Advancing Sports Science and Athlete Health through Research and Practice

In this issue of NEU Bulletin, we are honored to feature Prof. Dr. A. Haydar Demirel, a distinguished scientist in the fields of exercise physiology and sports medicine, whose academic career spans several decades of impactful research and international collaboration. Prof. Dr. Demirel has made significant contributions to our understanding of muscle physiology, particularly in the context of exercise-induced stress and adaptive mechanisms.

Having conducted pioneering research at leading institutions such as the University of Florida and Hacettepe University, his work has helped illuminate the molecular and physiological responses of skeletal and cardiac muscle to exercise. His studies on heat shock proteins and muscle adaptation have been widely cited, contributing to the advancement of both basic science and applied sports medicine.

Beyond his scientific achievements, Prof. Dr. Demirel has played an influential role in shaping sports science education and athlete health policies. His recent contributions to international forums on anti-doping and athlete biological passport systems further highlight his commitment to ethical performance and athlete safety.

In this interview, Prof. Dr. Demirel reflects on his academic journey, the evolution of exercise physiology, and the importance of integrating science, ethics, and performance in modern sports, while offering valuable insights for the next generation of researchers.

What was the main motivation that shaped your academic journey?

My academic journey was initially shaped by my strong interest in sports, which led me to pursue a degree in sport sciences. However, during the early months of my undergraduate education, my perspective began to evolve. Lectures delivered by internationally invited speakers, along with courses taught by faculty members with medical backgrounds, introduced me to the scientific and clinical dimensions of exercise.

This exposure sparked a deeper interest in exercise physiology and its relevance to human health, motivating me to further expand my training in medicine after completing my degree in sport sciences. My growing interest in physiological mechanisms, particularly those underlying exercise responses, ultimately guided me toward specialization in physiology.

In line with this direction, I pursued my doctoral training at the University of Florida under the mentorship of Dr. Scott Powers, a globally recognized scientist in the field. This experience allowed me to deepen my understanding of exercise physiology and shaped my current research focus on the physiological and molecular responses to exercise.

How did your academic experiences at Hacettepe University and the University of Florida influence your research approach?

My academic experiences at Hacettepe University and the University of Florida fundamentally shaped and refined my research approach. Before joining Hacettepe, I had the opportunity to work at a Sports Training, Health, and Research Center, where I was involved in evaluating elite athletes, identifying performance limitations, and developing strategies to optimize performance. This experience gave me a strong applied perspective and an appreciation for real-world problems in human performance.

However, over time, I felt the need to move beyond descriptive work toward a more question-driven approach. With this motivation, I joined the newly established School of Sports Sciences and Technology at Hacettepe University, which provided an environment where I could formulate research questions and actively seek answers rather than simply describing observations. During this period, I was also pursuing my PhD in Physiology at Ankara Medical School, which helped me develop a deeper understanding of the physiological mechanisms underlying human performance and strengthened my analytical thinking.

As my research interests evolved, I realized that the questions I was asking required more advanced methodologies and experimental approaches. In particular, I wanted to investigate mechanisms at the cellular and molecular levels and to conduct controlled experimental studies that are not always feasible in human participants. This led me to pursue further academic training at the University of Florida.

At the University of Florida, I was exposed to a highly advanced research environment that emphasized hypothesis-driven research, experimental design, and mechanistic investigation. Working with experimental models allowed me to explore physiological processes in greater depth and to better understand the underlying biological mechanisms of exercise and performance. This experience significantly strengthened my ability to integrate basic science with applied research.

Overall, Hacettepe University helped me transition toward a more inquiry-based and interdisciplinary research mindset, while the University of Florida provided the methodological tools and experimental framework to investigate these questions at a deeper, mechanistic level. Together, these experiences shaped my current research approach, which integrates applied human performance research with fundamental physiological mechanisms.

What scientific questions led you to focus on muscle physiology and exercise-induced stress as your primary research area?

My interest in muscle physiology began during my early years at the Sports Training, Health, and Research Center, where I was closely involved in evaluating athletic performance. I became particularly intrigued by fundamental questions related to skeletal muscle plasticity, such as whether muscle fiber types can truly change in response to exercise, and whether skeletal muscle, traditionally considered a postmitotic tissue, might exhibit hyperplasia rather than only hypertrophy.

In this context, the classical overload experiments by William J. Gonyea, demonstrating potential muscle fiber hyperplasia in animal models, had a strong influence on my thinking. These findings challenged conventional assumptions and encouraged me to explore skeletal muscle adaptation more deeply. I subsequently focused on identifying different myosin heavy chain isoforms, including the relatively newly characterized MHC-IID, using electrophoretic techniques, and investigating how exercise variables such as intensity, duration, and frequency influence muscle phenotype. This line of work led me to develop expertise in exercise experiments using animal models and related laboratory assays.

