Athletes’ subjective physical intensity counts.

Keeping track of the daily load that is imposed on players is considered central when interpreting physical performance, with elite teams typically using GPS-, LPS- or accelerometer-based data as monitoring-tools. Despite constituting slightly different metrics depending on the system and technology, these systems provide an insight into the external load (i.e. Player Load, total distance, sprint distance, accelerations, decelerations etc.)that is imposed on the players (1). While explaining external physical exertion of the players provides the practitioner with an insight into their physical capacity, this does not account for the internal response to the specific workloads.  

The internal load constitutes the individual internal response to a specific stimulus (i.e. training, match or gym session),providing greater granularity by including individual contextual factors like training status and potential sleep-deprivation, which influence the athlete’s readiness to cope with the specific stimulus. Internal load-markers are identified as, among others, heart rate-responses and accumulation of blood lactate (2). These markers represent the internal physiological responses to physical exertion, and requires supplementary monitoring tools to interpret the data (e.g. Heart rate-sensors).A less costly way of getting insight in to the internal load-responses of an athlete, is by gathering a rating of the perceived exertion (RPE) of each participating athlete following a specific stimulus. Despite being a less direct measure of internal loading, utilization of the RPE has proven both valid and reliable in interpreting the internal load of a player (3).

Rate of Perceived Exertion (RPE)

The RPE is typically measured through questionnaires, that athletes can access via their cellphones or computers. The questionnaire presents the ability to score the session on a scale from 1-10, with a score of 1constituting a very low perceived exertion and 10 reflecting a perceived maximal exertion (3). As the rating should reflect the perceived load of the total session and not the most recent activity, the questionnaire should be answered ~30 minutes following the session (4). While being a valid and reliable measure (3), the RPE also correlates with heartrate-responses during training sessions (4).

Hooper Index

As the RPE-method is a direct measure of the perceived session load, integration of wellness-questionnaires can further elaborate on the understanding of each player’s physical and mental state. By integrating wellness questionnaires alongside RPE, coaches gain insights into a broader range of parameters that influence training load. The Hooper Index emphasizes such parameters, as it analyses subjective levels of perceived fatigue, muscle soreness, stress levels and sleep quality, on a scale from 1-7, with 1 being “very, very low or good” and 7 being “very, very high or bad” (5). Integration of the Hooper Index provide a more holistic approach in understanding training loads, and presents coaches and sports scientists with the ability to adjust specific training modalities when applying appropriate loading of each player. Research has shown statistically significant correlations between Hooper Index-categories and RPE-measures for professional female soccer players (6). When analyzing its usefulness in describing the recovery time-course of match-induced fatigue, Rabbani and colleagues (2019) highlighted that the Hooper Index proved a more sensitive and stable measure when compared to Heart Rate Variability-measures (7).

How it works and recommended use

As a new integration in the Coach- and Player App, coaches can now get insights into each players’ perceived state of wellness (Hooper Index) and their subjective perceived load of every session(RPE) – all directly integrated in the app. As visualized in Picture 1, each player receives a message on their individual Player App-profile following participating in a training-session or match. Here, the player is presented the ability to numerically define how demanding the session was. As soon as the answer is entered, the registration is uploaded to the app, providing coaches with an updated overview of the player RPE’s.

Picture 2 visualizes the questionnaire that players are presented to each morning. As the answers are submitted, the Wellness-section of the app is updated with subjective wellness-measures of the specific days. Finally, players have the ability to add a comment to their registration. By applying both immediate workload and wellness-visualizations, coaches now have a monitoring tool of subjective loading and player wellness right at hand. The synergistic relationship between the RPE and Hooper Index, not only presents the immediate perceived load of each session, but also provide an insight into the readiness of each player prior to the session.

References

1.     Dudley, C, Johnston, R, Jones, B, et al. (2023). Methods of Monitoring Internal and External Loads and Their Relationships with Physical Qualities, Injury, or Illness in Adolescent Athletes: A Systematic Review and Best‐Evidence Synthesis. Sports Medicine, 53, pp. 1559-1593.

2.     Vanrenthergem, J, Nedergaard, NJ, Robinson, MA, Drust, B. (2017). Training Load Monitoring in Team Sports: A Novel Framework Separating Physiological and Biomechanical Load-Adaptation Pathways. Sports Medicine, 47(5), pp. 2135-2142.

3.     Haddad, M, Stylianides, G, Djaoui, L, et al. (2017). Session-RPE Method for Training Load Monitoring: Validity, Ecological Usefulness, and Influencing Factors. Frontiers in Neuroscience, 11, pp. 1-14.

4.     Impellizzeri, FM, Rampinini, E, Coutts, AJ, et al. (2004). Use of RPE-Based Training Load in Soccer. Medicine and Science in Sports and Exercise, 36(6), pp. 1042-1047.

5.     Hooper, SL, Mackinnon, LT, Howard, A, et al. (1995). Markers for Monitoring Over training and Recovery. Medicine and Science in Sports and Exercise, 27(1), pp.106-112.

6.     Fernandes, R, Brito, JP, Vieira, LHP, et al. (2021). In-Season Internal Load and Wellness Variations in Professional Women Soccer Players: Comparisons between Playing Positions and Status. International Journal of Environmental Research and Public Health, 18(23), pp. 1-13.

7.     Rabbani, A, Clemente, FM, Kargarfard, M, Chamari, K. (2019). Match Fatigue Time-Course Assessment Over Four Days: Usefulness of the Hooper Index and Heart Rate Variability in Professional Soccer Players. Frontiers in Physiology, 19,pp. 1-8.