Why Do Athletes With the Same Fitness Perform So Differently?
"I can't count on two hands the number of times I've given an athlete an easy run and then given them a run at one hour effort, and the one hour effort is slower than their easy run."
That's Ryne, and it's where episode 15 started before we even hit the intro. Our guest was Jeremy Meredith. He owned a CrossFit affiliate for fourteen and a half years before selling it at the end of 2024, he was an individual Games and regionals athlete, and he's now a full-time coach, mostly online, and coaches athletes with me at KRC. We met through a PT contact this year and haven't stopped talking training since. This conversation started on critical power and ended on handstand pirouettes, and most of it came back to why an athlete's fitness and their performance don't line up.
RPE is the best fallback, and CrossFit athletes are bad at it
Jeremy asked Ryne whether heart rate is the best fallback when you don't have paces. Ryne's answer was RPE, with a catch: "In the world of cyclical sports, comparing that to the world of CrossFit athletes, their RPEs are so skewed." His preference is concrete data. "This is your 5K, you have to run two minutes slower per mile than your 5K pace for easy runs. If you want to run faster than that, earn it by running a faster 5K."
I'm the black sheep here and still use heart rate for easy runs, and I ask myself whether I could hold the pace for a marathon. Ryne's point is that the answer is always no, because you don't have the tissue tolerance, "but from a metabolic standpoint, could you? And I think that's a better gauge."
Critical speed needs three tests between 3 and 15 minutes
For paces, I've been moving to a two- or three-test fit. With running I like the mile, 5K and 10K, but not every athlete has the tissue tolerance to go run a 10K time trial, so some of them get two tests. Ryne asked why not a 400 or an 800, and Jeremy's answer changed my mind. "The best fit for the critical speed test is three to fifteen minutes. Three tests spanning between three to fifteen minutes." I told them: "Alright, you've sold me. I'm overhauling my entire running system."
Jeremy's critical speed tests (running) 1K time trial 1 mile time trial 3K time trial All three land inside the window where the model fits best
The reason is the math. Critical speed and critical power are a mathematical definition of the fuzzy line that sits very close to LT2, and the model also calculates W prime, your anaerobic reserve. "If you do stuff that's too much on the short end, then it'll overpower your slope and it'll change the shape of that slope. If you do stuff that's too much on the long end, like if you do one mile, 5K, 10K, it's not gonna understand that peak and the drop-off."
Jeremy also explained what "sustainable" means here. Once W prime is exhausted, you drop to critical speed, because that's where the aerobic system can still keep up. "This common term that really throws people off a lot of the time is sustainable. Really, what it means is supply can meet demand. It doesn't mean indefinitely sustainable."
The 3-minute burpee test
Another way to find critical power is a 3-minute all-out test, and I've been running one with bar-facing burpees. The athlete sprints from 3, 2, 1, go. By 45 seconds to a minute they're in the suck, and by the last minute they're in survival mode. That last 30 seconds is the window into what's sustainable for them.
3-minute max burpee test 3:00 max bar-facing burpees, all-out from the start Sprint speed = the opening Sustainable speed = reps per minute over the last 30 seconds
What I'm finding is that even very high-level athletes vary a lot here. I tested a Games team athlete from this past year whose sustainable burpee speed was 16 per minute, and another Games team athlete I coach came in at 20. Their sprint speed was similar. Jeremy calls it a fallback test: "I think it's too hard for most people to do accurately."
Most athletes can't get to failure yet
That's the problem with every max test. Jeremy described failure as a curve we approach, where fatigue is how close we perceive ourselves to it. "Depending upon how motivated I am and how much that task is worth to me determines how close I can approach this intercept of failure." If you want accurate testing, he says, you need a ramp-up first, so athletes get comfortable. "It's not just their level of fitness, it's their self-efficacy, their ability to approach that line with confidence."
I see the same thing with velocity-based training. Give a well-trained athlete max-rep thrusters at 65% and they push so far into the set that you actually see the rep speed drop before they fail. A less well-trained athlete stops while their bar speed still looks fine. Ryne sees athletes subconsciously slow down early to get more reps, seven grindy reps over four true max-velocity reps.
Jeremy's word for it is self-advocacy, and he sees it every day in the affiliate where he still coaches. He'll prescribe deadlifts at RPE 8, two to three reps in reserve, and watch a set with five to ten left. "It's not to say that that wasn't RPE 8 for them, it's just what they experience RPE 8 as." "Is it accurate from a physiological standpoint? No. But it's accurate from a performance standpoint. And performance is subjective."