At the same time, I became interested in heat shock proteins (HSPs), which were an emerging topic at the time. These stress proteins are induced by various stressors, particularly heat, and play a critical role in cellular protection and adaptation. I was struck by the similarity between cellular responses to exercise and classical stress responses, which led me to hypothesize that exercise itself could induce HSP expression. More importantly, I considered that this response might not only contribute to performance adaptations but also provide protection against pathological conditions.

Given that cardiovascular diseases were, as they still are, a leading cause of mortality, I focused on whether exercise-induced HSP72 could protect the heart against ischemic injury. With the support of my mentor, Prof. Dr. Scott Powers, I conducted a series of studies using a rat model of myocardial ischemia. By directly catheterizing the left ventricle, I was able to assess cardiac contractile function in real time during ischemic conditions. Observing that exercise-trained animals were more resistant to ischemic stress and better preserved cardiac function was a pivotal and highly motivating experience for me.

These scientific questions and experimental experiences ultimately shaped my decision to focus on muscle physiology and exercise-induced stress, with an emphasis on understanding the underlying mechanisms and their potential translational implications for human health.

In your opinion, what is the most critical role of exercise physiology in today’s health sciences?

In my opinion, the most critical role of exercise physiology in today’s health sciences is its central contribution to understanding exercise as a form of medicine. Exercise is no longer viewed merely as a lifestyle choice, but as a powerful intervention that can prevent, delay, and even modulate the course of many chronic diseases. In fact, current pharmacological research is increasingly inspired by the biological pathways activated by exercise, with the aim of developing therapies that can mimic its effects.

Long-term observational evidence strongly supports this perspective. For example, findings from the Baltimore Longitudinal Study of Aging, one of the longest-running aging studies in the world, clearly indicate that the most effective factor in promoting healthy aging is not supplementation with antioxidants, vitamins, or protein, but regular physical activity. One of the key physiological markers underlying this relationship is maximal oxygen uptake (VO₂max), a fundamental measure in exercise physiology, which is consistently associated with healthy lifespan and longevity.

Beyond cardiorespiratory fitness, the preservation of skeletal muscle mass has emerged as a critical determinant of metabolic health. There is now strong scientific consensus that maintaining muscle mass plays a central role in preventing metabolic diseases and, consequently, a wide range of chronic conditions. From this perspective, skeletal muscle can be seen as a decisive factor in the balance between health and disease.

Importantly, our understanding of skeletal muscle has evolved significantly. It is no longer considered merely a mechanical tissue but is now recognized as an endocrine organ that secretes myokines with systemic effects. For instance, brain-derived neurotrophic factor (BDNF), released in response to exercise, contributes to the preservation of cognitive function and may play a protective role against neurodegenerative diseases such as Alzheimer’s. In addition, skeletal muscle is a primary site for glucose uptake and is therefore essential in preventing insulin resistance and maintaining metabolic homeostasis.

Exercise exerts these benefits through multiple, complementary mechanisms. Resistance exercise enhances muscle mass and quality, while endurance exercise promotes mitochondrial biogenesis, improves oxidative capacity, and increases fat utilization. Through these adaptations, exercise plays a key role in the prevention of numerous conditions, including cardiovascular diseases, type 2 diabetes, metabolic syndrome, non-alcoholic fatty liver disease, various cancers, and neurodegenerative disorders such as dementia and Alzheimer’s disease.

Therefore, exercise physiology stands at the center of modern health sciences. It not only helps us understand how these complex adaptations occur but also provides the scientific foundation for translating this knowledge into effective strategies for disease prevention, healthy aging, and improved quality of life.

How can the balance between science, ethics, and performance be maintained in modern sports?

Maintaining the balance between science, ethics, and performance in modern sports requires a clear commitment to athlete health, fairness, and scientific integrity. While scientific advances have significantly improved training methods, recovery strategies, and performance optimization, they also bring ethical challenges, particularly in the context of doping and performance-enhancing interventions.

From a scientific perspective, the primary goal should be to enhance performance through evidence-based, safe, and athlete-centered approaches. Exercise physiology, nutrition, recovery science, and technology all offer legitimate pathways to improve performance without compromising health. However, when scientific knowledge is misused to artificially enhance performance through prohibited substances or methods, it undermines both athlete well-being and the integrity of sport.

Doping represents one of the most critical points where this balance is challenged. My perspective on this issue has been shaped not only academically but also through direct professional experience. I served for 3.5 years as the director of the Hacettepe University Anti-Doping Control Laboratory, one of the approximately 30 laboratories worldwide accredited by the World Anti-Doping Agency (WADA). In addition, I have been a board member of the Turkish Anti-Doping Commission and currently serve as the Chair of the Therapeutic Use Exemption (TUE) Committee. These roles have provided me with comprehensive insight into both the scientific and regulatory dimensions of anti-doping, including the complexity of distinguishing legitimate medical use from performance enhancement.

