Dr. Dimitrije Cabarkapa Discusses New Research on Vertical Jump Metrics in Professional Basketball Players
In the Achievement & Assessment’s Publication Highlight series, we chat with staff, researchers, and faculty across AAI about a recently published article.
For this edition, we chatted with Dr. Dimitrije Cabarkapa, Associate Director of AAI’s Jayhawk Athletic Performance Laboratory. Dr. Cabarkapa discussed his journey to sports science – from NCAA Division-I collegiate athlete to researcher, how his research can help sports practitioners improve athletes’ performance, as well as the recently published article titled “Changes in Countermovement Vertical Jump Force-Time Metrics During a Game in Professional Male Basketball Players,” on which Dr. Cabarkapa served as lead author.
About Dimitrije Cabarkapa:
Strongly influenced by his personal playing experience, Dimitrije’s research interests are directed toward the field of sports science and athlete performance enhancement. Over the last five years, he has published more than 80 peer-reviewed research articles and presented at multiple regional, national, and international conferences. Also, Dimitrije successfully established strong collaborative relationships with many well-recognized sports organizations and academic institutions across the world, including the USA, Europe, Middle East, and Asia.
Some of his current and upcoming research projects are focused on examining biomechanical and neuromuscular performance characteristics of professional athletes, physical and physiological responses during training and competition, as well as the implementation of innovative technology for athlete performance monitoring. Earlier this year, Dimitrije received the Terry J. Housh Outstanding Young Investigator Award from the National Strength and Conditioning Association.
This interview has been edited for length and clarity.
AAI: To get started, can you tell me a little about your background and what got you into sports science?
Dimitrije Cabarkapa: I was born and raised in Serbia, in a large city called Novi Sad. I was a good basketball player and was highly recruited to play NCAA Division-I basketball in the U.S. After my first official visit, I fell in love with James Madison University in Virginia. That is where I got my bachelor's degree in exercise science and master's degree in nutrition and physical activity.
A big part of my journey was that during every training session, I listened to my coaches and I tried to figure out how everything that I learn can help me play better. I was like my own lab rat, applying everything I learned in the classroom to optimize my performance – starting with how to eat, recover, train, etc. Quickly, I realized it really worked. Experiencing it firsthand made me fall in love with sports science.
I was a good basketball player and a great three-point shooter. I had seasons where I was scoring 10 points per game with a 50% field-goal percentage and 40% three-point percentage. But when I finished, I decided to bypass a professional basketball career, even though I had multiple offers to play overseas. My cousin, Zarko Cabarkapa, was much more talented and he even played in the NBA. He was the 17th pick in the 2003 NBA draft when LeBron James, Carmelo Anthony, Chris Bosh, Dwayne Wade, and many other elite players were drafted.
AAI: Wow!
Dimitrije Cabarkapa: When I decided to pursue a research career instead of a professional basketball career, it shocked my coaches. I just saw the future in merging science and sport. I started my research career at Brigham and Women's Hospital, part of Harvard Medical School, in the endocrinology department. It was a great experience and I learned a lot, but I quickly realized that I needed to come back to my roots and return to sports.
I reached out to several places and received multiple fellowship offers for Ph.D. programs. One of the people that I met in 2017 during this process was Dr. Andy Fry, who is now my boss. We connected right away. You know how they say you can tell in seven seconds if you like someone or not? Well, I knew in three that I wanted to work for him. I completed my Ph.D. in exercise physiology in 2021. After graduation, I was immediately hired as a postdoc, and then after six months, I was promoted to Director of Basketball Research. I held that position for a year, before being promoted to Associate Director of Jayhawk Athletic Performance Laboratory a year and a half ago.
Working closely with Dr. Fry has been an amazing experience. Being mentored by him and now working for him gives me a chance to conduct sports science research projects based on the real problems that coaches and athletes encounter. That’s what drives us. Our research is driven by ideas that we obtain from coaches and athletes, including their personal experiences.
