The University of Kansas conducted a study measuring the cortisol levels in saliva samples from its men's basketball players over the course of a season. Cortisol is a hormone released in response to stress that can impact athletic performance. The study found some players had lower cortisol levels, making them better able to perform under pressure. A previous University of Nebraska study also found football contributors had lower cortisol responses. The Kansas researchers hope to use this data to help coaches manage players' stress, fatigue, and injury risk through tailored training programs.

1. 03/03/2014 ESPN The Magazine 69
FIVE HUNDRED YARDS from Allen Fieldhouse—
deep inside the dull-brown bowels of the
University of Kansas’ Robinson Health and
Physical Education Center—is a lab that holds
the story of the Jayhawks’ 2013 trip to the
Sweet 16. In a freezer set to a constant
minus-80 degrees Celsius are saliva samples,
taken weekly for 27 of 30 weeks, from 16 of
coach Bill Self’s players during a season cut
short by a Michigan team marching its way to
the championship game. Removed from the
freezer, thawed and then placed in a centrifuge
at 3,000 rpm, the samples are removed of
impurities, and stories are spun for each player.
Every finals exam, every fight with a girlfriend,
every head-coach chew-out is laid bare; every
week the thing that contributed to failure or
success on the court is an open book.
The samples are part of a study conducted by
Kansas that takes the concept of game prep
outside the gym and into the world of science
fiction. Using the Jayhawks’ 2012-13 men’s and
women’s basketball teams, researchers mea-
sured the cortisol levels of their saliva, looking
to determine what role the hormone might play
in making certain players excel in the heat of
battle while others fade. Why focus on cortisol?
It’s released by the brain to help the body deal
with physical and mental stress. But excess
cortisol has a catabolic effect on tissue (it
breaks it down), and prolonged elevated levels
have been proved to curtail the production of
necessary hormones that promote muscle
growth and repair. In other words, players
could be more susceptible to injury or may take
longer to heal. So for any athlete or coach,
managing healthy cortisol levels is key to
peak performance, and it’s something Kansas
WHICH PLAYERS ARE DESIGNED TO DELIVER
UNDER PRESSURE? KANSAS RESEARCHERS
ARE LOOKING FORTRUTH—INSALIVA.
TOUGHNESS
ANALYTICS
BIG PLAYS, NO SWEAT
The University of Nebraska studied its football
program for correlations between cortisol
reactivity and performance. In freshmen tested
in 2009 and ’10 (47 total), those who were
deemed contributors exhibited lower cortisol
levels than their noncontributing counterparts.
AVERAGE PERCENT INCREASE IN
CORTISOL AFTER A WORKOUT 66%
24%
BY IGOR GURYASHKIN I ILLUSTRATIONS BY EDDIE GUY
BUILT
TOLAST
CONTRIBUTORSNONCONTRIBUTORS

2. 70 ESPN The Magazine 03/03/2014
hopes to be able to address with tailored
exercise and stress reduction. “We looked
at playing minutes, we looked at practice
minutes, we looked at volume of free weight
exercises in the weight room, we looked at the
academic schedule, we looked at the travel
schedule, we looked at if they won or lost,” says
Andrew Fry, a professor in KU’s Department
of Health, Sport and Exercise Sciences, who is
helming the study.
It turns out, some athletes are indeed
“tougher,” at least from a cortisol standpoint. In
a previous study carried out at the University
of Nebraska, using its football program, there
illustration by DAVID DESPAU
PHOTO REFERENCE: CLIVE ROSE/GETTY IMAGES
CRAZY CRAP
ANALYTICS
CAN PROVE
ON-TARGET SHOT
PERCENTAGE
TEAMMATE
CHANCES/GAME
47.4% 2.9
THE BEST VS. THE REST
LUISSUAREZ
IS THE WORLD’S BEST SOCCER
PLAYER—AND IT ISN’T CLOSE
was a significant difference in cortisol levels
between the guys who played well and the ones
who were nonfactors (see chart on page 69)—
namely that the players who contributed over
the season had lower natural cortisol levels
when measured during summer practices.