In parallel, I have been actively involved in international policy and education initiatives. For more than a decade, I have served as the Chair of the UNESCO Türkiye, Physical Education and Sport Monitoring Group. Within this framework, we have collaborated with the Turkish Ministry of Youth and Sports to promote the integration of anti-doping education into the curricula of Faculties of Sport Sciences across Türkiye. As part of this effort, we organized a workshop held on April 3–4, 2026, in Istanbul, where we introduced a comprehensive educational resource developed with contributions from colleagues including Prof. Dr. H. Ulaş Yavuz from Near East University. The event brought together representatives from UNESCO, the Council of Europe, and various anti-doping organizations, reflecting a coordinated international effort to strengthen ethical awareness in sport.

These experiences reinforce that maintaining the balance between science, ethics, and performance depends not only on regulations but also on education and culture. Strong anti-doping frameworks must be supported by continuous scientific advancement, transparent practices, and a commitment to clean sport values. Athletes, coaches, and scientists all share responsibility in this process.

Ultimately, science should serve to enhance human performance within ethical boundaries, not to circumvent them. Protecting athlete health, ensuring fairness, and fostering integrity must remain at the core of modern sports.

Outside of your intense academic and administrative responsibilities, what helps you relax and mentally recharge

Thank you for asking this question. Despite a demanding academic and administrative schedule, I try to maintain a few habits that help me relax and mentally recharge.

Regular exercise is an essential part of my life. It not only helps me stay physically active but also provides a mental reset. During exercise, I often listen to podcasts, which allow me to stay updated on a wide range of scientific topics beyond my immediate field of expertise. In that sense, exercise becomes both a physical and intellectual activity for me. I also enjoy cycling regularly, which I find particularly refreshing.

Music is another important outlet. Although I do not always find enough time, occasionally picking up my guitar allows me to step away from the pace of daily life and clear my mind.

On a more personal note, spending time with my daughter is very meaningful to me. She graduated in economics from Bilkent University, yet for me she is still the 15-year-old I remember. Being with her is always a special and grounding experience. Perhaps it goes without saying that, through our conversations, I have also developed an interest in economic concepts and discussions, which I find myself enjoying and reflecting on in my free time.

I cannot say that I take frequent vacations; however, attending scientific meetings serves a similar purpose. These environments not only help me recharge but also reignite my curiosity and enthusiasm for research.

Overall, it is this combination of physical activity, intellectual engagement, and personal connections that helps me maintain balance and continue with renewed energy.

What is the most important advice you would give to young researchers?

If I had to give one piece of advice to young researchers, it would be this: stay curious, be persistent, and take ownership of your learning.

Curiosity is the foundation of meaningful research. When you encounter something, you do not understand, do not move on too quickly. Do not assume it is outside your field or not immediately relevant. In my own experience, even a single unclear sentence can lead to days or weeks of exploration. It may feel slow, but this is how deep understanding develops.

At the same time, young researchers should not overlook the importance of positioning themselves early in their careers. Seeking the right environment, mentors, and opportunities is essential. However, it is important to remember that academic titles or positions are not the ultimate goal. What truly matters is how deeply you understand your field and how open you are to learning what you do not yet know.

An academic is not simply someone who transfers information from one place to another. Our role is not to act as couriers of knowledge, but to question, interpret, and generate new understanding. In that sense, young researchers should reflect carefully on what kind of scientist they want to become: someone who merely transmits existing knowledge, or someone who actively engages with it, challenges it, and contributes to it.

Finally, even in today’s fast-paced world, with constant pressure for quick results, I would still encourage taking the time to truly understand. Because in the long run, it is this depth of understanding that satisfies curiosity and gives real meaning to scientific work.

About the Researcher

Prof. Dr. Haydar Demirel graduated from Ankara 19 Mayıs Youth and Sports Academy and Ankara University Faculty of Medicine, respectively. He completed his doctorates in Exercise Physiology/Sports Medicine at the University of Florida and in Physiology at Ankara University Faculty of Medicine. Dr. Demirel’s current main research area focuses on elucidating the mechanisms aimed at preventing skeletal muscle loss caused by immobilization and physical inactivity. He seeks to reveal these mechanisms by evaluating protein expression involved in mitochondrial biogenesis, skeletal muscle, cardiac muscle, adrenal gland response, and signal transduction in relation to physiological stressors such as immobilization, swimming and running exercises, whole-body vibration, heat/cold stress, and hypoxia.

Haydar Demirel, recipient of the Hacettepe University 2007 Health Sciences Science Award, has served as Dean of the Faculty of Sports Sciences at Hacettepe University, Head of the Department of Exercise and Sports Physiology, Director of the Turkish Doping Control Center, and faculty member in the Department of Sports Medicine at Hacettepe University. He currently serves as Director of the Sports Sciences Research Center and as a faculty member at the Faculty of Sports Sciences at Near East University.