For example, one of our studies published about six months ago looked at how resistance exercise impacts shooting proficiency. The findings of this study can help coaches and athletes improve their training regimens, especially when scheduling weight-lifting training sessions before or after practice. Our lab’s mission is to help coaches, not tell coaches how to do their jobs, which could be a disaster.
AAI: Yeah, no kidding.
Dimitrije Cabarkapa: Exactly. If I went to Bill Self and told him how to do his job, you can imagine how that would go! So, we’re always looking at how we can contribute and how we can help coaches make data-driven decisions that would ultimately improve athletes’ performance.
AAI: You all have an array of incredible equipment.
Dimitrije Cabarkapa: We have everything from force plates to markerless motion capture systems. When conducting research with athletes, it is important to consider overall environment and if collecting data to answer a specific research question is even feasible. For example, you’re not going to take blood samples five times during a game – that's just not practical. Instead, we use other non-invasive and time-efficient testing methods that offer deep insights into athletic performance. That’s why we also like markerless motion capture systems – they offer quick, efficient, and instant data analysis. The force plates, for instance, give a detailed lower-body neuromuscular performance assessment.
AAI: That brings me to the article where you are the lead author on "Changes in Counter-Movement Vertical Jump Force-Time Metrics During a Game in Professional Male Basketball Players." You worked with pro basketball players on this?
Dimitrije Cabarkapa: Yes, one of our goals is to study the performance of elite athletes and try to figure out what makes them elite. We aim to conduct research whose findings can be used by coaches to help athletes at various competitive levels reach their peak performance potential. In this specific study you mentioned, we analyzed changes in multiple force-time metrics throughout a simulated basketball game. To the best of our knowledge, we were the first to do this with a cohort of professional athletes.
We wanted to see if lower-body neuromuscular performance characteristics change during a game. For example, peak force and power production capabilities. Testing professional athletes multiple times during a game is tough logistically, which is one of the reasons why this paper was published in JSCR, one of the top journals in our field.
We tested the athletes before the game and then after each quarter, after the 1st, 2nd, 3rd, and 4th quarters. For this study, we used a European style of play with 10-minute quarters and an Elam ending. Interestingly, we found no statistically significant changes in the force-time metrics we measured.
AAI: What does it mean when there's no statistically significant change?
Dimitrije Cabarkapa: It means that these athletes were capable of sustaining game-like efforts. If you test a team and you see that these performance metrics fluctuate, it could indicate that the athletes aren’t well-trained to sustain the game-like exercise stimulus. So, in this case, having no statistically significant differences present is good.
Also, sometimes sports practitioners focus on interpreting jump height as a single performance metric, which may be misleading. Achieving a certain jump height is only one piece of a large puzzle. For example, as a consequence of fatigue, athletes may alter jumping strategy such as the depth of the countermovement, which may lead to inadequate conclusions. That is why comprehensive performance assessment is important and that is why we as sports practitioners need to focus on interpreting other force-time metrics alongside jump height.
AAI: You studied professional basketball players in Europe. In your personal experience and scientific research, how different do the styles of basketball translate when it comes to consistency like you were talking about?
Dimitrije Cabarkapa: Do you mean between American and European styles of play?
AAI: Yes.
Dimitrije Cabarkapa: For example, if you look at the Euro League, which is the top competitive level in Europe, you can see many former or future NBA players in that league. In my opinion, Euro League is the second-best league in the world after the NBA.
A significant portion of our research on professional athletes comes from Europe, specifically Serbia. The reason for this is that while the data is being collected daily in the NBA, it’s mainly for the team’s internal use and it is not meant to be published for general use such as research manuscripts. In Europe, it's a little bit different. It's not that we can't study American athletes such as NBA players, it’s just that the data is harder to publish and therefore less beneficial to the community.
AAI: You mentioned that the metrics explored in the study didn’t show any statistical change. But was there anything else in that study that surprised you?
