featuring Jennifer Ketterly, MS, RDN, CSSD, LDN
Duke Sports Sciences Institute • NBA Charlotte Hornets • NCAA Division I & Pro Tennis • 25+ Years in Elite Sport
| Originally recorded at the National High School Tennis Coaches Conference. This conversation was too good to keep in one room — so we’re sharing it with the broader Sport Field Life community. While the examples are tennis-specific, the principles apply across all competitive sports. |
Jennifer Ketterly joins us for a practical, science-backed conversation on the three pillars of nutrition that every coach and athlete needs to understand: fueling, hydration, and recovery. As Associate Director of Sports Performance at the Duke Sports Sciences Institute and a board-certified specialist in sports dietetics with over 25 years of experience at the collegiate and professional levels, Jennifer brings rare depth and clarity to topics that directly impact what happens when it matters most — in practice, in competition, and in the moments in between.
In this episode, Jennifer breaks down why carbohydrates are the non-negotiable fuel source for high-intensity sport, unpacks the science of sweat rate and individualized hydration, and introduces the 4Rs of recovery that can make or break performance across a demanding training week or competition schedule. She also tackles the very real challenge of under-fueling in female athletes, explains the warning signs of Relative Energy Deficiency in Sport (RED-S), and answers questions on everything from chocolate milk to protein shakes to pre-competition meal timing.
TOP 5 TAKEAWAYS
Carbohydrates are the engine. Tennis burns through carbohydrates fast—especially in the heat. If athletes aren’t fueling before, during, and after play, their performance will pay the price whether they feel it or not.
Hydration is personal, not one-size-fits-all. Every athlete loses fluid and electrolytes at a different rate. The only way to know an individual’s sweat rate is to measure it—a simple pre/post-practice weigh-in can reveal exactly how much needs to be replaced.
Under-fueling is a hidden performance killer. RED-S (Relative Energy Deficiency in Sport) is more common than coaches realize—and it silently undermines strength, recovery, hormones, and performance. Recognizing the signs early is critical, especially in female athletes.
The 4Rs of recovery are non-negotiable. Recovery isn’t passive—it’s a four-part strategy: Rehydrate, Refuel, Repair (with protein), and Rest. Each one has a window of opportunity, and missing it compounds over a training week or tournament.
Strategy beats spontaneity. From pre-match meals to in-match fueling to post-play recovery windows, the timing of what athletes eat matters as much as what they eat. Having a plan—even a simple one—separates prepared athletes from reactive ones.
TRY THIS TODAY
Build your athletes’ changeover fueling plan before the next match or practice.
The rule of thumb is simple: aim for 30–60 grams of carbohydrate for every hour of play, using easy-to-digest options at changeovers. Have each athlete pick two or three go-to foods that work for their stomach. Try one of these as a starting point:
- A banana or applesauce pouch
- A sports gel, chew, or date-based bite
- A sports drink (covers both hydration and carbohydrate in one)
The best fuel source is the one your athlete will actually use. The goal is having a strategy—not a perfect one, just a consistent one.
“Hydration is completely controllable. You can’t control how your competitor plays, but you can control whether you step on the court well hydrated. That has a direct impact on performance.” — Jennifer Ketterly
ABOUT JENNIFER KETTERLY
Jennifer Ketterly, MS, RDN, CSSD, LDN is the Associate Director of Sports Performance at the Duke Sports Sciences Institute and a faculty member in the Department of Orthopedics and Sports Medicine at Duke University. A board-certified specialist in sports dietetics, she brings over 25 years of experience across collegiate and professional sports, including seven years as the performance nutrition consultant for the NBA’s Charlotte Hornets. She is also a founding principal of Performance 365, a sports nutrition consulting group working with athletes and team organizations.
Connect with Jennifer: jenniferketterly@gmail.com
Duke Sports Sciences Institute: www.dukehealth.org/duke-sports-sciences-institute
