In Paula Radcliffe’s youth, the current women’s marathon world record holder hit a slump. Her coaches searched for a reason. They found the answer in a test that revealed a mild iron deficiency. Not long after correcting the problem, Radcliffe won the World Junior Cross Country Championships and eventually became one of the great runners of her generation. Yet her continued success wasn’t just a product of superior nutrition. Her ability to process oxygen was extremely high from a young age, owing to good genes. However, she didn’t succeed merely because she won the genetic lottery either. After years of running, Radcliffe’s economy improved, meaning that her body used less energy to run at 29 years old than when she was 18. A confluence of many factors made Radcliffe elite.

In his new book, Faster, Higher, Stronger, former Sports Illustrated staffer and current editor Mark McClusky writes about Radcliffe, other elite athletes and the researchers studying them. He delves into the science of what makes superstars perform at the highest level, from nutrition to genetics to practice. And though elites may be physiologically different than the rest of the population, the research and development that goes into making them great can trickle down to us weekend warriors. So we spoke with McClusky to see what he learned about elite athletes and what they can teach us.

PLAYBOY: Unfortunately, there’s no single magic solution to make us better at our favorite sport, but is there a framework for weekend warriors to get better faster?
MCCLUSKY: Data collection is incredibly helpful. You want to have a concrete goal, because once you have that you can start collecting data against it. If you want to run a faster 10K, you can break that down as, “Here is when the race is, here is how much I have to improve on the way to that goal,” and you can start charting the improvement. If you’re not gathering data, you’re just sort of doing stuff. I think that’s a huge first part—gathering as much information as you can, even if you don’t know exactly what to do with it at first. Then, figure out what to do with it.

Hudson Street Press

Hudson Street Press

PLAYBOY: And that can help people fight through a plateau, right?
MCCLUSKY: Most people get stuck exactly in the middle with endurance sports. They do lots of tempo work and it’s neither hard enough nor slow enough—it feels kind of hard-ish and most people would do better with much more polarized workouts—where some are really really really hard and then much easier endurance building and recovery days.

PLAYBOY: You grew up playing sports, like cycling, and you still ride and play golf today, did your reporting on the science of elite athleticism change the way you approach your training?
MCCLUSKY: Definitely. I think that the biggest thing is trying to be smarter about practice. There’s a chapter in the book about skill acquisition and how we learn new skills—the idea of random practice instead of block practice. I used to go to the driving range and do what everyone else does and that’s pull out the driver and hit 20 drives. Then pull out the 9-iron and hit 20 of those then repeat with my wedge. Now when I go to the range I’ll hit a drive, then hit a 6-iron because that’s what I do on the course. As I stand on the driving range, I try to simulate the shots that I’ll hit at the courses that I play in the order that I have to hit them and not just banging on the driver again and again and again. John Kessel from USA volleyball, whom I talk about in the book, has this great line which is “the game teaches the game better than anything else” So the more you can make your practice reflect the actual activity, the better.

PLAYBOY: It’s like how in Germany they started training soccer players with smaller fields and less players on each side so each of the players could get more touches in the course of practice to prepare them for the game.
MCCLUSKY: Exactly. It’s happening over here too. Seven-on-seven football leagues, especially down in Texas, have totally taken off. And with that you’re seeing this generation of young Texan quarterbacks in the league right now growing up and going to these tournaments on the weekends. They play six or seven games on a weekend and throw 300 passes. Which is a really different experience than playing that one game on a Friday and maybe throwing 30.

PLAYBOY: It’s not just notching 10,000 of practice, it helps to participate in very focused practice.
MCCLUSKY: The 10,000 hours thing, I have some issues with. But Ericsson’s [Anders Ericcson, the researcher whose study on practice Malcolm Gladwell popularized in his book Outliers] whole thing is with the power of deliberate practice; it’s not just 10,000 of doing the same. He doesn’t necessarily say 10,000 hours. He talks about deliberate practice, not just doing the activity.

PLAYBOY: Yet, the “10,000 Hours Rule” has taken hold in the popular imagination—people believe it to be the key to mastery.
MCCLUSKY: It’s a very American notion, culturally. We believe that or would like to believe that and in a lot of areas it’s true, but in elite sports it’s not. There is a genetic component that is a cost of entry. It’s not that the most genetically gifted athlete always wins, but if you don’t have—especially in sports like running, cycling and rowing, sports which are very physiologically oriented—if you don’t have the ability to process oxygen, you’re not going to win an Olympic gold medal; you’re not going to win the Tour de France.

