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  • Writer's pictureJo Clubb

What is Invisible Monitoring in Sports Science?

Updated: May 21

In sports science, gaining deeper insights into athlete performance through data already being collected is invaluable. This concept, termed "invisible monitoring," eliminates the need for additional testing, thus reducing the data collection burden on athletes.

What is Invisible Monitoring?

Invisible monitoring refers to leveraging existing data collected during regular training to assess an athlete’s fitness and fatigue status. This approach minimises the need for additional testing, which can add physical load and/or cognitive stress. The goal is to enhance the use of existing information to reduce the burden on athletes.

While some express concerns that invisible monitoring might infringe on athletes' privacy by assessing them without their knowledge, the intent is not to monitor covertly. Instead, it’s about optimising the use of current data to lessen additional testing needs. Effective communication and education are essential to ensure athletes understand and consent to the use of their data.

Tracking Internal and External Load

Invisible monitoring often involves analysing the relationship between internal and external training loads.

External Load:

The physical work done by the athlete, often measured in distances, sprints, accelerations, changes in direction, and/or technical counts like balls bowled or pitched.

Internal Load:

The physiological cost of performing the physical work, frequently represented via heart rate and/or perceived exertion.

By comparing these two dimensions, we can identify instances where the internal load is higher than expected for the given external load, potentially indicating fatigue or decreased fitness.

Submaximal Fitness Tests

Incorporating submaximal fitness tests (SMFT) into training sessions, often as part of the warm-up, is one method of invisible monitoring. These tests provide valuable data without additional setup.

Recent studies by Tzlil Shushan and colleagues (2022; 2023) highlight over 100 protocols for sub-maximal fitness tests, which they summarised in a recommended protocol. Watch the video below from the Global Performance Insights YouTube channel to learn more about this research:

Shushan’s research suggests a continuous, rectangular track for sub-maximal fitness tests, aiming for a constant intensity of 75-85% of maximum heart rate over three to four minutes. The mean heart rate during the last minute of exercise is the primary measure, providing the invisible monitoring outcome.

Case Study: PSG and Heart Rate Monitoring

A study by Paris St Germain, published with my mentor, the late Nick Broad listed as an author and the inspiration, demonstrated the use of heart rate monitoring to track fitness and fatigue. By predicting heart rate exertion during small-sided games and comparing it to actual heart rate data, significant correlations were found. This approach can replace formal fitness tests, aligning with the invisible monitoring concept.

Locomotor Efficiency

Another avenue is monitoring changes in athletes' running patterns, which can indicate neuromuscular fatigue. Research by Steve Barrett’s team at Hull, published in 2015, showed variations in locomotor efficiency during football matches, suggesting that accelerometry data could be used for invisible monitoring. Perhaps when athletes fatigue, they change how they move. As such, the relationship between outputs (i.e. distance) and movement profiles (i.e. accelerometry measures like Player Load) may diverge. However, individual differences and external load variations must be considered.

I have since been involved in research exploring this concept, such as this study in collaboration with Amber Rowell, which found a number of Player Load metrics that appeared to reflect changes in fatigue status during standardised small sided games.

Frequently Asked Questions (FAQs) on Invisible Monitoring

What is invisible monitoring?

Invisible monitoring uses data collected during regular training to assess athletes' fitness and fatigue, minimising the need for additional tests.

What methods are used in invisible monitoring?

Common methods include tracking the relationship between internal and external loads, submaximal fitness tests, and analysing locomotor efficiency.

What are the benefits of invisible monitoring?

Invisible monitoring is about maximising the value of existing data to reduce the burden of additional testing on athletes. It reduces any physical and mental fatigue associated with extra testing, providing insights from athlete monitoring data already collected.

For more information on invisible monitoring and other sports science topics, check out our YouTube channel’s Load Monitoring playlist.

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