But Fry and his department at Kansas
broadened their scope to look beyond just
performance data. They also focused on the
relationship between cortisol and fatigue
management, drilling down into the idea that
cortisol levels tend to spike when players are
overextended both on and off the court. “In the
past, they used other terms—burnout, over­
fatigued, overtraining—it’s more than that,”
says Fry. “It’s how do I make sure my people
are fatigued when I’m planning for it but that
Real Madrid forward Cristiano Ronaldo may have
been crowned the 2013 Ballon d’Or winner, but no
player in the world is impacting the game offensively
like Liverpool striker Luis Suarez.
After being criticized for his poor shot selection in
’12-13, Suarez is blasting 47.4% of his 5.5 shots per
game on goal this year, a more accurate rate than
that of Ronaldo (39.7%), Lionel Messi (44.2%) and
Franck Ribery (45.8%). The reason? His 9.3 touches
per game in the opposing team’s penalty area not
only outpaces Ribery (8.4), Ronaldo (7.6) and Messi
(7.2), it’s the highest mark in all of Euro soccer.
Still not convinced? Suarez creates 2.9 chances
for his teammates per game—third best in the EPL—
and his 60 total chances tops Ronaldo (34 in 21
games), Messi (34 in 16 games) and Ribery (40 in 14
games). And all three have better supporting casts.
So never mind that award. When you watch
Liverpool, know you’re watching the best player in
the world. —ADRIAN MELVILLE, ESPN INSIDER
LUIS
SUAREZ
FRANCK
RIBERY
LIONEL
MESSI
CRISTIANO
RONALDO
1.639.7%
2.945.8%
HOW TOUGH IS YOUR TEAM?
JAY BILAS RANKS THE
68 BEST IN COLLEGE HOOPS.
GO TO ESPN.COM AND
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2.144.2%
Through Feb. 12
they’re recovered when they need to perform.”
“We’ll see stiffness in a big game, and the
guys who have huge increases in stiffness don’t
play well,” adds Andrea Hudy, KU’s highly
lauded strength and conditioning coach, who
has been working with Fry and his team. But
now, with weekly cortisol-level breakdowns for
the players, Hudy hopes to finally have hard
evidence for what she has had suspicions about
but could never measure: psychological and
mental fatigue. “I think stress is a lot more psy-
chological than physical,” she says.
The task for Hudy and the coaching staff
would then be to manage the external stress
factors, either through herself, the sports
psychologist they have on staff or even Self,
who Hudy stresses “is hard on players but the
first to slap them on their ass after practice.”
She explains: “We looked at biological stiffness
and environmental stiffness. Biological
stiffness would be from strength training and
what you have genetically. That’s affected by
what we can prescribe and increase or
decrease for you. But then we looked at their
environmental stiffness—psychological
fatigue, stress, things we could control. It was
the big thing I got out of the cortisol study:
What psychological work can we do in that
time frame so the players don’t get stressed?”
So is cortisol the chemical metric game
changer in sports? When a hormone is
intrinsically linked with fatigue and underper-
formance—a product of physical and mental
stresses—it surely holds some promise.
Kansas and Nebraska certainly think so.
And if pro franchise owners begin to see it
as a way to keep their teams from losing a
few points, or losing millions of dollars a year
to injured-player salaries, it has to matter. “At
the moment, every team in sports is looking
for that silver bullet,” says William J. Kraemer,
professor of kinesiology, physiology and
neurobiology at the University of Connecticut,
whose studies have included looking at
the cortisol levels of the Huskies football
team. “Most, though, are not prepared to
finance that research because there’s no
guaranteed answer.”
Looks like Kansas is willing to put its money
where its mouth—and spit—is.
WHO NEEDS THE COMBINE?
According to Nebraska’s research, factoring in
cortisol levels gives coaches a 39% better
chance of finding a player who’ll contribute
significantly during a season.
Stats courtesy ESPN Stats & Info.