PLAYBOY: As someone who covers science do you ever get worried about reporting on a study that puts forward a really compelling idea, but the results may not be solid or repeatable?
MCCLUSKY: Repeatability is a huge thing. And it’s a super strong tension in the stuff that I’m writing about in this book. The populations are so small when it comes to elite athletes. By definition, there are not a lot of elite athletes. If they’re as different from normal folks physiologically as I think they are, do these interventions work really differently on them? Probably. Can you ever find a big enough cohort to write a big study about it? Probably not. And that’s where this idea to me that we’re all engaged in our own little experiment as athletes. The N always equals 1. The population is just you or me. Each of us responds so differently to everything. There’s always the danger of drawing too large of a conclusion, and that’s something I was always aware of when I wrote the book and that’s not to extrapolate too much from one study and find scientific consensus on.

PLAYBOY: Even long held ideas about physiology with more scrutiny can be proven wrong. Like the interesting section in the book where you explained how lactic acid isn’t behind us getting tired when we work out.
MCCLUSKY: Lactate is not fatigue. It’s one of the classic scientific things mistaking correlation for causation. Lactate appears during hard workouts so everyone thought it was the cause of fatigue. Our best understanding now of fatigue is that everyone thought it was a failure at the muscular level and the central governor theory is that a lot of it is happening in the brain and there’s pretty compelling evidence for that. My guess would be that there are still peripheral feedback loops that lead to that perception. Our brain is constantly integrating information from our muscles that generate that feeling of fatigue. But interesting things have been found in deception studies. In these studies researchers tell a participant that they’re going to run a shorter distance, then halfway through they tell them they’re going to run longer. The deceived people are able to run faster through than if you told them at the start that they were running the longer distance. That’s really compelling evidence that our brains are regulating how much energy that our bodies expend.

Glenn Glasser editor Mark McClusky (Photo by Glenn Glasser)

PLAYBOY: At the Australian Institute of Sport, you have found some pretty sound science, especially in the realm of supplements.
MCCLUSKY: What I like about what the AIS is done, is that it’s conservative. At the elite level you need to be a little bit more conservative than the everyday folks. One reason is the anti-doping rules and the other is that the margins are so small, you can’t risk having adverse effects on the athletes. So they’re pretty conservative with what they give the athletes. Elise Burke is on the cutting edge, so it’s a pretty good balance between what works for the elites and what is scientifically sound.

PLAYBOY: Some people may be surprised to see that creatine is a supplement they should consider taking, because in most people’s minds it’s associated with Major League Baseball steroid usage in the 1990s.
MCCLUSKY: It is certainly worth taking on the elite level, but anytime you’re talking about supplements I get a little skeeved out because it’s a weird world and your usual GNC is filled with things that are not effective or if they are, many are contaminated with steroids, which is terrifying. But creatine works. It is not a steroid. A lot of people think that it is somehow. It’s a combination of three amino acids usually produced in the liver. It’s part of the energy cycle in the cell, what it really does is allow you to regenerate ATP more quickly.

PLAYBOY: What are other supplements athletes should consider as well, as identified by AIS?
MCCLUSKY: A lot of times you don’t hear what elites are using because they want to keep a competitive advantage, but what’s great about AIS is that it shares its findings. They’ve identified a big three of vitamin and mineral supplementation: vitamin D, iron and calcium. A lot of athletes have vitamin D deficiency, especially indoor athletes because we synthesize vitamin D through sunshine, so if you’re a basketball player or gymnast, you may not be getting enough. An endurance athlete needs the red blood cell regeneration from iron and all athletes need calcium for bone strength.

Three more are sodium bicarbonate, caffeine and creatine. All of which have really good evidence bases behind them in terms of physical performance. Beet juice and beta alanine are right on that cusp, the literature is strong—especially strong on the side of having benefits with low potential harm. Minimizing the downside is important for athletes when they want to supplement their diets.

Jeremy Repanich is a Senior Editor at Playboy. Follow him on Twitter @racefortheprize.