Cardiopulmonary Performance in Sports: A 15-Year Analysis

The number of scientific studies on the physiological drivers of endurance performance has more than doubled since 2010, growing at a steady annual rate of 5.5%. This growth points to a mature, fast-moving field where understanding the body’s thresholds has become the central focus for improving athletic capacity.

## Mapping the Growth of a Scientific Field

To understand how this research area has evolved, Mehmet Soyal, Ömer Aksoy, and Nuri Çelik conducted a large-scale bibliometric analysis. They systematically examined nearly 2,750 unique scientific articles published between 2010 and 2025 from the Web of Science and Scopus databases. Their methodology went beyond simple counting. They used statistical trend analysis to confirm growth, applied Bradford’s Law to identify the most influential journals, and employed network analysis to visualize how key concepts and countries collaborate. This approach allowed them to map the entire structure of the field—its growth, its core ideas, and its global connections—in an objective way.

## A Consolidated and Internationally Collaborative Field

The findings reveal a research area that is both stable and expansive. The strong upward trend in publications (R² = 0.81) indicates sustained, systematic interest from the global scientific community. This research is not scattered randomly but concentrated in a core group of influential journals. Bradford’s Law showed that just seven journals account for 31.3% of all publications, providing a central hub for the most significant findings.

This consolidation is matched by extensive international teamwork. Analysis of country collaboration networks shows a densely connected web of researchers. The United States acts as a major hub, with strong collaborative ties to several European nations. This global network accelerates knowledge exchange, ensuring that discoveries in one lab can quickly inform work in another, benefiting the entire field of sports science. This collaborative spirit is also seen in related areas, such as research exploring how cardiovascular fitness lowers mortality risk across populations.

## Physiological Thresholds Are the Central Concept

The most telling insight comes from analyzing the keywords and themes within the 2,750 articles. The conceptual structure of the field is tightly organized around physiological determinants, not just performance outcomes. Keyword co-occurrence and thematic mapping clearly show that exercise, oxygen consumption, VO₂ max, anaerobic threshold, and ventilatory threshold form the backbone of the literature.

Researchers Soyal, Aksoy, and Çelik categorized these themes. VO₂ max and exercise performance emerged as “motor themes”—highly developed and central concepts that actively drive the research agenda forward. In contrast, ventilatory threshold and lactate threshold were identified as “basic themes.” This means they are foundational and essential to the field, but are considered more established, with research continuing to refine their application and understanding. This focus on thresholds directly informs modern training approaches, including the ongoing discussion about low vs high intensity exercise benefits.

## Practical Implications for Athletes and Coaches

For the informed athlete or coach, this analysis validates and clarifies the current approach to endurance training. The field’s maturity means the core principles are well-supported. The intense focus on physiological thresholds confirms that training should be guided by measurable metabolic events—like the lactate or ventilatory threshold—rather than just speed or distance.

The identification of VO₂ max as a “motor theme” underscores its continued importance as the ultimate benchmark of aerobic capacity, but it is not the only target. The foundational role of lactate and ventilatory thresholds highlights the critical importance of Zone 2 and threshold training. These are not fringe concepts but the basic pillars of a scientifically-grounded training plan. Improving these thresholds increases the body’s efficiency, allowing you to sustain a higher intensity before fatigue sets in. This mechanistic focus aligns with research into how the body adapts at a cellular level, such as how the PGC-1α exercise enzyme boosts muscle metabolism in response to endurance activity.

The field’s robust growth and international collaboration are good news for practitioners. It means training recommendations are built on a vast, continually updated, and globally-vetted evidence base. The median citation year of 2018 for referenced material indicates that the science is current but also respects proven, classic studies, providing a stable foundation for application.

*Source: Soyal, M., Aksoy, Ö., & Çelik, N. (2026). Global scientific evolution and conceptual structure of cardiopulmonary performance and threshold research in sports sciences: A comparative bibliometric analysis (2010–2025). *Frontiers in Research Metrics and Analytics*. https://doi.org/10.3389/frma.2026.1905302*