Stack the wins, and show athletes the rear view
Part of the coach's job is exposing athletes to intense work gradually, so confidence and physiology climb together. "You have to stack those wins," Jeremy said. "Every time they get a win, they gain confidence, and it allows them to approach that intersect much more closely."
Perspective matters as much as the wins. This week a client told me the rope climb progression felt so much harder. We started on 10-foot climbs six weeks ago and they're now on 15 feet with more volume, so I copied the week-one session into the text thread next to this week's. Jeremy: "We're always looking forward and laterally. We're comparing ourselves to our peers and we're looking at where we're going. And the rear view is always quite blurry."
What durability actually means
Then we got to the topic I wanted Jeremy on: durability, your ability to withstand the volume of contractions this sport requires. Nobody uses the word the same way, but in endurance physiology it's the preservation of your physiological state against fatigue: run close to critical speed and see how much heart rate drift you accumulate. Less drift is a more durable athlete. Two athletes with the same VO2max and the same LT2, and one can hold the same pace for longer.
CrossFit has the same thing. I've coached athletes with identical max sets of chest-to-bar and identical times for 100, and inside a metcon one of them falls apart at 120 or 150 reps. Jeremy's point was that in CrossFit we use functional tests to describe physiological traits, so you need more data points. "But what are their 2K rows? And what is their 1RM strict chest-to-bar pull-up?" If the athlete who holds up in metcons also has the faster 2K row, and the one who breaks down has the bigger strict chest-to-bar, the second one is "probably kind of hacking their way through it."
My hunch is that the athlete with the flatter speed curve on a three-point running test will also be the one holding on in a long chest-to-bar set. Jeremy's caution: transfer across domains is limited, and you bring a different history to every machine.
Over time Jeremy has widened his own definition to performance resilience, the physiological part plus "our ability to assess and kind of read what's going on and adjust pace accordingly." He calls the second half psychological durability, and he's clear that it's his term, not the literature's.
Expectations: execution versus outcome
That psychological side shows up in rope climbs more than anywhere for me. We spend a year improving an athlete's rope climbs, we have all the metrics to prove it, then a rope climb workout comes out and all the self-doubt comes back. People look down on that as a mental limitation you can just overcome. "No, they can't. That takes just as much work to solve as the physical limitations." Jeremy's comparison: "You can't just be like, you're better at rope climbs now, go out and kick ass."
The most common performance limiter I see is expectation: how they should perform, what they should be doing, how it's always gone before. Stop shoulding all over yourself. Ryne's the same: "When I let go of expectations or fear of disappointment and just say, you know what, I'm just gonna go do what I do and do it as I know how and have fun and not care about failure, then I perform at a much higher level."
Jeremy pushed back on throwing expectations out completely. They're useful when they come from known data: hold these paces and you'll finish around this time. That's an execution-based expectation, and it's very different from "I'm going to crush this, it's a wheelhouse workout." What you separate is what the result means on the leaderboard. "If you're like, I'm gonna win this workout, you're like, I don't know if you are, because I don't know what anybody else is gonna do."
Dallin Pepper won the Rogue Invitational last month without winning a single event, and you can average fifth place and stand on the podium at most high-level events. Ryne told an athlete who stopped scrapping once the podium was out of reach that finishing sixth instead of eleventh is the difference between 40 points off the podium next year and 110. Jeremy added that those last events are reps of the skill itself. "The more that you practice how do I give my best performance in every single instance, the more that becomes the norm of your behavior."
Ryne's rule from a runner friend is no DNFs unless you're injured. When an Open repeat clearly won't improve, he pulls the plug himself, "I'm the coach making this decision," and that takes a lot of guilt off the athlete.
Lighting yourself on fire
I asked Jeremy whether the ability to completely empty the tank is a requirement for high-level CrossFit. "You have to." Ryne asked us to define high level, and my answer was the top 15 at semifinals. I don't think I've coached anyone who finished there who couldn't absolutely end themselves when it was required.
I'm working with a Games athlete who was throwing up in training three days a week, so by week three we needed clear guardrails. How often should it happen? "Rarely," Jeremy said. "I think it's good to know that you have it when needed, but I don't think it's productive in terms of training." His number was a couple of times a year, because it sets you back days: after a true max effort he gets an exercise-induced histamine response: sniffly nose, chills, aches, down for a couple of days. The research on antihistamines blunting training adaptation is below, which is why I'd only use one to get back to baseline in competition, never in training.
The Echo is the anchor
Jeremy's physiological profiling starts on the Echo bike, because it's almost zero skill. He tests 5 and 10 minutes, compares average watts against the row, ski and run, and investigates any gap. My own add is 10-minute Echo total calories divided by body weight. Around 1.0 calories per pound tells me a lot about an athlete's engine, almost like watts per kilo from an FTP test.