Dimitrije Cabarkapa: We expected to see some changes, but as I mentioned, these were highly trained professional athletes who were prepared to compete at the start of a new season, likely at the peak of their performance. If we had studied athletes who were less prepared or athletes competing at lower levels of basketball competition, my hypothesis would be that we would see notable drops in force and power production.
AAI: Are coaches and teams using insights from your research? Are they putting it into practice?
Dimitrije Cabarkapa: It depends on the coach. Sports science is getting more popular, and I always say, "In God we trust; everyone else, bring data." If you have data, you can make a data-driven and educated decision. Many coaches appreciate what we do, and it's great to see many of them incorporating scientific principles into their training.
As I previously mentioned, our goal as sports scientists is to help coaches, not tell them how to do their job. We provide data so that they can make objective decisions based on their knowledge and experience. I've never seen a successful coach who denies anything that could help their team improve and play better. The evolution of sports science is happening, and I’m optimistic that very soon, every team will have a designated sports scientist on staff.
AAI: Given your background and research population it seems like European sport has exploded. Is that fair to say, especially in Serbia and other places?
Dimitrije Cabarkapa: Yes, it's true. There are multiple reasons for this. We're talking about both male and female sports, not just male sports. In the Balkan region, including Serbia, Slovenia, and Croatia, there's a large pool of highly talented athletes. Serbia, for instance, has a population of around 7 million, but it's remarkable how many elite athletes come from this region, such as Novak Djokovic in tennis, Nikola Jokic in basketball, and Tijana Boskovic in volleyball. If you compare the percentage of elite athletes from this small region of Europe to a giant country like the U.S., it’s very interesting. For example, for such as small country, Serbia has around 11 teams competing in the Olympics right now. Also, while there are many other reasons, European sports have exploded over the last decade due to changes in financial structures, with more investments and sponsorships targeting sports organizations.
AAI: It’s a universal language in some ways.
Dimitrije Cabarkapa: Yes, sports connections are magical. Most of my connections and friendships that I have today can be attributed to the game of basketball, including my wife whom I met 13 years ago at a basketball camp. As I previously mentioned, even the relationships and research that I've conducted over the last couple of years are rooted in my personal experience as an athlete. Sports truly connect people.
AAI: How much of the game is mental? Coaches often say the game is half mental. What do you think?
Dimitrije Cabarkapa: I believe that the power of sports psychology is underestimated. People often focus on physical abilities like strength and power, but the mental aspect is crucial. I use the analogy of a Porsche. You can have a powerful car with a great engine and breaks, but if it has faulty wiring, it won't perform optimally. So, I believe that sports psychology is one of the key pillars of elite athlete performance. Also, this should not be confused with clinical psychology, which is a completely different branch of psychology.
AAI: Have you been following the Olympics?
Dimitrije Cabarkapa: Yes, I have been watching. We had a chance to work with over 30 athletes currently competing in the Olympics. Our lab is proud to interact with such top performers, and we’re closely monitoring their progress and hoping for their success.
AAI: What have been some takeaways or surprises so far?
Dimitrije Cabarkapa: I’m a big fan of Novak Djokovic. Seeing him win despite a major knee injury was unbelievable. It’s a testament to mental toughness. The Serbian basketball team is great, including players such as Bogdan Bogdanovic and Nikola Jokic. I hope that they will be able to win a medal. Also, the talent in U.S. basketball is astonishing. Watching the team, with players like LeBron James and Anthony Edwards, and seeing their high field-goal shooting percentages, is incredible. It’s amazing to see such a talented group perform together.
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Publication Highlight: Article: “Changes in Countermovement Vertical Jump Force-Time Metrics During a Game in Professional Male Basketball Players”
Journal: The Journal of Strength and Conditioning Research
Authors: Dimitrije Cabarkapa, Quincy R Johnson, Damjana V Cabarkapa, Nicolas M Philipp, Drake A Eserhaut, Andrew C Fry
