Throughout his time coaching, South Dakota State University women’s soccer coach Brock Thompson has always looked to provide his team an edge. When Matt Vukovich, the associate dean of research in SDSU’s College of Education and Human Sciences, approached him about an upcoming research study, Thompson eagerly accepted.
“I thought it would, one, provide a lot of value to our student-athletes, and two, the ability to tie academic research into an athletic program—I thought it was a really cool thing,” said Thompson, who will start his sixth season as the Jackrabbits' head coach this fall.
The purpose of the study was to investigate the impact of nutrition, sleep, stress and training impact, sport performance and injury potential in female athletes. Student-athletes could volunteer for the study which would last approximately one year. The uniqueness of the study was the use of a device called WHOOP, a wearable wristband that monitors users’ sleep, recovery and daily activity, referred to as “strain.” WHOOP measures recovery by incorporating four physiological metrics: heart rate variability, resting heart rate, sleep performance and respiratory rate.
Each morning WHOOP provides users with a recovery percentage on a scale of 0 to 100. The “green” zone indicates good recovery, “yellow” is average and “red” is poor. When individuals receive a recovery percentage in the red, WHOOP recommends that the individual should rest and avoid strenuous activity. When WHOOP gives a green percentage, it’s a signal from WHOOP that individuals should be able to handle strenuous activity. Many professional athletes utilize WHOOP to monitor their training, including Olympic athletes, CrossFit athletes and professional athletes.
For WHOOP to gather the necessary data, participants wore a small black wristband at all times—even while sleeping. By wearing the wristband to bed, WHOOP tracks and analyzes one’s sleep. How many hours of REM sleep did you get last night? WHOOP gives a measurement. How many hours of sleep needed for full recovery? WHOOP also provides an estimate.
Each morning, participants also had to answer a few questions related to hydration and caloric intake.
Vukovich worked alongside researchers from Florida State University, the University of Nebraska-Lincoln, the University of North Carolina at Chapel Hill and Auckland University of Technology. Study participants included more than 400 female student-athletes in sports ranging from soccer to volleyball to cross country.
In addition, Thompson and his coaching staff were also provided with WHOOP bands and began tracking their own sleep and recovery.
The coaching staff monitored the entire team’s data through an online portal. The student-athletes could only see their own data but Thompson could see everyone’s results as they came in.
The data collection portion of the study lasted throughout the spring 2021 soccer season—which was moved from the fall due to COVID-19—and the ’21 fall season. During those seasons, SDSU compiled an undefeated record during league play in the spring and won the Summit League Championship during the fall season.
One of the big takeaways that Thompson had from the data was the impact of stress on recovery.
“The piece that was fascinating for me going through this was that I always associated strain as physical,” Thompson said. “I learned that mental, emotional and academic issues add to strain, which hinders recovery.”
For example—last fall—Thompson was working through who would be on the travel squad and who would stay behind. During this time period, Thompson’s WHOOP data showed his own recovery was in the red. Thompson was confused because he hadn’t been participating in strenuous workouts nor had his sleep seemingly been adversely effected. His recovery was in the red because of the stress related to deciding the travel squad.
“It was fascinating to learn how some of the nonphysical strain really effects the recovery performance,” Thompson said.
It was noticeable among the student-athletes as well. When groups of student-athletes had important tests or projects, Thompson saw their recovery data would generally be lower than both their usual and the rest of the team. Thompson contributed the lowered recovery to stress.
“That was the biggest takeaway for me—physical strain and stress are exactly the same when it comes to fatigue and recovery,” Thompson said.
For midfielder Avery LeBlanc, a junior from Longmont, Colorado, she noticed her recovery struggled when the team would travel—especially if they flew to a contest.
“For me, anytime I travel, I’m always in the red,” LeBlanc explained. “Being a student-athlete, you can tell the days that are super stressful with both schoolwork and travel. You can absolutely tell the impact it has on your recovery.”