Echo profiling 5:00 max Echo, average watts 10:00 max Echo, average watts and total calories Compare: row, ski, run against the Echo 10:00 total calories รท body weight in pounds, ~1.0 as a reference point
If the run lags, the gap gets investigated before anyone calls it physiology, because maybe they just haven't run much. Jeremy's minimum effective dose: easy running, 30 minutes, twice a week, then reassess.
Build transfer and play into the warm-up
Jeremy has been organizing exercises by near, moderate and far transfer after reading an article on skill transfer in sport (it's below). The best transfer for a muscle-up's dip timing is kipping ring dips, but you can only do so many in a week. So he adds lower-stress ring support and box support work. "People need to warm up. Why not warm up with some broadly transferable skills that may or may not improve other skills inside of CrossFit? Worst case scenario, they're still warm and ready to go for their work."
His example avatar: an athlete who struggles with handstand walks, jerks and handstand push-ups. Instead of only upper back strength and flexibility work, "what if we warmed up with handstand holds and wall walks and overhead carries?" That's what I've done for the double dumbbell overhead walking lunge, loaded PNF work and overhead carries four days a week for athletes likely to see it at quarterfinals or semifinals. What I didn't have was the system. Ryne adds kinesthetic awareness work, like bear crawls pulling a medicine ball, because pounding a skill that isn't good yet leads to injury.
Play is the piece I miss most as a coach. The best thing I ever did for my own double-unders was leave my rope at home for almost a year and grab a random one off the gym's wall every workout: long, short, thick cable, beaded. At Legends this year I passed most of the field on the beaded double-unders. Handstand horse taught me lateral walking, pirouettes and stairs, because failing is just part of the game. Jeremy's fix for blind spots like mine was a monthly reminder, "did you include any play in your program designs this week?" I'd add a rotation: handstand play one month, rings the next, and every athlete checks the box.
Referenced in this episode
- Critical power and the test window. Poole DC, Burnley M, Vanhatalo A, Rossiter HB, Jones AM. "Critical Power: An Important Fatigue Threshold in Exercise Physiology." Med Sci Sports Exerc 2016;48(11):2320-2334. doi.org/10.1249/MSS.0000000000000939. The review behind most of what Jeremy laid out: CP marks the boundary between the heavy and severe intensity domains, W prime is a finite amount of work available above CP, and the power-duration curve is built from separate efforts that end in exhaustion within about 2-15 minutes. CP sits close to the maximal lactate steady state, usually a little above it.
- The 3-minute all-out test. Vanhatalo A, Doust JH, Burnley M. "Determination of critical power using a 3-min all-out cycling test." Med Sci Sports Exerc 2007;39(3):548-555. doi.org/10.1249/mss.0b013e31802dd3e6. In 10 cyclists, average power over the last 30 seconds of a 3-minute all-out test matched CP from the conventional multi-day tests (287 W vs 287 W). The running version: Pettitt RW, Jamnick N, Clark IE, Int J Sports Med 2012;33(6):426-431.
- Durability. Maunder E, Seiler S, Mildenhall MJ, Kilding AE, Plews DJ. "The Importance of 'Durability' in the Physiological Profiling of Endurance Athletes." Sports Med 2021;51(8):1619-1628. doi.org/10.1007/s40279-021-01459-0. Defines durability as when, and how much, physiological profile characteristics deteriorate during prolonged exercise. Also Jones AM, "The fourth dimension: physiological resilience as an independent determinant of endurance exercise performance," J Physiol 2024 (online 2023), doi.org/10.1113/JP284205.
- Exercise, histamine and antihistamines. Van der Stede T, Blancquaert L, Stassen F, et al. "Histamine H1 and H2 receptors are essential transducers of the integrative exercise training response in humans." Sci Adv 2021;7(16):eabf2856. doi.org/10.1126/sciadv.abf2856. Six weeks of interval cycling with H1 and H2 blockers taken before every session (9 per group): time to exhaustion improved 31% vs 81% on placebo, and the mitochondrial marker citrate synthase 14% vs 33%.
- Skill transfer. Fransen J, McCall A, Nimphius S, Impellizzeri F. "A taxonomy for the transfer of skills in sport." Preprint, not yet peer reviewed. The article Jeremy sent after the episode. It treats transfer as a graded scale rather than a simple near or far split, and lays out thirteen dimensions for judging how far a practice task sits from the skill you actually want to improve.
- Bioenergetics course by Evan Peikon, where the two-identical-athletes durability example comes up.
Inside Ruth Performance Collective, Tuesday's call is In-Gym Testing, which is where tests like the burpee test and the Echo profile go into practice.
- Kyle