Impact of acute fatigue on the functional qualities of high-level athletes trained in team (and racquet) sports: contribution of the strength-velocity profile to their assessment

The project in brief

Despite recent improvements in training load and fatigue monitoring, fatigue status can have a negative impact on intrinsic risk factors, particularly in young footballers. Inter-individual analysis of fatigue responses highlights significant disparities between athletes, underlining the importance of individualized coping strategies. The aim of this study was therefore to better individualize the effects of fatigue after a 75-minute soccer training session in elite young players. Eighteen players (15.6 ± 1.7 years) underwent a battery of tests before and after a typical soccer training session. Assessments included capillary blood samples (HCO3-, lactate, pH) and subjective evaluations of muscle soreness and fatigue. Functional tests included a sprint, a drop jump (DJ) and a horizontal force-velocity (H-FV) test. The k-means method was applied to the first two dimensions of the principal component analysis of changes in the H-FV and DJ tests. The soccer training session resulted in significant physiological changes and functional impairments, in particular an increase in inter-limb asymmetry in the DJ test. No significant effects of fatigue were observed in the H-FV test. However, confirming the value of combining the two tests, clustering analysis revealed two subgroups with opposite fatigue profiles. In addition, one subgroup showed increased inter-limb asymmetry in the DJ test, indicating an increased risk of injury with fatigue.

This study highlights the contribution and complementarity of the H-FV and DJ tests in improving the detection of individual fatigue-related functional changes in footballers. These results underline the importance of individualized fatigue monitoring in young soccer players.

Future prospects

After identifying different fatigue profiles in 18 young footballers, the analysis was extended to include top-level adult athletes from a variety of disciplines, of different sizes and genders. The study continues by examining the evolution of the force-velocity (FV) profile during exercise in team sports athletes. This diversification aims to assess the robustness and relevance of this approach in contexts more representative of athletic diversity.

The approach developed in this research offers concrete applications for the assessment and monitoring of top-level athletes. The identification of differentiated fatigue profiles through analysis of the force-velocity (FV) profile makes it possible to adapt training, recovery and management strategies to the specific characteristics of each athlete. By integrating complementary tests on neuromuscular, physiological and metabolic aspects, this methodology enables a more detailed assessment of individual responses to fatigue, facilitating the implementation of performance optimization programs, injury prevention and support by medical staff.

Exploiting these results also paves the way for the development of new tools to refine analysis in the field. The integration of sensors and real-time evaluation tools could enable more individualized monitoring of athletes, by making analyses directly accessible to coaches, physical trainers and medical staff. A longitudinal approach, coupled with predictive models, would make it possible to anticipate the evolution of fatigue profiles and adjust interventions according to the specific needs of each athlete.

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