Another interesting note Thompson took away from the team’s participation was the need for some physical strain to help fully recover. This became clear to Thompson when the team had a day off from practice and many of the student-athletes would spend the day lounging around the house, most watching Netflix—without any real physical strain.
“They would expect their recovery to bounce back but it didn’t because you need a little bit of strain—a light workout—to aid in the recovery process,” Thompson said. “You can’t just do nothing and expect your recovery to bounce back. You actually have to be proactive and do some things to recover—whether that’s a walk around campus or a light workout—you have to do something, otherwise your body goes into this mode of just protecting itself.”
LeBlanc began incorporating walks or light runs into her scheduled recovery days to help her recover.
“I would normally just take the whole day off and stay on the couch and not do anything but the next day I would feel stiff and not very good,” LeBlanc said. “I started doing a light walk to get my heart rate up or I could even do a little workout, like Spikeball, which will get your heart rate going and will actually help your recovery.”
The recovery aspect of the data was what Thompson primarily used. During the spring season, Thompson noticed the team’s average weekly strains were getting higher and the team’s recovery was progressively getting lower. Utilizing the team’s collected data, Thompson gave the student-athletes an extra day off to help expedite their recovery.
The biggest takeaway LeBlanc had from the experience was the impact sleep had on her recovery, specifically type of sleep. LeBlanc could see her amount of REM sleep and deep sleep. She could also see how much time she spent awake at night. LeBlanc, a business economics major, learned she wasn’t quite getting the amount of hours of sleep she thought she was getting each night.
“If you go to bed at midnight, and you get up at 8, you say ‘Oh, I slept eight hours, that’s perfect.’ But that’s not always the case,” LeBlanc said. “Like for me, every night I’m in bed, I’m almost awake for an hour of how much of the time I think I actually slept.”
To improve not the only the amount of sleep but also the quality of sleep she was getting each night, LeBlanc made some subtle—but important—changes. She made a rule that once she got in bed, she couldn’t look at her phone. She saw improvements in both hours slept and quality of sleep.
Thompson also used the WHOOP data as an educational tool for his players.
“We used it primarily as a means to help educate our players to take ownership over their recovery,” Thompson said. “If your normal bedtime is at 10 p.m. and now it’s at 1 a.m., what impact does that have on you? What impact does nutrition and hydration and alcohol have on your performance? And now you have a tool that can help you draw your own conclusions and how it impacts you.”
“I just think it’s really cool that everyone can kind of figure it out for themselves, learning what needs to be changed so you can perform your best,” LeBlanc said. “We’re all just learning about ourselves and growing to be the best version of ourselves.”
Thompson continues to use the WHOOP data as have a few other student-athletes including LeBlanc.
“I’m grateful to Dr. Vukovich for giving us the opportunity to learn a little bit more about how to recover well and perform to our highest abilities,” Thompson said.
On June 3, at the American College of Sports Medicine annual meeting in San Diego, findings from the research study were presented.
The collected data supported two studies. The first, titled. “Pre-sleep Feeding in NCAA Division I Female Athletes,” investigated the self-reported frequency of pre-sleep feeding in female student-athletes.
Proper nutrition is important for optimizing training adaptions and pre-sleep feedings with adequate protein appear to improve recovery.
The second study, titled “Characteristics of Menstrual Cycle and Hormonal Contraceptive (HC) Use in Collegiate Female Athletes in the United States,” was the first to investigate HC use versus nonHC use in female student-athletes. The study also investigated menstrual cycle patterns.
“Knowledge of HC use and menstrual cycle patterns in female athletes is important in developing appropriate monitoring and management practices to optimize training adaptations in athletes,” the abstract explained.
The researchers are still analyzing the dataset and future outcomes will investigate the impact of nutrition, sleep, stress and training impact sport performance and injury potential in female athletes.
“Our goal is to work with coaches and athletes to improve performance and reduce the risk for injury.” Vukovich said. “We were excited to partner with WHOOP and the other universities. The research presented at ACSM is just the beginning and we hope to discover more information that will help athletes perform optimally.”