling is the highest multiple of basal metabolic rate a human body can sustain, and that multiple drops the longer the effort goes on. Over months, the limit is thought to sit around 2.5 times basal metabolic rate, a number built on real data from Tour de France riders and polar expeditions—athletes who aren't exactly average themselves.

Three full years of training data on Kristian Blummenfelt, the Olympic and Ironman world champion triathlete, from 2020 to 2022, showed his daily energy expenditure consistently above what the 2.5x ceiling would predict as sustainable. Total expenditure ranged from 7,019 to 8,506 kcal per day, measured using doubly labeled water, the gold standard for tracking real-world energy use.

This doesn't mean there isn't a metabolic ceiling, just that the data it was based on wasn't from athletes training at the level of Blummenfelt. What's sustainable for an average athlete, or even a Tour de France rider, falls short of what's actually possible.

 

2. Building for Tokyo

A coach and sport scientist mapped out a 43-week plan for Spanish triathlete Fernando Alarza, aimed at the Tokyo Olympics. Training zones, altitude camps, heat prep, and lab testing were all tracked in the lead-up to the Games.

Training shifted from a broad base of easy work early on to a mostly easy, mostly hard split as the Games approached, with average weekly volume of 14.7 hours. Peak oxygen uptake climbed 20% on the bike and 14% on the run, while body mass and skinfolds dropped and muscle mass held steady, a sign of real gains in power-to-weight and speed-to-weight. He went on to finish 12th in the individual event and 10th in the mixed relay.

A few principles from this plan carry over to any athlete building a season around one goal:

• Know what the event actually demands. The high-intensity work in this plan was built around race-specific pace, not generic hard efforts.
• Most training should be genuinely easy. The bulk of volume sat in low-intensity zones, especially early in the season.
• Taper the volume, not the intensity. Training load dropped mainly by cutting volume, while race-specific intensity stuck around, which limits fatigue without losing sharpness.
• Specificity includes environment. Tokyo was hot and humid, so sauna sessions, heat exposure, and time on the ground before racing were part of the plan, not an afterthought.

3. When Your Heart Rate Variability Stops Working

Heart rate variability, or HRV, is a common way to gauge how well an athlete's nervous system is recovering from training and stress. This study followed a top-10 Tour de France and Vuelta a España finisher for five months, tracking resting HRV alongside training load through two altitude camps and two competition blocks, including the Tour itself.

In structured training, HRV behaved as expected, tracking training load and giving a useful read on recovery. Racing broke that relationship though. During the Tour, daily load was about 63% higher than in training, but the rider couldn’t adjust based on HRV. The stage dictated the effort, not the recovery score.

HRV still showed strain. Root mean square of the successive differences (RMSSD) dropped by more than half, and resting heart rate rose from 47 to 54 bpm. But the day-to-day readings also became almost three times noisier, likely because of travel, hotels, poor sleep, and the chaos of racing, making it much harder to tell a bad day from a normal one. 

If you rely on your watch’s recovery score it’s worth knowing that HRV works best when life is stable. Once the environment gets messy, the numbers may reflect stress, but they stop being a clean decision-making tool.

4. Breaking Age Group Records

This one's technically a comparison of two people, not a single subject, the new 70 to 74 age-group marathon world record holder, measured directly in the lab, against published data from the man whose record he broke. It's included anyway because the sample is so small and the contrast so specific that it functions almost like a single-subject study with a built-in control.

The new record holder ran a 2:54:19 marathon at age 71. His VO2max, 46.6 ml/kg/min, was nearly identical to his predecessor's 46.9, not the gap you'd expect. The separator wasn't a bigger aerobic engine, it was running economy, how efficiently he used the oxygen he had, backed by a muscle biopsy showing over 90% slow-twitch fibers. He also averaged 139 km a week in the year before the record, almost double his predecessor's volume, and could handle it because his body had adapted to absorb it.

Once an athlete is already well trained, more raw aerobic capacity isn't always where the next gain comes from. Progress can come from getting more economical, and from staying healthy and consistent enough to keep accumulating volume over years.

5. Measurements Outside the Lab 

This last one is retrospective and modeled, not measured. Pogačar wasn't hooked up to a metabolic cart on these climbs. Instead, a researcher took publicly available climb data from six decisive ascents across the 2024 and 2025 Tours de France, combined it with his known weight and validated cycling power models, and worked backward to estimate what his body was doing physiologically.

The estimate came out to a mean power output of 442 watts and an oxygen consumption around 80 ml/kg/min, sustained for roughly 40 minutes. Based on known relationships between power and VO2max, his actual VO2max during the race likely exceeded 90 ml/kg/min, near the highest values ever recorded in endurance athletes.

It's a shakier kind of evidence than the doubly labeled water in Blummenfelt's case, there's no muscle biopsy or lab test behind it, just a model. But it points to something new: once a sport generates enough public data, climb splits, GPS, segment times, researchers can infer an extraordinary athlete's physiology from the trail their performance leaves behind, without ever needing direct access to their body.

So What Do We Actually Learn From Outliers?

Put these five outliers side by side, and a pattern reveals itself. Single-subject studies earn their place when they catch something a group study can't. A ceiling gets revised because one person blew past it under careful measurement. A periodization theory gets a real-world test case instead of a textbook diagram. A trusted recovery metric gets shown to have a blind spot in the exact context, competition, where people most want to trust it.

None of this replaces the group studies that tell us what's likely to work for most athletes most of the time. That's still the right tool for most questions. But if you want to know what's possible rather than what's typical, sometimes the only honest move is to find the person already doing it and watch closely.

If you learned something new from this article and are curious to know more, check out more articles and our growing list of weekly Blonyx Research Updates where we help you further improve your athletic performance by keeping you up to date on the latest findings from the world of sports nutrition.

– That’s all for now, train hard!

 

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