Dave Carolan: Internal & External training loads - The Evolution of Sport Science Over 30 Years

Episode 189: In this episode of the Sports Science Insights Podcast, powered by Inform Performance and hosted by Steve Barrett, we’re joined by Dave Carolan, a highly experienced Head of Performance, strategy advisor, and entrepreneur, currently leading the first team performance program at Derby County.

With over 30 years in elite professional sport, Dave brings a wealth of knowledge on the evolution of performance departments, athlete monitoring, and the changing landscape of sport science. From his early days pioneering innovation in football to his current strategic leadership role, Dave offers both historical context and forward-thinking insight.

Topics Discussed:

• The evolution of performance departments in elite sport

• How internal and external load monitoring has changed over three decades

• What innovation looked like in the early days of sport science

• Why players today are playing fewer games than 10–20 years ago

This is a must-listen for practitioners, coaches, and leaders seeking to understand the past, present, and future of performance strategy in elite sport.

Key-points:

• Early approaches to training load monitoring in professional football relied almost exclusively on internal load metrics, primarily using heart rate monitors such as the Polar watches. Each player wore a watch and chest strap during every session, and data collection was laborious, requiring manual distribution, collection, and individual downloading of each device. This process not only fostered a deep respect for the technology among practitioners but also necessitated meticulous attention to detail, as it was the sole method for quantifying physiological responses to training at the time .

• The internal load data collected from heart rate monitors was individualized using lactate testing to establish precise training zones for each player. These bespoke zones enabled tailored conditioning programs and allowed for more meaningful interpretation of heart rate data. Despite the sophistication of this approach, there were no external load metrics available, so practitioners relied heavily on their observational skills and direct communication with players to gauge training intensity and load .

• Subjective measures, such as the Borg scale, were integral to early load monitoring. Practitioners would conduct post-session debriefs with players, using visual scales to record perceived exertion. This qualitative feedback was systematically recorded and became foundational for research and practice, eventually evolving into the session RPE (sRPE) methodology widely used today. These subjective assessments were cross-referenced with physiological data to refine training prescriptions and monitor adaptation .

• The adoption of more invasive physiological testing, such as lactate, urea, and creatine kinase (CK) measurements, provided deeper insights into individual responses and recovery status. However, over time, logistical and financial constraints led many clubs to favor less resource-intensive mass testing protocols, such as the bleep or yo-yo tests. While these are easier to administer and less costly, they often lack the individual specificity and diagnostic power of laboratory-based assessments .

• The shift from subjective and internal load monitoring to a greater emphasis on external load metrics began in the early 2000s with the introduction of match analysis technologies like Prozone and Sport Universal. These systems provided objective data on distances covered and movement profiles during matches, which was revolutionary for practitioners seeking to quantify the physical demands of competition. However, this data was initially limited to match play, with no equivalent available for training sessions

• The evolution of training load monitoring has been characterized by a growing multidisciplinary approach. Early practitioners often wore multiple hats, managing everything from physiology and strength and conditioning to nutrition and performance analysis. This holistic perspective enabled a more integrated understanding of load and adaptation, but also highlighted the need for specialized expertise as the field expanded and technologies advanced .

• Despite technological advancements, the challenge of balancing individualized, in-depth physiological testing with the practical realities of team sport environments persists. While laboratory assessments offer valuable insights, their time and cost implications often lead clubs to opt for more scalable, albeit less precise, field-based testing. Partnerships with universities and external providers can help bridge this gap, but require strategic planning and resource allocation .

• The cultural acceptance of load monitoring technologies among players has shifted dramatically. Whereas early adoption of heart rate monitors and subjective scales met with resistance and required significant education and persuasion, contemporary athletes expect to wear a range of monitoring devices as part of routine practice. This normalization has facilitated more comprehensive and consistent data collection, enhancing the quality of load management .

• The current landscape of training load monitoring in professional sport is marked by an abundance of data and tools, but also by the ongoing need for critical interpretation and contextualization. Practitioners must navigate the complexities of integrating internal, external, and subjective load measures, ensuring that data-driven decisions are grounded in a nuanced understanding of individual and team dynamics. The future of load management will likely depend on continued innovation, interdisciplinary collaboration, and the ability to translate complex data into actionable performance strategies

Where you can find Dave:

•⁠  LinkedIn

•⁠ Website

•⁠ X

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